PURPOSE: This study aimed to determine if replacing time spent in high- and low-impact physical activity (PA) predicts changes in pediatric bone mineral density (BMD) and content (BMC). METHODS: We analyzed data from the longitudinal Bone Mineral Density in Childhood Study (N = 2337 with up to seven visits). The participants were age 5-19 yr at baseline, 51.2% were female, and 80.6% were nonblack. Spine, total hip, and femoral neck areal BMD and total body less head (TBLH) BMC Z-scores were calculated. Hours per day spent in high- and low-impact PA were self-reported. Standard covariate-adjusted (partition model) and time allocation-sensitive isotemporal substitution modeling frameworks were applied to linear mixed models. Statistical interactions with sex, self-reported ancestry, age, and bone fragility genetic scores (percentage of areal BMD-lowering alleles carried) were tested. RESULTS: In standard models, high-impact PA was positively associated with bone Z-score at all four skeletal sites (e.g., TBLH-BMC Z-score: beta = 0.05, P = 2.0 × 10), whereas low-impact PA was not associated with any of the bone Z-scores. In isotemporal substitution models, replacing 1 h·d of low- for high-impact PA was associated with higher bone Z-scores (e.g., TBLH-BMC Z-score: beta = 0.06, P = 2.9 × 10). Conversely, replacing 1 h·d of high- for low-impact PA was associated with lower bone Z-scores (e.g., TBLH-BMC Z-score: beta = -0.06, P = 2.9 × 10). The substitution associations were similar for each sex and ancestry group, and for those with higher and lower genetic scores for bone fragility (P-interactions > 0.05), but increased in strength among the older adolescents (P-age interactions < 0.05). CONCLUSIONS: Time-sensitive models suggest that replacing low-impact PA for high-impact PA would be beneficial for the growing skeleton in the majority of children.
PURPOSE: This study aimed to determine if replacing time spent in high- and low-impact physical activity (PA) predicts changes in pediatric bone mineral density (BMD) and content (BMC). METHODS: We analyzed data from the longitudinal Bone Mineral Density in Childhood Study (N = 2337 with up to seven visits). The participants were age 5-19 yr at baseline, 51.2% were female, and 80.6% were nonblack. Spine, total hip, and femoral neck areal BMD and total body less head (TBLH) BMC Z-scores were calculated. Hours per day spent in high- and low-impact PA were self-reported. Standard covariate-adjusted (partition model) and time allocation-sensitive isotemporal substitution modeling frameworks were applied to linear mixed models. Statistical interactions with sex, self-reported ancestry, age, and bone fragility genetic scores (percentage of areal BMD-lowering alleles carried) were tested. RESULTS: In standard models, high-impact PA was positively associated with bone Z-score at all four skeletal sites (e.g., TBLH-BMC Z-score: beta = 0.05, P = 2.0 × 10), whereas low-impact PA was not associated with any of the bone Z-scores. In isotemporal substitution models, replacing 1 h·d of low- for high-impact PA was associated with higher bone Z-scores (e.g., TBLH-BMC Z-score: beta = 0.06, P = 2.9 × 10). Conversely, replacing 1 h·d of high- for low-impact PA was associated with lower bone Z-scores (e.g., TBLH-BMC Z-score: beta = -0.06, P = 2.9 × 10). The substitution associations were similar for each sex and ancestry group, and for those with higher and lower genetic scores for bone fragility (P-interactions > 0.05), but increased in strength among the older adolescents (P-age interactions < 0.05). CONCLUSIONS: Time-sensitive models suggest that replacing low-impact PA for high-impact PA would be beneficial for the growing skeleton in the majority of children.
Authors: Luis Gracia-Marco; Luis A Moreno; Francisco B Ortega; Francisco León; Isabelle Sioen; Anthony Kafatos; David Martinez-Gomez; Kurt Widhalm; Manuel J Castillo; Germán Vicente-Rodríguez Journal: Am J Prev Med Date: 2011-06 Impact factor: 5.043
Authors: Jonathan A Mitchell; Alessandra Chesi; Okan Elci; Shana E McCormack; Sani M Roy; Heidi J Kalkwarf; Joan M Lappe; Vicente Gilsanz; Sharon E Oberfield; John A Shepherd; Andrea Kelly; Struan Fa Grant; Babette S Zemel Journal: J Bone Miner Res Date: 2016-08 Impact factor: 6.741
Authors: R J Kuczmarski; C L Ogden; L M Grummer-Strawn; K M Flegal; S S Guo; R Wei; Z Mei; L R Curtin; A F Roche; C L Johnson Journal: Adv Data Date: 2000-06-08
Authors: Nicole C Wright; Anne C Looker; Kenneth G Saag; Jeffrey R Curtis; Elizabeth S Delzell; Susan Randall; Bess Dawson-Hughes Journal: J Bone Miner Res Date: 2014-11 Impact factor: 6.741
Authors: Jonathan A Mitchell; Alessandra Chesi; Okan Elci; Shana E McCormack; Sani M Roy; Heidi J Kalkwarf; Joan M Lappe; Vicente Gilsanz; Sharon E Oberfield; John A Shepherd; Andrea Kelly; Struan Fa Grant; Babette S Zemel Journal: J Bone Miner Res Date: 2015-12-14 Impact factor: 6.741
Authors: A Morse; M M McDonald; N H Kelly; K M Melville; A Schindeler; I Kramer; M Kneissel; M C H van der Meulen; D G Little Journal: J Bone Miner Res Date: 2014-11 Impact factor: 6.741
Authors: Babette S Zemel; Mary B Leonard; Andrea Kelly; Joan M Lappe; Vicente Gilsanz; Sharon Oberfield; Soroosh Mahboubi; John A Shepherd; Thomas N Hangartner; Margaret M Frederick; Karen K Winer; Heidi J Kalkwarf Journal: J Clin Endocrinol Metab Date: 2010-01-26 Impact factor: 5.958