A classic among the training questions: how long should a muscle group rest after you train it? Most coaches will answer that question with 48 hours. That’s not far from the truth, but the best answer is: it depends.

FACTORS THAT DETERMINE RECOVERY TIME

After strength training, the trained muscles are (re)built in a process called muscle protein synthesis. To successfully complete that process, you need to give the muscle groups in question the necessary rest. How long muscle protein synthesis remains elevated as a result of training depends on several factors. We go through the main ones.

TRAINING INTENSITY

By training intensity we mean here the relative intensity, in other words the extent to which you train a set to muscle failure. If you train all your sets to muscle failure, you should rest the trained muscle group for 48 hours, according to research. If you only use 24 hours of rest, you will not be able to perform optimally. However, if you don’t train completely to muscle failure, the muscle may have recovered within 24 hours, according to other studies (1, 2).

The disadvantage of such studies is that they do not simulate reality well. After all, in practice you are dealing with a complete training program, and not with just a few exercises. In other words, in practice the total training volume is a lot higher, which brings us to the next point.

TRAINING VOLUME

Under training volume is generally understood to mean the number of sets per muscle group per week (excluding warm-up sets). In short, it is the workload of your training, which partly determines how long you need to rest. So it is logical that after 10 sets you need more recovery time for a certain muscle group than after 5 sets.

If you only do one or two exercises per muscle group during a workout, and you train close, but not completely, to muscle failure, chances are that you will have recovered sufficiently 24 hours later. But that also depends on other factors, as we’ll see next.

Do in one workout no more than 10 sets per muscle group. Doing more sets makes no sense for muscle growth (if you are natural anyway) and therefore requires an unnecessarily much from your recovery capacity. If you need to do more than 10 sets for a muscle group on a weekly basis, spread them over at least two training days, with enough recovery time in between.

TYPE OF EXERCISE

It also makes a difference whether you do compound exercises or isolation exercises. For example, you will recover less quickly from three sets of heavy squats than from three sets of leg extensions, which has also been proven by research.

TRAINING STATUS

The training status also plays a role in recovery time. Advanced strength athletes recover faster than beginners. A meta-study shows that in advanced athletes the peak of muscle protein synthesis often occurs within the first ten hours after training. After 24 hours, muscle protein synthesis shows little increase, depending on the training load.

In untrained individuals, the peak occurs much later and muscle protein synthesis often lasts at least 48 hours.

AGE

An admittedly small study suggests that middle-aged people recover just as quickly from strength training as young people. So you may also be in your forties and fifties with an average of 48 hours between two training sessions of the same muscle group.

Yet, in addition to acute fatigue, the muscle damage that occurs directly as a result of training, there is also cumulative fatigue. The latter is the fatigue that accumulates in muscles, joints and tendons over a longer period of training. It is plausible that middle-aged strength athletes suffer more from cumulative fatigue than young people. As an elderly strength athlete, you may therefore have to deload more often and pay more attention to lifestyle factors (see next point).

LIFESTYLE

How quickly you recover from strength training also depends on factors in your daily life. First and foremost, whether you sleep good and long enough: a good night’s sleep is crucial for recovery from strength training.

Another factor is mental stress. If you are under a lot of stress, from exam stress to relationship problems, this can double the required recovery time.

In addition, nutrition is important: for muscle recovery and growth you need to eat enough (in the bulk with a measured calorie surplus), especially enough proteins.

SEX

You wouldn’t think so, but women generally recover from strength training a bit faster than men. In addition, the ladies have the advantage that they often only train the buttocks and legs frequently and leave the upper body largely untouched. Overall, that means less training load to recover from.

CONCLUSION

On average, your muscles need 48 hours to recover from strength training.

You may need more rest time (72 hours) if you are a beginner and/or do many sets and/or train many of those sets to muscle failure.

You may be able to get by with less rest time (24 hours) if you are advanced and handle small volumes per workout, without training to muscle failure.

Lifestyle also plays a role: with a lot of stress and/or little sleep you have to use longer rest periods than normal.