Greater initial adaptations to submaximal muscle lengthening than maximal shortening

Hortobágyi, Tibor, Jason Barrier, David Beard, JohnBraspennincx, Peter Koens, Paul Devita, Line Dempsey, and Jean Lambert. Greater initial adaptations to submaximal muscle lengthening thanmaximal shortening. J. Appl. Physiol.81(4): 1677-1682, 1996.The purpose of this study was tocompare the short-term strength and neural adaptations to eccentric andconcentric training at equal force levels. Forty-two sedentary women(age = 21.5 yr) were ranked based on the initial quadriceps strengthscore, and trios of subjects were randomly assigned to either aneccentric (n = 14), a concentric (n = 14), or a nonexercising controlgroup (n = 14). Training involved atotal of 824 eccentric or concentric quadriceps actions at 1.05 rad ^· s¹administered in four sets of 6-10 repetitions, four times per weekfor 6 wk. Before and after training, all subjects were tested forunilateral maximal isometric and eccentric and concentric actions at1.05 rad ^· s¹and for a 40-repetition eccentric and concentric fatigue series of theleft and right quadriceps. Surface electromyographic activity of thevastus lateralis and medialis was monitored during testing. Concentrictraining increased concentric (36%, P < 0.05), isometric (18%, P < 0.05), and eccentric strength (13%), and eccentric training increasedeccentric (42%, P < 0.05),isometric (30%, P < 0.05), andconcentric (13%) strength. Eccentric training improved eccentric andisometric strength more (P < 0.05)than did concentric training. The electromyographic adaptations weregreater with eccentric training. Cross-education was 6%, and neithertraining mode modified fatigability. The data suggest that training ofthe quadriceps muscle with submaximal eccentric actions brings aboutgreater strength adaptations faster than does training withmaximal-level concentric actions in women. This greater adaptation islikely to be mediated by both mechanical and neural factors.