Functional Fatigue Alters Lower-extremity Neuromechanics during a Forward-side Jump

Area of Science:

• Biomechanics
• Neuromuscular Physiology
• Sports Science

Background:

• Neuromuscular fatigue significantly impacts lower extremity control.
• Understanding fatigue's effects on dynamic movements like jumping is crucial for injury prevention and performance optimization.

Purpose of the Study:

• To investigate how functional fatiguing exercises affect the sagittal-plane neuromechanics of the lower extremity during a forward-side jump.
• To analyze changes in joint angles, moments, and electromyography (EMG) amplitudes before and after fatigue.

Main Methods:

• 21 participants completed forward-side jumps pre- and post-fatiguing exercises.
• Functional analysis of variance (FANOVA) was used to compare neuromechanical variables.
• Joint kinematics, kinetics, and EMG data were analyzed during the stance phase of the jump.

Main Results:

• Fatigue decreased plantar, knee, and hip flexion during initial landing stages.
• Changes in joint moments were observed, with initial increases and subsequent decreases in knee extension moment.
• EMG activity of key lower extremity muscles (tibialis anterior, vastus lateralis, hamstrings, gluteus maximus) showed significant alterations post-fatigue.

Conclusions:

• Functional fatiguing exercises induce significant changes in lower extremity neuromechanics during forward-side jumps.
• Post-fatigue, participants adopted a more upright landing posture.
• This altered landing strategy may indicate an increased reliance on passive skeletal support to compensate for neuromuscular fatigue.