Generally the guidelines you will come across for resistance training rest intervals look something like this: 3-5 Minutes for Strength and 1-2 Minutes for Hypertrophy. For years this has been published in magazines, strength training manuals and personal trainer/exercise science educational books. As a matter of fact the first PT Certification I did made these exact recommendations. It has been thought for years that keeping rest intervals shorter will induce better Hypertrophy due to higher levels of metabolic stress, as well as acute hormonal responses that will lead to growth.

On the surface, this does make sense, but most of the recent literature is showing otherwise. In a 2016 Study comparing 1 vs 3 minute rest intervals the 3 minute group saw significantly greater increases in Strength AND Muscle Thickness. To many this is surprising, however ability to perform more total Volume is the key driver behind Strength and Hypertrophy gains. A longer rest interval will allow this to occur. When we put a time constraint on our rest intervals some issues in regards to volume can arise. Rushing into a set before the muscles are recovered and ready to go will ultimately lead to a reduction in volume on that particular set. More than likely a rep will be failed and this will unravel into the following set. As you can imagine doing this over time will lead to a lot less total volume performed. (Volume being Reps x Sets x Load). Lets look at an example to clarify this.

We have a lifter with a prescribed Squat day of 250x3x10 which is approximately 70 percent of their 1RM. This means 250 Pounds for 3 sets of 10 reps.

The lifter decides to keep rest intervals to 60-90 seconds.

Set 1: 10 Reps

Set 2: 8 Reps

Set 3: 7 Reps

After the first set they barely had time to recover. Since the legs and lungs were not full recovered they only achieved 8 on set 2 and then had a very grindy 7 reps on set 3. At this point they were DONE on Squats and more fatigued for their next movement. They accumulated 6,250 Pounds of Squat Volume (250 pounds x 25 Reps).

The following week they decided to come back and try again, only this time they decide rest roughly 3-5 Mins or as long as needed to be able to complete the next set.

Set 1: 10 Reps

Set 2: 10 Reps

Set 3: 10 Reps.

BOOM! They completed all 3 sets and the final set of 10 was smoother than the last set of 7 the week prior. Why? Because they did not get under the bar until they were ready to exert 100 percent effort into the set. This time they walked away with 7,500 pounds of squat volume (250 Pounds x 30 Reps). They were also more amped up to complete the next exercise in the program, unlike the week before when they were wrecked after Squatting.

So over time that extra 1,250 Pounds moved on the squat can add up. That is an extra 5,000 pounds monthly and 60,000 Pounds through the year. Imagine the difference these two approaches can yield across the board throughout all the exercises in a given program? That comes out to a whole lot of extra weight moved meaning more GAINZ to be made.

So what is the practical takeaway here? If Strength and/or Muscle Growth are your objectives with training, manipulations should be made to ensure that the most volume with which you can recover from and progress is performed in an efficient manner. Taking shorter rest intervals will almost always compromise the ability to do so. In my opinion it is best to take as long as needed, especially on your bigger compound exercises. These are also exercises which require a high level of technique and focus. Going too soon is not only detrimental to your ability to perform more work, but highly increases the likelihood of injury as well. On smaller Isolation exercises such as a Bicep Curl, Lateral Raise or Leg Extension a 1-2 Minute rest interval may be more appropriate. These types of exercises are much easier to recover from than say a Squat, Press, Row Or Deadlift.

At the end of the day, you will know your body. Waiting until you feel fully capable to perform a set with the best possible effort is your best bet. Some days it may be longer than others and this is where auto regulation comes into play. Being married to a specific rest time is probably not ideal. Remember, Volume and Progression over time are what you should be after, not minimized rest periods.