Effects of Weight-Bearing Activities on Bone Mineral Content and Density in Children and Adolescents: A Meta-Analysis

Abstract

Osteoporosis and associated fractures are a major health concern in Western industrialized nations. Exercise during growth is suggested to oppose the involutional bone loss later in life by increasing peak bone mass. The primary aim of the present metaanalysis was to provide a robust estimate of the effect of weight-bearing activities (WBAs) on bone mineral content (BMC) and areal bone mineral density (aBMD), during childhood and adolescence. To locate relevant studies up to June 2012, computerized searches of multiple bibliographic databases and hand searches of key journals and reference lists were performed. Results were extracted by two independent reviewers. The quality of the included trials was assessed via the Physiotherapy Evidence Database (PEDro) score. The study group effect was defined as the difference between the standardized mean change for the treatment and control groups divided by the pooled pretest SD. From 109 potentially relevant studies, only 27 met the inclusion criteria. The analyzed training programs were capable of significantly increasing BMC and aBMD during growth. However, the weighted overall effect sizes (ESs) for changes in BMC (ES 0.17; 95% confidence interval [CI], 0.05-0.29; p < 0.05) and aBMD (ES 0.26; 95% CI, 0.02-0.49) were small. Stepwise backward regression revealed that more than one-third of the observed variance (r 2 ¼ 0.35) between subgroups of the BMC dataset could be explained by differences in the amount of habitual calcium intake per day (beta 0.54, p < 0.01) and the maturational stage (beta À0.28, p < 0.01) at baseline. No significant moderators were identified for aBMD, possibly due to the small number of trials investigating WBAs on aBMD. The results of this meta-analysis conclude that WBAs alongside high calcium intake provide a practical, relevant method to significantly improve BMC in prepubertal children, justifying the application of this exercise form as an osteoporosis prophylaxis in this stage of maturity.

The effects of combined training on bone metabolic markers in postmenopausal women

“…Non-loading muscle exercise are ineffective for bone loss prevention [25], thus, it may be accepted that highintensity aerobics and resistance exercise seems to be more effective to increase bone metabolism than low-to moderate-intensity as walking exercise [26]. Nevertheless, the bone remodeling response to estrogen deficiency is an increase in the rate of bone remodeling activity and in the rate of bone resorption relative to formation, resulting in a net loss of bone mass [27].…”

Participation in sports in relation to adolescent growth and development

“…Physical activity improves bone health in children and adolescents, particularly at a weight-bearing site. Weight bearing activity improves cortical bone structure due to reduced endocortical expansion (24)(25)(26)(27)(28)(29)(30). In addition to exercise and nutrition (including calcium intake), factors such as genetics and hormonal status determine peak bone mass (16).…”

Effects of a Specialist-Led, School Physical Education Program on Bone Mass, Structure, and Strength in Primary School Children: A 4-Year Cluster Randomized Controlled Trial

“…(3,5) With the introduction of more advanced imaging tools such as peripheral quantitative computed tomography (pQCT) that can provide a three-dimensional assessment of bone, there is also evidence that targeted weight-bearing impact exercise programs in children can improve bone structure (cross-sectional area and/or cortical thickness) and estimates of bone strength at loaded sites. (3,6,7) Collectively these findings provide important information about what can be achieved with targeted bone loading programs, but whether more generalized PA opportunities within the physical education (PE) curriculum offered to all school-aged children can enhance bone structure and strength remains uncertain.…”