Abstract
PurposeRecent studies have suggested that turning is power intensive. Given the sporadic and irregular movement patterns of children, such findings have important implications for the assessment of true energy expenditure associated with habitual physical activity. The purpose of this study was to investigate the influence of walking speed and angle, and their interaction, on the energy expenditure of healthy children.Methods20 children (10.1 ± 0.5 years; 10 boys) participated in the study. On two separate days, participants completed a turning protocol involving 3-min bouts of walking at one of the 16 speed (2.5, 3.5, 4.5, and 5.5 km h− 1) and angle (0°, 45°, 90°, and 180°) combinations, interspersed by 3 min seated rest. The movement involved 5 m straight walking interspaced with prescribed turns with speed dictated by a digital, auditory metronome. Breath-by-breath gas exchange was measured, in addition to tri-axial acceleration and magnetic field intensity recorded at 100 Hz.ResultsMixed models revealed a significant main effect for speed (p < 0.006) and angle (p < 0.006), with no significant interaction between speed and angle (p > 0.006). Significant differences to straight-line walking energy expenditure within speed were established for 3.5 and 5.5 km h− 1 for 180° turns (~ 13% and ~ 30% increase, respectively).ConclusionThese findings highlight the importance of accounting for the magnitude and frequency of turns completed when estimating children’s habitual physical activity and have significant implications for the assessment of daily energy expenditure.
Highlights
Insufficient physical activity is one of the leading risk factors for global mortality, at least in part due to its association with obesity and non-communicable diseases (NCDs), such as cardiovascular disease, cancer, and diabetes (WHO 2017)
The findings presented highlight the importance of accounting for the magnitude of turn angle and the frequency of turns completed when estimating the habitual physical activity and energy expenditure of children; a failure to do so is likely to lead to erroneous conclusions regarding daily energy expenditure estimated from accelerometry data
The present study extends these findings to children, demonstrating that Cr in a straight line decreased with speed to a minimum energy expenditure attained at 5.5 km h− 1 (1.5 m s−1)
Summary
Insufficient physical activity is one of the leading risk factors for global mortality, at least in part due to its association with obesity and non-communicable diseases (NCDs), such as cardiovascular disease, cancer, and diabetes (WHO 2017). There are some limitations to accelerometer measurements as they are most commonly based upon linear regression models that emphasize that energy expenditure increases linearly with vertical accelerations (Freedson et al 2012), which tend to discredit non-locomotive activities, such as turning (Bassett and John 2010; Chen et al 2007; Van Remoortel et al 2012) In this regard, children are problematic, since their movement is highly sporadic (Baquet et al 2007; Sleap and Warburton 1996; Welk et al 2000), which presents challenges to power-use determination protocols that typically require steady-state conditions (Reilly et al 2004; Trost et al 2011). The development of new multi-sensor devices that integrate both accelerometer and magnetometer measurements have been extensively used as a proxy of V O2 in humans (McNarry et al 2017; Qasem et al 2012; Weippert et al 2013) as a result of the combined ability to capture additional information regarding how the body rotates during pathways that require turning (Williams et al 2017)
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