College of Public Health and Human Sciences

A walking cadence of 100 steps/min has been established as a heuristic (evidence-based, rounded) threshold for absolutely defined moderate intensity (3 Metabolic Equivalents, METs). This threshold was calibrated during treadmill (TM) walking, however few studies have assessed its classification accuracy during overground (OG) walking.

PURPOSE:To evaluate the classification accuracy of the100 steps/min cadence threshold originally established during TM walking to OG walking.

METHODS:Participants (n=75, 50.7 % men, 21-40 years of age, mean±SD age: 30.3±5.8 years, BMI: 24.8±3.4 kg/m2) performed a 13 m overground corridor walk back and forth at a self-selected pace for 5-min. Cadence was hand-tallied and METs were obtained using indirect calorimetry. Receiver Operating Characteristic curves were used to determine the optimal OG cadence threshold associated with moderate intensity (Youden’s index). Classification accuracies (counts and percentages for true positives and negatives, false positives and negatives) for the optimal OG and original TM heuristic (100 steps/min) thresholds were compared.

RESULTS:Table 1 reports the classification accuracies of optimal OG and original TM heuristic cadence thresholds for identifying moderate intensity. The optimal OG threshold displayed an overall accuracy (i.e., correctly classified bouts; true positives and negatives) of 74.6%, compared to 73.3% for the TM heuristic threshold. The positive predictive value (i.e., probability of achieving ≥3 METs at ≥100 steps/min) was 80.3%.

CONCLUSION:Optimal OG and original TM heuristic thresholds produced similar classification accuracies. The probability of achieving a moderate intensity when walking at a cadence ≥100 steps/min was >80%. The original TM heuristic (100 steps/min) threshold remains a valid heuristic threshold for achieving moderate intensity during overground walking.