Accuracy of Thresholds Based on Cadence and Lifestyle Counts per Minute to Detect Outdoor Walking in Older Adults With Mobility Limitations

Objective: To determine the optimal threshold, based on cadence and lifestyle counts per minute, to detect outdoor walking in mobility-limited older adults. Methods: Older adults (N = 25, median age: 77.0 years, interquartile range: 10.5) wore activity monitors during 80 outdoor walks. Walking bouts were identified manually (reference standard) and compared with identification using cadence thresholds (>= 30, >= 35, >= 440, >= 45, and >= 50 steps/min) and >760 counts per minute using low frequency extension analysis. Results: Median walking bout duration was 10.5 min (interquartile range 4.8) and median outdoor walking speed was 0.70 m/s (interquartile range 0.20). Cadence thresholds of >= 30, >= 35, and >= 40 steps/min demonstrated high sensitivity (1.0, 95% confidence intervals [0.95, 1.0]) to detect walking bouts; estimates for specificity and positive predictive value were highest for >= 40 steps/min. Conclusion: A cadence threshold of >= 40 steps/min is recommended for detecting sustained outdoor walking in this population.