When it comes to working out, many men spend a lot of time planning the exact exercises they will perform, but neglect to consider their rest periods. While actual exercise selection is important, the type of rest you take is also going to play a big role in the type of results you see from your workout.

It’s important to recognize that different programs will call for very different rest periods, so matching your goals with the right program is vital.

Rest Periods and Total CNS Output

The first thing to assess with your workouts in order to determine optimal rest periods needed is the amount of CNS (central nervous system) output that will be required during each set.

Typically, using heavy weight over low reps, sets with higher rep ranges and sets in which you are focusing on explosiveness will require a much higher output from the CNS and will require an extended amount of recovery time, somewhere around the 2 to 3 minute mark.

Alternatively, "bodybuilding" sets, using a moderate amount of weight for 8 to 12 reps, are not as CNS-intensive, so a rest of 30 seconds to 1 minute can be used.

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Hormonal Release

The second point to consider is what you want to accomplish hormonally with your training, as different rest periods have different effects on hormonal release.

To increase growth hormone output, aim for rest periods of 30 to 45 seconds, whereas to promote nervous system recovery, 60 seconds or more is a good option.

For testosterone release, studies have demonstrated that the highest response comes from training with a typical hypertrophy rep scheme of a higher number of sets performed for 10 reps at 75 percent of your one-rep max with a 2-minute rest interval.

Muscle Fiber Recruitment

Paying attention to how many muscle fibers are being worked is also critical in order to determine the rest period needed. If you’re doing a deadlift, for example, you’re using more muscle fibers than if you were to do a triceps kickback, therefore, rest is going to have to correspond to this.

Additionally, if you’re using advanced training principles such as supersets, drop sets, or negatives, you will also want to have more rest time in between sets in order to compensate.

Enhanced Fat Burning

While there is some truth to the fact that a shorter rest will help promote fat burning, you need to keep things in context. By incorporating 30-second rest periods into your workouts, you will be able to perform more overall work during the given time frame, increasing your calorie burn.

Also, there will be a great buildup of lactic acid during the workout and a higher amount of oxygen debt created (due to faster movement from exercise to exercise,) so you will experience a higher amount of excess post-exercise oxygen consumption and post-workout calorie burn.

However, total calories taken in versus total calories expended is what determines fat loss. By using lower reps, you will be able to lift heavier, so you'll have a greater chance of maintaining your muscle mass, which burns a higher amount of calories 24 hours a day. This will require a longer rest period, however.

This in itself will keep your metabolism revved up, so provided you are on a good diet, you can still get a very good rate of fat loss while keeping slightly longer rest periods.

Diet Design

On a low-carbohydrate diet, you won’t have as many stored muscle glycogen reserves, so they could be used up very quickly with short rest periods.

Additionally, you might find that you fatigue a lot quicker when on a low-carb diet, so trying to maintain an appreciable amount of weight using short rest periods would be harder.

For this reason, keeping rests between 90 seconds and 2 minutes when reducing carbs would be a smart plan.

Supplement Use

The last point you want to think about has to do with the type of supplements you’re taking. If you are taking creatine, you are going to have a full level of creatine phosphate in the muscle tissues, which will help synthesize adenosine triphosphate (which is used for muscle contractions) rapidly, allowing for shorter, 30-second rest periods.

If you are not on creatine and don’t eat a great deal of red meat, you may not have a full supply, and might fatigue a great deal faster when using shorter rest periods.

And the Rest...

As you can see, managing your rest periods is a fundamental part of making sure you're getting the results you want in the gym. Keeping these factors in mind when considering the pace you set for yourself throughout your training program will ensure you're giving your rest periods the attention they deserve.