Determining the interactions between postural variability structure and discomfort development using nonlinear...

Area of Science:

• Biomechanics and Ergonomics
• Physiology
• Complexity Science

Background:

• Postural control is crucial for prolonged standing.
• Understanding the relationship between postural variability and discomfort is essential for workplace ergonomics.
• Nonlinear analysis offers advanced methods to study complex biological signals.

Purpose of the Study:

• To investigate the relationship between postural variability structure and the development of discomfort during prolonged standing.
• To explore how nonlinear analysis can differentiate postural strategies related to discomfort.
• To assess the impact of standing work experience (SWE) on postural control and discomfort.

Main Methods:

• Twenty participants (gender and SWE balanced) underwent simulated long-term standing.
• Monitored variables included low back/leg discomfort, center of pressure, lumbar curvature, and muscle EMG.
• Applied nonlinear measures (Lyapunov exponent, multi-scale entropy, DFA) and linear metrics to analyze signal variability structure and amount.

Main Results:

• Increased postural variability (amount) was observed over time for most signals.
• Postural variability structure showed decreased complexity (increased regularity) with prolonged standing.
• Participants with standing work experience (SWE) reported less discomfort and demonstrated higher complexity in postural control.

Conclusions:

• Findings confirm changes in postural variability structure and amount during prolonged standing.
• Nonlinear analysis provides unique insights into postural strategies linked to perceived discomfort.
• Nonlinear tools show promise for evaluating standing tasks and informing ergonomic interventions.