european college of sport science

OP-BM03 Biomechanics 3
The present study showed that short-term pneumatic pressure is able to reduce the SLR during hopping. Based on additional protocols
not mentioned in this abstract it is argued that - with inflated cuff – the induced stretch is mechanically modulated. It is concluded that this
mechanical modulation of the stretch is suitable to investigate functional stretch reflexes during highly dynamic tasks.
Grey, M. J., Ladouceur, M., Andersen, J. B., Nielsen, J. B., & Sinkjaer, T. (2001). J.Physiol 534, 925-933.
Komi, P. V. & Gollhofer, A. (1997). J Applied Biomechanics 13, 451-460.
MAXIMAL AMPLITUDE OF THE M-WAVE IN SOLEUS MUSCLE DURING STANDING IN WATER
TAKAHARA, T., SEKI, K., YAMAGUCHI, H., ONODERA, S.
GRADUATE SCHOOL, KAWASAKI UNIVERSITY OF MEDICAL WELFARE
INTRODUCTION: The M-wave is compound muscle action potentials lead to stimulation of motor axons in peripheral nerves. Maximal
amplitude of the M-wave (Mmax) indicates that all α-motor fibers were recruited. Amplitude of the M-wave is also used as the stationary
of the electrical stimulus. Previously, it was considered that the M-wave did not influenced by the central nerves system. Recent study
reported that Mmax in soleus muscle (SOL) changed with the ankle joint angle. This result suggests that amplitude of the M-wave may
change with condition even though the stimulus intensity is constant. In water, human is affected by the physical characteristics of water
and different physiological responses are showed relative to land. The electromyographic (EMG) activity in SOL during standing, walking
and running in water differed from that on land. Therefore we speculated that Mmax in SOL during standing changes with somatosensory
inputs for lower legs. The purpose of this study was to investigate the effects of decreasing the body weight induced by the buoyancy
to Mmax in SOL during stationary standing. METHOD: Six healthy males participated in this study. Subjects stood on a waterproof force
platform. Subjects were tested under two randomly administered conditions; (1) standing on land and (2) standing in water. The experiments
in water were performed in a water tank. The depth of water inside the tank was adjusted on the gastrocnemius muscle belly of
each subject. The temperature of water was kept constant at 34 ℃. M responses were elicited in SOL during standing each condition
by electrical stimulation with single square pulse of 1ms duration to the tibial nerve in the popliteal fossa. Surface EMG was recorded
from SOL using bipolar electrodes. The electrodes were covered with water resistant adhesive microfilms. Mmax was defined peak to
peak amplitude of M-wave at the time of the disappearance of the H-wave associated with the increasing of stimulus intensity. RESULT
AND DISCUSSION: The average of ground reaction force (GRF) during standing in water was significantly lower (P 0.80; CV%, range 4.1-12.3%). The principal component analyses performed separately on both tests revealed factor structures that
suggest a high level of generalizability of the individual dependent variables across the tested muscle groups. Finally, despite being
about 20% lower, the peak force obtained from CMC highly correlated with the maximum voluntary force of SST.
Discussion: The present data suggest that the variables derived from CMC could be as reliable as the variables obtained from SST. Moreover,
in addition to presumably capturing muscular action typical for rapid and/or consecutive action of antagonistic muscle groups, the
peak force could also assess the maximum voluntary force exerted during a sustained contractions. Although the external validity of CMC
still remains to be explored, the present findings support development of CMC into a standard test of neuromuscular function.
References
Suzovic D, Nedeljkovic A, Jaric S. (2008). J Hum Kin, 20, 51-67.
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