Abstract
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 × 10-22), whereas low-impact PA was not associated with any of the bone Z-scores. In isotemporal substitution models, replacing 1 h·d-1 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 × 10-15). Conversely, replacing 1 h·d-1 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 × 10-15). 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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 977-986 |
| Number of pages | 10 |
| Journal | Medicine and Science in Sports and Exercise |
| Volume | 50 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 1 2018 |
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All Science Journal Classification (ASJC) codes
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation
Cite this
Physical Activity and Bone Accretion : Isotemporal Modeling and Genetic Interactions. / Mitchell, Jonathan A.; Chesi, Alessandra; McCormack, Shana E.; Cousminer, Diana L.; Kalkwarf, Heidi J.; Lappe, Joan M.; Gilsanz, Vicente; Oberfield, Sharon E.; Shepherd, John A.; Kelly, Andrea; Grant, Struan F.A.; Zemel, Babette S.
In: Medicine and Science in Sports and Exercise, Vol. 50, No. 5, 01.05.2018, p. 977-986.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Physical Activity and Bone Accretion
T2 - Isotemporal Modeling and Genetic Interactions
AU - Mitchell, Jonathan A.
AU - Chesi, Alessandra
AU - McCormack, Shana E.
AU - Cousminer, Diana L.
AU - Kalkwarf, Heidi J.
AU - Lappe, Joan M.
AU - Gilsanz, Vicente
AU - Oberfield, Sharon E.
AU - Shepherd, John A.
AU - Kelly, Andrea
AU - Grant, Struan F.A.
AU - Zemel, Babette S.
PY - 2018/5/1
Y1 - 2018/5/1
N2 - 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 × 10-22), whereas low-impact PA was not associated with any of the bone Z-scores. In isotemporal substitution models, replacing 1 h·d-1 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 × 10-15). Conversely, replacing 1 h·d-1 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 × 10-15). 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.
AB - 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 × 10-22), whereas low-impact PA was not associated with any of the bone Z-scores. In isotemporal substitution models, replacing 1 h·d-1 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 × 10-15). Conversely, replacing 1 h·d-1 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 × 10-15). 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.
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U2 - 10.1249/MSS.0000000000001520
DO - 10.1249/MSS.0000000000001520
M3 - Article
VL - 50
SP - 977
EP - 986
JO - Medicine and Science in Sports and Exercise
JF - Medicine and Science in Sports and Exercise
SN - 0195-9131
IS - 5
ER -