NOSAKA, K.; AOKI, M. S. Repeated bout effect: research update and future perspective. Brazilian Journal of
Biomotricity, v. 5, n. 1, p. 5-15, 2011. Responses to the same exercise are never the same, which is
particularly so for eccentric exercise. Eccentric exercise results in muscle damage when performed by
individuals who are unaccustomed to the exercise. However, when the same exercise is performed again
within a certain period of time, it does not induce as sever muscle damage as that was induced previously. It
looks as if a bout of eccentric exercise induced protective adaptation in the process of recovering from
muscle damage. This adaptation is referred to as the repeated bout effect. The protective adaptation against
“maximal†eccentric contractions is induced by submaximal eccentric contractions, a small number of
eccentric contractions, eccentric contractions at short muscle lengths, or slow velocity eccentric contractions,
which induce less muscle damage, as well as low-intensity eccentric contractions that do not induce any
muscle damage, or isometric contractions at a long muscle length. The protective effect could last up to
several months, but the remaining length of the effect appears to be influenced by the magnitude of muscle
damage in the initial bout. It seems that adaptations of muscle fibers and/or connective tissue are
responsible for the repeated bout effect, although neural adaptations are not totally discarded, and the
underlying mechanisms need to be investigated further. It should be noted that the magnitude of muscle
damage can be attenuated by the use of the repeated bout effect more efficiently than any other prophylactic
interventions such as nutritional supplementations, and the effect should be considered when designing a
study.
