Measuring moderate-intensity walking in older adults using the ActiGraph accelerometer

Abstract

BackgroundAccelerometry is the method of choice for objectively assessing physical activity in older adults. Many studies have used an accelerometer count cut point corresponding to 3 metabolic equivalents (METs) derived in young adults during treadmill walking and running with a resting metabolic rate (RMR) assumed at 3.5 mL · kg−1 · min−1 (corresponding to 1 MET). RMR is lower in older adults; therefore, their 3 MET level occurs at a lower absolute energy expenditure making the cut point derived from young adults inappropriate for this population. The few studies determining older adult specific moderate-to-vigorous intensity physical activity (MVPA) cut points had methodological limitations, such as not measuring RMR and using treadmill walking.MethodsThis study determined a MVPA hip-worn accelerometer cut point for older adults using measured RMR and overground walking. Following determination of RMR, 45 older adults (mean age 70.2 ± 7 years, range 60–87.6 years) undertook an outdoor, overground walking protocol with accelerometer count and energy expenditure determined at five walking speeds.ResultsMean RMR was 2.8 ± 0.6 mL · kg−1 · min−1. The MVPA cut points (95% CI) determined using linear mixed models were: vertical axis 1013 (734, 1292) counts · min−1; vector magnitude 1924 (1657, 2192) counts · min−1; and walking speed 2.5 (2.2, 2.8) km · hr−1. High levels of inter-individual variability in cut points were found.ConclusionsThese MVPA accelerometer and speed cut points for walking, the most popular physical activity in older adults, were lower than those for younger adults. Using cut points determined in younger adults for older adult population studies is likely to underestimate time spent engaged in MVPA. In addition, prescription of walking speed based on the adult cut point is likely to result in older adults working at a higher intensity than intended.

Sedentary behaviour, physical activity, and sarcopenia among older adults in the TSHA: isotemporal substitution model

“…Similarly, Barnett et al . determined an age‐specific LPA–MVPA transition threshold in a population of older adults (mean age 70.2), in a calibration study against indirect calorimetry . The use of these age‐specific thresholds in our study partially overcomes the previously described shortcomings.…”

“…10 Similarly, Barnett et al determined an age-specific LPA-MVPA transition threshold in a population of older adults (mean age 70.2), in a calibration study against indirect calorimetry. 20 The use of these age-specific thresholds in our study partially overcomes the previously described shortcomings. Nevertheless, and very importantly, we acknowledge that there could still be bias because of variability in several factors that might influence energy cost, such as sex, fitness, body weight, disability, movement impairment, and illnesses.…”

Validating Fitbit for Evaluation of Physical Activity in Patients with Knee Osteoarthritis: Do Thresholds Matter?

“…A walking speed of 2.5 km/h was considered consistent with MVPA for an older population , particularly one with elevated pain (mean Knee Injury and Osteoarthritis Outcome Score [KOOS] pain = 50) and limited function due to OA. We used an estimated stride length of 0.6 m (derived from a measured step length of 0.3 m) to conclude that at least 67 strides/min would be needed to achieve a speed of 2.5 km/h.…”

“…Triaxial, medical‐grade accelerometers like the ActiGraph GT3X+ (ActiGraph Corporation) are considered the gold standard for PA evaluation , yet guidelines for interpreting accelerometry data are not standardized in the literature . Studies have proposed multiple threshold cutoffs to relate ActiGraph counts to PA levels, and some have suggested that thresholds should be described as ranges to account for interperson variability . Furthermore, much accelerometry validation has involved young and healthy populations or uniaxial ActiGraphs , the results of which are not applicable to the older OA population using triaxial accelerometers .…”

International Mind, Activities and Urban Places (iMAP) study: methods of a cohort study on environmental and lifestyle influences on brain and cognitive health

“…Waistworn accelerometer data are used to derive average minutes/day of light, moderate and vigorous physical activity, while the inclinometer is used to assess sedentary behaviour using established protocols. 89 90 We quantify complexity of trip routes (i.e., the cognitive difficulty of Open access navigational activities) in terms of length, street intersections crossed and number of turns at intersections using GIS software. Wrist-worn accelerometer data are used to quantify total sleep time and efficiency, waking after sleep onset and number of long wake episodes.…”