The Studies:

I’ve been very interested in the ability of rest intervals to effect our training. Particularly, when do you prescribe a particular intra-session rest interval and what is the property duration depending on your goal.  What’s best for Strength, for endurance, and for hypertrophy.  I’ve found three studies that examined this topic and compiled them here for you to digest.

[divider]Muscle Strength[/divider]

This one is probably the most obvious considering a lot of powerlifter’s and training programs have their rest intervals outlined from the get-go.  Most say that your time between sets should be between 2-3 minutes for optimal strength. In other words, allowing yourself to rest over 120 seconds will allow you to lift more.  This doesn’t necessarily mean that you’ll GROW more, but just that your bench or squat may be greater than had you taken a shorter break.

It’s always refreshing to find multiple peer-reviewed studies that have the same findings, but are discovered different ways.  This is exactly the case in this scenario.  All three studies found that applying anywhere from 2 to 5 minutes between sets results in greater muscle strength for various exercises (hamstring workout, bench, squat) than 30-90 second intervals.  In one study, performance reductions were noted in the second set when using a sub 90 second rest while they weren’t noticed until the 3rd and 4th set with intervals greater than 90.  There was no significant difference between 2-5 minute intervals.

From a psychological perspective, even if 90 seconds doesn’t seem to affect you physically, from a mental standpoint the studies concluded that it may be beneficial when pursuing max exertion.

Conclusion: Use 2-5 minute intervals when focusing on strength.

[divider]Muscle Hypertrophy[/divider]

This one appeals more to the bodybuilders than the heavy lifters.  However, it was the least researched of the bunch.  The studies found that 30-60 second intervals for moderate-intensity workouts was the most conducive to muscle growth.  This was due to “greater acute levels of growth hormone”.

Conclusion: If you want to build muscle try to limit your rest intervals when performing moderate-intensity workouts to 30-60 seconds.  As a general suggestion from a bodybuilder, this usually isn’t applicable 24/7 otherwise you’d burn out fast.  I’d recommend maybe employing these rest intervals on your last two sets or maybe before performing a drop set.  These are great tricks to beat plateaus and maybe incorporating this rest interval will make it even more effective.

[divider]Muscle Endurance[/divider]

Muscle endurance may not appeal to powerlifters or bodybuilders, but it certainly would appeal to athletes.  Cross-fit, football, and any other athletes for example would certainly benefit from upping their endurance for performing an exercise.  The study found that “Shorter rest intervals of 20 seconds – 1 minute resulted in higher repetition velocities during repeated submaximal muscle actions and also greater total torque during a high-intensity cycle test.  In layman’s terms, you’ll up your conditioning thus your muscle endurance will increase.

Conclusion: Keep rest intervals between 20 seconds to 1 minute to improve your muscle endurance.

As always…thank you smart people for making our training better.