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David M. Koceja
INDIANA UNIVERSITY
BLOOMINGTON
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Chair, Kinesiology Department
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Associate Dean for Research,
School of Public Health-Bloomington
Education:
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Ph.D.
at Indiana University, 1989
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M.S.
at Indiana University, 1983
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B.S.
at University of Wisconsin-Milwaukee, 1981
Background:
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Director of Graduate Studies, Indiana University Department of
Kinesiology, 2001-2003
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National Institute of Aging Grant, 1996-2001
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Eli Lilly Endowment in conjunction with Indiana University and
the Pervasive Technologies Laboratory, 2004
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Grant Reviewer, National Institutes of Health
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Grant Reviewer, National Science Foundation
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Indiana University School of Health, Physical Education, and
Recreation Teaching and Research Award
Research:
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Neuromuscular control
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Spinal reflex system
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Elderly
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Motor control
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Balance
My research interests focus on the neuromuscular control of human
movement. I am currently investigating the role of the spinal reflex
system in controlling normal postural sway and recovery from
perturbations in elderly subjects.
The goal of these projects is to develop short- and long-term
intervention programs to improve the quality of life for elderly
individuals. In directing various graduate students, I have also
investigated the role of dysfunctional states on neuromuscular
function—particularly anterior cruciate ligament reconstruction and
persons with arthritis.
Most of my research is conducted in the Motor Control Research
Laboratory in the HPER building, where I work with graduate
assistants to perform balance tests on older adults. Through
strategically placed electrodes, we can test the response of neurons
and muscles in an individual's balance and postural control.
If the tests indicate that one or more of the subject's balance
systems is malfunctioning, we recommend physical activity designed
to retrain neurons so the person can regain the use of dormant
neurons and muscles.
Our mission is to motivate older adults to lead more active lives
and enjoy better balance and health. We work in partnership with a
number of groups to share the results of this research with elderly
citizens in our community and with health and wellness
practitioners.
Publications:
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Masaaki Tsuruike;
Koichi Kitano; David M Koceja; Zachary A Riley
Differential control of H-reflex amplitude in different
weight-bearing conditions in young and elderly subjects.
Clin
Neurophysiol 123, 2018 (2012)
Health Science Laboratory, Osaka University of Health and
Sport Sciences, 1-1 Asashirodai, Kumatoricho, Sennangun,
Osaka 590-0496, Japan. tsuruike@ouhs.ac.jp
This study measured the modulation of conditioned
(femoral nerve, paired-stimuli) and unconditioned
soleus H-reflexes in young and elderly subjects when
changing weight-bearing (WB) requirements and body
position. METHODS: Conditioned and unconditioned H-reflexes
were examined in 14 elderly subjects and 11 young
subjects during six different WB conditions: (1)
lying supine with no WB, (2) supine position
inclined by 30? with 50% WB, (3) standing with 50%,
(4) 75%, (5) 100% and (6) 125% WB. RESULTS: The
elderly subjects had consistently higher background
soleus EMG activity across the WB conditions
compared to the young. Femoral nerve conditioning
caused facilitation of the H-reflex that changed
across WB conditions in the young subjects, but not
in the elderly subjects. Finally, elderly subjects
had less depression with paired-stimulation (PRD)
across WB conditions, which was not observed in the
young subjects. CONCLUSIONS: The elderly may have
more direct activation of motoneurons from
descending pathways, coupled with less segmental
spinal control of inhibitory interneurons, as
evidenced by the increased background soleus
activity, H/M-max ratios and the lack of modulatory
control observed when conditioning the H-reflex.
SIGNIFICANCE: There was an age-specific response
from descending and segmental pathways during
conditions that involved either different WB
requirements or changes in body position.
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Christopher T
Robertson; Koichi Kitano; David M Koceja; Zachary A Riley
Temporal depression of the soleus H-reflex during passive
stretch.
Exp
Brain Res 219, 217 (2012)
Department of Sport and Exercise Science, Jacksonville
University, Jacksonville, FL 32211, USA.
Synaptic efficacy associated with muscle spindle
feedback is regulated via depression at the Ia-motoneurone
synapse. The inhibitory effects of repetitive Ia
afferent discharge on target motoneurones of
different sizes were investigated during a passive
stretch of ankle extensors in humans. H-reflex
recruitment curves were collected from the soleus
muscle for two conditions in ten subjects. H-reflexes
were elicited during passive stretch at latencies of
50, 100, 300, and 500 ms after a slow (20?/s)
dorsiflexion about the right ankle (from 100 to
90?). Control H-reflexes were recorded at
corresponding static (without movement) ankle angles
of 99, 98, 94, and 90? of flexion. The slope of the
H-reflex recruitment curves (Hslp) was then
calculated for both conditions. H-reflex values were
similar for the static and passive stretch
conditions prior to 50-100 ms, not showing the early
facilitation typical of increased muscle spindle
discharge rates. However, the H-reflex was
significantly depressed by 300 ms and persisted
through 500 ms. Furthermore, less than 300 ms into
the stretch, there was significantly greater H-reflex
depression with a lower stimulus intensity (20 %
Mmax) versus a higher stimulus intensity (Hmax),
though the effects begin to converge at later
latencies (>300 ms). This suggests there is a
distinct two-stage temporal process in the
depression observed in the Ia afferent pathway for
all motoneurones during a passive stretch.
Additionally, there is not a single mechanism
responsible for the depression, but rather both
heterosynaptic presynaptic inhibition and
homosynaptic post-activation depression are
independently influencing the Ia-motoneurone pathway
temporally during movement.
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Behdad Tahayor;
Zachary A Riley; Armaghan Mahmoudian; David M Koceja; Siang
Lee Hong
Rambling and trembling in response to body loading.
Motor Control 16, 144 (2012)
Dept. of Kinesiology, Indiana University, Bloomington, IN,
USA.
Various studies have suggested that postural sway is
controlled by at least two subsystems. Rambling-Trembling
analysis is a widely accepted methodology to
dissociate the signals generated by these two
hypothetical subsystems. The core assumption of this
method is based on the equilibrium point hypothesis
which suggests that the central nervous system
preserves upright standing by transiently shifting
the center of pressure (COP) from one equilibrium
point to another. The trajectory generated by this
shifting is referred to as rambling and its
difference from the original COP signal is referred
to as trembling. In this study we showed that these
two components of COP are differentially affected
when standing with external loads. Using Detrended
Fluctuation analysis, we compared the pattern of
these two signals in different configurations of
body loading. Our findings suggest that by applying
an external load, the dynamics of the trembling
component is altered independently of the area of
postural sway and also independently of the rambling
component. The dynamics of rambling changed only
during the backloading condition in which the
postural sway area also substantially increased. It
can be suggested that during loaded standing, the
trembling mechanism (which is suggested to be
activated by peripheral mechanisms and reflexes) is
altered without affecting the central influence on
the shifts of the equilibrium point.
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Behdad Tahayori;
Nicholas L Port; David M Koceja
The inflow of sensory information for the control of
standing is graded and bidirectional.
Exp
Brain Res 218, 111 (2012)
Department of Kinesiology and Program in Neuroscience,
Indiana University, Bloomington, IN 47405, USA. btahayor@indiana.edu
The control of upright standing is accomplished
through the integration of different sources of
sensory information and by providing an appropriate
motor program to control both expected and
unexpected perturbations imposed on the system.
However, the dynamic characteristics of postural
sway and its interplay with the regulation of Ia
sensory information within the spinal cord are
largely unknown. Here, using a stochastic technique
for analyzing the dynamics of upright standing, we
demonstrate that the changes in the dynamics of
postural sway were accompanied by modulation of the
soleus H-reflex during quiet standing. While the
causality of this relation was not established, the
results showed that these changes were independent
of the sway of the center of pressure and were
bidirectional and purposeful. With this novel
perspective, the appropriate reflex gain, which is
important for balance control, can be predicted from
the dynamic characteristics of postural sway. Our
current findings provide the first human behavioral
evidence to suggest the contribution of the spinal
cord in fulfilling the desired motor programming of
a complex task. This contribution is, by
conventional guess, carried out through
interneuronal adjustments, which are under the
control of different brain areas.
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Behdad Tahayori; David
M Koceja
Activity-dependent plasticity of spinal circuits in the
developing and mature spinal cord.
Neural Plast. 2012, 964843 (2012)
Department of Kinesiology and Program in Neuroscience,
Indiana University Bloomington, Bloomington, IN 47405-7109,
USA.
Part of the development and maturation of the
central nervous system (CNS) occurs through
interactions with the environment. Through physical
activities and interactions with the world, an
animal receives considerable sensory information
from various sources. These sources can be
internally (proprioceptive) or externally (such as
touch and pressure) generated senses. Ample evidence
exists to demonstrate that the sensory information
originating from large diameter afferents (Ia fibers)
have an important role in inducing essential
functional and morphological changes for the
maturation of both the brain and the spinal cord.
The Ia fibers transmit sensory information generated
by muscle activity and movement. Such use or
activity-dependent plastic changes occur throughout
life and are one reason for the ability to acquire
new skills and learn new movements. However, the
extent and particularly the mechanisms of activity-dependent
changes are markedly different between a developing
nervous system and a mature nervous system.
Understanding these mechanisms is an important step
to develop strategies for regaining motor function
after different injuries to the CNS. Plastic changes
induced by activity occur both in the brain and
spinal cord. This paper reviews the activity-dependent
changes in the spinal cord neural circuits during
both the developmental stages of the CNS and in
adulthood.
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Najmeh Hoseini; David
M Koceja; Zachary A Riley
The effect of operant-conditioning balance training on the
down-regulation of spinal H-reflexes in a spastic patient.
Neurosci. Lett. 504, 112 (2011)
Department of Kinesiology & Program in Neural Science,
Indiana University, Bloomington, IN 47405, USA.
Spasticity in chronic hemiparetic stroke patients
has primarily been treated pharmacologically.
However, there is increasing evidence that physical
rehabilitation can help manage hyper-excitability of
reflexes (hyperreflexia), which is a primary
contributor to spasticity. In the present study, one
chronic hemiparetic stroke patient operantly
conditioned the soleus H-reflex while training on a
balance board for two weeks. The results showed a
minimal decrease in the Hmax-Mmax ratio for both the
affected and unaffected limb, indicating that the H-reflex
was not significantly altered with training.
Alternatively, paired-reflex depression (PRD), a
measure of history-dependent changes in reflex
excitability, could be conditioned. This was evident
by the rightward shift and decreased slope of reflex
excitability in the affected limb. The non-affected
limb decreased as well, although the non-affected
limb was very sensitive to PRD initially, whereas
the affected limb was not. Based on these results,
it was concluded that PRD is a better index of
hyperreflexia, and this measurement could be more
informative of synapse function than simple H-reflexes.
This study presents a novel and non-pharmacological
means of managing spasticity that warrants further
investigation with the potential of being translated
to the clinic.
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Hongwei Guan; David M
Koceja
Effects of long-term tai chi practice on balance and H-reflex
characteristics.
Am.
J. Chin. Med. 39, 2510 (2011)
Department of Health Promotion and Physical Education,
Ithaca College, Ithaca, NY 14850, USA. hguan@ithaca.edu
The purpose of the present study was to examine the
effects of long-term Tai Chi practice on postural
balance and H-reflex. Sixteen healthy volunteers,
eight with three or more years of experience in Tai
Chi training (Tai Chi Group-TCG), and eight with no
experience in Tai Chi training (Control Group-CG)
participated in the study. Postural sways were
measured under four experimental conditions: (1)
Standing still with eyes open (EO); (2) Standing
still with eyes closed (EC); (3) Standing and
turning head to left and right with eyes open (EOT);
and (4) Standing and turning head to left and right
with eyes closed (ECT). Paired reflex depression (PRD)
of the soleus muscle was measured under two
conditions: supine and standing. Less significant
postural sway was observed in the TCG than in the CG
under four conditions including EO, EC, EOT, and ECT
(p < 0.01). The TCG demonstrated 14.1%, 30.6%, 33.3%
and 22.7% less postural sway, respectively.
