Phase-specific countermovement jump metrics — including braking rate of force development, modified reactive strength index, and eccentric work — are more sensitive indicators of residual neuromuscular fatigue than overall jump height in resistance-trained adults following high-volume resistance exercise, allowing for earlier detection of incomplete recovery.

After intense leg exercise, muscles accumulate waste products that slow down their ability to generate force, and the nervous system reduces its signals to muscles. This makes it harder to quickly stop and rebound during a jump, reducing the energy stored in tendons and the speed of force production. The body tries to compensate by changing how it moves, but this makes the jump less explosive, even if height stays the same.