Resting longer between sets lets you lift heavier or do more reps overall, and that extra work might be why your muscles grow a little more — not because of hormones or anything else.

Increasing rest intervals between sets enhances total training tonnage, which amplifies mechanical tension accumulation and thereby increases the hypertrophic stimulus.

Increasing rest intervals between sets enhances total training tonnage, which amplifies mechanical tension and thereby increases skeletal muscle hypertrophy.

If you take only 20 seconds between sets, you have to do way more sets to match the same total weight lifted as someone taking 2-minute breaks, making your workout longer and more intense.

Doing more sets in a workout helps you get stronger and bigger, but after a certain point, extra sets don’t help much—especially for strength. You hit your sweet spot for strength with fewer sets than you need for muscle growth.

If you work out more often, your muscles grow bigger — but only if you keep increasing your workouts, because your body gets used to the same routine and stops responding as well.