Significant PRD change from a supine to standing
position was observed between TCG and CG (p < 0.05).
A significant correlation between PRD change (from
supine to standing) and years of Tai Chi practice
was observed (r = 0.80, p < 0.05). The findings of
this study support the positive effects of Tai Chi
exercise on balance control under different
conditions. Long-term Tai Chi exercisers also
demonstrated different reflex modulation from a
supine to standing position, and long-term Tai Chi
practice may lead to a change of PRD modulation as
neuroadaptation.
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Behdad Tahayori;
Koichi Kitano; Siang L Hong; David M Koceja
Amplification of background EMG activity affects the
interpretation of H-reflex gain.
J
Electromyogr Kinesiol 20, 1219 (2010)
Department of Kinesiology and Program in Neural Sciences, 74
Motor Control Lab, HPER, E 7th Street, Bloomington, IN
47405, USA. behdadt@gmail.com
In many H-reflex studies, the modulation of the H-reflex
is usually compared relative to the normal EMG
activity within the muscle. Such comparisons enable
the investigators to infer whether the change in the
amplitude of the H-reflex was independent of
normally occurring muscle activity. This
interpretation of the H-reflex is regarded as H-reflex
gain, a popular dependent variable in human H-reflex
studies. However, in many studies to date, the
muscle activity level has been determined from the
same EMG signal from which the H-reflex is recorded.
This leads to an important methodological
consideration: measuring the ongoing normal EMG
activity from the same signal might result in an
inaccurate measurement, since this EMG signal will
need to be minimally amplified to capture the
synchronous volley of the H-reflex amplitude. In
this study we examined this possibility and found
that comparing the EMG activity level from the
seated position to standing position yields
different results (on average 8.03% in the
measurement of the increase of muscle activity).
This difference was both dependent on the task and
also on the EMG instrumentation used. To solve this
problem we suggest the bifurcation of the EMG signal
from the recording electrodes with differential
amplification of the signal. With this method, both
the naturally occurring muscle activity and the H-reflex
signal are collected from the same area of the
muscle and a more accurate measurement of the H-reflex
gain will be yielded.
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Arlene A Schmid;
Marieke Van Puymbroeck; David M Koceja
Effect of a 12-week yoga intervention on fear of falling and
balance in older adults: a pilot study.
Arch
Phys Med Rehabil 91, 576 (2010)
Veterans Affairs Health Services Research and Development,
Center of Excellence on Implementing Evidence-Based Practice,
and the Health Services Research and Development Stroke
Quality Enhancement Research Initiative, Richard L.
Roudebush Veterans Affairs Medical Center, Indianapolis, IN
46202, USA. Arlene.schmid@va.gov
To determine whether fear of falling (FoF) and
balance improved after a 12-week yoga intervention
among older adults. DESIGN: A 12-week yoga
intervention single-armed pilot study. SETTING: A
retirement community in a medium-sized university
town in the Midwest. PARTICIPANTS: A convenience
sample of adults (N=14) over the age of 65 years who
all endorsed an FoF. INTERVENTION: Each participant
took part in a biweekly 12-week yoga intervention.
The yoga sessions included both physical postures
and breathing exercises. Postures were completed in
sitting and standing positions. MAIN OUTCOME
MEASURES: We measured FoF with the Illinois FoF
Measure and balance with the Berg Balance Scale.
Upper- and lower-body flexibility were measured with
the back scratch test and chair sit and reach test,
respectively. RESULTS: FoF decreased by 6%, static
balance increased by 4% (P=.045), and lower-body
flexibility increased by 34%. CONCLUSIONS: The
results indicate that yoga may be a promising
intervention to manage FoF and improve balance,
thereby reducing fall risk for older adults.
Rehabilitation therapists may wish to explore yoga
as a modality for balance and falls programming;
however, future research is needed to confirm the
use of yoga in such programming.
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Salih Pinar; Koichi
Kitano; David M Koceja
Role of vision and task complexity on soleus H-reflex gain.
J
Electromyogr Kinesiol 20, 354 (2010)
Marmara University, School of Physical Education and Sports,
Istanbul, Turkey. spinar@indiana.edu
There exists extensive evidence supporting the
presence of reflex modulation in humans during a
variety of motor tasks. The soleus H-reflex has been
shown to be modulated during static and dynamic
balance conditions as well as during various motor
tasks. The purpose of this study was to examine the
effects of two different stance positions and visual
conditions on soleus H-reflex gain in 15 apparently
healthy adults (mean age=30.27+/-6.92 yrs). The
soleus H-reflexes were examined in two experimental
stance conditions: two-legged (stable) and one-leg (unstable),
and two visual conditions: eyes open and eyes closed.
To assess the reflex gain, subjects performed ten
trials under each of the four conditions and a
soleus H-reflex was elicited during the performance
of each trial. For each condition the peak-to-peak
amplitude of the H-reflex and the EMG activity 50 ms
prior to the stimulus was recorded. Differences in
the peak-to-peak amplitudes of the soleus H-reflex
for the experimental conditions were compared with a
2x2 (Stance x Vision) repeated measures ANOVA. The
level of significance was p<0.05. Results
demonstrated significant differences in reflex gain
for both the vision (F(l,15)=4.87, p<0.05) and the
stance condition (F(l,15)=14.86, p<0.05). Although
both the stance condition and vision significantly
affected the H-reflex gain, there was no interaction
between these two variables (F(l,15)=0.17). From
these results, we conclude that H-reflex gain was
decreased both as stance complexity increased and as
visual inputs were removed. Consistent with previous
reports, it may be speculated that changes in
presynaptic inhibition to the soleus Ia fibers
regulate these gain changes. We propose that vision
and stability of stance affect soleus H-reflex gain,
but do so without any interactive effects.
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Rachel Ryder; Koichi
Kitano; David M Koceja
Spinal reflex adaptation in dancers changes with body
orientation and role of pre-synaptic inhibition.
J
Dance Med Sci 14, 1550 (2010)
Motor Control Laboratory, Department of Kinesiology and
Program in Neuroscience, Indiana University, Bloomington,
Indiana 47405, USA. rabritto@indiana.edu
Dancers undergo specific activity-dependent
neuromuscular adaptations following long-term
training that allow them to develop the refined
motor skills required for success in dance. The
spinal stretch reflex circuit has demonstrated
specific adaptations following prolonged dance
training. Adaptations in the spinal stretch reflex
can be studied using H-reflex methodology, first
described by Paul Hoffmann in 1910. This article
discusses H-reflex methodology and presents data
that examine the neural mechanisms that contribute
to adaptations in the spinal stretch reflex with
dance training. Two groups of subjects, modern
dancers (N = 5) and untrained controls (N = 5), were
tested. On one-half of the trials common peronal
nerve (CPN) conditioning of the soleus H-reflex was
used to assess one spinal mechanism, pre-synaptic
inhibition; the other half tested the soleus H-reflex
only (unconditioned). The dependent variables were
the H(max)/M(max) ratios, unconditioned and with CPN
conditioning, expressed as percent values. The
results revealed three main findings: 1. Modern
dancers had smaller H(max)/M(max) ratios than
control subjects; 2. The H(max)/M(max) ratio was
smaller in standing posture than in prone among both
dancers and controls; and 3. Pre-synaptic inhibition
was not different between dancers and controls in
standing. In conclusion, modern dancers have smaller
H-reflexes than untrained controls, but pre-synaptic
inhibition does not appear to explain this
difference.
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Sarah B Goldman;
Teresa L Brininger; John W Schrader; Richard Curtis; David M
Koceja
Analysis of clinical motor testing for adult patients with
diagnosed ulnar neuropathy at the elbow.
Arch
Phys Med Rehabil 90, 1846 (2009)
United States Army Research Institute of Environmental
Medicine, Military Performance Division, 15 Kansas St,
Building 42, Natick, MA 01760, MA, USA. Sarah.goldman@us.army.mil
To compare the dichotomous results for 7 ulnar nerve
clinical motor tests (Froment's sign, Wartenberg's
sign, finger flexion sign, Jeanne's sign, crossed
finger test, Egawa's sign, presence of clinical
fasciculations) with motor nerve conduction velocity
findings. DESIGN: A static group comparison design
assessed for differences among dichotomous test
outcomes with respect to motor nerve conduction
velocity. SETTING: Five medical facilities
throughout the United States provided data for this
study. PARTICIPANTS: Records from participants
(N=26) with diagnosed ulnar neuropathy at the elbow
were included for data analysis. INTERVENTIONS: Not
applicable. MAIN OUTCOME MEASURES: Demographic data
included age, sex, handedness, duration of symptoms,
and the number of days between the clinical and
electrodiagnostic exam. Other dependent variables
included motor conduction velocity of the ulnar
nerve, compound muscle action potential amplitude,
and the dichotomous clinical motor test outcomes.
RESULTS: Two motor signs, the presence of clinical
fasciculations and a positive finger flexion sign,
were identified more frequently (each present in 11
patients) than the other motor signs. An analysis of
covariance revealed significant differences in motor
nerve conduction velocity between positive and
negative results for all the clinical motor tests
except for the finger flexion sign. Significant chi-square
analyses were found for the following comparisons:
the presence of clinical fasciculations and
Froment's sign, the finger flexion sign and the
crossed finger test, Egawa's sign and Froment's sign,
Warteberg's sign and Froment's sign, the crossed
finger test and Froment's sign, and Egawa's sign and
Wartenberg's sign. CONCLUSIONS: Some clinical motor
tests are better than others at identifying early
motor involvement, providing the rehabilitation
professional some insight regarding the relative
decrement of motor nerve conduction velocity when a
selected test is positive.
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Sarah B Goldman;
Teresa L Brininger; John W Schrader; David M Koceja
A review of clinical tests and signs for the assessment of
ulnar neuropathy.
J
Hand Ther 22, (2009)
Department of Kinesiology, Indiana University, Bloomington,
Indiana, USA. sarah.goldman@us.army.mil
As part of a comprehensive assessment for suspected
ulnar neuropathy, clinical testing plays an
important role in the initial identification of a
lesion and determining subsequent changes from
baseline. The purpose of this article was to review
ulnar nerve provocative testing and the substantial
collection of diagnostic signs and tests.
Administration procedures for each maneuver are
described as well as the resulting positive and
negative outcomes. The clinical tests described
constitute only one aspect of the examination and
should not substitute for other key components, such
as taking a thorough medical and occupational
history. Empirical research studies are indicated to
further quantify the relationship between the
testing outcomes and the severity of a lesion as
well as to determine the most robust motor signs
seen in the early stages of the disease.
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Donald W Zakutansky;
Koichi Kitano; David M Koceja; Janet P Wallace
The effect of blood flow on h-reflex and motor responses in
adults with type 2 diabetes.
J
Clin Neurophysiol 26, 201 (2009)
Clinical Exercise Physiology Laboratory, Indiana University,
Bloomington, Indiana 47405, USA.
