Author(s): MURGIA, A., D'EMANUELE, S., GHIOTTO, L., AMINI, M., PILERI, A., SCHIAVO, M., SCHENA, F., TARPERI, C., Institution: UNIVERSITY OF VERONA, Country: ITALY, Abstract-ID: 2040

INTRODUCTION:
High-eccentric demands in sport can differentially compromise force production and stretch–shortening cycle (SSC) behavior. Since the squat jump (SJ) emphasizes concentric output, whereas the drop jump (DJ) is more dependent on SSC efficiency and neuromuscular control [1], fatigue may induce task-specific performance decrements. Sex-related differences in muscle–tendon properties may modulate these responses, but evidence from functional jump tasks following eccentric tasks is limited. We examined sex differences in fatigability-related changes in SJ and DJ performance after incremental eccentric cycling to volitional exhaustion. We hypothesized that fatigue-induced decrements would differ by sex, particularly in DJ outcomes.
METHODS:
18 physically active subjects (9 F vs 9 M; 23±1 vs 23±2 years; 164.9±7.3 vs 177.4±8.0 cm; 55.8±4.6 vs 73.2±6.1 kg, respectively) matched for test duration, participated in the study. After a warm-up on a cycle ergometer, participants performed three SJs and three DJs in a randomized order, pre- and post-fatiguing task (within 2 min). Jump performance was assessed using an optical infrared system. Jump height was calculated for both SJ and DJ, and the reactive strength index (RSI) was calculated from DJ. The fatiguing task consisted of an incremental test on an eccentric cycle ergometer (starting at 100 W for males and 50 W for females +25 W·min⁻¹; starting workload was sex-specific to match time-to-exhaustion across participants; 65±5 rpm) until volitional exhaustion. Linear mixed models tested the effects of time, sex, and their interaction (participant as random intercept).
RESULTS:
A significant effect of time was observed for all performance variables (all p-values were ≤ 0.011), with SJ height decreasing by 7.67% (Δ=-2.23 cm, 95% CI -3.16 to -1.30 cm), DJ height by 11.94% (Δ=-3.49 cm, 95% CI -5.52 to -1.46 cm), and RSI by 18.24% (Δ=-0.21, 95% CI -0.36 to -0.07). Significant effects of sex were also found for all variables (all p-values were ≤ 0.011), with males exhibiting higher values than females in SJ height (Δ=7.59 cm, +31.43%, 95% CI 3.97 to 11.21 cm), DJ height (Δ=10.79 cm, +48.90%, 95% CI 6.11 to 15.48 cm) and DJ RSI (Δ=0.36, +41.94%, 95% CI 0.12 to 0.60). However, the time × sex interaction did not reach significance (SJ p=0.073), although point estimates suggested larger SJ height decrements in females than in males (−12.20 vs -4.07%).
CONCLUSION:
Eccentric cycling to volitional exhaustion impaired both concentric (SJ height) and SSC-related (DJ height and RSI) jump performance overall. Although men showed higher absolute values, the magnitude of fatigue-induced decrements did not differ significantly between sexes; SJ showed a non-significant tendency toward larger reductions in females. Practically, both SJ height and the SSC-related measures (DJ height and RSI) are sensitive markers of post-eccentric fatigue in mixed-sex settings, while SJ may be better suited to detect subtle sex-specific responses.

[1] Kyne H, Cronin JB.2025