There's a lot that goes into building and executing a training plan in order to reach your goals. Things like what exercises you're going to do, load, tempo, and the number of sets and reps all play a factor in whether or not the program is going to work. 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. If your goal is strength and you rest too little you won't be able to exert maximum effort on your next set. Or if your goal is to build muscle and you rest too long, you may compromise muscle growth.
Conventional Thinking on Rest Periods
There are certain prescribed rest periods that most lifters follow. Here's the conventional thinking.
Max strength training can be defined as training at an intensity of 90% of your 1 RM for <4 reps. Because of the intensity at which you're lifting and the energy system used, the conventional recommended rest time is anywhere from 2 minutes all the way up to 5 minutes.
Hypertrophy (Muscle Growth)
It's always been believed that shorter rest periods (30-90 seconds) are most beneficial for maximum muscle growth. Recent studies however have suggested that this isn't the case. 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."
Basically, 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. And if resting a little longer allows you to increase the volume and/or tension, then that's going to 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.
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 under one minute.
While your ability to lose fat will largely be determined by your diet, how long you rest between sets also has an impact on your metabolic environment and your ability to burn fat. Many fat loss programs combine the above training methods. However, since the main goal isn't to produce max strength or elicit muscle growth, normally you don't abide by those conventional rest times.
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.
Auto-Regulation & RPE
Auto-regulation is the practice of adjusting your programming (sets/reps/rest times) before or during your workout based on how you feel. With rest time specifically, it's timing your rest periods based on how you're feeling, rather than predetermined times.
Despite the fancy name, rest period auto-regulation is actually pretty simple. Basically, 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. Compound, multi-joint movements will require more rest, while isolation movements will require less.
The important thing to remember is rather than assigning yourself a rest time, you perform your next set when you feel ready, not when you're done checking Facebook.
A good 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. RPE works well because it allows you to regulate your rest periods based on how you feel that day. The same set may require a different level of physical exertion on different days, so RPE lets you regulate your rest times based on where you are on the scale on a given day.
You're going have days in the gym where you feel great, and then you'll have days where you feel like a sack of hot garbage. Auto-regulation allows you to keep the volume of your workouts high by taking longer rest periods when you need them.
There are a number of benefits to auto-regulating your training, especially if your goal is max strength or muscle growth. Self-selecting your rest periods will allow you to give the maximum effort needed for each set.
Take a near-max effort deadlift for example. Your goal for the day is to complete 3 sets of 3 reps at 90% of your 1 RM, with 3-4 minutes of rest in between sets. The first set goes great but the second leaves you feeling fatigued. You know you're not going to be able to do the third set at the current weight with only 4 minutes of rest.
So if your goal is max strength, which is going to benefit you more: reducing the weight so you can stick to your prescribed rest period, or resting an extra minute to be able to lift the weight you have on there? Obviously it's resting an extra minute.
The same can be said about muscle building. Volume is the main driver of growth, so resting an extra 30 seconds or a minute is going to be much more beneficial if it allows you to maintain a higher volume.
The biggest drawback to rest period auto-regulation is that it requires you to honestly assess how you train. You can't just rest however long you want; you need to be honest with yourself about how long you NEED to rest.
Auto-regulation may also not be the best way to regulate 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.
- J Strength Cond Res. 2015 Nov 20. Longer inter-set rest periods enhance muscle strength and hypertrophy in resistance-trained men.