Countermovement jump performance after metabolically, but not mechanically demanding exercise: limited sensitivity to prolonged low-frequency force depression.

rationalePrevious studies indicate that countermovement jump (CMJ) parameters may reflect neuromuscular fatigue following exhaustive exercise. However, changes in CMJ performance in response to non-muscle damaging exercise, and its relation to prolonged low-frequency force depression (PLFFD) is yet unknown. PURPOSE: This study aimed to evaluate the relationship between PLFFD and CMJ test parameters following exhaustive cycling exercise to task failure.

methodsA sample of 11 recreationally active adults completed an incremental cycling protocol to task failure. CMJ performance, low-frequency (10 Hz) force, and maximal voluntary contraction (MVC) force output were assessed at baseline (pre-exercise), immediately after task failure (0 min), and at 8 min, 15 min, 60 min, 24 h, and 48 h post-task failure. PLFFD was assessed as the ratio of 10 Hz to MVC force.

resultsCompared to baseline, PLFFD was larger from 0 min (7.4%) to 60-min (6.7%, p < 0.002). In contrast, no substantial changes in CMJ parameters were observed, except for a reduced concentric impulse (ConImp) lasting 8 min post-exercise.

conclusionThe results show that CMJ parameters remain unchanged following non-eccentrically loaded exhaustive exercise, while PLFFD is significantly higher for up to 60 min post-exercise. This raises questions about the utility of CMJ as a fatigue assessment tool in athletic populations. This suggests that CMJ testing may not effectively detect the presence of PLFFD following non-muscle damaging exercise and future research should explore alternative measures for monitoring neuromuscular fatigue in training contexts.