Behavior
Association between cadence (steps/min) and intensity during treadmill activity among 18–20 year olds: the SKyRoCKeT study Tahmina Begum* Tahmina Begum Laura H. Gunn Catrine Tudor-Locke Cayla R. McAvoy Agnes Bucko Mariya Boikova Trudy Moore-Harrison Michael Dulin Daheia J. Barr-Anderson Leah Patterson Spencer Ingoglia Maha Raya Sicong Ren
Background: Physical activity studies often use treadmill protocols to assess cadence (steps/minute) as an indicator of ambulatory intensity. Accurately quantifying intensity is essential for surveillance, research, and clinical/public health applications. This study aimed to determine cadence-intensity thresholds that reliably translate to predictable metabolic equivalents (METs) during treadmill activity.
Methods: Participants ages 18-20 years (n=72) completed up to 12 5-minute bouts on a treadmill incrementally from 0.5–6.0 miles/hour. Steps were visually counted (video validated) and intensity was objectively measured using a portable metabolic system. MET thresholds were defined for moderate (≥3 to <6 METs) and vigorous (≥6 METs) intensities. Optimal cadence thresholds for moderate and vigorous intensity were identified using a segmented log-level regression model and receiver operating characteristic (ROC) curve. Age, sex, race/ethnicity, body mass index (BMI), body fat %, and leg length were also explored.
Results: A total of 670 bouts were collected. Participants’ (51.4% female; 41.7% non-Hispanic white) mean values were: age 19.0 (SD 0.8) years; BMI 23.9 (SD 4.7) kg/m2; body fat 20.6% (SD 9.8%); and leg length 81.0 (SD 7.7) cm. In the segmented regression model, with a breakpoint of 81 steps/minute, moderate and vigorous intensity thresholds were 73.0 (99% CI 67.5, 79.8) [and via ROC analysis 83.1; 99% CI 77.9, 92.5] and 118.2 (99% CI 115.5, 121.0) [112.5; 99% CI 107.1, 118.9] steps/minute, respectively. The segmented regression R2 value was 0.87, thus supporting a good fit. The ROC area under the curve (AUC) values were ≥0.95, indicating excellent classification accuracy. Other variables were non-significant (p≥0.094).
Conclusions: Cadence-intensity thresholds can be used to accurately assess cadence-intensity/METs during treadmill walking and running. Accounting for cadence, other variables were not associated with intensity.
Funding: NICHD-R01HD105768