Moderate Intensity Walking Cadence (Steps/min) in 61-85 Year Old Adults

Abstract

Consistent evidence supports a strong relationship between walking cadence (steps/min) and intensity. However, this relationship has primarily been examined in young adults. PURPOSE To identify a heuristic (evidence based, reasonable, rounded) cadence threshold associated with absolutely-defined moderate intensity defined as 3 METs (metabolic equivalents; MET=3.5 mL/kg/min) in older adults (61-85 years of age). METHODS Thirty-seven participants (23 women; age=71.6±14.0 years; BMI=25.8±4.7 kg/m2) completed a progressive treadmill walking test. The protocol included 5 minute bouts increasing by 0.5 mph increments from 0.5 to 6.0 mph until: 1) the participant naturally selected to jog or run, 2) reached >75% of their age-predicted maximum heart rate, or 3) reported a Borg scale rating of perceived exertion (RPE) >13. Oxygen consumption (VO2; mL/kg/min) was measured using indirect calorimetry and cadence was determined by dividing directly-observed steps by bout duration. METs were calculated as the average VO2 over the last two minutes of each bout, divided by 3.5 mL/kg/min. Receiver Operator Characteristic (ROC) curves and Youden’s index were used to determine moderate intensity based on cadence. Additionally, the cadence-intensity relationship was evaluated using a segmented regression model with random coefficients. RESULTS: All but three participants reached at least 3 METs during treadmill walking. The ROC cadence threshold for absolutely-defined moderate intensity was 100.3 steps/min. Specificity and sensitivity values were above 85% for moderate intensity. The cadence-intensity relationship was also explained by bi-linear relationship with a breakpoint at 94.4 steps/min, where cadence explained 74% of the variance. The cadence threshold for absolutely-defined moderate intensity was 101.3 (95% Prediction Intervals=68.2-112.8). CONCLUSION A growing number of studies have provided evidence supporting the utility of 100 steps/min as a reasonable heuristic threshold value associated with absolutely-defined moderate intensity walking in younger adults. This study confirms that 100 steps/min is also as an appropriate proxy threshold of absolutely-defined moderate intensity in ambulatory and ostensibly healthy older adults. FUNDING: NIH-NIA-5R01AG049024