Stretch–shortening cycle exercise produces acute and prolonged impairments on endurance performance: is the peripheral fatigue a single answer?

Abstract

Objective: This study aimed to verify the acute and prolonged effects of stretch–shortening cycle exercise (SSC) on performance and neuromuscular function following a 4-km cycling time trial (4-km TT). Methods: On separate days, individuals performed a 4-km TT without any previous exercise (CON), immediately (ACUTE) and 48 h after (PROL) SSC protocol (i.e., 100-drop jumps). Neuromuscular function was measured at baseline SSC (baseline), before (pre-TT) and after (post-TT) 4-km TT. Muscle soreness and inflammatory responses also were assessed. Results: The endurance performance was impaired in both ACUTE (− 2.3 ± 1.8%) and PROL (− 1.8 ± 2.4%) compared with CON. The SSC protocol caused also an acute reduction in neuromuscular function, with a greater decrease in potentiated quadriceps twitch-force (Qtw.pot − 49 ± 16%) and voluntary activation (VA − 6.5 ± 7%) compared for CON and PROL at pre-TT. The neuromuscular function was fully recovered 48 h after SSC protocol. Muscle soreness and IL-10 were elevated only 48 h after SSC protocol. At post-TT, Qtw.pot remained lower in ACUTE (− 52 ± 14%) compared to CON (− 29 ± 7%) and PROL (− 31 ± 16%). Conclusion: These findings demonstrate that impairment in endurance performance induced by prior SSC protocol was mediated by two distinct mechanisms, where the acute impairment was related to an exacerbated degree of peripheral and central fatigue, and the prolonged impairment was due to elevated perceived muscle soreness.