There are many factors to consider when putting together a workout routine, like what exercises you’re going to do, how much weight, the speed of the reps, and the number of sets.  However, one of the biggest factors is often the most overlooked – rest periods.

How long you rest determines a lot of the effectiveness of your program.  Here’s the conventional thinking based on workout goals:

Rest Time for Strength

Maximal strength training can be defined as training at an intensity of 90% of your 1 rep max weight for <4 reps.  Due to the intensity of lifting heavier weights, the conventional recommended rest time is anywhere from 2 minutes all the way up to 5 minutes.   The thought is that if your goal is strength and you don’t rest long enough, you won’t be able to exert maximum effort on your next set.

Rest Time for Hypertrophy (Muscle Growth)

Traditional belief is that shorter rest periods (30-90 seconds) are most beneficial for maximum muscle growth.  

Rest Time for Muscular Endurance

The purpose here is to increase fatigue resistance. Endurance training is done with light weight and a high rep range (15 to 20 or more).  In order to produce fatigue under these circumstances, your rest periods need to be short, generally less than one minute.

Rest Time for Fat Loss

When fat loss is the primary goal, you want to crank up the metabolic furnace as much as possible. To do this, you’ll generally limit rest periods to 30 seconds or less for less-fatiguing exercises like bodyweight, kettlebell, and dumbbell work, and up to 2 minutes for more intense compound exercises.

So What’s The Answer?

Recent studies have suggested that shorter rest periods aren’t necessary for muscle growth.  A study by Henselmans and Schoenfeld found that there was little basis to the claim that shorter rest periods were more beneficial for size gains.  According to Schoenfeld, “It would appear from current evidence that you can self-select a rest period that allows you to exert the needed effort into your next set without compromising muscular gains.”

What they found was that since volume and tension were the two biggest drivers of muscle growth, shortening your rest time can cause a reduction in the amount of weight you can lift.  So if resting a little longer allows you to increase the volume and/or tension, then this will lead to more muscle gains.

So, rest periods for hypertrophy should vary anywhere from 1 to 3 minutes, depending on the exercises and amount of weight being used.

Looking at even more recent studies it seems that resting closer to the 2 minute range is best for hypertrophy/muscle growth.  One study actually showed that a 5 minute rest period stimulated more growth in muscle tissue than a 2 minute rest period!  

Now many authors comment that the shorter rest periods are best for inducing increases in testosterone and growth hormone.  That may be true but the latter study clearly showed that the longer intervals gave more pure gains in muscle no matter the hormone levels.  So hormone levels may be higher systemically during shorter rest intervals but may not be higher locally in the muscle (at least enough to cause any actual changes in muscle tissue itself).  

 So 5 minutes may be the best rest period for strength and hypertrophy.  Of course not all of us have the time to rest this long for every routine, so do this when you can.  When you are short on time than resting at least closer to 2 minutes is the next best thing in terms of muscle growth. 

There is another way though . . .

Feel The Power!

Another way to adjust your workouts is more flexible and subjective.  Auto-regulation is the practice of adjusting your programming (sets/reps/rest times) during your workout based on how you feel.  The basis of this theory is to time your rest periods based on how you’re feeling, rather than predetermined times.  This may not be the best way to utilize rest periods during a fat loss program, as the design of a lot of these programs is to complete your sets under high levels of fatigue to increase calorie burning.

So doing it this way you do a set and when your heart rate returns to near normal and you “feel” ready to perform your next set, you do it. This feeling is going to vary depending on what you’re doing and your overall level of fitness.  Compound, multi-joint movements will require more rest, while isolation movements will require less.

A more objective way to determine this feeling is by using the RPE (Rate of Perceived Exertion) scale. This is where you rate the intensity of your exercise on a scale from 1-10, with 1 being little or no exertion and 10 being failure.  This method allows you to regulate your rest periods based on how you feel that day.  Obviously this is going to vary- some days you will feel like you’re ready to conquer the world and other days you will feel like just staying in bed.  If you feel real bad it may be best to take an off day or do a light workout; but if you’re just a bit off then listen to your body and tone it down and/or take longer rest periods.

So if your goal is maximal strength, resting an extra minute or more so you are sure you can crank the next set is going to be the best way to go!  The same can be said about muscle building. Volume is the main driver of growth, so resting a bit longer is going to be much more beneficial if it allows you to maintain a higher volume.  The key with this method is that you can’t just rest however long you want; you need to be honest with yourself about how long you NEED to rest.

So there you have it; when in doubt rest a bit more, but go by how you feel!   

References

J Strength Cond Res. 2015 Nov 20. Longer inter-set rest periods enhance muscle strength and hypertrophy in resistance-trained men.

Schoenfeld, Brad J. et al. “Longer Interset Rest Periods Enhance Muscle Strength and Hypertrophy in Resistance-Trained Men.” Journal of Strength & Conditioning Research: July 2016 – Volume 30 – Issue 7 – p 1805–1812.

Exp Physiol 2016 Apr 29.

Short inter-set rest blunts resistance exercise-induced increases in myofibrillar protein synthesis and intraceullar signaling in young males.McKendry J, Pérez-López A, McLeod M, Luo D, Dent R, Smeuninx B, Yu J, Taylor AE, Philp A, Breen L.