When you lift weights until your muscles burn, the buildup of waste products might help your muscles grow bigger, but scientists aren't sure yet if it's actually causing the growth or just happening...

When you lift weights until your muscles burn and feel fatigued, the buildup of waste products might help your muscles grow bigger, but the main reason they grow is still from the physical force you're using.

Even if you make your muscles feel that burning, swollen 'pump' feeling during a workout by boosting certain chemicals, it doesn't actually make your muscles grow bigger—studies show muscle growth doesn't happen just from that sensation.

Even when your muscles burn and feel fatigued during a tough workout because of buildup of certain chemicals, that burning feeling itself doesn’t make your muscles grow bigger.

When your muscles burn and swell up during a tough workout, that feeling isn't actually what makes your muscles grow bigger—other things are responsible for the growth.

Even though your muscles feel swollen and burn during a tough workout, that feeling itself doesn’t actually make your muscles grow bigger—something else must be responsible.