Inter-Limb Asymmetry and Its Limited Role in Physical Performance and Match Demands in Football Players with Spastic Hemiparesis-An Exploratory Team Study.

Background

Inter-limb asymmetry has been widely studied as a potential determinant of physical performance in able-bodied athletes; however, its functional relevance in athletes with neurological impairments such as spastic hemiparesis remains unclear. This study aimed to examine the associations between lower-limb isometric strength, inter-limb asymmetry, physical performance, and match external-load variables in elite CP football players.

Methods

Eleven male football players with spastic hemiparesis from the Spanish national team competing at the 2024 IFCPF World Cup participated in this observational cross-sectional study. Maximal isometric strength of the plantar flexors, adductors, and hamstrings was assessed using a belt-stabilised dynamometer. Inter-limb asymmetry was calculated as a percentage difference between affected and non-affected limbs. Physical performance was evaluated using sprint, change-of-direction, dribbling, and intermittent endurance tests. Match external-load variables were collected during official competition using inertial measurement units. Associations were analysed using Spearman's rank correlations, and between-group comparisons were conducted using a median split based on asymmetry magnitude.

Results

Inter-limb asymmetry did not significantly differentiate physical performance outcomes across any field-based tests (p > 0.05). Associations between isometric strength or asymmetry and field-based performance were limited and did not remain statistically significant after false discovery rate correction. In contrast, plantar flexor asymmetry showed significant negative associations with mechanical work (ρ = -0.84; q = 0.010) and metabolic power (ρ = -0.83; q = 0.010), which remained robust after multiple-comparison control.

Conclusions

Inter-limb strength asymmetry did not appear to be a primary determinant of field-based physical performance in CP football players with spastic hemiparesis. Most associations between strength, asymmetry, and performance should be considered exploratory. However, plantar flexor asymmetry showed a consistent association with selected mechanical and metabolic match-load variables, suggesting that neuromuscular asymmetry may influence specific aspects of match demands. Given the exploratory team-study design and limited sample size, these findings should be interpreted cautiously and require confirmation in larger cohorts.