Effects of Weight-Bearing Exercise on Bone Health in Girls: A Meta-Analysis
- 1.2k Downloads
Because growing bone possesses a greater capacity to adapt to mechanical loading than does mature bone, it is important for girls to engage in weight-bearing activities, especially since the prevalence of osteoporosis among older women is considerably higher than that of older men. In recent years, the osteogenic potential of weight-bearing activities performed by children and adolescents has received increasing attention and accumulating evidence suggests that this type of activity may improve bone health prior to adulthood and help prevent osteoporosis later in life.
Because previous interventions have varied with respect to the exercise parameters studied and sometimes produced conflicting findings, this meta-analysis was undertaken to evaluate the impact of weight-bearing exercise on the bone health of female children and adolescents and quantify the influence of key moderating variables (e.g. pubertal stage, exercise mode, intervention strategy, exercise duration, frequency of exercise, programme length and study design) on skeletal development in this cohort.
A comprehensive literature search was conducted using databases such as PubMed, MEDLINE, CINAHL, Web of Science, Physical Education Index, Science Direct and ProQuest. Search terms included ‘bone mass’, ‘bone mineral’, ‘bone health’, ‘exercise’ and ‘physical activity’. Randomized- and non-randomized controlled trials featuring healthy prepubertal, early-pubertal and pubertal girls and measurement of areal bone mineral density (aBMD) or bone mineral content (BMC) using dual energy x-ray absorptiometry were examined. Comprehensive Meta-Analysis software was used to determine weighted mean effect sizes (ES) and conduct moderator analyses for three different regions of interest [i.e. total body, lumbar spine (LS), and femoral neck].
From 17 included studies, 72 ES values were retrieved. Our findings revealed a small, but significant influence of weight-bearing exercise on BMC and aBMD of the LS (overall ES 0.19; 95 % confidence interval (CI) 0.05, 0.33 and overall ES 0.26, 95 % CI 0.09, 0.43, respectively) and BMC of the femoral neck (ES 0.23; 95 % CI 0.10, 0.36). For both aBMD and BMC, overall ES was not affected by any moderator variables except frequency of exercise, such that weight-bearing activity performed for more than 3 days per week resulted in a significantly greater ES value for LS aBMD compared with programmes lasting 3 or fewer days per week [Cochran’s Q statistic (Qbetween) = 4.09; p < 0.05].
The impact of weight-bearing activities seems to be site specific, and a greater frequency of weight-bearing activities is related to greater aBMD of LS in growing girls. Future investigations are warranted to better understand the dose-response relationship between weight-bearing activity and bone health in girls and explore the mediating role of pubertal status in promoting skeletal development among female youth.
This work was not supported by any funding. All authors state that they have no conflicts of interest. We thank Dr. Heather Macdonald for providing us with information needed for this analysis.
- 2.National Institutes of Health. Osteoporosis and Related Bone Diseases National Resource Center [online]. http://www.niams.nih.gov/bone (Accessed 31 July 2011).
- 21.Valdimarsson O, Linden C, Johnell O, et al. Daily physical education in the school curriculum in prepubertal girls during 1 year is followed by an increase in bone mineral accrual and bone width: data from the prospective controlled Malmo pediatric osteoporosis prevention study. Calcif Tissue Int. 2006;78:65–71.PubMedCrossRefGoogle Scholar
- 22.Hasselstrom HA, Karlsson MK, Hansen SE, et al. A 3-year physical activity intervention program increases the gain in bone mineral and bone width in prepubertal girls but not boys: the prospective Copenhagen school child interventions study (CoSCIS). Calcif Tissue Int. 2008;83:243–50.PubMedCrossRefGoogle Scholar
- 28.Karlsson MK, Nordqvist A, Karlsson C. Physical activity increases bone mass during growth. Food Nutr Res. 2008;52.Google Scholar
- 40.Lipsey MW, Wilson DB. Practical meta-analysis. Thousand Oaks: SAGE Publications, Inc.; 2001. p. 247.Google Scholar
- 41.Hedges LV, Olkin I. Statistical methods for meta-analysis. Orlando: Academic Press Inc.; 1985. p. 361.Google Scholar
- 42.Cohen J. Statistical power for the behavioral sciences. 2nd rev. ed. Hillsdale: Erlbaum; 1999. p. 569.Google Scholar
- 45.Morseth B, Emaus N, Jorgensen L. Physical activity and bone: the importance of the various mechanical stimuli for bone mineral density. A review. Nor Epidemiol. 2011;20:173–9.Google Scholar
- 56.Baxter-Jones AD, Eisenmann JC, Sherar LB. Controlling for maturation in pediatric exercise science. Pediatr Exerc Sci. 2005;17:18–30.Google Scholar
- 60.Karlsson MK, Nordqvist A, Karlsson C. Sustainability of exercise-induced increases in bone density and skeletal structure. Food Nutr Res. 2008 (Epub 2008 Oct 1).Google Scholar
- 68.Stewart SR. The effects of an 18-month weight-training and calcium-supplementation program on bone mineral of adolescent girls [dissertation]. Vancouver: University of British Columbia; 1997. p. 357.Google Scholar