'No pain, no gain' is a harmful, inaccurate myth

Pain during a set is usually a signal to stop, not to push through

The phrase 'no pain, no gain' blends two completely different sensations: the burn from metabolite buildup in a working muscle (normal, even useful for growth) and actual pain — sharp, acute, localized in a joint or tendon (a warning sign worth respecting). The problem is beginners are often taught to push through any pain as proof of a 'real' workout.

The burn toward the end of a set comes from acidification and metabolite buildup like lactate — this is genuinely one of the mechanisms that drives growth through cellular stress. Sharp pain in a knee, shoulder, or lower back during a movement, on the other hand, usually signals a technique breakdown, joint overload, or ligament strain, and it risks an injury that can set you back months.

Good rule of thumb: burning in the muscle at the end of a set — fine. Sharp pain in a joint — stop. Learning to tell these two signals apart is one of the skills that separates an experienced lifter from a beginner.