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RESEARCH PRODUCT
Time Course of Neuromuscular Alterations during a Prolonged Running Exercise
Gaëll DeleyRomuald LepersNicolas PlaceGuillaume Y. Milletsubject
Adultmedicine.medical_specialtyPhysical Therapy Sports Therapy and RehabilitationPhysical exerciseElectromyographyRunningVoluntary contractionHeart RateInternal medicinemedicineHumansOrthopedics and Sports MedicineTreadmillmedicine.diagnostic_testKnee extensorsElectromyographybusiness.industryOxygen uptakeElectric StimulationOxygenElectrophysiologyTime courseCardiologyPhysical therapyFrancebusinessMuscle Contractiondescription
PLACE, N., R. LEPERS, G. DELEY, and G. Y. MILLET. Time Course of Neuromuscular Alterations during a Prolonged Running Exercise. Med. Sci. Sports Exerc., Vol. 36, No. 8, pp. 1347–1356, 2004. Purpose: This study investigated the time course of contractile and neural alterations of knee extensor (KE) muscles during a long-duration running exercise. Methods: Nine well-trained triathletes and endurance runners sustained 55% of their maximal aerobic velocity (MAV) on a motorized treadmill for a period of 5 h. Maximal voluntary contraction (MVC), maximal voluntary activation level (%VA), and electrically evoked contractions (single and tetanic stimulations) of KE muscles were evaluated before, after each hour of exercise during short (10 min) interruptions, and at the end of the 5-h period. Oxygen uptake was also measured at regular intervals during the exercise. Results: Reductions of MVC and %VA were significant after the 4th hour of exercise and reached 28% (P 0.001) and 16% (P 0.01) respectively at the end of the exercise. The reduction in MVC was highly correlated with the decline of %VA (r 0.98, P 0.001). M-wave was also altered after the fourth hour of exercise (P 0.05) in both vastus lateralis and rectus femoris muscles. Peak twitch was potentiated at the end of the exercise ( 18%, P 0.01); 20- and 80-Hz maximal tetanic forces were not altered by the exercise. Oxygen uptake increased linearly during the running period (18% at 5 h, P 0.001). Conclusion: These findings suggest that KE maximal voluntary force generating capability is depressed in the final stages of a 5-h running exercise. Central activation failure and alterations in muscle action potential transmission were important mechanisms contributing to the impairment of the neuromuscular function during prolonged running. Key Words: MAXIMAL VOLUNTARY CONTRACTION, ELECTROMYOGRAPHY, M-WAVE, CENTRAL FATIGUE, LONGDURATION EXERCISE
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2004-08-01 | Medicine & Science in Sports & Exercise |