Some food for thought if you're planning to phase out resistance training leading up to an important competition. Here's a graph from a meta-analysis on the effects of stopping resistance training on muscular performance, published earlier this year in the Scandinavian Journal of Medicine & Science in Sports, by Laurent Bosquet's group at the universities of Poitiers and Montreal:
What you're looking at is the change in muscular power after resistance training was halted, based on meta-analysis of 103 studies. Note that power is different from absolute strength -- power is your ability to deliver large amounts of force in a short period of time, which is often more relevant to athletic performance than plain strength is. And the interesting thing to note is that, 8 to 14 days after stopping, power appears to be a little higher than it was during training, though it's not statistically significant. (The graph for strength, which I didn't show, starts declining immediately.)
Is there something significant going on here? According to Nicolas Berryman, one of the co-authors of the study, this apparent rebound may be the result of an "overshoot" in fast-twitch muscle fibers following the cessation of training, an effect that was first observed by a Danish group back in 2000. Heavy training seems to suppress fast-twitch fibers, and then when you stop training they overcompensate to a higher-than-initial level. More fast-twitch fibers boost power -- and, intriguingly, Berryman raises the possibility that this effect may also boost running economy (though, to be clear, that's just a hypothesis at this point).
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Speculation aside, if you're an endurance athlete who includes resistance training in your regimen, you have to eliminate or reduce it at some point before race day. The graph above suggests that one to two weeks in advance might be an interesting time to stop.
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