Fatigue modifies hip and knee kinematics during single- and double-leg dynamic tasks: An investigation with female handball players.

This study investigated the effect of a handball-specific fatigue protocol on hip and knee kinematics. Twenty female handball athletes performed three trials of the single-leg landing (SLL), sidestep cutting manoeuvre (SCM), and drop vertical jump (DVJ) before and after the fatigue protocol. Knee and hip angle waveforms were compared using statistical parametric mapping (p < 0.05). During the SLL, the fatigue increased hip adduction (4-7% cycle) and knee abduction (4-9% and 25-27%). For the SCM, hip flexion was reduced under fatigue during 14-29% and 44-68% of the cycle. Similarly, the knee flexion decreased between 7-36% and 53-73%. Besides, during the fatigue state, the athletes reduced the hip abduction between 0-11% of the cycle and increased the knee abduction between 20-23%. During the DVJ task, when fatigued, the hip flexion decreased between 19-44% of the cycle and the knee flexion between 1-16% and 18-77%. The fatigue protocol altered the lower limb kinematics, decreasing knee and hip flexions during the SCM and DVJ and increasing the knee valgus during both single-leg landing tasks.

The rapid recovery of vertical force propulsion production and postural sway after a specific fatigue protocol in female handball athletes.

BACKGROUND: Muscle fatigue is characterized by a decrease in muscle performance, accompanied by an increase in perceived exertion to produce a desired amount of force. The duration of the fatigue effects is not completely clear regarding postural sway and force production in athletes. RESEARCH QUESTION: What is the effect of a specific fatigue protocol in postural sway and force production in female handball athletes and the recovery time necessary for these variables? METHODS: Twenty female handball athletes participated in this study. Specific handball actions composed the fatigue protocol in the format of a circuit with the gradual increment of laps. They stood upright in one-leg posture on a force plate. For the maximum propulsion force (FMAX), they performed a countermovement jump on the force plate. The center of pressure (COP) and the FMAX were obtained at baseline, immediately after the exhaustion due to the fatigue protocol and every minute during the first 10 min of the recovery phase. RESULTS: The FMAX decreased ∼9.5% after the fatigue protocol, whereas de COP area increased 224%. During the recovery phase, the FMAX and the COP area returned to baseline values after five minutes. SIGNIFICANCE: The first five minutes immediately after the fatigue protocol represent the time interval where the fatigue effects are still present. Future studies willing to investigate the effects of fatigue in athletes should perform the analysis within this short time-window.