Knee extensor fatigability after bedrest for 8 weeks with and without countermeasure.
We analyzed the effects of gravitational unloading on muscular fatigability and the effectiveness of resistive vibration exercise to counteract these changes. Changes in knee extensor fatigability as a consequence of 8 weeks of horizontal bedrest with or without daily resistive vibration exercise were evaluated in 17 healthy male volunteers. Bedrest increased fatigability (% decrease in maximal voluntary isometric torque per minute exercise) from -7.2 +/- 0.5 to -10.2 +/- 1.0%/min (P < 0.05), which was accompanied by a decline (of 52.0 +/- 3.7%, P < 0.05) in muscle blood flow. Daily resistive vibration exercise training during bedrest prevented increases in fatigability (from -10.8 +/- 1.8 to -8.4 +/- 1.6%/min, P < 0.05), and mitigated the reduction in blood flow (decline of 26.1 +/- 5.1%, P < 0.05). Daily resistive exercise may thus be suggested as an effective countermeasure during spaceflight and illness-related prolonged bedrest to combat the detrimental changes in muscle endurance that result from gravitational unloading.
Radboud University Nijmegen Medical Center, Department of Clinical Neurophysiology, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. e.mulder@neuro.umcn.nl
Edwin R
ER
Mulder
Wolfgang M
WM
Kuebler
Karin H L
KH
Gerrits
Joern
J
Rittweger
Dieter
D
Felsenberg
Dick F
DF
Stegeman
Arnold
A
de Haan
D000328:Adult; D001510:Bed Rest / Q000009:adverse effects*; D001783:Blood Flow Velocity; D004576:Electromyography; D005081:Exercise Therapy / Q000379:methods*; D017079:Exercise Tolerance; D006801:Humans; D007717:Knee / Q000503:physiopathology; D008297:Male; D009119:Muscle Contraction; D018763:Muscle Fatigue; D018908:Muscle Weakness / Q000209:etiology / Q000503:physiopathology* / Q000517:prevention & control; D020966:Muscular Disorders, Atrophic / Q000209:etiology / Q000503:physiopathology* / Q000517:prevention & control; D010809:Physical Fitness; D052097:Quadriceps Muscle / Q000098:blood supply / Q000503:physiopathology*; D019265:Spectroscopy, Near-Infrared; D013997:Time Factors; D016896:Treatment Outcome; D014732:Vibration / Q000627:therapeutic use