The Relationship Between Cadence (steps/min) and Rating of Perceived Exertion in Older Adults: the Cadence-Adults Study

A cadence of 100 steps/min has been reported as a heuristic (rounded, evidence-based) threshold for absolutely-defined moderate intensity walking (≥ 3 metabolic equivalents [METs]) in adults. Yet, less is known about the relationship between cadence and rating of perceived extertion (RPE), a relatively-defined measure of moderate intensity, in older adults 61-85 years of age. PURPOSE: To identify a heuristic cadence threshold associated with relatively-defined moderate intensity in older adults using the Borg RPE scale that is commonly used in exercise prescription. METHODS: Ninety-eight older adults (mean [SD]; age = 72.6 [7.0] years, BMI = 25.9 [3.5] kg/m2) performed a progressive treadmill walking protocol consisting of 5-minute bouts increasing from 0.5 mph (13.4 m/min) up to 6.0 mph (160.9 m/min), with 2-minute rest between bouts. The protocol terminated after the bout when adults naturally selected to run, reached 75% age-predicted heart rate (HR) max, and/or reported an RPE > 13 (above the threshold of 12, or moderate intensity). RPE intensities were interpreted as 11 = light, 12 = moderate, and 13 = somewhat hard. Cadence was directly observed, and a chest-worn monitor continuously measured HR. Segmented mixed regression models with 95% prediction intervals, as well as Receiver Operating Characteristic (ROC) curve analyses maximizing Youden’s index, identified the cadence associated with an RPE ≥ 12. Classification accuracy was evaluated in terms of sensitivity, specificity, positive and negative predictive value, and overall accuracy of cadence thresholds derived from both analyses. RESULTS: The segmented regression model identified 112.8 steps/min (accuracy = 70.2%) and the ROC analysis identified 100.5 steps/min (accuracy = 73.5%) as cadence thresholds associated with a Borg RPE > 12. Considering both models, the cadence threshold of 105 steps/min corresponds with relatively-defined moderate intensity, balances specificity and sensitivity measures, and is rounded for ease of application. CONCLUSIONS: With Borg RPE as the criterion, ambulatory older adults appear able to tolerate walking at a relatively-defined moderate intensity cadence (105 steps/min), which is slightly higher than the cadence associated with absolutely defined moderate intensity (100 steps/min).