Many athletes want to get strong, but never actually take the time to think about how their rest times affect the outcome of strength adaptations.
Knowing the recovery rates of the various energy systems, the training goal, and how much time you have to train are keys to knowing how much time you need to rest for.
First, we need to look at the dominant energy system we’re using, and how long that energy system generally takes to recover from the bout of work its performing.
We have three main energy systems:
- ATP/PC (Alactic)
- Glycolytic (Lactic)
- Aerobic (Oxidative)
All energy systems are active during exercise, no matter the intensity or duration. However, the intensity and duration of exercise are going to determine which energy system is the most dominant.
- ATP/PC = Dominant for up to the first 10 seconds
- Glycolytic = Dominant from 10 seconds to 2 minutes
- Aerobic = Dominant from 2 minutes and beyond
So, from a lifting point of view, our most dominant energy systems are going to be the ATP/PC, and glycolytic energy systems, as working sets are usually not going to last beyond 60 seconds depending on how many repetitions you’re doing.
Now without getting too deep in to the physiology of muscle, to make ATP (which is the fuel we use to contract a muscle) we need phosphocreatine (PCr). PCr in the muscle can be used to resynthesise ATP at a very high rate – much faster than that of using carbohydrates and fats. This high rate of energy transfer is required to produce high power outputs; however, the energy availability is small.
If we were to look at the recovery rates of these energy systems required to fuel our strength and power training, this is what the breakdown would look like:
ATP – 100% restoration of ATP takes 3-5 minutes.
PCr – 100% restoration of PCr takes around 8 minutes.
Muscle Glycogen – 20-24 hours to restore (depending on intensity and duration of training session).
The rates of recovery for ATP and PCr are given for one high intensity bout of exercise. So, once we start throwing repeated bouts of exercise at these energy systems, the recovery rate stretches out to a much longer time frame, because the fuel readily available becomes less and less each time. Therefore:
EVERY TRAINING SESSION IS GOING TO ELICIT SOME FORM OF FATIGUE THAT REQUIRES RECOVERY.
Unless of course, your whole training session is just one set of 3 reps. Then you’ll probably be alright after 10 minutes…but adaptation doesn’t work that way.
Therefore, depending on the time available and training goal, our rest period will play a major role in dictating the level of fatigue reached in each subsequent set and at the end of a training session.
What does the research say?
One review study compared the effects of short (<60s) versus long (>60s) rest periods between sets and looked at changes in muscle size. The authors showed that resting for greater than 60 seconds was more beneficial to muscle growth than resting for less than 60 seconds.
This is likely because the ability to use greater training volumes when the rest period is longer, which allows for greater recovery in muscle energy stores.
Another study looked at the changes in muscle strength, endurance, and size in two groups, one that rested for 1-minute between sets, the second who’s rest was 3-minutes between sets. The study showed long rest periods were superior for strength gains (1RM squat and bench press) and hypertrophy gains, whilst muscle endurance was not significantly greater between groups. The authors of this study concluded that, in young resistance-trained men, longer rest periods are superior to increase muscle strength and size.
How Does This Apply?
So, looking at both the physiology of the energy systems and the applied research, it’s pretty comprehensive to say that for maximising strength gains and athlete performance, longer rest periods are superior. But that’s not to say shorter rest periods are not important, they still have their place in the training program. When training for endurance or doing hypertrophy work in the later sets of a training session, having shorter rest periods can produce great levels of metabolic stress (a build-up of waste products from using energy) in the muscle. Metabolic stress may play a role at developing muscle size and improving endurance by being able to resist the build-up of fatigue.
From an application point of view, we need to take in to account that there isn’t usually the time for 5-8-minute rest periods when training strength and power to allow full recovery. So, rest times will depend largely on the individual, and how they’re responding to the set, rep, and loading parameters.
I personally tend to use a ‘minimum’ rest time when training for strength and power. I’ll make sure my athletes rest for at least a given length of time, and once that period is over they are free to perform the exercise once they feel as though they’re ready.
My minimum rest periods are as follows:
Low load power (3-5 reps): 60-90 seconds
High load power (2-4 reps): 90-120 seconds
Max Strength (1-5 reps): 3-4 minutes
Hypertrophy/Endurance (8-20+ reps): 30-90 seconds
For most athletes I’ve worked with, these ranges work well. However, they aren’t set in stone. It all gets back to the needs of the athlete, and making sure they can perform the next set with high quality reps.
Grgic J, Lazinica B, Mikulic P, Krieger JW, Schoenfeld BJ. The effects of short versus long inter-set rest intervals in resistance training on measures of muscle hypertrophy: A systematic review. European Journal of Sport Science. 2017 Sep 14;17(8):983-93.
Maughan RJ, Gleeson M. The biochemical basis of sports performance. Oxford University Press; 2010 May 20.
Schoenfeld BJ, Pope ZK, Benik FM, Hester GM, Sellers J, Nooner JL, Schnaiter JA, Bond-Williams KE, Carter AS, Ross CL, Just BL. Longer interset rest periods enhance muscle strength and hypertrophy in resistance-trained men. The Journal of Strength & Conditioning Research. 2016 Jul 1;30(7):1805-12.