Impact of timing of pubertal maturation on growth in black and white female adolescents: The National Heart, Lung, and Blood Institute Growth and Health Study.

OBJECTIVES: To evaluate the impact of early, mid-onset, and late maturation, as assessed by timing of menarche, on height, height velocity, weight, body mass index, and sum of skinfolds in a group of white and black girls. STUDY DESIGN: The Growth and Health Study recruited 9- and 10-year-old girls from Richmond, California, Cincinnati, Ohio, and Washington, DC. There were 616 white and 539 black participants recruited at age 9 and 550 white and 674 black participants recruited at age 10. Participants were seen annually for 10 visits. Longitudinal regression models were used to test for differences in each growth measure by timing of menarche across all ages and to determine whether these differences change with age. RESULTS: Mean age at menarche among white participants was 12.7 years, and among black participants, 12.0 years. According to race-specific 20th and 80th percentiles, early maturers were tallest at early ages and shortest after adult stature had been attained. Peak height velocity and post-menarche increment in stature were greatest in early maturers and least in late maturers. Weight was greatest in early and least in late maturers, as was body mass index. Sum of skinfolds was also greatest in early and least in late maturers. There was no impact of timing of maturation on two common measures of regional fat distribution. CONCLUSIONS: Girls who matured early were shorter in early adulthood, despite having greater peak height velocity and post-menarchal increment in height. Throughout puberty, early maturers had greater ponderosity and adiposity, although there was no association with regional distribution of fat.

Sexual maturation and racial differences in blood pressure in girls: the National Heart, Lung, and Blood Institute Growth and Health Study.

OBJECTIVE: To evaluate racial differences in blood pressure in girls aged 9 to 10 years in the National Heart, Lung, and Blood Institute Growth and Health Study (NGHS) and to evaluate the extent to which racial differences in blood pressure are explained by other factors, including sexual maturation and body size. METHODS: The NGHS enrolled 539 black and 616 white girls aged 9 years, and 674 black and 550 white girls aged 10 years. Racial differences in blood pressure were examined. Relationships of stage of sexual maturation, height, and skinfold thickness with systolic and diastolic blood pressure were evaluated by multiple regression analysis. RESULTS: The black girls had significantly higher systolic (102.0 +/- 8.90 vs 100.5 +/- 9.42 mm Hg, p <0.001) and diastolic (58.0 +/- 12.0 vs 56.5 +/- 12.51 mm Hg, p <0.01) blood pressures than the white girls. The black girls were also more advanced in sexual maturation and were taller (142.9 +/- 7.94 vs 139.6 +/- 7.05, p <0.001) and heavier (39.6 +/- 11.24 vs 35.3 +/- 8.73 kg, p <0.001) than the white girls. Both systolic and diastolic blood pressure were significantly correlated with level of maturation, height, weight, and sum of skinfolds. Stage of maturation was found to account for the difference in blood pressure between black girls and white girls. In a multiple regression analysis, controlling for height (for diastolic blood pressure) and for both height and sum of skinfolds (for systolic blood pressure) eliminated the effects of race and stage of maturation on blood pressure. CONCLUSION: Racial differences in blood pressure were observed for 9- and 10-year-old girls and are explained by the fact that black girls were more mature than white girls. The effect of sexual maturation on blood pressure appears to operate through height and body fat. The effect of obesity may be more important for systolic than for diastolic blood pressure. Continuation of racial differences in blood pressure may result in a higher prevalence of hypertension for black women.

Sexual maturation and obesity in 9- and 10-year-old black and white girls: the National Heart, Lung, and Blood Institute Growth and Health Study.

OBJECTIVE: To assess the relationship between pubertal maturation and obesity in 9- and 10-year-old black and white girls. METHOD: Cross-sectional analysis of cohort baseline data. SUBJECTS: A cohort of 2379 girls recruited from selected schools in Richmond, Calif., and greater Cincinnati, Ohio, and from the membership rolls of a prepaid group practice in greater Washington, D.C. RESULTS: Sixty-four percent of black girls had begun pubertal maturation compared with 33% of white girls. In prepubertal girls, racial differences in height, weight, body mass index (kilograms per square meter) and skin-fold thickness were not significant. Within each race, onset of pubertal maturation was associated with greater height, weight, body mass index, and skin-fold measurements. Within 9-year-old girls who had begun pubertal maturation but not reached menarche, black girls were taller and heavier than white girls. Among pubertal but premenarcheal 10-year-old subjects, black girls were taller and heavier and had greater body mass index and subscapular skin-fold values. After analyses were adjusted for pubertal maturation stage by means of pubic hair development, 10-year-old pubertal black girls remained taller and heavier, but racial differences in body mass index and the sum of skin-fold measurements ceased to be significant. CONCLUSIONS: These findings suggest that the initiation of racial differences in obesity are related, at least temporally, to pubertal maturation.

Relative importance of calorie intake needed to gain weight and level of physical activity in anorexia nervosa.

We assessed whether level of physical activity of anorexia nervosa patients could influence caloric consumption needed to gain weight during hospitalization. Seventy-three percent of patients with anorexia nervosa had higher levels of motor activity than did healthy female volunteers. Anorectics required 8301 +/- 2272 kcal (mean +/- SD) to gain 1 kg body wt. Activity levels and caloric consumption needed to gain 1 kg were significantly correlated; the most active patients needed to consume more calories to gain weight. A median split of anorectic patients by level of activity showed that the group with lower activity levels gained 1 kg every 5.1 +/- 1.2 d, whereas the group with higher activity levels gained 1 kg every 7.2 +/- 1.9 d. These data suggest that the rate of weight gain can be accelerated, and the cost of hospitalization decreased, by restricting exercise in anorectics during refeeding.