Reliability of a Lower-Extremity Shear Force Control Task in Young, Uninjured Adults

Area of Science:

• Biomechanics
• Neuromuscular Control
• Sports Medicine

Background:

• A novel shear force control task has been used to identify neuromuscular control strategies in various populations.
• The reliability of this task, particularly in individuals without lower-extremity injuries, has not been previously established.

Purpose of the Study:

• To determine the test-retest reliability of a novel shear force control task.
• To assess the reliability of measuring force control variability using largest Lyapunov exponent values in a healthy population.

Main Methods:

• Thirteen healthy individuals (7 men, age 24.7 ± 4.8 years) performed a standing shear force control task (medial/lateral and anterior/posterior directions) on each leg.
• Testing was conducted on two separate occasions, one week apart.
• Intraclass correlation coefficients (ICCs), standard error of measurement (SEM), and minimum detectable change (MDC) were calculated to assess reliability.

Main Results:

• The shear force control task demonstrated good to excellent reliability across all measures (ICC range: 0.78–0.92).
• Reliability was highest for the medial/lateral direction in the right lower extremity (ICC = 0.92).
• The largest Lyapunov exponent values showed consistent and reliable measurements.

Conclusions:

• The novel shear force control task exhibits good to excellent reliability in healthy individuals.
• This methodology is suitable for reliably measuring force control variability.
• The task holds potential for providing insights into neuromuscular control strategies, particularly in the context of injury and rehabilitation.