Device-specific Cadence (steps/min) Thresholds For Metabolic Intensities of Walking

Abstract

In studies where steps are directly observed, walking cadences of 100 steps/min and 130 steps/min have emerged as thresholds for absolutely-defined moderate (MOD; 3 metabolic equivalents [METs]) and vigorous (VIG; 6 METs) intensities, respectively. However, there is limited information regarding device-specific cadence thresholds provided for guidance. PURPOSE: To estimate device-specific cadence thresholds for MOD and VIG in 61-85 year old adults. METHODS: Thirty-seven healthy older adults (62.3% women; age=68.5±4.6 years; BMI=26.3±3.8 kg/m2) walked on a treadmill for 5-min bouts. The first bout was conducted at 0.5 mph. Speed increased in 0.5 mph increments until participants reached 75% of their age-predicted maximum heart rate, started to run, or reported a Borg Rating of Perceived Exertion > 13. Cadence (steps/min) was measured across all speeds with multiple devices: ActiGraph GT9x (hip and wrist), activPAL (thigh), StepWatch (ankle), Fitbit Zip (waist), and Garmin vívoactive® 3 (wrist). Oxygen uptake was measured with indirect calorimetry and converted to METs. Receiver Operator Characteristic (ROC) analysis was used to determine optimal cadence thresholds associated with MOD and VIG intensity using Youden’s index. RESULTS: Device-specific cadence thresholds for MOD and VIG intensity are presented in Table 1. The optimal device-specific cadence thresholds were associated with very good to excellent classification accuracy for both intensities (AUC > 0.8). Except for the wrist-worn ActiGraph, which had relatively lower specificity for identifying thresholds, optimal cadence thresholds for all devices ranged from 86-104 steps/min for MOD and 125-140 steps/min for VIG intensity. CONCLUSION: Device-specific cadence thresholds appear to be acceptable indicators of MOD and VIG walking intensities. FUNDING: NIH-NIA-5R01AG049024Table 1: Device- specific cadence thresholds by intensity