The effect of a Wingate-based fatigue protocol on single-leg hop performance and knee extensor and flexor isometric strength characteristics

Introduction: Fatigue is one of the factors that may predispose an athlete to sustain an anterior cruciate ligament injury. This study aimed to analyse the effect of a Wingate-based fatigue protocol on variables frequently investigated in relation to lower extremity neuromuscular control and potential ACL injury mechanisms.

Methods: Sixty-two physically active volunteers completed two separate 30-second maximal effort Wingate tests (fatigue protocol) interspersed with a 4-minute rest period. Single-leg hop distance, landing mechanics (knee valgus and flexion angles evaluated via two-dimensional video analysis) and maximal isometric strength on an isokinetic dynamometer were assessed at baseline and after the corresponding Wingate.

Results: After the second Wingate test (PRE vs POST), peak torque (PT) (Extensors = 174.80±38.81 vs 164.22±37.80 N·m, p<0.001 and Flexors=111.83±30.55 vs 104.43±27.52 N·m, p<0.001) and rate of torque development (RTD) values were significantly reduced in all time intervals for both muscle groups (e.g., with reductions of 32.97±19.43%, p<0.001 and 19.82±42.34%, p<0.001 in RTD50 for knee extensors and flexors, respectively). PT and RTD50 H:Q ratios were not modified after the fatigue protocol. In addition, the jumping distance was also decreased after the first Wingate (146.36±32.46 vs 111.33±31.32 cm, 24.44±11.48% reduction, p<0.001), but none of the evaluated knee kinematics variables showed statistically significant changes.

Conclusion: The fatigue protocol employed is effective to reduce torque production in both knee extensors and flexors and jump distance. However, it does not induce statistically significant changes in either the H:Q ratios or knee kinematics as assessed via the two-dimensional methodology employed.