Elroy J. Aguiar

Step-based Physical Activity Metrics and Cardiometabolic Risk: Nhanes 2005–2006

Purpose This study aimed to catalog the relationships between step-based accelerometer metrics indicative of physical activity volume (steps per day, adjusted to a pedometer scale), intensity (mean steps per minute from the highest, not necessarily consecutive, minutes in a day; peak 30-min cadence), and sedentary behavior (percent time at zero cadence relative to wear time; %TZC) and cardiometabolic risk factors. Methods We analyzed data from 3388 participants, 20+ yr old, in the 2005–2006 National Health and Nutrition Examination Survey with ≥1 valid day of accelerometer data and at least some data on weight, body mass index, waist circumference, systolic and diastolic blood pressure, glucose, insulin, HDL cholesterol, triglycerides, and/or glycohemoglobin. Linear trends were evaluated for cardiometabolic variables, adjusted for age and race, across quintiles of steps per day, peak 30-min cadence, and %TZC. Results Median steps per day ranged from 2247 to 12,334 steps per day for men and from 1755 to 9824 steps per day for women, and median peak 30-min cadence ranged from 48.1 to 96.0 steps per minute for men and from 40.8 to 96.2 steps per minute for women for the first and fifth quintiles, respectively. Linear trends were statistically significant (all P < 0.001), with increasing quintiles of steps per day and peak 30-min cadence inversely associated with waist circumference, weight, body mass index, and insulin for both men and women. Median %TZC ranged from 17.6% to 51.0% for men and from 19.9% to 47.6% for women for the first and fifth quintiles, respectively. Linear trends were statistically significant (all P < 0.05), with increasing quintiles of %TZC associated with increased waist circumference, weight and insulin for men, and insulin for women. Conclusions This analysis identified strong linear relationships between step-based movement/nonmovement dimensions and cardiometabolic risk factors. These data offer a set of quantified access points for studying the potential dose–response effects of each of these dimensions separately or collectively in longitudinal observational or intervention study designs.

How fast is fast enough? Walking cadence (steps/min) as a practical estimate of intensity in adults: a narrative review

Background Cadence (steps/min) may be a reasonable proxy-indicator of ambulatory intensity. A summary of current evidence is needed for cadence-based metrics supporting benchmark (standard or point of reference) and threshold (minimums associated with desired outcomes) values that are informed by a systematic process. Objective To review how fast, in terms of cadence, is enough, with reference to crafting public health recommendations in adults. Methods A comprehensive search strategy was conducted to identify relevant studies focused on walking cadence and intensity for adults. Identified studies (n=38) included controlled (n=11), free-living observational (n=18) and intervention (n=9) designs. Results There was a strong relationship between cadence (as measured by direct observation and objective assessments) and intensity (indirect calorimetry). Despite acknowledged interindividual variability, ≥100 steps/min is a consistent heuristic (e.g, evidence-based, rounded) value associated with absolutely defined moderate intensity (3 metabolic equivalents (METs)). Epidemiological studies report notably low mean daily cadences (ie, 7.7 steps/min), shaped primarily by the very large proportion of time (13.5 hours/day) spent between zero and purposeful cadences (<60 steps/min) at the population level. Published values for peak 1-min and 30-min cadences in healthy free-living adults are >100 and >70 steps/min, respectively. Peak cadence indicators are negatively associated with increased age and body mass index. Identified intervention studies used cadence to either prescribe and/or quantify ambulatory intensity but the evidence is best described as preliminary. Conclusions A cadence value of ≥100 steps/min in adults appears to be a consistent and reasonable heuristic answer to ’How fast is fast enough? during sustained and rhythmic ambulatory behaviour. Trial registration number NCT02650258

Cadence (steps/min) and intensity during ambulation in 6–20 year olds: the CADENCE-kids study

