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2001 Publications

ELECTROMYOGRAPHIC ANALYSIS OF REPEATED BOUTS OF ECCENTRIC EXERCISEby McHugh MP, Connolly DAJ, Eston RG, Gartman EJ, Gleim GW - last modified 2012-11-27 00:00
Journal of Sports Sciences. 19: 163-170, 2001.


The repeated bout effect refers to the protective effect provided by a single bout of eccentric exercise against muscle damage from a subsequent similar bout. The purpose of this study was to determine if the repeated bout was associated with either an increase in motor unit activation relative to force production, increased recruitment of slow-twitch motor units or increased motor unit synchronisation.

Surface electromyographic (EMG) signals were recorded from the hamstring muscles during two bouts of sub-maximal isokinetic (2.6 rad.s-1) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions separated by two weeks. EMG per unit torque and median frequency (MF) were analysed.

The initial bout of eccentric exercise resulted in strength loss, pain and muscle tenderness while the repeated eccentric bout resulted in a slight increase in strength, no pain and no muscle tenderness (bout by time effects P<0.05).

Strength, pain and tenderness were unaffected by either bout of concentric exercise. EMG per unit torque and MF were not different between the initial and repeated bouts of eccentric exercise. EMG per unit torque and MF increased during both bouts of eccentric exercise (P<0.01) but did not change during either concentric bout.

In conclusion, there was no evidence that the repeated bout effect was due to a neural adaptation.