A comparison of the associations between bone health and three different intensities of accelerometer-derived habitual physical activity in children and adolescents: a systematic review

Abstract

Positive associations have been identified between bone outcomes and accelerometer-derived moderate (MPA) and vigorous (VPA) physical activity (PA) in youth; however, it remains unclear which intensity is most beneficial. This systematic review aimed to summarise accelerometer-derived methods used to estimate habitual PA in children and adolescents and determine whether the magnitude of association was consistently stronger for a particular intensity (MPA/MVPA/VPA). Observational studies assessing associations between accelerometer-derived MPA and/or MVPA and VPA with bone outcomes in children and adolescents (≤ 18 years) were identified in MEDLINE, EMBASE, Web of Science, SPORTDiscus and the Cochrane Central Register of Controlled Trials. Thirty articles were included (total n = 20,613 (10,077 males), 4–18 years). Chi-square tests determined whether the proportion of significant associations and strongest within-study associations differed significantly between intensities. Results demonstrated that accelerometer methods were highly variable between studies. Of the 570 associations analysed, 186 were significant (p < 0.05). The proportion of within-study strongest associations differed by PA intensity (3 × 2 χ2 = 86.6, p < 0.001) and was significantly higher for VPA (39%) compared to MVPA (5%; 2 × 2 χ2 = 55.3, p < 0.001) and MPA (9%, 2 × 2 χ2 = 49.1, p < 0.001). Results indicated a greater benefit of VPA over MPA/MVPA; however, variability in accelerometer-derived methods used prevents the precise bone-benefitting amount of VPA from being identified. Long epochs and numerous intensity cut-point definitions mean that bone-relevant PA has likely been missed or misclassified in this population. Future research should explore the use of shorter epochs (1 s) and identify bone-specific activity intensities, rather than using pre-defined activity classifications more relevant to cardiovascular health.

Improving the identification of bone‐specific physical activity using wrist‐worn accelerometry: A cross‐sectional study in 11–12‐year‐old Australian children

“…The beneficial intensity of >700 mg identified in the present study is equivalent to the VPA threshold identified in calibration studies using wrist-worn raw accelerometry in children (Hildebrand et al, 2014;Phillips et al, 2013). Several previous cross-sectional studies have also reported that accelerometer-derived VPA is most strongly associated with bone outcomes in comparison to other predefined PA intensities (e.g., MPA and MVPA) (Brailey et al, 2022).…”

“…[MPA] and vigorous PA [VPA]), using cut-points (numerous) that are selected at the outset (Brailey et al, 2022). As a result, the short bursts of high-intensity activity that are required to initiate osteogenesis (Turner et al, 2003) and sporadically performed by children (Bailey et al, 1995;Baquet et al, 2007) are "over-smoothed" and misclassified as lower intensity activity (Nilsson et al, 2002).…”

“…Large scale observational studies, such as Australia's Child Health CheckPoint (Clifford et al, 2019), have been instrumental in demonstrating that significant associations between bone outcomes and habitual PA measured using a wrist-worn accelerometer in children do exist, with higher activity levels resulting in greater bone mass, geometry and strength (Osborn et al, 2018), contributing to a reduction in fracture risk (Kalkwarf et al, 2011). However, the use of traditional intensity classifications (e.g., MVPA) and long epoch lengths has prevented the precise amount and intensity of PA required to benefit bone health from being identified (Brailey et al, 2022).…”

First report card on physical activity for children and adolescents in Slovakia: a comprehensive analysis, international comparison, and identification of surveillance gaps

“…A large body of evidence has already established that increased amounts and higher intensity levels of physical activity (PA) in children and adolescents are associated with many beneficial health outcomes [ 1 ]. For instance, PA was found to be positively associated with bone health [ 2 – 4 ], cardiorespiratory fitness [ 5 , 6 ], brain activation and microstructural plasticity [ 7 ], self-rated health [ 8 ], well-being and quality of life [ 9 ], and negatively associated to adiposity and cardiometabolic risk score [ 5 ].…”

Clustering temporal step-counting patterns for 24 hours with machine learning revealed potential heterogeneity in the categorization by a traditional tertile procedure

“…A recent meta-analysis reported that taking more steps per day was associated with lower mortality risk, where the risk plateaued at approximately 6,000–8,000 steps or 8,000–10,000 steps per day for older (≥60 years) or younger adults (<60 years), respectively (Paluch et al, 2022). Most of the previous research on physical activity has concentrated on how the total amount of activity based on its intensity and duration is linked to health (Amagasa et al, 2018; Brailey et al, 2022; Lu et al, 2022). However, analyzing only the total amount of physical activity might overlook a complete understanding of the activity behavior since the metrics of the total amount of physical activity tends to exclude or underestimate the effect of temporal variations of physical activity.…”