BackgroundSteps/day is widely utilized to estimate the total volume of ambulatory activity, but it does not directly reflect intensity, a central tenet of public health guidelines. Cadence (steps/min) represents an overlooked opportunity to describe the intensity of ambulatory activity. We sought to establish thresholds linking directly observed cadence with objectively measured intensity in 6–20xa0year olds.MethodsOne hundred twenty participants completed multiple 5-min bouts on a treadmill, from 13.4xa0m/min (0.80xa0km/h) to 134.0xa0m/min (8.04xa0km/h). The protocol was terminated when participants naturally transitioned to running, or if they chose to not continue. Steps were visually counted and intensity was objectively measured using a portable metabolic system. Youth metabolic equivalents (METy) were calculated for 6–17xa0year olds, with moderate intensity defined as ≥4 and <u20096 METy, and vigorous intensity as ≥6 METy. Traditional METs were calculated for 18–20xa0year olds, with moderate intensity defined as ≥3 and <u20096 METs, and vigorous intensity defined as ≥6 METs. Optimal cadence thresholds for moderate and vigorous intensity were identified using segmented random coefficients models and receiver operating characteristic (ROC) curves.ResultParticipants were on average (± SD) aged 13.1u2009±u20094.3xa0years, weighed 55.8u2009±u200922.3xa0kg, and had a BMI z-score of 0.58u2009±u20091.21. Moderate intensity thresholds (from regression and ROC analyses) ranged from 128.4 steps/min among 6–8xa0year olds to 87.3 steps/min among 18–20xa0year olds. Comparable values for vigorous intensity ranged from 157.7 steps/min among 6–8xa0year olds to 119.3 steps/min among 18–20xa0year olds. Considering both regression and ROC approaches, heuristic cadence thresholds (i.e., evidence-based, practical, rounded) ranged from 125 to 90 steps/min for moderate intensity, and 155 to 125 steps/min for vigorous intensity, with higher cadences for younger age groups. Sensitivities and specificities for these heuristic thresholds ranged from 77.8 to 99.0%, indicating fair to excellent classification accuracy.ConclusionsThese heuristic cadence thresholds may be used to prescribe physical activity intensity in public health recommendations. In the research and clinical context, these heuristic cadence thresholds have apparent value for accelerometer-based analytical approaches to determine the intensity of ambulatory activity.

Are Older Adults With Symptomatic Knee Osteoarthritis Less Active Than the General Population? Analysis From the Osteoarthritis Initiative and the National Health and Nutrition Examination Survey

To compare objectively measured physical activity in older adults with symptomatic knee osteoarthritis (OA) with similarly aged adults without osteoarthritis (OA) or knee symptoms from the general population.

Changes to gait speed and the walk ratio with rhythmic auditory cuing

BACKGROUNDnStep length and cadence (i.e., step frequency or steps/minute) maintain an invariant proportion across a range of walking speeds, known as the walk ratio (WRu202f=u202fstep length/cadence). While step length is a difficult parameter to manipulate, cadence is readily modifiable using rhythmic auditory cuing (RAC; e.g., synchronizing step timing to a metronome or music tempo).nnnRESEARCH QUESTIONnThe purpose of this study was to determine the effects of RAC-guided cadences on enacted cadence, step length, WR, and gait speed during overground walking.nnnMETHODSnSixteen healthy young adults repeatedly crossed a GAITRite electronic walkway while attempting to synchronize step timing to RAC-guided (metronome) tempos of 80 to 140 beats per minute. Mean absolute percent error (MAPE) was used to compare RAC tempos to enacted cadence. Repeated-measures analyses of variance were performed to test for the effects of RAC on cadence, step length, WR, and gait speed. Moreover, simple linear regressions were used to determine the precise stepwise relationship between RAC conditions and each variable.nnnRESULTSnParticipants successfully matched their cadence to RAC beats (MAPE < 1.1%). Cadence increased proportionally to RAC (linear regression slopeu202f=u202f1.02), while step length also increased but at a slower rate (slopeu202f=u202f0.40). These dissimilar slopes resulted in a modified WR that systematically decreased with increasing cadence, although ultimately gait speed increased with increasing cadence (slopeu202f=u202f1.41). This relationship indicates that every 10 steps/minute incremental increase in cadence corresponded with a 14 cm/s increase in gait speed.nnnSIGNIFICANCEnGait speed appears to increase in a predictable manner when cadence is guided by RAC during overground walking irrespective of apparent changes to the WR.