Exploring the relationship between step count, step length and walked distance in mobile-aided six-minute walk test

Area of Science:

• Digital Health and Wearable Technology
• Clinical Biomechanics and Rehabilitation

Background:

• Clinical assessments like the 6-Minute Walk Test (6MWT) measure walking speed and distance.
• Home-based monitoring using wearables and smartphones faces challenges with indoor distance measurement (e.g., GPS unreliability).
• Step counting presents a simpler data collection method via digital technologies.

Purpose of the Study:

• To investigate the correlation between step count and the standardized 6-Minute Walk Distance (6MWD).
• To evaluate step count as a reliable proxy for 6MWD, particularly in challenging environments.

Main Methods:

• Analysis of 176 6-Minute Walk Tests (6MWTs) from 55 participants.
• Comparison of step count data against ground truth distance measurements.
• Evaluation of step count reliability versus a state-of-the-art algorithm for low-quality outdoor tests.

Main Results:

• A high correlation (0.83) was found between ground truth distance and the number of steps taken during 6MWTs.
• Step count demonstrated significantly higher reliability (MAE of 22.5m) compared to a state-of-the-art algorithm (MAE of 93.8m) for low-quality outdoor tests.
• Step count emerges as a robust metric for estimating walking distance.

Conclusions:

• Step count is a valid proxy for estimating 6-Minute Walk Distance (6MWD).
• This method is a promising candidate for continuous patient physical health monitoring in free-living conditions.
• Digital step counting offers a feasible alternative for remote patient assessment.