What are rest times?
Well as the name implies it’s the time you spend resting in between exercises.
What are their purpose?
Is it just to break up your sets, so you can grab a drink of water and talk to your friends? No, their purpose is to allow your muscles to recover so you can keep performing sets at the intensity you need.
Now what tends to happen is that when doing bigger compound movements like the deadlift or squat people naturally wait longer between sets as these exercises use a lot of different muscle groups and a hard set can leave you feeling quite drained.
However, when it comes to isolation exercises they maybe stop for 30 seconds and then keep right on going as they feel fine after this.
Also, we commonly see recommendations for rest times as being longer when training for strength vs training to grow muscle.
The usual rest time suggested when training to build muscle is from 30 seconds up to a minute and a half. Now on these smaller exercises you might not feel completely shot and you might feel ok after a short break.
Why then think about rest times when you feel fine after a few seconds?
Let’s assume that you are training to build muscle (if you’re after a conditioning effect that’s a different topic and shorter rest times can certainly have their place).
If the object is to grow muscle you want to get the most out of every ounce of effort you put in to lifting those weights and as it turns out short rest times are not optimal for gaining muscle.
We can look to a particularly informative study published in the Journal of Strength and Conditioning comparing short versus long rest times and their effect on both muscle size and muscle strength.
They took two groups and had them complete 3 total body workouts a week for 8 weeks.
Half completed the workouts taking 1 minute of rest.
The others completed theirs with 3 minutes of rest between sets.
Both did 7 exercises per session and had their strength in the bench press and squat tested.
Also, their muscle thickness in the biceps, triceps and quadriceps was measured before during and after the study.
The results showed that the group who had 3 minutes of rest saw significantly greater increases in their strength on both the squat and bench.
They also saw much greater growth in their muscles.
The biceps had a 5.4% increase in thickness in the 3-minute group as opposed to just 2.8% in the other. The triceps showed by far the biggest difference with a 7% increase and only 0.5% for the 1-minute subjects. The quadriceps had almost double the growth with 6.9% for the shorter rest group and 13.3% for the longer group.
These results, I think, can put to bed once and for all the old recommendations for rest times when it comes to training for muscle gain.
We see quite clearly that 1 minute is vastly inferior to 3 so we can rightly conclude that 30 seconds would fair even worse.