Monday 21 March 2016

The Best Rest Interval for Building Muscle & Strength

Want to pack on some muscle? For optimal results, you need to get the important training variables nailed down. Among these variables is your rest time between sets. Check out what the latest research says about how long you should rest between sets to build the most muscle and strength.

Study Reference:
Schoenfeld, BJ., et al. Longer inter-set rest periods enhance muscle strength and hypertrophy in resistance-trained men. Journal of Strength & Conditioning Research. Post Acceptance: November 20, 2015. 

In this study, 23 university-aged men (with a minimum of 6 months lifting experience) were divided into 2 groups. Each group did a 3 day per week, whole body resistance training program consisting of 7 exercises each done for 3 sets of 8-12 reps to momentary concentric failure (i.e. couldn’t lift the weight one more time). One group rested 1 minute between sets and the other group rested 3 minutes between sets. The study lasted 8 weeks.

Due to the longer rest times, the 3 minute rest group ended up doing higher volume load (weight x reps x sets). The longer rest time group achieved greater size gains in their biceps, triceps and quads. The longer rest interval group also had greater gains in their 1 rep max squat and bench press. Rest interval time did not seem to influence increases in muscular endurance.

Overall, this was a great study. However, there were a few limitations. With only 23 subjects (and 2 dropped out), this is quite a small sample size. The length of time (8 weeks) is not that long of a time – especially for hypertrophy research. This is because gains in muscular size typically come after various neuromuscular adaptations (e.g. motor unit recruitment, skill) have taken place. Also there was minimal nutritional control. The subjects were instructed to maintain normal nutritional practices and given a post-workout shake.

I really like this study. I really appreciate Brad Schoenfeld’s research. The unique thing about Brad is that he spent a long time as trainer before he became such a respected researcher. I love how Brad designs studies that really matter to trainers – the outcome studies. It is nice to know that a certain type of training intervention caused a temporary spike in testosterone, increased protein synthesis or that a certain exercise caused great EMG muscle activation. These types of studies help us grow in our understanding of why certain training protocols work. However, none of this matters if a training program fails to deliver results. As a trainer I really care about the outcome studies. I want to know what works better achieve the things that my client and athletes care about – muscle gains, fat loss, strength gains and performance improvement. 

Outcome studies are way harder to do and take a lot more time. This is why you may see things like small sample sizes and variables (e.g. nutrition, sleep) that are not meticulously controlled. However these limitations are worth it to learn what really matters – your results!

Real World Application for You and Your Training
We have known for a long time that sufficient rest is important for getting stronger. For size gains, the traditional recommendation has been to use shorter rest intervals. However, while shorter rest intervals cause more metabolic fatigue, volume load seems to be the critical variable in building muscle. If you short-chance your rest intervals, you hinder your ability to lift heavy enough weight for a sufficient volume and thus limit your muscle gains.

Longer rest times does not necessarily mean that you need way longer training sessions. For example, I often (in my own training and the programs I write) use alternating sets. For example I might do a set of weighted chin-ups, rest, do a set of overhead press, rest and then return to the chin-up. This gives me around 2-3 minutes rest before my next set up chin-ups, but I use some of that rest time to train the opposing muscles and this make my training way more time efficient with minimal interference to my volume load. 

Don’t use this research to limit yourself to only longer rest intervals. While this length time may be best for the majority of your lifts, you can still benefit from some use of shorter rest intervals to induce more metabolic fatigue. For example, on a main lift like the overhead press, you could rest 3 minute between sets to allow you to move some respectable weight. Then, on side raises, you could use shorter rest intervals to really accumulate some metabolic fatigue.

This research is especially beneficial for athletes. If you are an athlete who wants to get bigger, you must get both bigger AND stronger. If your mass increases disproportionately to your strength, you could actually make your strength-to-weight ration worse and hurt your performance. However, for bodybuilders looking to pack on the most amount of muscle regardless of their strength-to-weigh ratio a combination of long and short rest intervals is ideal.

Optimal rest times can differ depending on many factors such as: training age, fiber type dominance, work capacity, aerobic fitness, the systematic stress of an exercise and more. For more information on rest intervals, check out my post: How to Personalize Your Rest Intervals for Optimal Results.

How about you? How long do you typically rest between sets? I invite you to leave your questions and comments below or on my Facebook page.

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