Greater initial adaptations to submaximal muscle lengthening than maximal shortening

Abstract

Hortobágyi, Tibor, Jason Barrier, David Beard, John Braspennincx, Peter Koens, Paul Devita, Line Dempsey, and Jean Lambert.Greater initial adaptations to submaximal muscle lengthening than maximal shortening. J. Appl. Physiol.81(4): 1677–1682, 1996.—The purpose of this study was to compare the short-term strength and neural adaptations to eccentric and concentric training at equal force levels. Forty-two sedentary women (age = 21.5 yr) were ranked based on the initial quadriceps strength score, and trios of subjects were randomly assigned to either an eccentric ( n = 14), a concentric ( n = 14), or a nonexercising control group ( n = 14). Training involved a total of 824 eccentric or concentric quadriceps actions at 1.05 rad ⋅ s−1 administered in four sets of 6–10 repetitions, four times per week for 6 wk. Before and after training, all subjects were tested for unilateral maximal isometric and eccentric and concentric actions at 1.05 rad ⋅ s−1 and for a 40-repetition eccentric and concentric fatigue series of the left and right quadriceps. Surface electromyographic activity of the vastus lateralis and medialis was monitored during testing. Concentric training increased concentric (36%, P< 0.05), isometric (18%, P < 0.05), and eccentric strength (13%), and eccentric training increased eccentric (42%, P < 0.05), isometric (30%, P < 0.05), and concentric (13%) strength. Eccentric training improved eccentric and isometric strength more ( P < 0.05) than did concentric training. The electromyographic adaptations were greater with eccentric training. Cross-education was 6%, and neither training mode modified fatigability. The data suggest that training of the quadriceps muscle with submaximal eccentric actions brings about greater strength adaptations faster than does training with maximal-level concentric actions in women. This greater adaptation is likely to be mediated by both mechanical and neural factors.