Background: Insufficient rigidity of the foot owing to its ligaments and muscles can decrease the attenuation of the ground reaction force during landing. Therefore, dysfunction of the ankle invertors may increase the proximal joint load during landing.
Research question: What are the effects of the fatigued ankle invertors on workload in the lower extremity joints during single-leg landing?
Methods: Twenty-seven young adults (13 men and 14 women) performed landing trials in the forward and medial directions before and after exercise-induced fatigue of the ankle invertors. The exercise consisted of repeated concentric and eccentric ankle inversions until the maximum torque was below 80% of the baseline value. Negative joint workload during the landing tasks was calculated for the hip, knee, and ankle in the sagittal and frontal planes. Additionally, lower extremity work (the sum of the work of the hip, knee, and ankle) was calculated.
Results: Invertor fatiguing exercise resulted in a significant increase in negative joint work in the frontal and sagittal plane hip and the frontal plane knee during medial landing, whereas no significant change in negative joint work was observed during forward landing.
Significance: These findings suggested that ankle invertor dysfunction may induce a high load on the proximal joints and have direction-specific effects.
Keywords: Ankle invertors; Fatigue; Landing; Negative joint work.
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