Fatigue-induced changes in tonic vibration response (TVR) in humans: relationships between electromyographic and biochemical events.
Fatigue-induced changes in the proprioceptive reflex loop were explored in humans by using the tonic electromyographic (EMG) response to vibration (TVR) and relating it to lactic acidosis (LA) and oxidative stress. TVR was measured in flexor digitorum superficialis before and after sustained or intermittent handgrip at maximal voluntary contraction (MVC). TVR variations were compared with the changes in EMG power spectrum preceding contractile fatigue, the Hoffman reflex (H-reflex), and plasma concentrations of LA and thiobarbituric acid reactive substances (TBARS). After both sustained and intermittent handgrips, TVR amplitude first declined then increased, independently from the changes in EMG power spectrum and H-reflex. TVR depression and facilitation were respectively concomitant with increases in LA and TBARS. The TVR depression was proportional to the increased LA level. The origin of TVR changes after muscle fatigue is questioned because the relationship between TVR depression and LA accumulation might be temporal, not causal, and changes in muscle stiffness were not explored.
Brerro-Saby
Christelle
C
UMR MD2, Physiologie et physiopathologie en conditions d'oxygénation extrêmes, Institut Jean Roche, Faculté de Médecine, Université de la Méditerranée, Bd. Pierre Dramard, 13916, Marseille, France.
Delliaux
Stéphane
S
UMR MD2, Physiologie et physiopathologie en conditions d'oxygénation extrêmes, Institut Jean Roche, Faculté de Médecine, Université de la Méditerranée, Bd. Pierre Dramard, 13916, Marseille, France.
Steinberg
Jean Guillaume
JG
UMR MD2, Physiologie et physiopathologie en conditions d'oxygénation extrêmes, Institut Jean Roche, Faculté de Médecine, Université de la Méditerranée, Bd. Pierre Dramard, 13916, Marseille, France.
Jammes
Yves
Y
UMR MD2, Physiologie et physiopathologie en conditions d'oxygénation extrêmes, Institut Jean Roche, Faculté de Médecine, Université de la Méditerranée, Bd. Pierre Dramard, 13916, Marseille, France.
D000328:Adult; D004558:Electric Stimulation; D004576:Electromyography / Q000379:methods; D005260:Female; D006181:H-Reflex / Q000502:physiology; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology*; D013057:Spectrum Analysis; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism*; D014732:Vibration
D017392:Thiobarbituric Acid Reactive Substances; D019344:Lactic Acid