The effect of an inclined landing surface on biomechanical variables during a jumping task
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Recent advances in the understanding of the repeated bout effect: the protective effect against muscle damage from a single bout of eccentric exercise
by
McHugh MP.
—
last modified
2009-10-09 15:16
Scand J Med Sci Sports. 2003 Apr;13(2):88-97.
The repeated bout effect refers to the adaptation whereby a single bout of
eccentric exercise protects against muscle damage from subsequent eccentric
bouts. While the mechanism for this adaptation is poorly understood there have
been significant recent advances in the understanding of this phenomenon. The
purpose of this review is to provide an update on previously proposed theories
and address new theories that have been advanced. The potential adaptations have
been categorized as neural, mechanical and cellular. There is some evidence to
suggest that the repeated bout effect is associated with a shift toward greater
recruitment of slow twitch motor units. However, the repeated bout effect has
been demonstrated with electrically stimulated contractions, indicating that a
peripheral, non-neural adaptation predominates. With respect to mechanical
adaptations there is evidence that both dynamic and passive muscle stiffness
increase with eccentric training but there are no studies on passive or dynamic
stiffness adaptations to a single eccentric bout. The role of the cytoskeleton in
regulating dynamic stiffness is a possible area for future research. With respect
to cellular adaptations there is evidence of longitudinal addition of sarcomeres
and adaptations in the inflammatory response following an initial bout of
eccentric exercise. Addition of sarcomeres is thought to reduce sarcomere strain
during eccentric contractions thereby avoiding sarcomere disruption. Inflammatory
adaptations are thought to limit the proliferation of damage that typically
occurs in the days following eccentric exercise. In conclusion, there have been
significant advances in the understanding of the repeated bout effect, however, a
unified theory explaining the mechanism or mechanisms for this protective
adaptation remains elusive.