High intensity, quick, in-and-out workouts are all the rage in fitness centers across America these days. The significant time crunches most gym-goers are up against, which preclude them from leisurely workouts, help explain this trend. So, too, does over a decade’s worth of research linking high intensity interval training to greater fat loss.
Swifter bursts of exertion may increase metabolism and help make us slimmer. But many exercisers (and some fitness professionals) have mistakenly inferred from these observations that reducing rest periods between weight lifting sets confers comparable benefits — not only to the rate at which we burn calories but also in terms of how greatly our muscles can grow. Under this assumption, they cap their rests between sets at one minute or less.
One new study challenges the notion that allowing no more than a minute of rest between lifting sets courts the best hormonal and growth response to strength training. In a paper published in April’s edition of Experimental Physiology, researchers from the University of Birmingham offer evidence that, in some cases, up to three minutes of rest between weight lifting sets invites the biggest potential for protein synthesis in muscle cells. Shorter rest intervals, their evidence also suggests, may actually impair this process.
The researchers monitored the hormonal and protein synthesis response of 16 males to four sets of resistance exercises. Half of the males were instructed to rest between sets for one minute. The other half was instructed to chill for five. Prior to beginning their workouts, researchers obtained biopsies from the muscle groups these men worked (in this case: the quadriceps, as they were doing knee extensions). Additional biopsies were repeated four hours, 24 hours, and 28 hours after these men completed their routines.
Subjects who’d taken longer periods of rest between sets saw a 152% increase in a measure of muscular growth response called myofibrillar protein synthesis (aka MPS). Those who’d capped their rest periods at one minute saw only a 76% increase in MPS.
In a press release lead author of the above study Leigh Breen, Ph.D., points out that better trained individuals may not need as much time as novice weight lifters to maximize the growth response that takes place in their muscles following strength training sets. But he recommends a two to three minute window of opportunity to recover between bouts of lifting to ensure all exercisers’ attempts to build muscle achieve their fullest potential.
Whether or not you actually have time to take these pauses in your own workout? Well, that’s another story entirely. If nothing else, let’s take this study as one more piece of evidence that more is not always better — and pausing, pacing, or slowing down is just as important for our physical (and mental) health as speeding things up can be.
