Lifestyle choices influence 20–40 % of adult peak bone mass. Therefore, optimization of lifestyle factors known to influence peak bone mass and strength is an important strategy aimed at reducing risk of osteoporosis or low bone mass later in life. The National Osteoporosis Foundation has issued this scientific statement to provide evidence-based guidance and a national implementation strategy for the purpose of helping individuals achieve maximal peak bone mass early in life. In this scientific statement, we (1) report the results of an evidence-based review of the literature since 2000 on factors that influence achieving the full genetic potential for skeletal mass; (2) recommend lifestyle choices that promote maximal bone health throughout the lifespan; (3) outline a research agenda to address current gaps; and (4) identify implementation strategies. We conducted a systematic review of the role of individual nutrients, food patterns, special issues, contraceptives, and physical activity on bone mass and strength development in youth. An evidence grading system was applied to describe the strength of available evidence on these individual modifiable lifestyle factors that may (or may not) influence the development of peak bone mass (Table 1). A summary of the grades for each of these factors is given below. We describe the underpinning biology of these relationships as well as other factors for which a systematic review approach was not possible. Articles published since 2000, all of which followed the report by Heaney et al. [1] published in that year, were considered for this scientific statement. This current review is a systematic update of the previous review conducted by the National Osteoporosis Foundation [1].Lifestyle FactorGrade Macronutrients  FatD ProteinC Micronutrients  CalciumA Vitamin DB Micronutrients other than calcium and vitamin DD Food Patterns  DairyB FiberC Fruits and vegetablesC Detriment of cola and caffeinated beveragesC Infant Nutrition  Duration of breastfeedingD Breastfeeding versus formula feedingD Enriched formula feedingD Adolescent Special Issues  Detriment of oral contraceptivesD Detriment of DMPA injectionsB Detriment of alcoholD Detriment of smokingC Physical Activity and Exercise  Effect on bone mass and densityA Effect on bone structural outcomesB Considering the evidence-based literature review, we recommend lifestyle choices that promote maximal bone health from childhood through young to late adolescence and outline a research agenda to address current gaps in knowledge. The best evidence (grade A) is available for positive effects of calcium intake and physical activity, especially during the late childhood and peripubertal years—a critical period for bone accretion. Good evidence is also available for a role of vitamin D and dairy consumption and a detriment of DMPA injections. However, more rigorous trial data on many other lifestyle choices are needed and this need is outlined in our research agenda. Implementation strategies for lifestyle modifications to promote de...

We validated whole body composition estimates from dual-energy X-ray absorptiometry (DEXA) against estimates from a four-component model to determine whether accuracy is affected by gender, race, athletic status, or musculoskeletal development in young adults. Measurements of body density by hydrostatic weighing, body water by deuterium dilution, and bone mineral by whole body DEXA were obtained in 172 young men (n = 91) and women (n = 81). Estimates of body fat (%Fat) from DEXA (%FatDEXA) were highly correlated with estimates of body fat from the four-component model [body density, total body water, and total body mineral (%Fatd,w,m); r = 0.94, standard error of the estimante (SEE) = 2.8% body mass (BM)] with no significant difference between methods [mean of the difference +/- SD of the difference = -0.4 +/- 2.9 (SD) % BM, P = 0.10] in women and men. On the basis of the comparison with %Fatd,w,m, estimates of %FatDEXA were slightly more accurate than those from body density (r = 0.91, SEE = 3.4%; mean of the difference +/- SD of the difference = -1.2 +/- 3.4% BM). Differences between %FatDEXA and %Fatd,w,m were weakly related to body thickness, as reflected by BMI (r = -0.34), and to the percentage of water in the fat-free mass (r = -0.51), but were not affected by race, athletic status, or musculoskeletal development. We conclude that body composition estimates from DEXA are accurate compared with those from a four-component model in young adults who vary in gender, race, athletic status, body size, musculoskeletal development, and body fatness.

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Excess weight in the form of fat mass does not provide additional benefits, and may potentially be negative, for adolescent bone.