To examine the effect of blood flow on peripheral
nerve function in adults with type 2 diabetes. Ten
adults with type 2 diabetes and 10 age- and body
mass index-matched controls participated in the
study. Soleus H-reflex and motor recruitment curves
were determined for subjects at baseline, during 10
minutes of ischemia by femoral artery occlusion, and
after a 10-minute bout of leg exercise. At baseline,
the H-reflex threshold occurred at 77.44% +/- 1.12%
and 92.23% +/- 0.04% (mean +/- SE) of motor
threshold at baseline for the diabetes and control
groups, respectively. During ischemia, the H-reflex
threshold occurred at 72.44% +/- 7.19% and 88.79%
+/- 7.80% of motor threshold at baseline for the
diabetic and control groups, respectively. Following
exercise, the H-reflex threshold occurred at 64.44%
+/- 8.47% and 94.93% +/- 4.30% of motor threshold at
baseline for the diabetes and control groups,
respectively, which significantly differed from
baseline. Hmax/Mmax ratios were significantly
reduced with acute ischemia for the diabetes group
(25.6%). Postexercise, the Hmax/Mmax ratio returned
to baseline for controls while remaining
significantly lower than baseline in the diabetes
group. H-reflex and motor responses were
hypoexcitable with an accompanying hyperemia for
controls. In the diabetes group, the postexercise
period resulted in a hyperexcitable H-reflex and
motor response. Acute ischemia decreases H-reflex
thresholds in adults with diabetes and exercise-induced
increases in blood flow further decrease these
thresholds. These responses are markedly more
pronounced than those of their peers without
diabetes and are accompanied by changes in sensory
transmission to the motoneuron.
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JoEllen M Sefton;
Charlie A Hicks-Little; Tricia J Hubbard; Mark G Clemens;
Christopher M Yengo; David M Koceja; Mitchell L Cordova
Sensorimotor function as a predictor of chronic ankle
instability.
Clin
Biomech (Bristol, Avon) 24, 451 (2009)
Department of Kinesiology, Auburn University, Auburn, AL
36849-5323, USA. jmsefton@auburn.edu
Recurrent
ankle injury occurs in 70% of individuals
experiencing a lateral ankle sprain. The cause of
this high level of recurrence is currently unknown.
Researchers have begun to investigate sensorimotor
deficits as one possible cause with inconclusive and
often conflicting results. The purpose of this study
was to further the understanding of the role of
sensorimotor deficits in the chronically unstable
ankle by establishing which specific measures best
distinguish between chronically unstable and healthy
ankles. METHODS: Twenty-two participants with
chronic ankle instability and 21 healthy matched
controls volunteered. Twenty-five variables were
measured within four sensorimotor constructs: joint
kinesthesia (isokinetic dynamometer), static balance
(force plate), dynamic balance (Star Excursion
Balance Test) and motoneuron pool excitability (electromyography).
FINDINGS: The above variables were evaluated using a
discriminant function analysis [Wilks'Lambda=0.536
chi(2)(7, N=43)=22.118, P=0.002; canonical
correlation=0.681]. The variables found to be
significant were then used to assess group
discrimination. This study revealed that seven
separate variables from the static balance
(anterior/posterior and medial/lateral displacement
and velocity) and motoneuron pool excitability
constructs (single-legged recurrent inhibition and
single- and double-legged paired reflex depression)
accurately classified over 86% of participants with
unstable ankles. INTERPRETATION: These results
suggest that a multivariate approach may be
necessary to understand the role of sensorimotor
function in chronic ankle instability, and to the
development of appropriate rehabilitation and
prevention programs. Out of the four overall
constructs, only two were needed to accurately
classify the participants into two groups. This
indicates that static balance and motoneuron pool
excitability may be more clinically important in
treatment and rehabilitation of chronic ankle
instability than functional balance or joint
kinesthesia.
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Koichi Kitano; David M
Koceja
Spinal reflex in human lower leg muscles evoked by
transcutaneous spinal cord stimulation.
J.
Neurosci. Methods 180, 111 (2009)
Department of Kinesiology and Program in Neuroscience,
Indiana University, HPER 121 Bloomington, IN 47405, USA.
The H-reflex is one of the most common and useful
techniques in the field of motor control. However,
the H-reflex technique also involves difficulty in
data interpretation when stimulus intensity is high
enough to stimulate both sensory and motor fibers (antidromic
current). On the other hand, transcutaneous
stimulation applied on the spinous processes is able
to stimulate the dorsal root, resulting in selective
stimulation of only sensory fibers without evoking a
direct motor response and antidromic current on the
motor fibers. The purpose of this study was to
examine the maximal reflex response that can be
elicited in the lower leg muscles using
transcutaneous spinal stimulation. Seven subjects
participated in the study. EMG signals were recorded
from triceps surae (SOL, MG, LG) in the prone
position. Transcutaneous stimulation was applied
both to the spinous process (between T11 and T12,
spinal stimulation, SS) and to the popliteal fossa (peripheral
stimulation, PS). Using SS and PS, H(max) amplitudes
of triceps surae muscles were measured and
standardized with M(max). H(max) values in MG and LG
by SS (31% and 41%) were significantly greater than
those by PS (20% and 23%, respectively). Although
not significant, H(max) amplitude in SOL by SS (76%)
was also greater than that by PS (60%). It is
suggested that transcutaneous stimulation is able to
evoke H-reflex without a direct motor response.
H(max) amplitudes traditionally measured by
stimulation applied to a mixed nerve may
underestimate the potential connectivity between the
sensory and motor systems in humans.
-
JoEllen M Sefton;
Charlie A Hicks-Little; Tricia J Hubbard; Mark G Clemens;
Christopher M Yengo; David M Koceja; Mitchell L Cordova
Segmental spinal reflex adaptations associated with chronic
ankle instability.
Arch
Phys Med Rehabil 89, 1991 (2008)
Department of Kinesiology, Auburn University, Auburn, AL
36849-5323, USA.
To further understanding of the role that segmental spinal
reflexes play in chronic ankle instability (CAI). DESIGN: A
2 x 2 repeated-measures case-control factorial design. The
independent variables were ankle group with 2 levels (healthy,
CAI) and stance with 2 levels (single, double legged).
SETTING: University research laboratory. PARTICIPANTS:
Twenty-two participants with CAI and 21 matched healthy
controls volunteered. INTERVENTIONS: Not applicable. MAIN
OUTCOME MEASURES: The dependent variables were 2 measures of
motoneuron pool excitability: paired reflex depression (PRD)
and recurrent inhibition. RESULTS: A 2 x 2 repeated-measures
multivariate analysis of variance revealed a significant
interaction between group and stance on the linear
combination of PRD and recurrent inhibition variables (Wilks
lambda=.808, F(2,40)=4.77, P=.014). Follow-up univariate F
tests revealed an interaction between group and stance on
the PRD (F(1,41)=9.74, P=.003). Follow-up dependent t tests
revealed a significant difference between single- and double-legged
PRD in the healthy participants (t(20)=-3.76, P=.001) with
no difference in CAI participants (t(21)=-0.44, P=.67).
Finally, there was a significant difference in recurrent
inhibition between healthy (mean, 83.66) and CAI (mean,
90.27) (P=.004). CONCLUSIONS: This study revealed that,
compared with healthy participants, CAI participants were
less able to modulate PRD when going from a double- to a
single-legged stance. Additionally, CAI participants showed
higher overall levels of recurrent inhibition when compared
with healthy matched controls.
-
M Tsuruike; D M Koceja;
C T Robertson; K Yabe
Implications for using H-max/M-max ratio in H-reflex
parameters for elderly subjects compared with young subjects.
Electromyogr Clin Neurophysiol 46, 285 (2006)
Health Science Laboratory, Department of Health and Sport
Management, Osaka University of Health and Sport Sciences,
Osaka 590-0496, Japan. tsuruike@ouhs.ac.jp
The H-max/M-max ratio has long been used to
understand motoneuron excitability induced by the Ia
fibers. However, we contend that when comparing
young and elderly subjects, this measurement can be
controversial. We compared the modulation of the
soleus H-max and M-max at five different muscle
lengths between elderly and young subjects. The
young subjects demonstrated a significant modulation
of both H-max and M-max between dorsiflexion (DF)
and plantarflexion (PF) positions. In contrast, the
elderly subjects demonstrated no difference in H-max
and M-max between DF and PF positions. However, it
was more interesting to note that those elderly
subjects who had similar H-max/M-max ratios to the
young subjects at 0 deg showed identical modulation
of H-max and M-max to that of the young In this
paper, we discuss that H-reflex comparisons between
young and elderly subjects may be confounded by the
initial H-max/M-max ratio. This finding has
implications for both the statistical analysis of
this data as well as the theoretical interpretation
of H-reflex measurements.
-
Kristin I Stanford;
Timothy D Mickleborough; Shahla Ray; Martin R Lindley; David
M Koceja; Joel M Stager
Influence of menstrual cycle phase on pulmonary function in
asthmatic athletes.
Eur.
J. Appl. Physiol. 96, 703 (2006)
Biomedical Sciences, University of California-San Diego, La
Jolla, CA 92093, USA.
Swiss Replica Watches
The main aim of this study was to investigate
whether there is a relationship between menstrual
cycle phase and exercise-induced bronchoconstriction
(EIB) in female athletes with mild atopic asthma.
Seven eumenorrheic subjects with regular 28-day
menstrual cycles were exercised to volitional
exhaustion on day 5 [mid-follicular (FOL)] and day
21 [mid-luteal (LUT)] of their menstrual cycle.
Pulmonary function tests were conducted pre- and
post-exercise. The maximal percentage decline in
post-exercise forced expiratory volume in 1 s
(FEV(1)) and forced expiratory flow from 25 to 75%
of forced vital capacity (FEF(25-75%)) was
significantly greater (P<0.05) on day 21 (mid-LUT
phase) (-17.35+/-2.32 and -26.28+/-6.04%,
respectively), when salivary progesterone
concentration was highest, compared to day 5 (mid-FOL
phase) (-12.81+/-3.35 and -17.23+/-8.20%,
respectively), when salivary progesterone
concentration was lowest. The deterioration in the
severity of EIB during the mid-LUT phase was
accompanied by worsening asthma symptoms and
increased bronchodilator use. There was a negative
correlation between the percent change in pre- to
post-exercise FEV(1) and salivary progesterone
concentration. However, no such correlation was
found between salivary estradiol and the percentage
change in pre- to post-exercise FEV(1). This study
has shown for the first time that menstrual cycle
phase is an important determinant of the severity of
EIB in female athletes with mild atopic asthma.
Female asthmatic athletes may need to adjust their
training and competition schedules to their
menstrual cycle and to consider the potential
negative effects of the LUT phase of the menstrual
cycle on exercise performance.
-
Donald W Zakutansky;
Koichi Kitano; Janet P Wallace; David M Koceja
H-reflex and motor responses to acute ischemia in apparently
healthy individuals.
J
Clin Neurophysiol 22, 210 (2005)
Clinical Exercise Physiology Laboratory, Indiana University,
Bloomington, Indiana 47405, USA.
The authors examined the effect of acute ischemia on
peripheral nerve function in healthy subjects. It
was hypothesized that acute ischemia would interfere
with the ability of sensory and motor nerves to
propagate an impulse. Twelve young, apparently
healthy adults participated in the study. Soleus H-reflex
and motor recruitment curves were determined for
subjects during a control condition, after 5 minutes
of ischemia by femoral artery occlusion, and after a
5-minute recovery. During ischemia, the stimulus
intensity required to evoke an H-reflex or M-wave
was reduced by 18.3% and 18.4%, respectively. Hmax/Mmax
ratios were significantly reduced with acute
ischemia (mean +/- standard error) 66.29% +/- 5.4%
and 58.81% +/- 6.7% for control and ischemia,
respectively, owing to a decrease in Hmax during
acute ischemia with no change in Mmax. After
ischemia, the Hmax/Mmax returned to control values,
as did the M-threshold. However, although the H-threshold
slightly recovered, it failed to return to control
threshold after 5 minutes of recovery. The results
suggest that acute ischemia decreases motor and H-reflex
thresholds in healthy individuals with a longer
lasting effect for the H-reflex. In addition, a
decrease in Hmax/Mmax ratio was observed, suggesting
that acute ischemia has differential effects on
sensory nerve propagation and synapse transmission.
