Two Different Fatigue Protocols and Lower Extremity Motion Patterns During a Stop-Jump Task

<jats:sec> <jats:title>Context:</jats:title> <jats:p>Altered neuromuscular control strategies during fatigue probably contribute to the increased incidence of non-contact anterior cruciate ligament injuries in female athletes.</jats:p> </jats:sec> <jats:sec> <jats:title>Objective:</jats:title> <jats:p>To determine biomechanical differences between 2 fatigue protocols (slow linear oxidative fatigue protocol [SLO-FP] and functional agility short-term fatigue protocol [FAST-FP]) when performing a running-stop-jump task.</jats:p> </jats:sec> <jats:sec> <jats:title>Design:</jats:title> <jats:p>Controlled laboratory study.</jats:p> </jats:sec> <jats:sec> <jats:title>Setting:</jats:title> <jats:p>Laboratory.</jats:p> </jats:sec> <jats:sec> <jats:title>Patients or Other Participants:</jats:title> <jats:p>A convenience sample of 15 female soccer players (age = 19.2 ±0.8 years, height = 1.67±0.05m, mass = 61.7 + 8.1 kg) without injury participated.</jats:p> </jats:sec> <jats:sec> <jats:title>Intervention(s):</jats:title> <jats:p>Five successful trials of a running–stop-jump task were obtained prefatigue and postfatigue during the 2 protocols. For the SLO-FP, a peak oxygen consumption (V˙o2peak) test was conducted before the fatigue protocol. Five minutes after the conclusion of the V˙o2peak test, participants started the fatigue protocol by performing a 30-minute interval run. The FAST-FP consisted of 4 sets of a functional circuit. Repeated 2 (fatigue protocol) × 2 (time) analyses of variance were conducted to assess differences between the 2 protocols and time (prefatigue, postfatigue).</jats:p> </jats:sec> <jats:sec> <jats:title>Main Outcome Measure(s):</jats:title> <jats:p>Kinematic and kinetic measures of the hip and knee were obtained at different times while participants performed both protocols during prefatigue and postfatigue.</jats:p> </jats:sec> <jats:sec> <jats:title>Results:</jats:title> <jats:p>Internal adduction moment at initial contact (IC) was greater during FAST-FP (0.064 ±0.09 Nm/kgm) than SLO-FP (0.024±0.06 Nm/kgm) (F1,14 = 5.610, P=.03). At IC, participants had less hip flexion postfatigue (44.7°±8.1°) than prefatigue (50.1°±9.5°) (F1,14 = 16.229, P=.001). At peak vertical ground reaction force, participants had less hip flexion postfatigue (44.7°±8.4°) than prefatigue (50.4°±10.3°) (F1,14 = 17.026, P=.001). At peak vertical ground reaction force, participants had less knee flexion postfatigue (−35.9°±6.5°) than prefatigue (−38.8°±5.03°) (F1,14 = 11.537, P=.001).</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions:</jats:title> <jats:p>Our results demonstrated a more erect landing posture due to a decrease in hip and knee flexion angles in the postfatigue condition. The changes were similar between protocols; however, the FAST-FP was a clinically applicable 5-minute protocol, whereas the SLO-FP lasted approximately 45 minutes.</jats:p> </jats:sec>