GREATER ADAPTATIONS WITH SUBMAXIMAL MUSCLE LENGTHENING THAN MAXIMAL SHORTENING CONTRACTIONS 761

The purpose of this study was to compare the strength and neural adaptations following eccentric and concentric training at equal force levels. Forty-two sedentary women (age = 21.5 y) 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 non-exercising control group (n = 14). Training involved 824, 1.05-rad·s-1 eccentric or concentric quadriceps contractions administered in 4 sets of 6-10 repetitions, 4 times per week for 6 weeks. The concentric group exercised with maximal contractions and the eccentric group exercised at the same force average and thus used submaximal eccentric contractions. Before and after training all subjects were tested for unilateral maximal isometric, eccentric, and concentric contractions at 3 velocities and a 40-repetition eccentric and concentric fatigue series in the left and right quadriceps. Surface electromyo-graphic (EMG) activity of the vastus lateralis and medialis was monitored during testing. Concentric training increased concentric (36%, p<.05), isometric (18%, p<.05), and eccentric strength (13%) and eccentric training increased eccentric (42%, p<.05), isometric (30%, p<.05), and concentric (13%) strength. Eccentric training improved eccentric and isometric strength more (p<.05) than concentric training improved concentric and isometric strength. The EMG adaptations paralleled the strength adaptations. The cross transfer of strength was 6% and neither training modality modified fatigue-resistance. The data suggest that training with submaximal eccentric contractions brings about greater strength adaptations than does training with maximal level concentric contractions in women. This greater adaptation is likely to be mediated by both mechanical and neural factors.