Everyone’s body responds differently to workouts—what works wonders for one person might be too much or too little for another, because of differences in genes, energy use, and how fast they recover.

Total training volume, training intensity, and consistency are more significant determinants of muscle hypertrophy than the specific muscle length at which training occurs.

The total amount of work done (weight × reps × sets) seems to matter for muscle growth — more work generally leads to more muscle, even if the weights are light.

If you lift weights, your muscles grow bigger — but only up to about 45 sets a week per muscle group; after that, you don’t get much extra growth no matter how much more you train.

Lifting weights more often each week helps you build more muscle—but only up to a point. After a certain amount, you don’t get much extra benefit, so there’s a sweet spot for the best results.

Your muscles grow bigger not because of just one thing like lifting heavy weights or doing lots of reps, but because of how all the workout factors—like how hard you push, how often you train, and how well you recover—work together.