BACKGROUND
Deficits in calf muscle performance and altered lower limb kinetics exist in patients after an Achilles tendon rupture (ATR). However, the influence of fatigue on functional performance is unclear. The aim of this study was to determine the effect of fatigue on a single-leg drop counter movement jump (drop CMJ) after an ATR.
MATERIAL AND METHODS
Twenty-seven subjects (22 male) with the mean (SD) age of 42.8 (9.3) years were evaluated 23.5 (8.4) months after ATR. Conventional motion capture procedures were used for data collection as participants performed drop CMJs before and after a standard fatigue protocol, consisting of bilateral single-leg standing heel-rise test followed by a 5-minute progressive slide board protocol. Data analysis focused on: a) eccentric and concentric ankle joint power (AJP); b) time from initial contact to peak eccentric and concentric AJP.
RESULTS
A significant limb by fatigue interaction was found for both eccentric (involved -0.83 W/kg; uninvolved -1.44 W/kg, p<0.001) and concentric AJP (involved -0.20 W/kg; uninvolved -0.71 W/kg, p<0.001), reflecting greater effects of fatigue on the uninvolved side. There was also significant difference in how fatigue delayed time to peak power during concentric (involved 15ms; uninvolved 29ms, p<0.001) but not eccentric AJP (p=0.854)
CONCLUSION
Fatigue had a greater effect on the uninvolved compared to the involved side. Since the uninvolved side seems to compensate for deficits in the involved side, there is a risk that the uninvolved side is more prone to injuries when returning back to sports after an ATR.