RESUMO
OBJECTIVE: To evaluate the effects of an elementary school-based physical education exercise intervention program on bone mineral accrual in prepubertal and early pubertal girls. STUDY DESIGN: A total of 14 schools were randomly assigned to control (C) and intervention (I) groups. Girls in the I group completed a 10-minute, 3 times per week circuit of varied jumping activities over 7 months. We measured total body, lumbar spine, proximal femur, femoral neck, and trochanteric bone mineral content and areal bone mineral density and estimated femoral neck volumetric bone mineral density at baseline and final measurement in 87 girls in the I group and 90 girls in the C group. Girls were between 8.7 and 11.7 years at baseline. Tanner stage 1 girls were considered prepubertal; Tanner stages 2 and 3 girls were considered early pubertal. We used analysis of covariance (adjusting for baseline bone values, change in size, age, and maturity) to compare 7-month change in bone mineral content, areal bone mineral density, and volumetric bone mineral density between C and I groups within prepubertal and early pubertal girls. RESULTS: There was no difference in 7-month change in bone parameters between prepubertal I and C groups. Early pubertal girls in the I group gained 1.5% to 3.1% more bone at the femoral neck and lumbar spine than early pubertal girls in the C group (P <.05); gain at other sites did not differ. CONCLUSIONS: In girls, early puberty may be a particularly opportune time during growth for simple exercise interventions to have a positive effect on bone health.
Assuntos
Densidade Óssea/fisiologia , Exercício Físico/fisiologia , Puberdade/fisiologia , Serviços de Saúde Escolar , Absorciometria de Fóton , Antropometria , Composição Corporal/fisiologia , Criança , Fenômenos Fisiológicos da Nutrição Infantil/fisiologia , Feminino , Fêmur/diagnóstico por imagem , Fêmur/fisiologia , Humanos , Estilo de Vida , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/fisiologia , Estudos Prospectivos , Fatores de TempoRESUMO
BACKGROUND: Of the few exercise intervention studies focusing on pediatric populations, none have confined the intervention to the scheduled physical education curriculum. OBJECTIVE: To examine the effect of an 8-month school-based jumping program on the change in areal bone mineral density (aBMD), in grams per square centimeter, of healthy third- and fourth-grade children. STUDY DESIGN: Ten elementary schools were randomized to exercise (n = 63) and control groups (n = 81). Exercise groups did 10 tuck jumps 3 times weekly and incorporated jumping, hopping, and skipping into twice weekly physical education classes. Control groups did regular physical education classes. At baseline and after 8 months of intervention, we measured aBMD and lean and fat mass by dual-energy x-ray absorptiometry (Hologic QDR-4500). Calcium intake, physical activity, and maturity were estimated by questionnaire. RESULTS: The exercise group showed significantly greater change in femoral trochanteric aBMD (4.4% vs 3.2%; P <.05). There were no group differences at other sites. Results were similar after controlling for covariates (baseline aBMD change in height, change in lean, calcium, physical activity, sex, and ethnicity) in hierarchical regression. CONCLUSIONS: An easily implemented school-based jumping intervention augments aBMD at the trochanteric region in the prepubertal and early pubertal skeleton.
Assuntos
Densidade Óssea , Exercício Físico , Educação Física e Treinamento , Absorciometria de Fóton , Composição Corporal , Estatura , Desenvolvimento Ósseo , Criança , Feminino , Quadril/diagnóstico por imagem , Humanos , MasculinoRESUMO
After an 8-month physical activity intervention in children with cerebral palsy, increases in femoral neck bone mineral content (BMC) (9.6%), volumetric bone mineral density (v BMD) (5.6%), and total proximal femur BMC (11.5%) were observed in the intervention group (n = 9) compared with control subjects (n = 9; femoral neck BMC, -5. 8%; v BMD, -6.3%; total proximal femur BMC, 3.5%).
Assuntos
Paralisia Cerebral/reabilitação , Terapia por Exercício , Espasticidade Muscular/reabilitação , Osteoporose/prevenção & controle , Suporte de Carga , Absorciometria de Fóton , Análise de Variância , Densidade Óssea , Paralisia Cerebral/complicações , Criança , Feminino , Fêmur/fisiologia , Humanos , Masculino , Espasticidade Muscular/complicações , Espasticidade Muscular/etiologia , Osteoporose/etiologiaRESUMO
BACKGROUND AND OBJECTIVES: The greatest increase in bone mineral content occurs during adolescence. The amount of bone accrued may significantly affect bone mineral status in later life. We carried out a longitudinal investigation of the magnitude and timing of peak bone mineral content velocity (PBMCV) in relation to peak height velocity (PHV) and the age at menarche in a group of adolescent girls over a 6-year period. METHODS: The 53 girls in this study are a subset of the 115 girls (initially 8 to 16 years) in a 6-year longitudinal study of bone mineral accretion. The ages at PBMCV and PHV were determined by using a cubic spline curve fitting procedure. Determinations were based on height (n = 12) and bone (n = 6) measurements over 6 years. RESULTS: The timing of PBMCV and menarche were coincident, preceded approximately 1 year earlier by PHV. Correlation showed a negative relationship between age at menarche and both peak bone mineral accrual (r = -0.42, P < .002) and PHV (r = -0.45, P < .001). CONCLUSIONS: This longitudinal study demonstrated the close association between age at PBMCV and age at menarche and confirmed the relationship between greater PBMCV and PHV in earlier, as compared with later, maturing girls.
Assuntos
Densidade Óssea/fisiologia , Menarca/fisiologia , Adolescente , Estatura/fisiologia , Criança , Feminino , Humanos , Estudos Longitudinais , Valores de ReferênciaRESUMO
A longer duration of breast-feeding and later introduction to solids may protect against excessive adiposity in infancy. This study investigated infant feeding practices and their relationship to two measures of adiposity--body mass index (BMI) and sum of skinfold thicknesses (SUMSF)--in 331 4-y-old Anglo- (43%) and Mexican-American (57%) children. No associations were detected between any of the infant feeding variables of duration of breast-feeding and introduction to solids and formula and measures of the child's adiposity. Mother's physical measures of BMI and SUMSF explained the largest portion of variance for both measures of childhood adiposity, BMI (9.5%), and SUMSF (8.3%). Genetic and environmental factors other than infant feeding practices appear to have a greater influence on a 4-y-olds' adiposity.