-
John F Yannessa; David
M Koceja
A comparison of falls efficacy among older United States
adults living independently and in group dwellings: health
education implications.
Int
Q Community Health Educ 24, 65 (2005)
Coastal Carolina University, Conway, SC 29528, USA. yannessa@coastal.edu
The objective was to examine the relationship
between a community based balance measure and
perceptions of balance among individuals from
different elderly living environments. The research
was a cross-sectional between groups comparison
design. Data collection was conducted in a community
setting, in both older adult group housing
facilities and in older adult community centers.
Data analysis was conducted on a sample of 74 older
adults that included independent and group dwellers.
Instruments used to collect information from the
older adults were the Berg Balance Scale and the
Tinetti Falls Efficacy Scale. Results indicate that
significant differences (p < .05) in Falls Efficacy
by location were found (t(72) = 2.04, p = .044).
Many group dwelling older adults believe their
ability to perform activities of daily living (ADLs)
is compromised simply as a result of their living
situation. This research indicates that this fear
may be unfounded. In the future, we suggest that
health educators working with older adults focus
their efforts on education designed to increase
senior falls efficacy.
-
D A Patikas; C
Kotzamanidis; C T Robertson; D M Koceja
The effect of the ankle joint angle in the level of soleus
Ia afferent presynaptic inhibition.
Electromyogr Clin Neurophysiol 44, 503 (2004)
Department of Physical Education and Sport Science,
Aristotle University of Thessaloniki, Greece.
The factors that are responsible for the
relationship between motoneuron excitability and
muscle length may have both mechanical and/or
neurophysiologic origins. The aim of the study was
to investigate the changes in the level of
presynaptic inhibition, as measured with a soleus H-reflex
conditioning protocol, and muscle length. Ten
healthy volunteers were measured at three different
ankle angles: 30 degrees plantar flexion, neutral
position (0 degrees) and 15 degrees dorsiflexion. At
each position the soleus H-reflex and the maximum M-wave
were measured while the limb was relaxed. The H-reflex
was conditioned by a stimulation of the common
peroneal nerve, 100 ms prior to the tibial nerve
stimulation. The results revealed that the level of
presynaptic inhibition was higher at the neutral
position in comparison to the dorsiflexed or
plantarflexed positions. Additionally, the HMAX/MMAX
ratio was significantly decreased when the joint
position was set at dorsiflexion. Further, there was
a significant correlation, independent of ankle
joint angle, between presynaptic inhibition levels
and the HMAX/MMAX ratio. The above findings support
the concept that peripheral feedback from passive,
static modifications in the joint angle and
consequently in muscle length, can modify the input/output
threshold of the motoneurons on a presynaptic level.
-
David M Koceja; Edwin
Davison; Christopher T Robertson
Neuromuscular characteristics of endurance- and power-trained
athletes.
Res
Q Exerc Sport 75, 23 (2004)
Department of Kinesiology and Program in Neural Science at
Indiana University, Bloomington 47405, USA. koceja@indiana.edu
In response to chronic physical training, the human
neuromuscular system undergoes significant and
specific adaptations. More importantly, these
influences are the result of the type and quantity
of physical activity. One of the simplest
neuromuscular mechanisms is the spinal stretch
reflex. The reflex system was previously viewed as
inflexible, with a relatively fixed response that
could vary only slightly. However, more recent data
have identified an adaptive plasticity in the reflex
system. In this respect, the reflex system can be
used to assess training and aging adaptations of the
human neuromuscular system. Due to their
methodological simplicity, both the tendon-tap
reflex and the electrically evoked Hoffmann reflex
(H-reflex) can be used to assess training
adaptations of the human neuromuscular system. The
purpose of this paper is to review briefly the
tendon-tap and H-reflex paradigms and delineate the
research findings pertaining to changes in the
reflex system with physical training. For purposes
of clarity, this discussion will be divided into the
following: (a) differences observed in the tendon-tap
reflex, (b) differences observed in the H-reflex,
and (c) role of interneurons in mediating these
changes.
-
B S Hale; J S Raglin;
D M Koceja
Effect of mental imagery of a motor task on the Hoffmann
reflex.
Behav. Brain Res. 142, 81 (2003)
Department of Kinesiology, Indiana University, HPER 112,
Bloomington, IN 47404, USA. brehale@indiana.edu
Research has found that mental imagery of a motor
task may influence the Hoffmann reflex (H-reflex).
However, this work has not examined the potential
influence of background EMG (BEMG) on the H-reflex.
In this study 23 adult participants (M=23.3 years,
S.D.=3.2) were instructed to mentally image plantar
flexion of the right foot at four intensities: 40,
60, 80 and 100% of maximum voluntary contraction (MVC)
after completing practice trials of actual
contractions at these intensities. Dependent
measures were the BEMG activity and the peak-to-peak
amplitude of the H-reflex. On each trial the peak-to-peak
amplitude of the soleus H-reflex was measured in the
right leg and averaged, BEMG (40 ms bin) was
measured in the soleus and tibialis anterior of both
legs. Following trials of plantar flexion at the
target intensities participants completed 5 imagery
trials at each intensity and 15 trials while
performing this motor task. Five resting control
trials were administered prior to and following the
completion of all test trials. Administration of
test trials was randomized within conditions. A main
effect (P<0.05) for trial blocks was observed for H-reflex
amplitude but not BEMG. The H-reflex increased
linearly throughout testing, suggesting that the H-reflex
was modified by the practice of imagery rather than
the intensity of the imagined task.
-
Masaaki Tsuruike;
David M Koceja; Kyonosuke Yabe; Norihiro Shima
Age comparison of H-reflex modulation with the Jendr?ssik
maneuver and postural complexity.
Clin
Neurophysiol 114, 945 (2003)
Health Science Laboratory, Department of Health and Sport
Management, Osaka University of Health and Sport Sciences,
Japan. tsuruike@ouhs.ac.jp
Research has found that mental imagery of a motor
task may influence the Hoffmann reflex (H-reflex).
However, this work has not examined the potential
influence of background EMG (BEMG) on the H-reflex.
In this study 23 adult participants (M=23.3 years,
S.D.=3.2) were instructed to mentally image plantar
flexion of the right foot at four intensities: 40,
60, 80 and 100% of maximum voluntary contraction (MVC)
after completing practice trials of actual
contractions at these intensities. Dependent
measures were the BEMG activity and the peak-to-peak
amplitude of the H-reflex. On each trial the peak-to-peak
amplitude of the soleus H-reflex was measured in the
right leg and averaged, BEMG (40 ms bin) was
measured in the soleus and tibialis anterior of both
legs. Following trials of plantar flexion at the
target intensities participants completed 5 imagery
trials at each intensity and 15 trials while
performing this motor task. Five resting control
trials were administered prior to and following the
completion of all test trials. Administration of
test trials was randomized within conditions. A main
effect (P<0.05) for trial blocks was observed for H-reflex
amplitude but not BEMG. The H-reflex increased
linearly throughout testing, suggesting that the H-reflex
was modified by the practice of imagery rather than
the intensity of the imagined task.
-
C T Robertson; D M
Koceja
Post-activation depression of the soleus H-reflex in the
elderly.
Electromyogr Clin Neurophysiol 43, 103 (2003)
Motor Control Laboratory, Department of Kinesiology, Program
in Neural Science, HPER 112, Indiana University,
Bloomington, IN 47405, USA.
This study examined the effect of age on the spinal
mechanism post-activation depression (PD) and its
relationship with postural sway. METHODS: Two
groups, young (n = 10, 25.2 +/- 5.2 yr) and elderly
(n = 10, 74.6 +/- 6.3 yr) participated in this
study. Soleus H-reflex amplitude (peak-to-peak EMG)
was measured prior to and after a passive
dorsiflexion about the ankle (from 120 degrees
plantarflexion to 110 degrees plantarflexion at 15
degrees/s). All H-reflex measurements were recorded
at an ankle joint angle of 110 degrees. For each
group, stimulus intensity was set at 25% of maximal
motor response (M-max) and PD measurement intervals
were randomly assigned at 0, 1, 2, 3, 4, 5, 10, 15,
and 18 seconds post-movement. To ascertain whether
PD was related to postural sway, standing sway area
(mm2) was also measured. Subjects stood motionless
(20 second duration) on a Kistler force platform
during two conditions: with and without vision.
RESULTS: A split-plot ANOVA (Group x Interval)
indicated significant differences (F(1.18) = 14.80,
p < 0.05) in PD between young and elderly, as well
as a Group x Interval interaction (F(10, 180) =
16.02, p < 0.05). Simple main effects identified
significant (p < 0.05) intervals at 0, 1, 2, and 3
seconds. The elderly had on average 16.1% less
H-reflex depression during the first three seconds
after muscle activation. Additionally, a split-plot
ANOVA (Group x Condition) indicated significant
differences (F(1, 18) = 10.72, p < 0.05) in sway
area between young and elderly, but regression
analysis indicated post-activation depression and
postural sway were not significantly correlated.
CONCLUSIONS: It is concluded that the integrity of
the Ia-motoneuron synapse as measured with a PD
protocol, is different between young and elderly
subjects, but that this difference is not related to
postural sway.
-
Donald R Earles; Jason
T Dierking; Christopher T Robertson; David M Koceja
Pre- and post-synaptic control of motoneuron excitability in
athletes.
Med
Sci Sports Exerc 34, 1766 (2002)
Motor Control Laboratory, Department of Kinesiology, Indiana
University, Bloomington, 47405, USA.
The purpose of this study was to examine the
efficacy of two spinal mechanisms in gating
motoneuron excitability in power-trained athletes (N
= 9), endurance-trained athletes (N = 9), and
untrained subjects (N = 9). METHODS: The dependent
variable for each protocol was the peak-to-peak
amplitude of the conditioned soleus Hoffmann reflex
(H-reflex). Modulations of the test reflex amplitude
were evaluated for each subject by using two
experimental conditioning protocols: recurrent
inhibition (RI) and paired-reflex depression (PRD).
Also, to assess the effects of different levels of
input on motoneuron excitability, two H-reflex
stimulus intensities were used (10% and 30% of
maximal motor response (M-max)). For each protocol,
seven conditioned H-reflex trials were obtained from
each subject during quiet stance. The RI protocol
consisted of two reflex responses that were
separated by 10 ms. The first was of the same
intensity as the unconditioned trials. The second
stimulus was of an intensity great enough to elicit
a supramaximal motor response. The PRD protocol
utilized two reflex stimuli of the same intensity
separated by 80 ms. A group by intensity (3 x 2)
analysis of variance was performed to determine
group differences within each condition. RESULTS:
For both protocols, increases in stimulus intensity
resulted in significantly greater inhibition.
Significant differences were observed between the
trained groups for both the RI and the PRD protocols.
For the RI protocol, the endurance-trained athletes
demonstrated significantly less RI than either the
power-trained athletes or the untrained subjects.
For the PRD protocol, the endurance-trained athletes
demonstrated significantly greater PRD than either
the power-trained athletes or the untrained subjects.
CONCLUSIONS: These observations indicate
differential control of motoneuron excitability as a
result of segmental reflex pathways among
differently trained athletes.
-
Richard G Mynark;
David M Koceja
Down training of the elderly soleus H reflex with the use of
a spinally induced balance perturbation.
J.
Appl. Physiol. 93, 127 (2002)
Motor Control Laboratory, Department of Exercise and Sport
Science, University of North Carolina, Chapel Hill 27599,
USA. mynark@email.unc.edu
The purpose of this study was to determine the
ability of the elderly central nervous system to
modulate spinal reflex output to functionally
decrease a spinally induced balance perturbation. In
this case, the soleus H reflex was used as the
source of perturbation. Therefore, decreasing (down
training) of the soleus H reflex was necessary to
counteract this perturbation and to better maintain
postural control. In addition to assessing the
effect of this perturbation on the H reflex, static
postural stability was measured to evaluate possible
functional effects. Ten healthy young subjects (age:
27.0 +/- 4.6 yr) and 10 healthy elderly subjects (age:
71.4 +/- 5.1 yr) participated in this study.
