Bodybuilders like to feel a muscle working, but for us regular folks, that's not actually a rule you need to follow.

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Creating a physique that can win at the highest level of professional bodybuilding requires superhuman self-discipline, intense training and genetic good fortune. Increasingly, say the people familiar ...

The latest science shows you might not have to choose.

Muscle contraction is the tightening, shortening, or lengthening of muscles when you do some activity. It can happen when you hold or pick up something, or when you stretch or exercise with weights.