Real-world walking in multiple sclerosis: Separating capacity from behavior.

Area of Science:

• Neurology
• Rehabilitation Medicine
• Biomedical Engineering

Background:

• Habitual physical activity (HPA) measurement is crucial for understanding the real-world impact of multiple sclerosis (MS) on walking.
• Interpreting HPA in MS is challenging due to the interplay between disease-specific walking capacity and general physical activity behaviors.

Purpose of the Study:

• To develop and validate novel statistical measures of HPA for assessing MS-associated walking capacity.
• To differentiate between disease-related limitations and behavioral influences on walking in MS.

Main Methods:

• Eighty-eight individuals with MS and 38 controls underwent clinical walking tests and wore accelerometers for 7 days.
• Habitual physical activity (HPA) was analyzed using conventional metrics (average daily steps) and new statistics: maximum step rate (MSR) and habitual walking step rate (HWSR).
• Validation was performed by correlating HPA statistics with clinical walking outcome measures.

Main Results:

• The six-minute walk (6MW) step rate showed the strongest correlation with MSR (r=0.863) and HWSR (r=0.815) compared to average daily steps (r=0.676).
• A combination of MSR and HWSR demonstrated a higher correlation with 6MW step rate (r=0.884) than either measure alone.
• MSR tended to overestimate and HWSR to underestimate the 6MW step rate, indicating distinct aspects of capacity captured.

Conclusions:

• Conventional HPA metrics like average daily steps are insufficient for measuring capacity in MS due to behavioral variability.
• Maximum step rate (MSR) and habitual walking step rate (HWSR) are valid and specific measures of real-world walking capacity in MS.
• MSR and HWSR provide distinct insights into an individual's highest and preferred walking pace, respectively.