Subjects underwent balance perturbation on 2
consecutive days. On day 1 of perturbation,
significant down training of the soleus H reflex was
demonstrated in both young (-20.4%) and elderly
(-18.7%) subjects. On day 2 of perturbation,
significant down training of the soleus H reflex was
again demonstrated in both young (-24.6%) and
elderly (-21.0%) subjects. Analysis of static
stability after the 2 days of balance perturbation
revealed a significant 10.1% decrease in the area of
sway in elderly subjects. In conclusion, this study
demonstrated that healthy, elderly subjects compared
with young subjects were equally capable of down
training the soleus H reflex in response to a
balance perturbation. Furthermore, the improvement
in static stability through balance training may
provide further evidence that balance can be
retrained and rehabilitated in subjects with
decreased reflex function.
-
D Patikas; C
Michailidis; H Bassa; C Kotzamanidis; S Tokmakidis; S
Alexiou; D M Koceja
Electromyographic changes of agonist and antagonist calf
muscles during maximum isometric induced fatigue.
Int
J Sports Med 23, 285 (2002)
Department of Physical Education and Sport Science,
Aristotle University of Thessaloniki, Thessaloniki, Greece.
dpatikas@phed.auth.gr
The purpose of this study was to examine
electromyographic changes of the agonist and
antagonist muscles during fatigue. Nine healthy,
untrained subjects exerted a maximum voluntary heel
lifting contraction with their dominant limb. The
EMG activity over the soleus and the tibialis
anterior muscles was recorded during the contraction.
The results showed that the torque output during
heel lifting and the soleus EMG activity decreased,
whereas the tibialis anterior EMG revealed a small
but non-significant decrease. However, the ratio of
the tibialis anterior to the soleus EMG increased
significantly at the end of the fatigue protocol, a
fact that reveals that the decrease rate of the
antagonist's activity was significantly lower than
the decrease rate of the agonist activity. It is
concluded that during a maximal fatigue protocol,
both the agonist and antagonist muscle activity may
decline, however, the slower rate of antagonist's
activity decrease relative to the agonist's activity
is a finding that requires further investigation.
This finding may reflect a higher level of agonist
and antagonist muscle co-activation and probably a
relatively higher opposing torque from the
antagonist muscles at the end of the fatigue session.
-
D R Earles; H H
Morris; Chao-Ying J Peng; D M Koceja
Assessment of motoneuron excitability using recurrent
inhibition and paired reflex depression protocols: a test of
reliability.
Electromyogr Clin Neurophysiol 42, 159 (2002)
Motor Control Laboratory, Department of Kinesiology, Program
in Neural Science, Indiana University, Bloomington, IN
47405, USA. dearles@indiana.edu
Motor output may be regulated by both pre- and post-synaptic
mechanisms. The purpose of this study was to
investigate the reliability of two measurement
protocols, which purport to examine spinal
mechanisms responsible for gating motoneuron
excitability. Nine subjects (aged 29 +/- 5 years)
were tested using two soleus H-reflex protocols; 1)
recurrent inhibition (RI) and 2) paired reflex
depression (PRD). The dependent variable for each
protocol was the peak-to-peak amplitude of the
conditioned Hoffmann reflex (H-reflex). Seven trials
were obtained for each subject under each condition
as well as control values to assess test-retest
reliability. After all trials were collected the
subjects rested for at least five minutes after
which the process was repeated. Each subject
returned to the lab after a period of no less than
24 hours at which time the process was repeated.
Protocol #1: Control reflexes (20% of maximal motor
response) were obtained during quiet stance. After
obtaining control trials two reflex responses were
elicited which were separated by 10 ms on each trial
to assess recurrent inhibition (Pierrot-Deseilligny
et al., 1976; Bussel and Pierrot-Deseilligny, 1977).
Protocol #2: Again a double-pulse technique was used
to assess reflex activation history on motoneuron
pool output (Trimble et al., 2000). This protocol
utilized two reflex stimuli of the same intensity
separated by 80 ms. The peak-to-peak amplitude of
the control, RI conditioned and PRD conditioned H-reflexes
exhibited intraclass reliability estimates of .97,
.97 and .93 respectively. To achieve a reliability
of rI > or = .80, it is recommended that a minimum
of 2 trials be used for the RI protocol and that 4
trials be used for the PRD protocol. The results
indicate that both techniques provide a means to
objectively and reliably measure spinal mechanisms
for gating motoneuron pool output.
-
D Earles; V Vardaxis;
D Koceja
Regulation of motor output between young and elderly
subjects.
Clin
Neurophysiol 112, 1273 (2001)
Motor Control Laboratory, Department of Kinesiology and
Program in Neural Science, HPER 112, Indiana University,
Bloomington, IN 47405, USA.
Considerable information exists concerning the
differences in motoneuron pool (MP) excitability
between young and elderly subjects. A recent study
demonstrated decreased heteronymous Ia facilitation
with aging, suggesting increased presynaptic
inhibition (PI) with increasing age as a mechanism
for this change (Morita et al., Exp Brain Res 104
(1995) 167). It has been suggested that during
voluntary movement, supraspinal, and possibly,
segmental mechanisms (Hultborn et al., J Physiol 389
(1987) 757) modulate this inhibition. It is
theorized that PI can modulate the recruitment gain
of the MP during movement without altering the
excitability of the motoneurons. Therefore, the
purpose of this study was to examine the roles of PI
and volitional volleys in modulating MP output in
young and elderly subjects. METHODS: Twenty
apparently healthy females participated in this
study, 10 college aged (mean age, 22.4+/-2.8 years)
and 10 independent, community dwelling elderly (mean
age, 77.6+/-5.4 years). All subjects were tested in
a semi-recumbent position. H-reflexes were elicited
at rest, and at 10 and 20% of maximal voluntary
contraction. To assess MP output, background
electromyography (EMG) was monitored prior to
stimulation. The stimulus intensity was adjusted
during volitional contractions to ensure similar
control reflexes (25% of the maximal motor response
(M-max)) at each level of contraction. RESULTS:
Control reflexes at each level of volitional
contraction (rest, 10 and 20%) were similar for both
groups. To assess PI and to estimate the extent to
which a change in the H-reflex amplitude reflects a
change in MP gating, the common peroneal nerve was
stimulated at 1.5 times the motor threshold 100 ms
prior to stimulation of the tibial nerve.
Significantly greater PI was observed for the young
subjects at rest (5 vs. 13% M-max). At both 10 and
20% levels of voluntary contraction, the conditioned
reflex was significantly different from rest for the
young subjects. The elderly subjects, in contrast,
failed to modulate the conditioned reflex until the
20% of maximal voluntary contraction (MVC) condition.
When examining the recruitment gain in the MP during
the PI condition (H-reflex amplitude as a function
of EMG levels), a significant group effect was
observed, with the young subjects demonstrating
significantly higher PI gain. CONCLUSIONS: These
results indicate differential control of MP output (e.g.
PI vs. volitional volleys) in young and elderly
subjects.
-
D R Earles; D M Koceja;
C W Shively
Environmental changes in soleus H-reflex excitability in
young and elderly subjects.
Int.
J. Neurosci. 105, 1 (2000)
Department of Kinesiology and Program in Neural Science,
Indiana University, Bloomington 47405, USA.
The purpose of this study was to examine the role of
task complexity on soleus H-reflex modulation in
young and elderly subjects. Twelve young (mean age =
29.2yrs) and 10 elderly (mean age = 75.1 yrs)
apparently healthy individuals were examined under
four experimental conditions: (1) eyes open on
normal floor surface; (2) eyes open on foam floor
surface; (3) eyes closed on normal floor surface;
and (4) eyes closed on foam surface. Under each
condition, soleus H-reflexes, and background
electromyography (EMG) (40 ms window prior to
stimulation in both the soleus and the tibialis
anterior) were recorded. Postural sway in each
condition was also assessed using a Kistler force
platform. Results indicated differential reflex
modulation between young and elderly subjects.
Specifically, young subjects depressed the amplitude
of the reflex as task complexity was increased.
Elderly subjects, on the other hand, increased the
amplitude of the H-reflex when utilizing visual cues,
but decreased H-reflex amplitude when vision was
occluded. Postural sway in both groups increased as
task complexity was increased. There existed a
significant difference in the relationship between
tibialis anterior activation and soleus H-reflex
between the two groups. These results demonstrate
differential reflex adjustments between young and
elderly subjects as task complexity is increased,
and may provide useful information pertaining to
postural control in the elderly.
-
D M Koceja; R G Mynark
Comparison of heteronymous monosynaptic Ia facilitation in
young and elderly subjects in supine and standing positions.
Int.
J. Neurosci. 103, 1 (2000)
Motor Control Laboratory, Department of Kinesiology and
Program in Neural Science, HPER 112, Indiana University,
Bloomington, IN 47405, USA. koceja@indiana.edu
The control of posture and balance is a primary
concern among the elderly. Postural instability has
been identified as a contributor to the greater
incidence of falling among this segment of the
population. One important neuromuscular mechanism
identified as important in the control of posture
and balance is the segmental reflex system. The
purpose of this study was to examine the role of
presynaptic inhibition in modulating the reflex
system in young and elderly subjects. METHODS: To
estimate the influence of body position on
presynaptic inhibition to the soleus motor pool
between young and elderly subjects, 11 young (mean
age=23.9 yrs.) and 9 elderly (mean age=72.1 yrs.)
subjects were examined in two different body
positions: supine and standing. This study utilized
the heteronymous facilitation protocol, as described
by Hultborn et al. (1987), to estimate presynaptic
inhibition of the Ia afferent pathway onto the
soleus alpha-motoneuron pool. Maximal soleus H-reflex
(H-max) and motor response (M-max) amplitudes were
determined prior to testing at each condition, and
the H-max/M-max ratio at each body position was
determined. To estimate presynaptic inhibition at
each body position, subjects received 24 test soleus
H-reflex stimuli ( approximately 15% M-max), and 24
soleus H-reflexes conditioned by stimulation of the
ipsilateral femoral nerve. RESULTS: Results
demonstrated a significant decrease in H-max/M-max
ratio from supine (66.1%) to standing (56.8%) for
the young subjects, whereas the elderly subjects
demonstrated no changes in the H-max/M-max ratio
between body positions (39.8% supine; 39.8% standing).
The conditioning stimulus produced a significant
change in the test reflex for the young subjects
during supine testing (51.1% increase) but not
standing (3.4% increase). The elderly subjects
demonstrated no significant changes in the test
reflex produced by the heteronymous conditioning at
either condition (17.6% increase supine; 4.9%
increase standing). CONCLUSIONS: These results
demonstrate differential effects of both H-reflex
modulation and heteronymous conditioning for elderly
subjects when compared with young adults. These
differences may be an adaptive phenomenon of the
aging neuromuscular system, exemplified by a
decreased ability to modulate the reflex system in
the elderly group.
-
D M Koceja; D Allway;
D R Earles
Age differences in postural sway during volitional head
movement.
Arch
Phys Med Rehabil 80, 1537 (1999)
Department of Kinesiology and Program in Neural Science,
Indiana University, Bloomington 47405, USA.
To examine the role of a volitional self-paced head-turn
movement on the postural sway characteristics of
healthy young and elderly subjects. DESIGN: Cross-sectional
design. SETTING: Motor control research laboratory.
SUBJECTS: Ten young adults and 10 elderly subjects.
