Why Your Tendons Lag Your Muscle by 6 to 8 Weeks

Added: 2026-05-17

[00:00:00]Well, Kubo and colleagues ran a study where subjects trained their calves with hard, sustained contractions for several months while researchers tracked both the muscle and the Achilles tendon over time. It's in the back of your leg, by your ankle. Muscle strength went up by month two, but tendon stiffness didn't catch up until month three. Even when the protocol was specifically designed to drive tendon adaptation, the tendon was still weeks behind the muscle.

[00:00:25]Think about this like the muscle's the engine in the car, and the tendon is the chassis that transmits the engine's power to the road. In early training, the engine be builds faster, it gains more horsepower than the chassis. The muscle can produce way more force before the tendon has finished reinforcing itself for it.