Eccentric exercise, exercise induced muscle damage and the repeated bout effect: A brief review

Eccentric training has the ability to improve strength and power as well as being a stimulus for hypertrophy gains. However a possible negative side effect is exercise induced muscle damage, which can have a detrimental effect on performance. The symptoms and causes of exercise induced muscle damage and the ability of the RBE to protect against muscle damage are discussed in this review. A search of the literature was conducted for; eccentric; training; methods; exercise induced muscle damage (EIMD); RBE. After this search 82 papers were selected to form the basis of this review. The finding of this review suggest if isometric contractions are used as a preconditioning exercise these should be completed at long muscle lengths with 10 isometric contractions reported to result in the greatest protective effect. Results of previous studies indicate that 30 repetitions of eccentric contractions at 10 - 40% maximal isometric strength (low intensity and volume) and ~4 s in duration have resulted in a RBE with little initial damage. Studies that have investigated low volume maximal eccentric contractions (6 – 24 reps, ~ 4 s in duration) have reported increased initial EIMD followed by a protective effect against further damage. When utilising maximal eccentric contractions the protective effect is reported to last up to 6 months in comparison to a low intensity bout that may only offer protection for 3 weeks. In summary it is suggested athletes should initially complete low intensity low volume eccentric training. Athletes should then progress to low load maximal or supramaximal eccentric training prior to completing higher volume sessions to allow the RBE to offer protection against muscle damage.