Abstract
BACKGROUND: Changes in neuromuscular ability in middle age (MA) may lead to deterioration of postural control. The aim of this study was to investigate the anticipatory response of the peroneus longus muscle (PL) to landing after a single-leg drop-jump (SLDJ), and its postural response after an unexpected leg-drop in MA and young adults. A second aim was to investigate the influence of neuromuscular training on PL postural responses in both age groups. METHODS: Twenty-six healthy MA (55.3 ± 4 years) and 26 healthy young adults (26.3 ± 3.6 years) participated in the study. Assessments were performed before (T0) and after (T1) PL EMG biofeedback (BF) neuromuscular training. Subjects performed SLDJ, and PL EMG activity in preparation for landing (% of flight time) was calculated. To measure PL time to activation onset and time to peak activation in response to an unexpected leg-drop, subjects stood on a customized trapdoor device that produced a sudden 30° ankle inversion. RESULTS: Before training, the MA group showed significantly shorter PL activity in preparation for landing compared to the young adults (25.0% vs. 30.0%, p = 0.016), while after training there was no difference between the groups (28.0% vs. 29.0%, p = 0.387). There were no differences between groups in peroneal activity after the unexpected leg-drop before and after training. CONCLUSIONS: Our results suggest that automatic anticipatory peroneal postural responses are decreased at MA, whereas reflexive postural responses appear to be intact in this age group. A short PL EMG-BF neuromuscular training may have an immediate positive effect on PL muscle activity at MA. This should encourage the development of specific interventions to ensure better postural control in this group. TRIAL REGISTRATION: ClinicalTrials.gov NCT05006547.