MAIN OUTCOME MEASURES: Postural sway characteristics
of each subject were examined using a Kistler force
platform. Each subject was tested under four
experimental conditions: (1) static postural sway
with vision; (2) static postural sway without vision;
(3) postural sway with vision and self-paced head-turn
movement; and (4) postural sway with no vision and a
self-paced head-turn movement. Subjects performed
six 15-second trials in each experimental condition.
Dependent variables analyzed on each trial were mean
sway amplitude (in millimeters), sagittal sway
standard deviation, lateral sway standard deviation,
and frequency of sway (in hertz). RESULTS: During
the static conditions (e.g., no voluntary movement),
the young subjects produced significantly less
postural sway than the elderly in both the vision
condition (sway amplitude in the young, 3.80 mm; in
the elderly, 4.89 mm) and the no-vision condition (young,
5.44 mm; elderly, 5.95 mm). This increased sway was
the result of greater lateral sway in the elderly
for the vision condition (3.73 vs. 2.68 mm), and
greater sagittal sway for the elderly in the no-vision
condition (5.55 vs. 4.70 mm). There were no
significant differences between the groups in the
frequency of sway. When asked to initiate and
complete the head-turn, elderly subjects
significantly increased their mean sway amplitude
and decreased their frequency of sway, whereas the
young subjects did not significantly alter their
postural sway profiles. CONCLUSIONS: These results
demonstrate different postural sway control
strategies for young and elderly subjects when asked
to perform volitional movements.
-
M Tsuruike; D M Koceja
Conditioned patellar tendon-tap reflexes in patients with
ACL reconstruction.
Int
J Sports Med 20, 263 (1999)
Department of Kinesiology, Indiana University, Bloomington,
USA. tsuruike@ouhs.ac.jp
The patellar tendon-tap stretch reflexes were
examined in six neurologically healthy young
subjects (mean age = 27.1 yrs) who had developed
persistent quadriceps strength deficit due to ACL
reconstruction. Each subject was tested on two
separate days. A specially designed apparatus was
used to examine the unilateral and conditioned
patellar tendon-tap reflex response utilizing three
different conditioning intervals: 25 ms, 75 ms, 150
ms, and a unilateral reflex (control). Peak
isometric force and contraction time were measured
by using a strain gauge. Also, peak-to-peak EMG was
measured by using bipolar surface electrodes which
were placed over the middle of the rectus femoris.
All data were collected with a microcomputer (sample
rate = 1 kHz). Due to the small sample, the Kruskal-Wallis
nonparametric analysis of variance was performed.
All subjects demonstrated quadriceps strength
deficits in the ACL leg when compared with the
contralateral leg. This analysis determined that for
both the ACL leg and the Non ACL leg the size of
stretch reflex was facilitated at the long-latency
conditioning intervals (75 and 150 ms), whereas it
was inhibited at the short-latency conditioning
interval (25ms). However, the ANOVA model failed to
reveal any differences in the conditioned stretch
reflex between the ACL leg and the Non ACL leg. Also,
no differences were observed at the unilateral
condition. Taken together, these results indicate
that ACL reconstruction results in significant
strength deficits, but does not alter unilateral or
conditioned reflex profiles.
-
R M Angulo-Kinzler; R
G Mynark; D M Koceja
Soleus H-reflex gain in elderly and young adults: modulation
due to body position.
J.
Gerontol. A Biol. Sci. Med. Sci. 53, (1998)
Department of Kinesiology, Indiana University, Bloomington,
USA.
The control of posture and balance in the elderly is
a primary health concern. Postural instability
directly leads to a greater incidence of falling in
the elderly population. One important neuromuscular
mechanism instrumental in the control of posture and
balance is the reflex system. The purpose of this
study was to examine the gain of the soleus H-reflex
in young and elderly adults in two different body
positions: standing and prone. METHODS: Eighteen
neurologically healthy volunteers were categorized
by age in two groups: young (n = 9, mean age = 23.3
yr) and elderly (n = 9, mean age = 71.7 yr). In each
position, the resting H-max/M-max ratio was
determined. The gain of the reflex was also assessed
by instructing the subject to perform voluntary
contractions of 10, 20 and 30% of their maximum
voluntary contraction, using real-time EMG
biofeedback. Data were sampled on-line using custom
designed software (sample rate = 2 kHz). Dependent
variables included the average background EMG of the
soleus muscle (40 ms window prior to stimulation)
and the peak-to-peak amplitude of the elicited
soleus H-reflex. To examine the gain of the reflex,
the peak-to-peak amplitude of the H-reflex was
plotted against the background EMG activity for each
contraction intensity. RESULTS: Results indicated
the following: young subjects significantly
depressed the H-max/M-max ratio when standing (69.3%
prone, 55.1% standing), whereas elderly subjects
increased the ratio (36.1% prone, 54.5% standing).
Also, the young subjects modulated the gain of the
reflex from prone to standing (3.30 prone, 3.68
standing), and the elderly subjects demonstrated no
gain modulation in the different body positions
(2.23 prone, 1.91 standing). In both body positions
the young subjects demonstrated significantly higher
gain that the elderly subjects. CONCLUSIONS: The
results demonstrate different control strategies for
young and elderly subjects between prone and
standing body positions.
-
R G Mynark; D M Koceja;
C A Lewis
Heteronymous monosynaptic Ia facilitation from supine to
standing and its relationship to the soleus H-reflex.
Int.
J. Neurosci. 92, 171 (1997)
Department of Kinesiology, Indiana University, Bloomington
47405, USA. rmynark@indiana.edu
To measure changes in presynaptic inhibition, 10
subjects (5 male, 5 female) were tested under two
conditions: supine and standing. This study utilized
the heteronymous facilitation protocol, as described
by Hulborn et al. (1987a), to measure presynaptic
inhibition of the Ia afferent pathway onto the
soleus alpha-motoneuron pool. The magnitude of the
facilitation produced by the conditioning stimulus
provides an indirect assessment of presynaptic
inhibition from supine to standing. Maximal soleus
H-reflex (H-max) and motor response (M-max)
amplitudes were determined prior to testing at each
condition. Subjects received 24 test H-reflex
stimuli (approximately 15% M-max), and 24
conditioned stimuli at each body position. Results
demonstrated a significant decrease in H-max/M-max
ratio from supine (68.7%) to standing (54.8%). This
was the result of changes in H-max between the two
body positions with no significant changes in M-max.
Significant inhibition of the conditioned H-reflex
was also demonstrated from supine to standing (30.7%
M-max vs 17.5% M-max). Furthermore, it was
demonstrated that a strong correlation (r = .85)
existed between individual changes in H-max/M-max
ratio and the changes in facilitation of the
conditioned H-reflex from supine to standing. This
relationship helps explain the modulation of the H-reflex
during static changes in body position, and it could
also provide insight into the reflex modulation
associated with more functional activities such as
walking or running. These results are consistent
with the hypothesis that presynaptic inhibition
increases as body position is changed from supine to
standing.
-
W F Brechue; D M
Koceja; J M Stager
Acetazolamide reduces peripheral afferent transmission in
humans.
Muscle Nerve 20, 1541 (1997)
Department of Kinesiology, Indiana University, Bloomington
47405, USA.
Carbonic anhydrase has been localized in skeletal
muscle and nerve, thus, inhibition with
acetazolamide (ACZ) may alter nerve and/or muscle
function in healthy humans. ACZ (3 oral doses 14, 8,
and 2 h prior to testing) reduced isometric force
(37%) and peak to peak electromyographic (EMG)
amplitude (1.38 mV to 0.83 mV), while increasing EMG
latency associated with a unilateral Achilles tendon-tap.
Reflex recovery profiles, following a contralateral
conditioning tap, were similar in both placebo and
ACZ experiments. ACZ led to significant changes in
Hmax/Mmax ratio (52.19/14.42 to 45.73/15.65) and H-reflex
latency (34.18 +/- 2.54 ms to 35.24 +/- 2.74 ms).
Motor nerve conduction velocity and maximal
voluntary isometric torque (knee extensors) were
unaltered by ACZ. These data suggest that inhibition
of the tendon-tap reflex and associated isometric
force, following ACZ, is related to impairment of
synaptic integrity between la fibers of the muscle
spindle and the alpha motor neuron and not
impairment of the muscle spindle or force-generating
capacity.
-
R G Mynark; D M Koceja
Comparison of soleus H-reflex gain from prone to standing in
dancers and controls.
Electroencephalogr Clin Neurophysiol 105, 135 (1997)
Department of Kinesiology, Indiana University, Bloomington
47405, USA. rmynark@indiana.edu
To examine the differences in soleus H-reflex gain
between trained dancers and control subjects, the
soleus H-reflex amplitude and background muscle
activity of 9 trained dancers (means of 20.3 +/- 2.1
years of age, and 14.3 +/- 3.8 years of training)
and 9 control subjects (mean 23.3 +/- 3.2 years of
age) were compared at rest and at 10, 20, and 30% of
a maximal voluntary soleus contraction during two
conditions: prone and standing. The ratio of the
maximal H-reflex (H-max) to the maximal motor
response (M-max) was also measured during both
conditions. Correlation was performed between
background EMG and the resultant H-reflex to
determine reflex gain. The results demonstrated that
the control subjects and the dancers displayed a
similar reflex gain during the prone condition (slope
= 3.30 vs. 3.64, respectively). However, during the
standing condition, dancers demonstrated a
significantly lower reflex gain (slope = 1.78) than
did control subjects (slop = 3.68). Furthermore,
although both groups significantly decreased the H-max/M-max
ratio from prone to standing, no differences were
found between groups at either condition. This
suggests that the differences in standing reflex
gain between the dancers and control subjects were a
product of differential control of reflex modulation
involved in postural control. An initial hypothesis
explaining the differences between the standing
reflex gain of the groups relates to plasticity of
central inhibitory control mechanisms, primarily
presynaptic and/or reciprocal inhibition.
-
M A Hoffman; D M
Koceja
Dynamic balance testing with electrically evoked
perturbation: a test of reliability.
Arch
Phys Med Rehabil 78, 290 (1997)
Department of Kinesiology, Indiana University, Bloomington
47405, USA.
To investigate the reliability of a newly developed
perturbation protocol for assessing dynamic balance.
DESIGN: Each subject was tested in two experimental
balance conditions, static and dynamic. The
dependent variables for the static condition were
sway area (SA), sway path length (SPL), sagittal
sway standard deviation (SSD), and lateral sway
standard deviation (LaSD). During the dynamic
condition trials a stimulus was delivered to the
tibial nerves of both legs to perturb the subjects.
The subjects were instructed to return to the pre-perturbation
level of steadiness as soon as possible after the
stimulation. The dependent variables for the dynamic
condition were dynamic phase duration (DPD), sway
path mean (SPM), linear sway standard deviation (LiSD),
and sagittal sway standard deviation (SSD). SETTING:
The motor control laboratory of a university
department of kinesiology. PATIENTS: Ten subjects
from a population-based sample of healthy adults.
MAIN OUTCOME MEASURE: An intraclass reliability
estimate for all dependent measures in the static
and dynamic conditions. RESULTS: In the static
condition, the variables SA, SPL, SSD, and LaSD had
reliabilities of .94, .98, .86, and .92,
respectively, and in the dynamic condition the
reliability estimates for DPD. SPM, LiSD, and SSD
were .90, .71, .80, and .92, respectively.
CONCLUSIONS: The results indicate the current
technique provides a means of objectively measuring
a subject's ability to regain static postural
stability following electrically induced
perturbation.
-
J R Burke; M C
Schutten; D M Koceja; G Kamen
Age-dependent effects of muscle vibration and the Jendrassik
maneuver on the patellar tendon reflex response.
Arch
Phys Med Rehabil 77, 600 (1996)
Motor Control Laboratory, Indiana University, IN, USA.
