The Role of Fatigue in Return to Sport Testing Following Anterior Cruciate Ligament Reconstruction.
Justin C Tallard, Corbin Hedt, Bradley S Lambert and 1 others
PMID 34386283WHAT IT FOUND
Fatigue reduced performance more in the healthy leg than the injured leg in 21 athletes ready for return to sport.
This narrows the gap between legs, potentially hiding deficits if testing is done while tired. Assess both limbs in fresh and fatigued states.
Key findings
01In a non-fatigued state, the operated leg showed significantly reduced hop distance and height compared to the healthy leg.
02In a fatigued state, the healthy leg's performance dropped more than the operated leg's, making the two limbs look more similar.
03The study did not support the hypothesis that fatigue would worsen the operated leg's performance relative to the healthy leg.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Small sample size (21 participants). Fatigue was defined by vertical jump height, which may not fully capture neuromuscular fatigue in all lower limb muscles. Rehabilitation programs prior to the study were not standardized or controlled. The study did not measure movement quality or kinematics, only distance and time. The healthy limb's greater fatigue response could be due to detraining or lack of specific endurance training in the non-operated leg.
The easy way to misread this
Do not interpret improved Limb Symmetry Index scores in a fatigued state as evidence of readiness. The healthy leg may fatigue more severely, masking the operated leg's deficit. A passing LSI while tired may reflect the healthy leg's weakness rather than the operated leg's strength.