Submaximal-exercise-induced impairment of human muscle to develop and maintain force at low frequencies of electrical stimulation

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T1 - Submaximal-exercise-induced impairment of human muscle to develop and maintain force at low frequencies of electrical stimulation

AU - Ratkevicius, A

AU - Skurvydas, A

AU - Lexell, Jan

PY - 1995

Y1 - 1995

N2 - The aim of this study was to test the hypothesis that low intensity exercise-induced low frequency fatigue is caused by failure of excitation-contraction coupling. Changes in knee extension torque at 5, 10, 15, 20 and 50 Hz electrical stimulation of quadriceps muscle in ten healthy, young, male subjects were recorded during 20-min voluntary exercise followed by 60-min recovery. In seven of the ten subjects, changes in torque during 3 min of 10-Hz stimulation were recorded 2 min and 20 min after 20 min voluntary exercise. Exercise was performed at 30% of maximal voluntary contraction with a contraction plus relaxation period of 6 plus 4 s. Torque at 5, 10, 15, 20 and 50-Hz stimulation at the end of exercise was reduced to mean 91.0 (SEM 5.4)%, 68.7 (SEM 5.4)%, 67.2 (SEM 3.9)%, 66.5 (SEM 4.5)% and 74.7 (SEM 4.3)% of control values, respectively. During the first 30 s of the 3 min 10-Hz stimulation, torque was reduced in exercised muscle and increased in nonfatigued muscle. The reduction in torque was more marked 20 min after exercise than after 2 min. In conclusion, the pattern of depression and recovery of muscle force observed was in agreement with the hypothesis that the main cause of low intensity exercise-induced low frequency fatigue is an impairment of excitation-contraction coupling.

AB - The aim of this study was to test the hypothesis that low intensity exercise-induced low frequency fatigue is caused by failure of excitation-contraction coupling. Changes in knee extension torque at 5, 10, 15, 20 and 50 Hz electrical stimulation of quadriceps muscle in ten healthy, young, male subjects were recorded during 20-min voluntary exercise followed by 60-min recovery. In seven of the ten subjects, changes in torque during 3 min of 10-Hz stimulation were recorded 2 min and 20 min after 20 min voluntary exercise. Exercise was performed at 30% of maximal voluntary contraction with a contraction plus relaxation period of 6 plus 4 s. Torque at 5, 10, 15, 20 and 50-Hz stimulation at the end of exercise was reduced to mean 91.0 (SEM 5.4)%, 68.7 (SEM 5.4)%, 67.2 (SEM 3.9)%, 66.5 (SEM 4.5)% and 74.7 (SEM 4.3)% of control values, respectively. During the first 30 s of the 3 min 10-Hz stimulation, torque was reduced in exercised muscle and increased in nonfatigued muscle. The reduction in torque was more marked 20 min after exercise than after 2 min. In conclusion, the pattern of depression and recovery of muscle force observed was in agreement with the hypothesis that the main cause of low intensity exercise-induced low frequency fatigue is an impairment of excitation-contraction coupling.

KW - Electrical stimulation

KW - Fatigue Muscle contraction

KW - Muscles

U2 - 10.1007/BF00865025

DO - 10.1007/BF00865025

M3 - Article

VL - 70

SP - 294

EP - 300

JO - European Journal of Applied Physiology

JF - European Journal of Applied Physiology

SN - 0365-0863

IS - 4

ER -