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Context: Altered neuromuscular control strategies during fatigue probably contribute to the increased incidence of noncontact anterior cruciate ligament injuries in female athletes.
Objective: To determine biomechanical differences between 2 fatigue protocols (slow linear oxidative fatigue protocol [SLOFP] and functional agility short-term fatigue protocol [FAST-FP]) when performing a running-stop-jump task.
Design: Controlled laboratory study.
Setting: Laboratory.
Patients or Other Participants: A convenience sample of 15 female soccer players (age = 19.2 ± 0.8 years, height = 1.67 ± 0.05 m, mass = 61.7 ± 8.1 kg) without injury participated.
Intervention(s): Five successful trials of a running-stopjump task were obtained prefatigue and postfatigue during the 2 protocols. For the SLO-FP, a peak oxygen consumption (V02peak) test was conducted before the fatigue protocol. Five minutes after the conclusion of the V02peak 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) x 2 (time) analyses of variance were conducted to assess differences between the 2 protocols and time (prefatigue, postfatigue).
Main Outcome Measure(s): Kinematic and kinetic measures of the hip and knee were obtained at different times while participants performed both protocols during prefatigue and postfatigue.
Results: Internal adduction moment at initial contact (lC) was greater during FAST-FP (0.064 ± 0.09 Nm/kgm) than SLOFP (0.024±0.06 Nm/kgm) (FI14=5.610, P=.03). At IC, participants had less hip flexion' postfatigue (44.7° ± 8.1 0) than prefatigue (50.1°±9S) (F1,14=16.229, P=.001). At peak vertical ground reaction force, participants had less hip flexion postfatigue (44.7° ± 8.4 0) 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°) (FI14= 11.537, P= .001).
Conclusions: bur 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.
Key Words: anterior cruciate ligament, hip, knee, biomechanics
Key Points
* Both the slow linear oxidative fatigue protocol (SLO-FP) and the functional agility short-term fatigue protocol (FAST-FP) demonstrated that the lower extremity is at a higher risk for sustaining injury when...