Training intensity is the MAIN driver of progression and growth. Training with a high intensity is only safe if you’re resting properly and know how to perform each exercise.

Intensity is the proximity to failure you reach on any given set. Volume is only effective if done with enough intensity with each set.

¹Sets taken to failure yield the same growth as sets with 0-3 reps in reserve according to studies. However beginner trainees usually think they’re going to failure, but they’re not, so telling them to train at 3 reps in reserve will most likely lead to lower quality sets, which leads to lower quality volume, which can then lead to junk volume and much less growth in that same time period.

Taking a set beyond failure would be done using a high intensity technique. Examples of that would be:

Drop sets – doing the same exercise but with lower weight right after the main set with no rest. Usually, it’s a good idea to only keep lowering the weight until 50-60% of the initial weight. Done at the very end of the workout usually, or after the last set for the exercise.

Myo-reps – repeating the exercise for as many reps as possible 10-15 seconds after the initial set. Can be repeated multiple times, usually done if you don’t hit a rep goal with the initial set.

Partial reps – should only be done once you hit technical failure to reach muscular failure as well. Once you finish a set you simply keep trying to lift the weight as hard as you can, not doing full reps. These do not count as actual reps, but can be noted down as half reps.

Cheat reps – these should mostly be used as a high intensity technique. Once you can no longer lift the load concentrically, you can use momentum to get it up, then slowly let it down with full control.

An immensely popular method that utilizes extremely high intensity at the cost of you doing low volume and low frequency is HIT (high intensity training). A general explanation: you do one true working set after warming up. Then you finish your one and only working set for the exercise. Upon finishing it, you use every single imaginable high intensity technique. That is the only set you will do for said exercise, then you will take at least a week off from training that muscle.

It’s an extreme example, however if a training system based solely upon high intensity can work, that shows just how important it is. Systems based on only high volume, but no intensity only work for genetically gifted people on steroids. Most people must utilize intensity to build muscle to its fullest potential.

The reason why I recommend starting off with about 6-8 sets per week for each muscle group is intensity. Learning to put intent into each set and move the weight as hard as possible, then control the descent, and then repeat to muscular failure is very important. It will lead to far more gains than high volume with no intensity ever could. You only really need to start adding sets to each workout if you’re recovering way before your next training session or if you’re no longer progressing.

There is a use to training with lower intensity. Limiting intensity and staying away from failure is a really good way to progress on the big main lifts (squat, bench, deadlift, overhead press). Part of the reason for that is that fatigue doesn’t build up nearly as fast if you limit intensity. Joint stress also doesn’t ramp up as fast.

Essentially, intensity is what stimulates the body to grow and get stronger. If you train with enough intensity you will grow.

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4731492/ ↩︎