General muscle fatigue changed joint regulations in static and dynamic balance

Area of Science:

• Biomechanics
• Human Physiology
• Sports Science

Background:

• Muscle fatigue is a common condition affecting motor control.
• Maintaining balance relies on complex joint regulations and body sway.
• Understanding fatigue's impact on balance is crucial for injury prevention and performance.

Purpose of the Study:

• To investigate joint regulations and body sway following general muscle fatigue.
• To analyze kinematic changes during static and dynamic balance tasks post-fatigue.
• To assess the effects of fatigue on whole-body and joint-specific stability.

Main Methods:

• Cross-sectional study involving twelve healthy young individuals.
• Motion analysis to capture kinematic changes before and after running-induced fatigue.
• Calculation of six linear and nonlinear stability metrics for body and joint variations.

Main Results:

• Significant increases in instability at the hip, knee, and whole body during static balance post-fatigue.
• Elevated velocity path length and approximate entropy in knee and hip post-fatigue.
• Whole-body center of mass metrics also showed significant increases after fatigue.
• Ankle stability remained unaffected during static and dynamic standing.
• Dynamic standing showed minimal effects, except for nonlinear metrics in proximal joints.

Conclusions:

• General muscle fatigue adversely affects knee and hip stability.
• The ankle demonstrates a compensatory role in response to proximal joint instability.
• Fatigue significantly impacts static balance control, particularly at proximal joints.
• Dynamic balance appears more resilient to fatigue compared to static balance.