Light-load (30% 1RM) resistance exercise to failure produces greater total muscle activation volume (iEMG) and more prolonged impairment of isokinetic torque recovery at 48 hours than heavy-load (80% 1RM) resistance exercise, despite similar molecular responses.

When muscles are worked with light weights until exhaustion, they contract many more times than with heavy weights, which drains energy stores and builds up metabolic waste. This stress disrupts the muscle's ability to release calcium, which is needed to make the muscle contract forcefully. Without enough calcium, the muscle cannot generate full force, and it takes longer to recover. Even though the muscle's growth signals and cleanup systems work the same as with heavy weights, the fatigue lasts longer because calcium handling recovers slowly.