Active Tension

The most important characteristic of a muscle is its ability to develop tension and to exert a force on the body lever. Active tension refers to the tension developed by the contractile elements of the muscle — that is, by crossbridge formation and the movement of actin and myosin.

Related facts in the source:

• A muscle contracts toward the middle of the muscle belly from both ends (insertion to origin).
• Two-joint muscles generate the greatest force when not required to shorten over both joints simultaneously.

• Active tension = tension from the muscle's contractile elements.
• Generated by crossbridge formation and the movement of actin and myosin.
• A muscle's defining characteristic is its ability to develop tension / exert force on the body lever.
• Muscle contracts toward the middle of the belly from both ends (insertion to origin).
• Two-joint muscles produce greatest force when not shortening over both joints at once.

• length-tension-relationship — how tension varies with muscle length.
• skeletal-muscle-structure — actin/myosin contractile machinery.
• atp-molecule — energy crossbridges use to generate tension.