Mechanical tension

Mechanical tension is the force generated within a muscle as it contracts against resistance. Sensed by the muscle's mechanoreceptors, it is considered the principal stimulus that triggers the signalling for muscle growth.

It matters because it reframes what makes training effective: not simply feeling a pump or fatigue, but producing high tension through challenging loads and full range of motion across enough hard sets.

In practice, tension is maximised by lifting appreciable loads with control, especially through the lengthened portion of a movement, and taking sets reasonably close to failure.