Feed-forward lower extremity muscle activation and onset timing following functional fatigue during lateral hop landing

Abstract

Abstract Background Fatigue-induced alterations in neuromuscular control may compromise dynamic ankle stability during landing tasks. However, limited evidence exists regarding the effects of fatigue on feed-forward lower-extremity muscle activation in athletes with different levels of dynamic balance performance. Therefore, this study investigated the effects of functional fatigue on anticipatory muscle activation and onset timing during lateral hop landing in athletes with lower versus higher dynamic balance performance. Methods Participants were classified into lower dynamic balance ( n = 10) and higher dynamic balance ( n = 12) groups according to normalized Y-Balance Test (YBT) performance. Surface electromyography was used to assess feed-forward muscle activation and onset timing of the peroneus longus, tibialis anterior, lateral gastrocnemius, and gluteus medius during a lateral hop-landing task before and after a functional fatigue protocol consisting of maximal forward running, side-stepping, directional changes, and backward running. Electromyographic amplitudes were normalized to maximum voluntary isometric contractions. Linear mixed-effects models were used to examine the effects of time, group, and the Time × Group interaction, with participant included as a random effect. Results Significant Time × Group interaction was observed for tibialis anterior activation ( p = 0.007, η² p = 0.329), with activation increasing after fatigue in the lower dynamic balance group but decreasing in the higher dynamic balance group. No significant Time × Group interactions were found for peroneus longus, lateral gastrocnemius, or gluteus medius activation ( p = 0.338, 0.931, and 0.357, respectively). A significant main effect of Time was observed for lateral gastrocnemius activation ( p = 0.047). For muscle onset timing, no significant Time × Group interactions were observed for peroneus longus, tibialis anterior, lateral gastrocnemius, or gluteus medius (all p > 0.05). Conclusion Functional fatigue affected tibialis anterior activation during lateral hop landing. No significant fatigue-related between-group differences were observed for peroneus longus, lateral gastrocnemius, gluteus medius, or muscle onset timing. These findings suggest that dynamic balance performance may influence the neuromuscular response to functional fatigue, particularly tibialis anterior activation.