To explore possible effects of aging on the
excitability of spinal reflexes. DESIGN: Using a
cross-sectional design, the influences of muscle
vibration and the Jendrassik maneuver on patellar
tendon reflex function were compared between 30
young adults and 15 older adults. SETTING: Motor
control research laboratory. SUBJECTS: The young
adults were volunteers of college age. The older
adults (74.5 +/- 4.14 yr) were volunteers from the
local community. All subjects were free of
medications and neurological conditions that would
affect normal neuromuscular responses. MAIN OUTCOME
MEASURES: A force-time curve analysis of the
patellar tendon reflex response was used to assess
the inhibition and facilitation of spinal reflexes.
In the experimental protocol to assess spinal reflex
inhibition, 100 Hz vibration was applied to the
right quadriceps muscle. In another experimental
protocol, spinal reflex facilitation was assessed
using the Jendrassik maneuver. To perform the
Jendrassik maneuver, subjects were instructed to
grasp their hands together and to pull as hard as
possible while breathing normally. After a 2-second
count, the tendon tap was delivered to the right leg
and the subject was instructed to relax. In both
experimental protocols, control patellar tendon
reflexes were collected. RESULTS: Analysis of
variance for reflex peak force revealed a
significant 30% reduction in the amount of vibration-induced
reflex inhibition with increasing age, and a similar
33% reduction in the amount of Jendrassik maneuver
facilitation observed for the older adults as
compared with the younger adults. CONCLUSION: These
results support the hypothesis that inhibitory and
excitatory influences acting on the alpha motoneuron
pool are different in young and older adults.
-
J S Raglin; D M Koceja;
J M Stager; C A Harms
Mood, neuromuscular function, and performance during
training in female swimmers.
Med
Sci Sports Exerc 28, 372 (1996)
Department of Kinesiology, Indiana University-Bloomington
47401, USA.
The effect of seasonal changes in training load on
mood, neuromuscular function, and measures of
physical power were examined in 12 collegiate women
swimmers. These subjects were studied at three
training stages during a competitive swim season:
baseline (5,000 m.d-1), peak training (8,300 m.d-1),
and taper (2,300 m.d-1). Mood was evaluated with the
Profile of Mood States. Neuromuscular function was
measured via the soleus Hoffmann-reflex (H-reflex).
Anaerobic swimming power was assessed with a 30-s
tethered swim test, and maximal aerobic power was
determined following a maximal 378-m swim. Repeated
measures ANOVA revealed that at peak training H-reflex
and peak anaerobic swimming power were reduced (P <
0.05) below baseline values by 8.6% and 9.4%,
respectively, and total mood disturbance was
elevated above baseline (P < 0.01). These variables
returned to baseline values at the taper assessment.
H-reflex values were correlated with peak (r = 0.52,
P < 0.01) and mean (r = 0.39, P < 0.05) anaerobic
swimming power. Total mood disturbance was
correlated (r = -0.34, P < 0.05) with mean swimming
power. The results suggest that neurological
mechanisms play a role in the adaptations that
result from periodized training.
-
D M Koceja; C A Markus;
M H Trimble
Postural modulation of the soleus H reflex in young and old
subjects.
Electroencephalogr Clin Neurophysiol 97, 387 (1995)
Department of Kinesiology, Indiana University, Bloomington
47405, USA.
The influence of different static postures on the
soleus H reflex was assessed in 15 old (mean age =
76.3 years) and 10 young (mean age = 24.2 years)
subjects. H reflex and M wave recruitment curves
were obtained under 2 randomly administered
conditions: (1) standing; and (2) prone. Once in
place, the recording and stimulating electrodes were
not removed until the completion of testing, to
ensure that exact placement was maintained. A 1 msec
current pulse was given transcutaneously to elicit
the H reflex and M response. Static postural sway
area (cm2) was assessed on a Kistler force platform
using custom software (sample rate = 50 Hz/15 sec
trials). Results demonstrated that the young
subjects reduced the amplitude of the H reflex from
the prone (Hmax/Mmax = 73.6%) to the standing (Hmax/Mmax
= 59.9%) condition, whereas the old subjects did not
(prone = 32.4%, standing = 38.2%). However, within
the old group, 2 subgroups emerged--those who
depressed the reflex similar to the young subjects
(O-D, n = 6) and those who did not depress the
reflex (O-ND, n = 9). Furthermore, there were
significant differences in postural sway scores
between the young and old, between the O-D and O-ND,
but not between the O-D and young groups. These
results suggest differences in the manner in which
young and old subjects modulate the soleus H reflex
when standing, and support the view that modulation
of the stretch reflex may be important in the
control of static posture.
-
M A Hoffman; D M
Koceja
The effects of vision and task complexity on Hoffmann reflex
gain.
Brain Res. 700, 303 (1995)
Department of Kinesiology, Indiana University, Bloomington
47405, USA.
Previous research demonstrates modulation of the
Hoffmann reflex amplitude and gain during changes in
environmental conditions. H-reflex gain (defined in
this study as the ratio of H-reflex amplitude to
average soleus background EMG) is considered a
functional measure of reflex modulation. In this
study the effects of manipulating visual input and
surface stability were to investigated in 17
subjects under four experimental conditions: (1)
vision-stable surface, (2) no vision-stable surface,
(3) vision-unstable surface, and (4) no vision-unstable
surface. In each condition, subjects performed
fifteen trials of a single leg stance for 7 s. The
H-reflex was electrically elicited at the end of
each trial by delivering a 1 ms square wave
stimulation to the tibial nerve in the popliteal
online for each trial (sampling rate = 2 kHz). An
analysis of variance revealed significant decreases
in H-reflex gain for the visual (F1.16 = 4.71, P <
0.05) and, surface conditions (F1.16 = 7.67, P <
0.05), however there was no interaction (F1.16 =
0.48, P < 0.05), between these variables. These
results suggest that supraspinal mechanisms,
possibly presynaptic inhibition, modulate H-reflex
gain across environmental conditions. We conclude
that visual and possibly cutaneous inputs were
responsible for driving presynaptic inhibition and
thus decreasing H-reflex gain.
-
J M Lazar; D M Koceja;
H H Morris
Effects of auditory radio interference on a fine, continuous,
open motor skill.
Percept Mot Skills 80, 739 (1995)
Department of Kinesiology, Indiana University, USA.
The effects of human speech on a fine, continuous,
and open motor skill were examined. A tape of
auditory human radio traffic was injected into a
tank gunnery simulator during each training session
for 4 wk. of training for 3 hr. a week. The
dependent variables were identification time, fire
time, kill time, systems errors, and acquisition
errors. These were measured by the Unit Conduct Of
Fire Trainer (UCOFT). The interference was
interjected into the UCOFT Tank Table VIII gunnery
test. A Solomon four-group design was used. A 2 x 2
analysis of variance was used to assess whether
interference gunnery training resulted in
improvements in interference posttest scores. During
the first three weeks of training, the interference
group committed 106% more systems errors and 75%
more acquisition errors than the standard group. The
interference training condition was associated with
a significant improvement from pre- to posttest of
44% in over-all UCOFT scores; however, when examined
on the posttest the standard training did not
improve performance significantly over the same
period. It was concluded that auditory radio
interference degrades performance of this fine,
continuous, open motor skill, and interference
training appears to abate the effects of this
degradation.
-
D M Koceja
Quadriceps mediated changes in soleus motoneuron
excitability.
Electromyogr Clin Neurophysiol 35, 25 (1995)
Department of Kinesiology, Indiana University, Bloomington
47405, USA.
The effects of human speech on a fine, continuous,
and open motor skill were examined. A tape of
auditory human radio traffic was injected into a
tank gunnery simulator during each training session
for 4 wk. of training for 3 hr. a week. The
dependent variables were identification time, fire
time, kill time, systems errors, and acquisition
errors. These were measured by the Unit Conduct Of
Fire Trainer (UCOFT). The interference was
interjected into the UCOFT Tank Table VIII gunnery
test. A Solomon four-group design was used. A 2 x 2
analysis of variance was used to assess whether
interference gunnery training resulted in
improvements in interference posttest scores. During
the first three weeks of training, the interference
group committed 106% more systems errors and 75%
more acquisition errors than the standard group. The
interference training condition was associated with
a significant improvement from pre- to posttest of
44% in over-all UCOFT scores; however, when examined
on the posttest the standard training did not
improve performance significantly over the same
period. It was concluded that auditory radio
interference degrades performance of this fine,
continuous, open motor skill, and interference
training appears to abate the effects of this
degradation.
-
M H Trimble; D M
Koceja
Modulation of the triceps surae H-reflex with training.
Int.
J. Neurosci. 76, 293 (1994)
Indiana University School of Medicine, Department of
Physical Therapy, Indianapolis 46202-5119.
Thirteen neurologically healthy adults were asked to
balance on a specially designed balance board. This
board allowed rotation in the sagittal plane only.
Muscle activity of the triceps surae and tibialis
anterior was sampled at 2 kHz and recorded. When the
subject was balanced, soleus H-reflexes were
elicited in the right leg with a constant-current
stimulus pulse. The peak to peak amplitude of the
soleus H-reflex served as the perturbation to the
subject's balance as well as the dependent variable
in question. Subjects performed three blocks (7 H-reflexes/block)
of standing control trials with the balance board
supported, and seven blocks of balancing trials.
Prior to each block, maximal M-waves were recorded
to ensure electrode stability across blocks. Results
indicated that the subjects were able to
significantly reduce (p < .001) the gain the soleus
H-reflex while balancing and after the balance
training. As a group, the subjects decreased their
peak to peak amplitude of the soleus H-reflex by
26.2 percent from the initial standing block to the
last balancing block. Moreover, subjects were also
able to significantly reduce the gain of their
standing control H-reflexes, supporting the notion
of longer-term adaptability of the spinal stretch
reflex. It is concluded that the progressive
reduction in the H-reflex gain with short-term
training may represent functional adaptation in the
central nervous system.
-
D M Koceja; M H
Trimble; D R Earles Best Replica Watches
Inhibition of the soleus H-reflex in standing man.
Brain Res. 629, 155 (1993)
Department of Kinesiology, Indiana University, Bloomington
47405.
Thirteen neurologically healthy adults were asked to
balance on a specially designed balance board. This
board allowed rotation in the sagittal plane only.
Muscle activity of the triceps surae and tibialis
anterior was sampled at 2 kHz and recorded. When the
subject was balanced, soleus H-reflexes were
elicited in the right leg with a constant-current
stimulus pulse. The peak to peak amplitude of the
soleus H-reflex served as the perturbation to the
subject's balance as well as the dependent variable
in question. Subjects performed three blocks (7 H-reflexes/block)
of standing control trials with the balance board
supported, and seven blocks of balancing trials.
Prior to each block, maximal M-waves were recorded
to ensure electrode stability across blocks. Results
indicated that the subjects were able to
significantly reduce (p < .001) the gain the soleus
H-reflex while balancing and after the balance
training. As a group, the subjects decreased their
peak to peak amplitude of the soleus H-reflex by
26.2 percent from the initial standing block to the
last balancing block. Moreover, subjects were also
able to significantly reduce the gain of their
standing control H-reflexes, supporting the notion
of longer-term adaptability of the spinal stretch
reflex. It is concluded that the progressive
reduction in the H-reflex gain with short-term
training may represent functional adaptation in the
central nervous system.
-
J R Burke; D M Koceja;
G Kamen
The relationship between body height extremes and the
conditioned patellar tendon reflex response.
Int.
J. Neurosci. 72, 45 (1993)
Department of Kinesiology, Indiana University, Bloomington
47405.
