Walking Speed Explains Apparent Ground Reaction Force Differences in Parkinson's Disease: A Waveform-Level SPM...

Area of Science:

• Biomechanics
• Neurology
• Human Movement Science

Background:

• Ground reaction force (GRF) alterations are noted in Parkinson's disease (PD), but these may be influenced by slower walking speeds characteristic of the condition.
• Virtual reality (VR) interventions might affect gait kinetics, but it's unclear if these effects are independent of speed changes in PD.

Purpose of the Study:

• To investigate if differences in GRF waveforms between individuals with PD and controls persist when walking speed is statistically controlled.
• To determine if VR influences gait kinetics in individuals with PD in a manner independent of walking speed.

Main Methods:

• 14 adults with mild-to-moderate PD and 17 age-matched controls walked under normal and immersive VR conditions.
• Three-dimensional kinematics and GRFs were recorded, with discrete variables analyzed via ANOVA and continuous GRF waveforms using statistical parametric mapping (SPM) ANCOVA, including walking speed as a covariate.

Main Results:

• Individuals with PD walked significantly slower than controls in both conditions.
• While VR modulated some discrete GRF variables, waveform-level analyses controlling for walking speed showed no persistent group or group × task effects.
• Walking speed strongly correlated with vertical and mediolateral GRF trajectories.

Conclusions:

• Apparent kinetic differences in overground walking for individuals with mild-to-moderate PD are largely coupled to walking speed.
• These findings emphasize the critical need for speed-aware modeling when interpreting gait kinetics and evaluating VR-based interventions in Parkinson's disease.