Jack finishes a focused set of exercises and re-racks the weight. His legs are wobbly, he feels light headed and he takes a big swig from his water bottle. He looks down at his watch and presses the start button to begin counting down backwards from 2 minutes.

Somebody told him that 2 minutes is the ideal rest time between sets in the gym, and he wants to get it exact. Every time the watch beeps, he’ll be back in the squat rack to perform another set. He stands up tall and paces around trying to catch his breath in preparation for his next battle.

When thetime is up he doesn’t feel really ok. His legs still feel weak, but it doesn’t matters how he feels, because his 2 minutes have passed and he have to go back to perform another set of exercises.

So, he starts the next set. His legs are burning and he wishes that he could have had more time to prepare for this set. He starts the set, but just with a mediocre effort. He finishes the set. Again, he push the button. He does’nt know but, just as a lot of guys in another gyms, he is making a big mistake.

By having a set rest interval between sets, he is forcing his body to train at an effort level that is far less than his maximum potential and is severely sacrificing the amount of muscle growth he can ultimately stimulate because of this.

Muscles grow because of an adaptive response to stress. You lift X amount of weight for Y number of reps, and your body adapts to this level of stress. In order to see continual gains in muscle size, you must continually force X and Y to higher and higher levels.

In other words, building muscle is all about progression in both weight and reps. It is about lifting as much weight as you possibly can for the greatest number of reps that you possibly can (within a given rep range of course) and then continually striving to improve.

If you don’t rest enough between sets, you will not reach your maximum strenght potential sacrificing the amount of weight you can lift, and also sacrificing the amount of muscle you can build. So, to begin the next set qhen you are still tired is the big mistake you should not make.

A watch will never tell you when you are ready to begin the next set. Instead of it, listen to your body and you will know when to follow your training.

A deadlift and a tricep pressdown aren’t exactly in the same boat here. After a heavy set of deadlifts to failure I’ll usually be resting for at least 5 minutes, often even more. A set of tricep pressdowns is obviously not as taxing and may only require a rest period of 2.5 minutes for me to feel fully recovered.