Soccer is a highly osteogenic sport in pubescent adolescents and adults, particularly in weight-bearing bones. However, little is known about its effects in children despite the fact that soccer practice usually starts before puberty. The aim of this study was to verify whether soccer was able to increase bone mineral content (BMC) of weight-bearing bones by modifying bone remodelling in relation to the level of training in prepubescent boys compared to controls.

At baseline we investigated 39 prepubescent soccer players (11.7±0.8 years) divided into two groups according to the duration of training (2 and 4h/week) and 13 controls (10.7±0.6 years). BMC and bone resorption marker (CTX) were measured, respectively, by dual-energy X-ray absorptiometry (DEXA) and ELISA. Then, measurements were performed twice during a 10-month survey: only 27 boys remaining prepubescent were analysed.

At baseline, no BMC difference was found in weight-bearing sites between soccer players and controls. Nevertheless, soccer players BMC gain significantly increased in total hip (+10.7%, P<0.05), lumbar spine (+10.5%, P<0.05) and legs, the increase being more marked in the longest duration training group (4h/weeks), particularly after a summer resting period. Meanwhile, resorption activity decreased. At the same time, cranial BMC was decreased in soccer players (-4.6%, P<0.001).

BMC is not significantly enhanced in soccer prepubescent boys in comparison with controls. Nevertheless, the annual gain is greater in soccer players than in controls, especially after a rest period.