The purpose of this study was to evaluate the effects of a functional agility fatigue protocol on lower extremity biomechanics between two unanticipated tasks (stop-jump and sidestep). The subjects consisted of fifteen female collegiate soccer athletes (19 ± 0.7 years, 1.67 ± 0.1 m, 61.7 ± 8 kg) free of lower extremity injury. Participants performed five trials of stop-jump and sidestep tasks. A functional short-term agility protocol was performed, and immediately following participants repeated the unanticipated running tasks. Lower extremity kinematic and kinetic values were obtained pre and post fatigue. Repeated measures analyses of variance were conducted for each dependent variable with an alpha level set at 0.05. Knee position post-fatigue had increased knee internal rotation (11.4 ± 7.5° vs. 7.9 ± 6.5° p = 0.011) than pre-fatigue, and a decreased knee flexion angle (−36.6 ± 6.2° vs.−40.0 ± 6.3°, p = 0.003), as well as hip position post-fatigue had decreased hip flexion angle (35.5 ± 8.7° vs. 43.2 ± 9.5°, p = 0.002). A quick functional fatigue protocol altered lower extremity mechanics of Division I collegiate soccer athletes during landing tasks. Proper mechanics should be emphasized from the beginning of practice/game to aid in potentially minimizing the effects of fatigue in lower extremity mechanics.
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 [SLO-FP] 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 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 fatigue and unanticipated movement are combined.• Similar lower extremity biomechanical modifications occurred after 5 minutes of fatigue during the FAST-FP and after 45 minutes of fatigue during the SLO-FP.• Fatigue-induced decreases in hip and knee flexion resulted in a more extended landing posture, which can increase anterior tibial translation and thus increase strain on the anterior cruciate ligament.
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