UNIGE document Scientific Article
previous document  unige:24707  next document
add to browser collection
Title

Unchanged H-reflex during a sustained isometric submaximal plantar flexion performed with an EMG biofeedback

Authors
Duclay, Julien
Lepers, Romuald
Martin, Alain
Published in Journal of Electromyography and Kinesiology. 2009, vol. 19, no. 6, p. e395-402
Abstract The aim of this study was to assess H-reflex plasticity and activation pattern of the plantar flexors during a sustained contraction where voluntary EMG activity was controlled via an EMG biofeedback. Twelve healthy males (28.0+/-4.8 yr) performed a sustained isometric plantar flexion while instructed to maintain summed EMG root mean square (RMS) of gastrocnemius lateralis (GL) and gastrocnemius medialis (GM) muscles fixed at a target corresponding to 80% maximal voluntary contraction torque via an EMG biofeedback. Transcutaneous electrical stimulation of the posterior tibial nerve was evoked during the contraction to obtain the maximal H-reflex amplitude to maximal M-wave amplitude ratio (H(sup)/M(sup) ratio) from GL, GM and soleus (SOL) muscles. Neuromuscular function was also assessed before and immediately after exercise. Results showed a decrease in SOL activation during sustained flexion (from 65.5+/-6.4% to 42.3+/-3.8% maximal EMG, p<0.001), whereas summed EMG RMS of GL and GM remained constant (59.7+/-4.8% of maximal EMG on average). No significant change in the H(sup)/M(sup) ratio was found for SOL, GL and GM muscles. Furthermore, it appears that the decrease in maximal voluntary contraction torque (-20.4+/-2.9%, p<0.001) was related to both neural and contractile impairment. Overall, these findings indicate that the balance between excitation and inhibition affecting the motoneuron pool remains constant during a sustained contraction where myoelectrical activity is controlled via an EMG biofeedback or let free to vary.
Keywords AdultBiofeedback, Psychology/methodsElectromyography/methodsFoot/physiologyH-Reflex/physiologyHumansIsometric Contraction/physiologyMaleMuscle, Skeletal/innervation/physiologyPhysical Exertion/physiology
Identifiers
PMID: 19216091
Full text
Article (Published version) (610 Kb) - document accessible for UNIGE members only Limited access to UNIGE
Structures
Citation
(ISO format)
PLACE, Nicolas et al. Unchanged H-reflex during a sustained isometric submaximal plantar flexion performed with an EMG biofeedback. In: Journal of Electromyography and Kinesiology, 2009, vol. 19, n° 6, p. e395-402. https://archive-ouverte.unige.ch/unige:24707

242 hits

0 download

Update

Deposited on : 2012-12-18

Export document
Format :
Citation style :