The Rest Period Broscience Is Wrong
Takeaway Points:
Rest periods are a topic that I think is often overblown, and as a coach I'm asked about it a lot more than the amount of attention I think the topic deserves.
The old, broscience belief is that we need to either shorten or lengthen rest periods depending on the amount of metabolic stress that we want to have, and how much of an endurance adaptation we want to provoke. Short rest periods = more metabolic stress, long rest periods = more strength.
Recent research has suggested that metabolic stress is not at all based on rest periods, and greater rest may always be better.
Rest periods between sets are one of the most common questions that I’m asked about from new clients. I think that, like many things in fitness, the importance of precise rest periods has been hyped up, and we’ve been led to believe that they’re a lot more important and magical than they actually are.
The old broscience stance on rest periods was pretty common, and believed that we should use rest periods of different lengths based on our training goals:
For Endurance - When training for endurance (whether this is cardio or lifting), the name of the game is high reps (or long duration) and short rest periods. Being able to complete more reps or a longer duration of cardiovascular training “unbroken” (with little to no rest) is a common test of endurance, so it seems to stand to reason that taking minimal rests between sets in your training makes sense. By keeping rest periods short, we can “maximize” the amount of metabolic stress placed on the body by allowing minimal time for our bodies to recover, and thus result in more total time training in a metabolically stressed state.
For Strength - Strength training, due to its higher relative intensity, tends to be a bit more mentally and physically exhausting per individual rep. As a result, many strength-focused lifters quickly get very exhausted and require longer rest times in order to recover. So, the typical recommendation here is that strength-focused lifters should be doing sets of fewer reps at a higher overall weight, and with 3-5 minutes of rest per set.
For Size - Size is seen as a cross between the short rest periods of endurance and the long rest periods of strength - so, you’ll typically see bodybuilders recommending rest periods of 1-3 minutes, max. The idea here is that you’re not training for endurance (so you want longer rest periods to maximize how many reps you can complete) but you also want to still keep your rest periods somewhat short (so that you can take advantage of the endurance-style metabolic stress to provoke further growth).
For a long time, these broscience rules got passed around - even though there was never any science to support them. Thankfully, research has started to catch up.
More recently, Brad Schoenfeld conducted a careful study to test the old-school theories. In this study, subjects were assigned to two groups: one that rested 1 minute between sets, and one that rested 3 minutes between sets. Their training plans were otherwise identical.
The results were surprising: the 3 minute rest period group was both stronger and bigger. This seems to suggest that longer rest periods are just… better, across the board.
Why is this? Schoenfeld suggests that it may simply be due to the fact that more rest = more recovery between sets = more reps/weight on subsequent sets. This makes intuitive sense - if what matters most is the total volume of training you’re able to complete (and thus the stimulus you’re able to provoke), then inhibiting that by artificially lowering your rest periods is basically just unnecessarily exhausting you - you’re just preventing yourself from performing as well as you could. I tend to agree with this assessment.
While this gives us a general picture that longer rests are probably better in general, it’s not very precise research - there’s a lot left out that this study doesn’t tell us. Luckily, a more recent study tells us more.
This study compared three different rest periods - rest periods of either 30, 60, or 120 seconds. In keeping with the results of the Schoenfeld study, the shorter rest periods compromised training quality and thus results.
But more interestingly, this study also examined the metabolic effect of each set by testing blood lactate levels. What they found was that the metabolic effect of these sets was the same regardless of the rest period used - so the old school claim that you could “increase the metabolic stress” by keeping rest periods short just isn’t true.
The amount of stress is directly related to the stimulus of the training itself, and has little to do with how recovered you are between sets. This makes sense when you think of metabolic stress not as a result of your body’s reaction to exercise, but simply as a result of the exercise itself independent of your body’s reaction to it.
This is more solid evidence that there’s not really much point to worrying about keeping your rest periods short. So what do I recommend?
There are some exercises where long rests are more important than others. Between maximal intensity efforts (heavy compound exercises, sprints, high intensity cardio), you’ll definitely want to rest as long as you can. But between lower intensity efforts (bicep curls, isolation exercises, low intensity cardio) it’s probably fine to keep your rests a bit shorter if you want, since these exercises are less taxing and you'll recover from them more quickly.
Theoretically, too long of a rest period would be a problem. If you’re doing heavy sets of squats with 10 minutes between, you may cool down completely between sets, requiring a new warmup or a greater risk of injury. So, a max of 3-5 minutes seems prudent so that you can stay warmed up across all sets. I would also guess that longer rest periods are also subject to diminishing returns after a few minutes, so it probably wouldn’t be worth it to wait that long anyway.
Another big concern is that we don’t all have infinite time to spend in the gym. If you rested 5+ minutes between every set like clockwork, even a relatively small number of sets of training would take you a long time to complete. So if you’re someone with limited time to spend in the gym, you may want to improve your workout efficiency by focusing on time-saving methods, or it may be worth it to time your rest periods and cut them a bit shorter, even if this means shaving your results down a bit. Chances are that if you’re someone with limited time in the gym, you don’t need to worry about maximizing every percentage point of your performance anyway, so it's a moot point.
So the ultimate answer is - it depends. Rest as long as you feel like you need, but feel free to cut rest periods shorter on lighter work, or if you’re pressed for time.
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