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Catrine Tudor-Locke and Elroy J. Aguiar

Step counting is now a widespread and acceptable approach to self-monitoring physical activity courtesy of the recent surge in wearable technologies. Nonetheless, there remains no recommendation for steps/day in federal physical activity guidelines. The authors review current scientific literature to consider evidence regarding the volume, dose (frequency, intensity, duration, timing), and dose-response relationships for step-based metrics, including steps/day (volume), cadence (steps/min; intensity), peak 30-min cadence (steps/min; composite index of frequency, intensity, and duration), and zero cadence (proxy for sedentary behavior). Preliminary evidence suggests that communicating federal physical activity guidelines using step-based metrics could facilitate individuals’ ability to comprehend and achieve a physically active lifestyle.

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Christopher C. Moore, Aston K. McCullough, Elroy J. Aguiar, Scott W. Ducharme and Catrine Tudor-Locke

Background: The authors conducted a scoping review as a first step toward establishing harmonized (ie, consistent and compatible), empirically based best practices for validating step-counting wearable technologies. Purpose: To catalog studies validating step-counting wearable technologies during treadmill ambulation. Methods: The authors searched PubMed and SPORTDiscus in August 2019 to identify treadmill-based validation studies that employed the criterion of directly observed (including video recorded) steps and cataloged study sample characteristics, protocol details, and analytical procedures. Where reported, speed- and wear location–specific mean absolute percentage error (MAPE) values were tabulated. Weighted median MAPE values were calculated by wear location and a 0.2-m/s speed increment. Results: Seventy-seven eligible studies were identified: most had samples averaging 54% (SD = 5%) female and 27 (5) years of age, treadmill protocols consisting of 3 to 5 bouts at speeds of 0.8 (0.1) to 1.6 (0.2) m/s, and reported measures of bias. Eleven studies provided MAPE values at treadmill speeds of 1.1 to 1.8 m/s; their weighted median MAPE values were 7% to 11% for wrist-worn, 1% to 4% for waist-worn, and ≤1% for thigh-worn devices. Conclusions: Despite divergent study methodologies, the authors identified common practices and summarized MAPE values representing device step-count accuracy during treadmill walking. These initial empirical findings should be further refined to ultimately establish harmonized best practices for validating wearable technologies.

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Elroy J. Aguiar, Zachary R. Gould, Scott W. Ducharme, Chris C. Moore, Aston K. McCullough and Catrine Tudor-Locke

Background: A walking cadence of ≥100 steps/min corresponds to minimally moderate intensity, absolutely defined as ≥3 metabolic equivalents (METs). This threshold has primarily been calibrated during treadmill walking. There is a need to determine the classification accuracy of this cadence threshold to predict intensity during overground walking. Methods: In this laboratory-based cross-sectional investigation, participants (N = 75, 49.3% women, age 21–40 y) performed a single 5-minute overground (hallway) walking trial at a self-selected preferred pace. Steps accumulated during each trial were hand tallied and converted to cadence (steps/min). Oxygen uptake was measured using indirect calorimetry and converted to METs. The classification accuracy (sensitivity, specificity, overall accuracy, and positive predictive value) of ≥100 steps/min to predict ≥3 METs was calculated. Results: A cadence threshold of ≥100 steps/min yielded an overall accuracy (combined sensitivity and specificity) of 73.3% for predicting minimally moderate intensity. Moreover, for individuals walking at a cadence ≥100 steps/min, the probability (positive predictive value) of achieving minimally moderate intensity was 80.3%. Conclusions: Although primarily developed using treadmill-based protocols, a cadence threshold of ≥100 steps/min for young adults appears to be a valid heuristic value (evidence-based, rounded, practical) associated with minimally moderate intensity during overground walking performed at a self-selected preferred pace.

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Dylan C. Perry, Christopher C. Moore, Colleen J. Sands, Elroy J. Aguiar, Zachary R. Gould, Catrine Tudor-Locke and Scott W. Ducharme

Background: While previous studies indicate an auditory metronome can entrain cadence (in steps per minute), music may also evoke prescribed cadences and metabolic intensities. Purpose: To determine how modulating the tempo of a single commercial song influences adults’ ability to entrain foot strikes while walking and how this entrainment affects metabolic intensity. Methods: Twenty healthy adults (10 men and 10 women; mean [SD]: age 23.7 [2.7] y, height 172.8 [9.0] cm, mass 71.5 [16.2] kg) walked overground on a large circular pathway for six 5-min conditions; 3 self-selected speeds (slow, normal, and fast); and 3 trials listening to a song with its tempo modulated to 80, 100, and 125 beats per minute. During music trials, participants were instructed to synchronize their step timing with the music tempo. Cadence was measured via direct observation, and metabolic intensity (metabolic equivalents) was assessed using indirect calorimetry. Results: Participants entrained their cadences to the music tempos (mean absolute percentage error = 5.3% [5.8%]). Entraining to a music tempo of 100 beats per minute yielded ≥3 metabolic equivalents in 90% of participants. Trials with music entrainment exhibited greater metabolic intensity compared with self-paced trials (repeated-measures analysis of variance, F 1,19 = 8.05, P = .01). Conclusion: This study demonstrates the potential for using music to evoke predictable metabolic intensities.

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Elroy J. Aguiar, John M. Schuna Jr., Tiago V. Barreira, Emily F. Mire, Stephanie T. Broyles, Peter T. Katzmarzyk, William D. Johnson and Catrine Tudor-Locke

Walking cadence (steps per minute) is associated with the intensity of ambulatory behavior. This analysis provides normative values for peak 30-min cadence, an indicator of “natural best effort” during free-living behavior. A sample of 1,196 older adults (aged from 60 to 85+) with accelerometer data from the National Health and Nutrition Examination Survey 2005–2006 was used. Peak 30-min cadence was calculated for each individual. Quintile-defined values were computed, stratified by sex and age groups. Smoothed sex-specific centile curves across the age span were fitted using the LMS method. Peak 30-min cadence generally trended lower as age increased. The uppermost quintile value was >85 steps/min (men: 60–64 years), and the lowermost quintile value was <22 steps/min (women: 85+). The highest 95th centile value was 103 steps/min (men: 64–70 years), and the lowest 5th centile value was 15 steps/min (women: 85+). These normative values may be useful for evaluating older adults’ “natural best effort” during free-living ambulatory behavior.