By Stefan Ianev, Head Of Educational Development, Clean Health Fitness Institute
Welcome to the 6th installment of train like a pro. So far we have covered exercise selection, volume, intensity, type of contraction and tempo. We have learned how to manipulate each of these variables from the beginner to advanced trainee in terms of how to optimise hypertrophic adaptations. Before we delve into this month’s topic of rest intervals let’s do a quick recap of what we have learned so far;
- Beginners should generally perform 1-2 exercises per body part for 3-4 sets of 10-15 reps each using a controlled tempo
- Intermediates should generally perform 2-3 exercise per body part for 3-4 sets of 6-12 reps each with a combination of fast and controlled tempos
- Advanced lifters should generally perform 3-4 exercises per body part for 4-5 sets doing anywhere between 3 to 30 reps and using a combination of fast and controlled tempos
This month’s topic of rest intervals refers to the length of period between working sets. It is an important piece of the equation and needs to be looked at in context with all the other loading parameters because it determines whether the adaptations will be primarily neural or metabolic.
It is generally accepted that longer rest periods are optimal for strength development while shorter rest periods favour hypertrophy and fat loss. This is because complete recovery is required to lift maximal loads thus favouring strength gains while metabolic stress due to incomplete recovery is a key factor for fat loss and hypertrophy.
When determining optimal rest periods for a specific goal both neural and ATP recovery need to be considered. The nervous system may take up to 3 to 4 minute to fully recover between maximal efforts. Maximal efforts are generally considered sets of 5 reps or less taken to failure. When sets are not taken to failure neural recovery is a lot faster.
In terms of ATP recovery, the initial resynthesis is very rapid then begins to taper off. For example, after 1 minute 75% of ATP is resynthesised and after 3 minutes nearly all the ATP is resynthesised. This is demonstrated in the graph below;
|Rest (sec)||ATP Replenished (%)|
For maximal strength development, we already discussed that a full 3-4 minutes may be required for complete neural recovery so that already takes care of ATP recovery as well.
For hypertrophy the general recommendation is to keep rest periods down to 60 seconds or less. This is based on previous research that showed a greater growth hormonal response occurs when using shorter (1 min) vs longer (3 mins) rest periods (1).
Recent research however seems to suggest that the acute hormonal response from training may only play a minor role in the hypertrophic response (2). In fact, a recent study conducted by world leading hypertrophy researcher Brad Schoenfeld showed that longer rest periods not only led to greater strength increases but also were associated with a greater hypertrophy response (3).
We must be must be careful however when interpreting this literature as the subject were only matched for volume not volume load. Given that the longer rest periods permit the use of greater loads, the total work would be greater than when using shorter rest periods. In the real world, shorter rest periods allow for greater total volume to be performed for a given period so that could very well skew the data in favour of shorter rest periods since hypertrophy is largely a function of the volume of work performed.
Shorter rest periods are also associated with a greater metabolic response, which has been identified as one of the key factors for increasing hypertrophy (4,5). My personal recommendations for rest periods to maximize hypertrophy are as follows;
- For beginners, I generally recommend 60 to 90 seconds between sets unless they are very de-conditioned. Since they are generally not lifting very heavy or pushing to failure and beyond neural recovery is of far lesser concern. A moderate rest period will allow them to lift relatively heavy while also accumulating some metabolic fatigue but not to any excessive degree.
- For intermediates I may allow up to 2 minutes between their heaviest sets. As they are now much stronger those heavier sets start to take a much greater toll on the body in terms of both neural and metabolic fatigue. For example, squatting 120kg x 10 reps is much more demanding on the muscles, nervous system and cardiovascular system then say squatting 60kg x 10 reps.
- For advanced trainees, I usually limit the rest periods to 45 to 60 secs up to a maximum of 90 secs between their heaviest sets. Often advanced bodybuilders are not that much stronger than an intermediate but what sets them apart is their capacity to repeat high intensity efforts with minimal rest periods.
For example, even early on in his career the great Arnold Schwarzenegger was extremely strong because he trained more like a powerlifter using longer rest periods and maximum poundages. Later, when his physique was a lot more developed and refined he wasn’t all that much stronger but he had the capacity to repeat those heavy lifts with minimal rest periods. Arnold reported that even between his heaviest sets he only rested 1 minute and often he performed supersets, trisets and even giant sets.
Ronnie Coleman was another example of a highly successful bodybuilder who started out as a powerlifter. The heavy strength work with longer rest periods build his foundation of strength and mass early on but it wasn’t until later in his career when he started training with higher volume and shorter rest periods that he developed the freaky mass and conditioning that earned him 8 Mr Olympia titles. He was still freakishly strong but his strength increase wasn’t proportional to all the extra muscle mass he had accumulated from the higher density training.
Another benefit of shorter rest periods aside from allowing you to do more work for a given period is an increased expression of mitochondrial enzymes. Mitochondria are the cells where energy produced therefore recovery and fat burning are both enhanced. This not only makes it much easier to get lean in the first place but also to stay lean in the off-season with very little effort. This is one reason why Arnold and the bodybuilders from the 70s who used very high volume and short rest periods did very little cardio.
That about wraps up this segment on rest periods. Tune in next month for the final installment as we look at frequency.
- Kraemer WJ, Marchitelli L, Gordon SE, et al. Hormonal and growth factor responses to heavy resistance exercise protocols. J Appl Physiol. Oct 1990;69(4):1442-1450.
- Schoenfeld BJ, Postexercise hypertrophic adaptations: a reexamination of the hormone hypothesis and its applicability to resistance training program design. J Strength Cond Res. 2013 Jun;27(6):1720-30.
- Schoenfeld BJ, et al. Longer Interset Rest Periods Enhance Muscle Strength and Hypertrophy in Resistance-Trained Men. J Strength Cond Res. 2016 Jul;30(7):1805-12.
- Schoenfeld, BJ. Potential mechanisms for a role of metabolic stress in hypertrophic adaptations to resistance training. Sports Med. 43: 179-194, 2013.
- Schoenfeld, BJ. The mechanisms of muscle hypertrophy and their application to resistance training. J Strength Cond Res24(10): 2857-2875, 2010