Physical Activity During Life Course and Bone Mass

A Systematic Review of Methods and Findings From Cohort Studies With Young Adults

Renata M Bielemann; Jeovany Martinez-Mesa; Denise P Gigante

Disclosures

BMC Musculoskelet Disord. 2013;14(77) 

In This Article

Background

Currently osteoporosis, which is characterized by a reduction in bone mass,[1] is a worldwide health problem with great social and financial impact on society.[2] Osteoporosis increases the risk of fracture due to low bone mass and deterioration of its structure which causes bone fragility.[1]

There is some evidence to suggest that the risk of osteoporosis and its related-problems may be reduced by maximizing the accrual of peak bone mass in the first few decades of life.[3] In addition, the bone mass present at a given time in life is determined by the factors that influence the gain, maintenance or bone loss across the lifespan, including modifiable and lifestyle factors.

Physical activity is a relevant factor to prevent or treat osteoporosis for its capacity to increase or reduce bone loss due to modifications in bone structure and geometry caused by mechanical loads applied from physical activity to bones that stimulate osteogenic responses.[4] Moreover, physical activity also improves strength, flexibility, coordination, balance, reaction time and endurance. However, there are uncertainties about the type, the intensity, the duration, and the frequency of the physical activities that are optimal for an increase in bone mineral density.[5]

Evidence supporting the role of physical activity in bone health has accumulated from cross sectional, cohort and intervention studies. Cross-sectional studies have limitation of temporality, because such studies often have difficult determining the time order of events. On the other hand, randomized-controlled trials show large dropout rates and need long periods of time to achieve measurable changes in bone mass.[6] Furthermore, RCTs are carried out using specific types of activities with different volumes, duration and intensities, which do not represent physical activity general populations. Thereat, the knowledge from longitudinal observational studies (cohorts) is relevant, in which it is possible to evaluate the effect of physical activity on bone mass at a given time in life or across the lifespan, when there are only a few if any RCTs. Moreover, observational studies allow for different kinds of the same exposure to be analyzed in the same sample, making the comparison between effects of different activities easier.

Therefore, the purpose of this study was to review the literature about cohort studies which evaluated the longitudinal association between physical activity during the life course (childhood, adolescence and adulthood) and bone mineral content or density in young adults, describing their samples, methods, quality, differences, findings and fragilities.

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