Acute muscle damage as a stimulus for training-induced gains in strength

Purpose: The purpose of this study was to investigate the effect of a singl e acute bout of maximal eccentric work upon the strength gains during 9 sub sequent weeks of strength training, Eccentric work causes acute muscle dama ge that may initiate compensatory hypertrophy and enhance training-induced gains in strength. Methods: Twenty-six healthy adults (21 +/- 1 yr, 7 women ) trained the elbow flexors 3 d per week for 9 wk. One arm (C) performed pu rely conventional isotonic training, i.e.. lifting and lowering. The other arm (E) began with a single bout of maximal eccentric work but thereafter u ndertook identical isotonic training. Every week dynamic lifting strength ( I RM) and isometric strength were measured. Results: The results indicated that an acute bout of eccentric muscle damage does not accentuate training- induced gains in strength. Isometric strength of arm E fell by 15 +/- 2% (m ean +/- SEM) 2 d after the bout of eccentric work, and. 4 d afterward, plas ma creatine kinase levels were 1502 +/- 397 IU L-1. Although arm E displaye d rapid gains in strength from 2 d after the bout of eccentric work, these were not sustained, and for several weeks arm E showed significantly smalle r gains in strength than ana C (isometric strength, 2 wk; dynamic lifting s trength, 5 wk). Conclusions: After 9 wk of training, the gains in both isom etric and dynamic lifting strength were similar for the two arms. A single bout of damaging eccentric work did not enhance the response tc, convention al strength training and significantly compromised strength gains for sever al weeks.