Objectively Measured Physical Activity Predicts Hip and Spine Bone Mineral Content in Children and Adolescents Ages 5–15 Years: Iowa Bone Development Study

Abstract

This study examined the association between physical activity (PA) and bone mineral content (BMC; gram) from middle childhood to middle adolescence and compared the impact of vigorous-intensity PA (VPA) over moderate- to vigorous-intensity PA (MVPA). Participants from the Iowa bone development study were examined at ages 5, 8, 11, 13, and 15 years (n = 369, 449, 452, 410, and 307, respectively). MVPA and VPA (minutes per day) were measured using ActiGraph accelerometers. Anthropometry was used to measure body size and somatic maturity. Spine BMC and hip BMC were measured via dual-energy x-ray absorptiometry. Sex-specific multi-level linear models were fit for spine BMC and hip BMC, adjusted for weight (kilogram), height (centimeter), linear age (year), non-linear age (year2), and maturity (pre peak height velocity vs. at/post peak height velocity). The interaction effects of PA × maturity and PA × age were tested. We also examined differences in spine BMC and hip BMC between the least (10th percentile) and most (90th percentile) active participants at each examination period. Results indicated that PA added to prediction of BMC throughout the 10-year follow-up, except MVPA, did not predict spine BMC in females. Maturity and age neither modify the PA effect for males nor females. At age 5, the males at the 90th percentile for VPA had 8.5% more hip BMC than males in the 10th percentile for VPA. At age 15, this difference was 2.0%. Females at age 5 in the 90th percentile for VPA had 6.1% more hip BMC than those in the 10th percentile for VPA. The age 15 difference was 1.8%. VPA was associated with BMC at weight-bearing skeletal sites from childhood to adolescence, and the effect was not modified by maturity or age. Our findings indicate the importance of early and sustained interventions that focus on VPA. Approaches focused on MVPA may be inadequate for optimal bone health, particularly for females.

Systematic review of the relationships between objectively measured physical activity and health indicators in school-aged children and youth

“…Total PA explained 1%-2% of the variability in BMC (Janz et al 2006) Children who maintained high levels of PA over the 3-y period (≥50th percentile) accrued, on average, 14% more trochanteric BMC and 5% more whole-body BMC relative to peers maintaining low levels of PA (<50th percentile) (Janz et al 2006) 1 study found that spending a higher proportion of total PA in MPA-VPA relative to LPA was favourably associated with BMC, BMD, and bone area (Heidemann et al 2013 (1/1 studies; Tobias et al 2007); Hip BMC: favourable associations (2/2 studies; Janz et al 2001Janz et al , 2014a; Spine BMC: associations were favourable (2/3 studies; Janz et al 2001 and …”

“…d Includes 7 longitudinal studies (Janz et al 2006(Janz et al , 2007(Janz et al , 2010(Janz et al , 2014a(Janz et al , 2014bHeidemann et al 2013;Francis et al 2014) from 2 unique samples. Six studies reported data from the Iowa Bone Development Study (Janz et al 2006(Janz et al , 2007(Janz et al , 2010(Janz et al , 2014a(Janz et al , 2014bFrancis et al 2014) and 1 study reported data from the CHAMPS study sample (Heidemann et al 2013). Results are reported separately and participants are only counted once.…”

“…f Includes 14 cross-sectional studies (Janz et al 2001(Janz et al , 2004(Janz et al , 2008(Janz et al , 2014aHasselstrøm et al 2007;Tobias et al 2007;Farr et al 2011;Gracia-Marco et al 2011aSayers et al 2011;Cardadeiro et al 2012;Deere et al 2012;Francis et al 2014), from 6 unique samples. Five studies reported data from the Iowa Bone Development Study (Janz et al 2001(Janz et al , 2004(Janz et al , 2008(Janz et al , 2014aFrancis et al 2014), 3 studies from the ALSPAC (Tobias et al 2007;Sayers et al 2011;Deere et al 2012), 3 studies from HELENA (Gracia-Marco et al 2011a, and 1 study from each of CoSCIS (Hasselstrøm et al 2007), EYHS (Cardadeiro et al 2012), and Jump-In: Building Better Bones (Farr et al 2011). Results are reported separately and participants are only counted once.…”

“…One longitudinal study found that spending a higher proportion of total PA engaged in MPA and VPA relative to LPA was prospectively associated with higher BMC, bone mineral density (BMD), and bone area (Heidemann et al 2013). There were mixed (favourable and null) associations between VPA and spine or hip BMC (2/2 studies; Francis et al 2014;Janz et al 2014a). Mixed (favourable and null) prospective associations were observed between MVPA and whole-body, hip and spine BMC (3/3 studies; Janz et al 2010Janz et al , 2014aFrancis et al 2014), hip BMD (1/1 studies; Janz et al 2014b), femoral neck cross-sectional area and section modulus (2/2 studies; Janz et al 2007Janz et al , 2014b, and measures of bone strength (bone stress index and polar moment of inertia; 1/1 studies; Janz et al 2014b).…”

“…VPA was favourably associated with whole-body BMC (2/2 studies; Janz et al 2001;Tobias et al 2007), but in 1 study the associations were significant only in boys (null in girls; Janz et al 2001). VPA was favourably associated with cortical BMC (1/1 studies; Sayers et al 2011), BMC of the hip (2/2 studies; Janz et al 2001Janz et al , 2014a and spine (2/3 studies; Janz et al 2001Janz et al , 2014a, and with upper (1/1 studies; Tobias et al 2007) but not lower (0/1 studies) limb BMC. VPA was not associated with whole-body, upper, or lower limb BMC after adjusting for bone area (1/1 studies; Tobias et al 2007).…”