Adverse effects of unilateral transfemoral amputation on para-alpine sit skiers and mitigation methods

Objectives: This study aimed to evaluate the adverse effects of unilateral transfemoral amputation on neuromuscular and kinematic parameters in alpine sit skiers, and to determine if additional restraints on the human–bucket interface could help mitigate the effects. Design: Cross-sectional, repeated measures study. Methods: Simulated skiing tests were conducted indoors involving 10 skiers with unilateral transfemoral amputation and 10 able-bodied participants. A Paralympic silver medalist performed slalom skiing tests on snow. These tests were conducted with and without additional strapping on the residual limb. Surface electromyography of trunk muscles and athletic performance was measured, and the asymmetry index was calculated. Results: Athletes were significantly dependent on muscle activation on the dominant side (asymmetry index = 7.8 %–28.3 %, p < 0.05). Worse athletic performance to the dominant side was found based on inclination angles of the indoor board (asymmetry index = − 9.8 %, p = 0.014) and outdoor sit ski (− 11.1 %, p = 0.006), and distance to the gate poles during skiing turns (18.6 %, p < 0.001). After using additional restraints, the above asymmetry index declined significantly (asymmetry index < 4.5 %, p < 0.05). Furthermore, athletic performance was significantly improved on both body sides by 11.1 %–30.7 % (p < 0.05). Conclusions: Unilateral transfemoral amputation caused the dependence on the trunk muscles of the dominant side and the corresponding unilateral poor performance in athletes. Adjusting restraints in the human–equipment interface by additional strapping could mitigate the asymmetry issues and improve athletic performance.