Short stature and later maturation of youth artistic gymnasts are often attributed to the effects of intensive training from a young age. Given limitations of available data, inadequate specification of training, failure to consider other factors affecting growth and maturation, and failure to address epidemiological criteria for causality, it has not been possible thus far to establish cause–effect relationships between training and the growth and maturation of young artistic gymnasts. In response to this ongoing debate, the Scientific Commission of the International Gymnastics Federation (FIG) convened a committee to review the current literature and address four questions: (1) Is there a negative effect of training on attained adult stature? (2) Is there a negative effect of training on growth of body segments? (3) Does training attenuate pubertal growth and maturation, specifically, the rate of growth and/or the timing and tempo of maturation? (4) Does training negatively influence the endocrine system, specifically hormones related to growth and pubertal maturation? The basic information for the review was derived from the active involvement of committee members in research on normal variation and clinical aspects of growth and maturation, and on the growth and maturation of artistic gymnasts and other youth athletes. The committee was thus thoroughly familiar with the literature on growth and maturation in general and of gymnasts and young athletes. Relevant data were more available for females than males. Youth who persisted in the sport were a highly select sample, who tended to be shorter for chronological age but who had appropriate weight-for-height. Data for secondary sex characteristics, skeletal age and age at peak height velocity indicated later maturation, but the maturity status of gymnasts overlapped the normal range of variability observed in the general population. Gymnasts as a group demonstrated a pattern of growth and maturation similar to that observed among short-, normal-, late-maturing individuals who were not athletes. Evidence for endocrine changes in gymnasts was inadequate for inferences relative to potential training effects. Allowing for noted limitations, the following conclusions were deemed acceptable: (1) Adult height or near adult height of female and male artistic gymnasts is not compromised by intensive gymnastics training. (2) Gymnastics training does not appear to attenuate growth of upper (sitting height) or lower (legs) body segment lengths. (3) Gymnastics training does not appear to attenuate pubertal growth and maturation, neither rate of growth nor the timing and tempo of the growth spurt. (4) Available data are inadequate to address the issue of intensive gymnastics training and alterations within the endocrine system.Electronic supplementary materialThe online version of this article (doi:10.1007/s40279-013-0058-5) contains supplementary material, which is available to authorized users.

Context:Changes in serum vitamin D metabolites and calcium absorption with varying doses of oral vitamin D3 in healthy children are unknown.Objective:Our objective was to examine the dose-response effects of supplemental vitamin D3 on serum vitamin D metabolites and calcium absorption in children living at two U.S. latitudes.Design:Black and white children (n = 323) participated in a multisite (U.S. latitudes 34° N and 40° N), triple-masked trial. Children were randomized to receive oral vitamin D3 (0, 400, 1000, 2000, and 4000 IU/d) and were sampled over 12 weeks in winter. Serum 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)2D) were measured using RIA and intact PTH (iPTH) by immunoradiometric assay. Fractional calcium absorption was determined from an oral stable isotope 44Ca (5 mg) in a 150-mg calcium meal. Nonlinear and linear regression models were fit for vitamin D metabolites, iPTH, and calcium absorption.Results:The mean baseline 25(OH)D value for the entire sample was 70.0 nmol/L. Increases in 25(OH)D depended on dose with 12-week changes ranging from −10 nmol/L for placebo to 76 nmol/L for 4000 IU. Larger 25(OH)D gains were observed for whites vs blacks at the highest dose (P < .01). Gains for 1,25(OH)2D were not significant (P = .07), and decreases in iPTH were not dose-dependent. There was no dose effect of vitamin D on fractional calcium absorption when adjusted for pill compliance, race, sex, or baseline 25(OH)D.Conclusion:Large increases in serum 25(OH)D with vitamin D3 supplementation did not increase calcium absorption in healthy children living at 2 different latitudes. Supplementation with 400 IU/d was sufficient to maintain wintertime 25(OH)D concentrations in healthy black, but not white, children.

Elite level or heavily involved female gymnasts may experience attenuated growth during their years of training and competition followed by catch-up growth during reduced training schedules or the months following retirement. However, a cause-effect relation between gymnastics training and inadequate growth of females has not been demonstrated.

The purpose of this study was to determine whether the assumed density and composition of the fat-free mass (FFM) and estimates of percent fat (%Fat) from body density by use of the Siri equation (%Fatd) are valid in weight trainers with high musculoskeletal development. Measures of body density by underwater weighing (Db), body water by deuterium dilution, and bone mineral by whole body dual-energy X-ray absorptiometry were obtained in young white men: 14 weight trainers with high musculoskeletal development and 14 non-weight-training controls with average musculoskeletal development. %Fatd was significantly higher (P < or = 0.05) than %Fat estimated from body density, water, and mineral (%Fatd,w,m) by use of a four-component model in weight trainers (17.3 +/- 4.6 vs. 13.2 +/- 5.1%) but not in controls (14.8 +/- 3.1 vs. 14.2 +/- 3.6%). The greater discrepancy between %Fatd and %Fatd,w,m was explained by lower density of fat-free mass (Dffm) in weight trainers (1.089 +/- 0.005 g/ml) than in controls (1.099 +/- 0.007 g/ml). The lower Dffm in the weight trainers was due to higher water (74.8 +/- 1.2 vs. 72.6 +/- 20%) and lower mineral (5.3 +/- 0.6 vs. 5.9 +/- 0.4%) and protein (19.9 +/- 1.4 vs. 21.5 +/- 1.9%) fractions of the FFM. We conclude that, in young white men with high musculoskeletal development, Dffm is lower than the assumed value of 1.1 g/ml and %Fat is overestimated from Db by use of the Siri equation.