TY - JOUR
T1 - Assessment of H reflex sensitivity with M wave alternation consequent to fatiguing contractions
AU - Hwang, Ing Shiou
AU - Huang, Cheng Ya
AU - Wu, Pei Shan
AU - Chen, Yi Ching
AU - Wang, Chun Hou
N1 - Funding Information:
The authors are grateful to Tzer-Bin Lin, PhD, for his critical review and valuable comments on this manuscript, as well as J. F. Kuo, C. H. Zhang, and J. H. Su for their assistance in data collection. This research was partially supported by a grant from the National Science Council, R.O.C., under grant no. NSC 90-2314-B006-142.
PY - 2008/9
Y1 - 2008/9
N2 - The objective of this study was to examine the changes in H reflex sensitivity after neuromuscular fatigue associated with fluctuations of the M wave. In the maximal and submaximal voluntary contraction (MVC and SMVC) paradigms, subjects performed voluntary plantarflexion at 100% MVC and 40% MVC respectively until the limit of torque maintenance was reached. In the submaximal electrical stimulation (SMES) paradigm, the tricep surae was exhausted with sustained electrical stimulation of 40% of the maximal tolerable intensity at a 40-Hz stimulus rate. The H reflexes and maximal M waves (Mmax) of the soleus were recorded before and after the three fatigue paradigms, and the H reflex was standardized with Mmax to minimize possible bias due to fatigue-induced M wave fluctuation. The results showed a significant increase in the standardized H reflex due to the SMES paradigm in spite of Mmax potentiation. The SMVC paradigm led to a reduction in size of the standardized H reflex without modification of Mmax, whereas the standardized H reflex was not mediated by the MVC paradigm, which contributed to a noticeable Mmax potentiation. The present study underscored the fact that the H reflex sensitivity and M wave amplitude were not necessarily suppressed consequent to neuromuscular fatigue, but varied with the activation history of a muscle for size-dependent efficacy of the Ia transmission pathways and postactivation potentiation.
AB - The objective of this study was to examine the changes in H reflex sensitivity after neuromuscular fatigue associated with fluctuations of the M wave. In the maximal and submaximal voluntary contraction (MVC and SMVC) paradigms, subjects performed voluntary plantarflexion at 100% MVC and 40% MVC respectively until the limit of torque maintenance was reached. In the submaximal electrical stimulation (SMES) paradigm, the tricep surae was exhausted with sustained electrical stimulation of 40% of the maximal tolerable intensity at a 40-Hz stimulus rate. The H reflexes and maximal M waves (Mmax) of the soleus were recorded before and after the three fatigue paradigms, and the H reflex was standardized with Mmax to minimize possible bias due to fatigue-induced M wave fluctuation. The results showed a significant increase in the standardized H reflex due to the SMES paradigm in spite of Mmax potentiation. The SMVC paradigm led to a reduction in size of the standardized H reflex without modification of Mmax, whereas the standardized H reflex was not mediated by the MVC paradigm, which contributed to a noticeable Mmax potentiation. The present study underscored the fact that the H reflex sensitivity and M wave amplitude were not necessarily suppressed consequent to neuromuscular fatigue, but varied with the activation history of a muscle for size-dependent efficacy of the Ia transmission pathways and postactivation potentiation.
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U2 - 10.1080/00207450802055606
DO - 10.1080/00207450802055606
M3 - Article
C2 - 18698513
AN - SCOPUS:49549096257
VL - 118
SP - 1317
EP - 1330
JO - International Journal of Neuroscience
JF - International Journal of Neuroscience
SN - 0020-7454
IS - 9
ER -