The purpose of this study was to determine the
effects of extreme body heights on the conditioned
patellar tendon reflex response in an attempt to
differentiate between the contributions of
supraspinal and spinal mechanisms on long-latency
reflex facilitation. Unilateral and conditioned
right patellar tendon reflexes were assessed in 10
extremely short males and females and 10 extremely
tall males and females. The conditioning stimulus
was a contralateral patellar tendon tap and the
conditioning intervals were 10, 15, 25, 50, 60, 75,
100, 150, and 300 ms. There was a long-latency
facilitation of quadriceps excitability beginning at
the 75 ms conditioning interval regardless of the
height of the subject. It is hypothesized that the
similar conditioned patellar tendon recovery
profiles in the extremely short subjects and the
extremely tall subjects reflects the activation of a
spinal polysynaptic pathway as the predominant
mechanism for our long-latency reflex facilitation.
-
D M Koceja
Influence of quadriceps conditioning on soleus motoneuron
excitability in young and old adults.
Med
Sci Sports Exerc 25, 245 (1993)
Department of Kinesiology, Indiana University, Bloomington
47405.
In an effort to investigate neuromuscular changes
with age, the isometric force-time curve of the
Achilles tendon-tap reflex (ATR) was measured in 10
college age (M = 20.9 yr) and 10 healthy active old
subjects (M = 74.3 yr). In an effort to investigate
spinal interneuronal pathways, the tendon-jerk was
also conditioned with a tap to the ipsilateral or
contralateral patellar tendon. The conditioning
stimulus preceded the ATR by 25, 40, 55, 70, 85,
100, 115, 130, or 145 ms. Three trials were elicited
at each conditioning interval plus three unilateral
trials, for 30 trials per experimental session.
Results indicated that the force production of the
unilateral Achilles tendon-tap reflex was
significantly reduced and the half-relaxation times
were significantly lengthened in the old subjects.
Moreover, ipsilateral conditioning produced short-latency
facilitation and long-latency inhibition to the
triceps surae in young subjects, whereas the same
conditioning produced only a delayed long-latency
inhibition in the old subjects. Similarly, the
contralateral conditioning produced short-latency
facilitation in the young subjects, with no changes
observed in the old subjects. It is concluded that
unilateral Achilles tendon-tap responses are
different for the two groups, and that the reflex
recovery profiles for the two groups are different.
Several neurophysiological mechanisms are proposed
to contribute to these differences.
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D M Koceja; G Kamen
Contralateral influences on triceps surae motoneuron
excitability.
Electroencephalogr Clin Neurophysiol 85, 177 (1992)
Department of Kinesiology, Indiana University, Bloomington
47405.
In an effort to more fully investigate spinal reflex
pathways in humans, we measured the isometric force-time
curve of the tibial nerve H-reflex in 12 college age
subjects. We also conditioned the reflex with a
contralateral H-reflex stimulus or a contralateral
tendon-tap, to ascertain the effects of crossed
spinal segmental inputs on alpha motoneuron
excitability. The conditioning stimulus preceded the
test reflex by 10, 25, 40, 55, 70, 85, 100, 115, 130
or 145 msec. The results demonstrate that a
conditioning tibial nerve H-reflex produced marked
facilitation onto the contralateral triceps surae
motoneurons, predominantly at longer-latency
intervals. Conversely, a conditioning Achilles
tendon-tap produced long-latency inhibition to the
triceps surae. These results demonstrate that
differential motoneuron excitability changes can be
produced by electrical and mechanical conditioning
stimuli. Moreover, these excitability changes may be
long lasting and only appear after a relatively long
latency. Several neurophysiological mechanisms are
proposed to contribute to these changes.
-
D M Koceja; G Kamen
Segmental reflex organization in endurance-trained athletes
and untrained subjects.
Med
Sci Sports Exerc 24, 235 (1992)
Department of Kinesiology, Indiana University, Bloomington
47405.
In an effort to investigate the effects of training
on spinal reflex pathways in humans, we measured the
isometric force-time curve of the patellar (PTR) and
Achilles (ATR) tendon-tap reflex in 12 endurance-trained
(ET) athletes and 12 control (C) subjects. We also
conditioned the tendon jerk with a contralateral or
ipsilateral tendon-tap stimulus, to ascertain the
effects of segmental inputs on crossed-spinal reflex
activity. The conditioning stimulus preceded the
test reflex by 25, 40, 55, 70, 85, 100, 115, 130, or
145 ms. The results demonstrated significant
differences in control reflexes and conditioned
reflexes between the two groups. A contralateral
patellar tendon-tap produced a significantly greater
excitatory effect to the contralateral quadriceps
motoneurons for the ET group, whereas a contra- or
ipsilateral conditioning caused a significantly
greater inhibitory effect to the triceps surae
motoneurons for the ET athletes. These results
demonstrate that motoneuron excitability changes can
be produced as a result of ipsi- and contralateral
segmental inputs, and raise the possibility that
trained athletes demonstrate different reflex
recovery profiles. Several neurophysiological
mechanisms are proposed to contribute to these
changes.
-
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D M Koceja; J R Burke;
G Kamen
Organization of segmental reflexes in trained dancers.
Int
J Sports Med 12, 285 (1991)
Department of Kinesiology, Indiana University, Bloomington
47405.
Unilateral and conditioned Achilles tendontap reflex
(ATR) characteristics were examined in a group of
skilled dancers and a group of sedentary, untrained
subjects (n = 7/group). For the conditioned reflex,
the right ATR was conditioned by a tap to the left
Achilles tendon using intervals of 10, 40, 70, 100,
130, 160 and 190 ms. Peak isometric force,
contraction time and half-relaxation time were
examined on each trial. The results indicated that
the trained dancers exhibited less unilateral
isometric force and longer half-relaxation times (p
less than 0.05) than the untrained subjects.
Moreover, the contralateral conditioning stimulus
caused a more marked short-latency facilitation as
well as a long-latency inhibition in the reflex
force characteristics for the trained dancers when
compared with the untrained subjects. These
differences in both simple and conditioned reflexes
in individuals trained for dance activities may
reflect differences in muscle stiffness, tissue
compliance or neural organization.
-
D M Koceja; G Kamen
Interactions in human quadriceps-triceps surae motoneuron
pathways.
Exp
Brain Res 86, 433 (1991)
Department of Kinesiology, Indiana University, Bloomington
47405.
In an effort to more fully investigate spinal reflex
pathways in humans, we measured the isometric force-time
curve of the patellar (PTR) and Achilles (ATR)
tendon-tap reflex in 12 college age subjects. We
also conditioned the tendon jerk with a
contralateral or ipsilateral tendon-tap stimulus, to
ascertain the effects of segmental inputs on crossed-spinal
reflex activity. The conditioning stimulus preceded
the test reflex by 25, 40, 55, 70, 85, 100, 115, 130
or 145 ms. The results demonstrate that a tap to the
contralateral patellar tendon produced long-latency
excitation of quadriceps motoneurons, but a tap to
the contralateral Achilles tendon produced short-latency
facilitation and long-latency inhibition of the
triceps surae motoneurons. Also, a conditioning tap
to the contra- or ipsilateral patellar tendon
produced a brief short-latency facilitation that was
followed by a distinct, long-latency inhibition of
triceps surae motoneurons. These results demonstrate
that motoneuron excitability changes can be produced
as a result of ispi- and contralateral segmental
inputs. Moreover, these excitability changes may be
long-lasting and only appear after a relatively
long-latency. Several neurophysiological mechanisms
are proposed to contribute to these changes.
-
D M Koceja; G Kamen; J
R Burke
Quadriceps excitability is enhanced by a conditioning tap to
the Achilles tendon.
Electromyogr Clin Neurophysiol 30, 415 (1990)
Motor Control Laboratory, Indiana University, Bloomington.
In an effort to more fully investigate spinal reflex
pathways in humans, we measured the isometric force-time
characteristics of the patellar tendon-tap reflex in
ten college-age subjects. We also conditioned the
tendon jerk with a tap to the contralateral Achilles
tendon or the ipsilateral Achilles tendon. The
results clearly demonstrated that a conditioning tap
to the Achilles tendon produced a marked (greater
than 200 percent) excitatory effect onto the
quadriceps muscle. Also, this effect occurred sooner
when the quadriceps was conditioned by an
ipsilateral stimulus rather than a contralateral
stimulus. It is concluded that in accord with other
conditioning studies to date, the quadriceps muscle
is characterized by a predominantly excitatory
effect caused by a conditioning stimulus, and that
this arousal is independent of the origin of the
conditioning stimulus.
-
J R Burke; G Kamen; D
M Koceja
Long-latency enhancement of quadriceps excitability from
stimulation of skin afferents in young and old adults.
J
Gerontol 44, (1989)
Motor Control Laboratory, Indiana University.
This study examined the role of cutaneous input on
spinal excitability in young and old adults.
Patellar tendon reflexes were elicited in 15 old
adults (M = 75 yrs) and 25 young adults (M = 26 yrs)
at intervals ranging from 15 to 175 ms following
cutaneous stimulation to one of four skin sites: (a)
ipsilateral calf, (b) contralateral calf (old adults
only), (c) ipsilateral anterior thigh, and (d)
contralateral anterior thigh. The younger adults had
a more vigorous reflex response than the older
adults, as indicated by peak force. Force latencies
were also faster for the younger adults than the
older adults. However, both age groups showed a
long-latency facilitation of quadriceps excitability
regardless of cutaneous stimulation site. Thus, it
seems that low threshold cutaneous afferents
contribute an excitatory input to the extensor
motoneuron pool that is maintained with age.
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G Kamen; D M Koceja
Contralateral influences on patellar tendon reflexes in
young and old adults.
Neurobiol. Aging 10, 311 (1989)
Department of Physical Therapy, Boston University, MA 02215.
In an effort to more fully investigate age-related
changes in spinal reflex parameters, we measured
force-time characteristics of the patellar tendon
reflex in aged subjects and contrasted these with
data obtained from college-age individuals. We also
conditioned the tendon jerk with a tap to the
contralateral tendon. The results showed a marked
tendon reflex enhancement in the old group,
consisting of greater overall reflex force produced
by the quadriceps. In both groups, the contralateral
conditioning stimulus produced a short-latency
inhibition (at 25 msec) followed by a longer-latency
facilitation (beginning at 75 msec). Both the early
inhibition and the later reflex enhancement were
greater in the aged subjects. We suggest that some
age-related change may occur at the spinal level to
compensate for decrements in more complex motor
functioning.
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D M Koceja; G Kamen
Conditioned patellar tendon reflexes in sprint- and
endurance-trained athletes.
Med
Sci Sports Exerc 20, 172 (1988)
Indiana University Motor Control Laboratory, Bloomington
47405.
Tendon reflex characteristics were examined in
endurance-trained, sprint-trained, and control
subjects (10 SS/group) using a conditioned patellar
tendon reflex (PTR) paradigm. Paired PTRs were
administered using inter-tap intervals of 0, 25, 50,
75, 150, and 300 ms, with the left leg reflex
elicited first, followed by a right leg PTR. A force
transducer secured at the ankle was used to measure
peak force, time to peak force, and reflex latency.
In the unilateral condition, significant differences
(P less than 0.05) existed between athletic groups,
with the sprint-trained athletes exhibiting greater
peak force, faster time to peak force, and faster
reflex latency than the endurance athletes.
Significant differences Replica Watches
(P less than 0.05) also
existed for the conditioned reflex. There was a
slight depression in reflex parameters in the
untrained and sprint-trained groups up to an
interval of 50 ms. At later intervals (greater than
50 ms), a marked enhancement occurred in all groups
for all dependent measures studied. This longer
latency excitatory effect persisted until the 150 ms
interval. These differences in both simple and
conditioned reflexes in individuals trained for
endurance and sprint activities may reflect inherent
differences in muscle-tendon stiffness or neural
organization.
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