The effect of 12-month participation in osteogenic and non-osteogenic sports on bone development in adolescent male athletes. The PRO-BONE study

Abstract

Objectives

Research investigating the longitudinal effects of the most popular sports on bone development in adolescent males is scarce. The aim is to investigate the effect of 12-month participation in osteogenic and non-osteogenic sports on bone development.

Design

A 12-month study was conducted in adolescent males involved in football, swimming and cycling and compared with an active control group.

Methods

116 adolescent males (13.1 ± 0.1 years at baseline): 37 footballers, 37 swimmers, 28 cyclists and 14 active controls were followed for 12 months. Bone mineral content (BMC) was measured by dual-energy X-ray absorptiometry, and bone stiffness was measured by quantitative ultrasound. Bone outcomes at 12 months were adjusted for baseline bone status, age, height, lean mass and moderate to vigorous physical activity.

Results

Footballers had higher improvement in adjusted BMC at the total body, total hip, shaft, Ward’s triangle, legs and bone stiffness compared to cyclists (6.3–8.0%). Footballers had significantly higher adjusted BMC at total body, shaft and legs compared to swimmers (5.4–5.6%). There was no significant difference between swimmers and cyclists for any bone outcomes. Swimming and cycling participation resulted in non-significant lower bone development at most sites of the skeleton compared to controls (−4.3 to −0.6%).

Conclusions

Football participation induces significantly greater improvements in BMC and bone stiffness over 12 months compared to cycling and swimming.

Clinical trial registration

ISRCTN17982776.

Introduction

Bone development occurs most rapidly during childhood and adolescence, with 80–90% of peak bone mass (PBM) acquired by late adolescence depending on the site of the skeleton.¹ PBM is largely determined by genetics² and by modifiable factors, such as nutrition and physical activity (PA).3, 4 Exercise during this period of life can enhance bone mineral content (BMC) and bone mineral density (BMD)⁵ and be maintained into adulthood.⁶ Football, cycling and swimming are among the most popular sports performed by adolescents around the world.⁷ However, participation in these sports may have different effects on bone development.⁸ Participation in “osteogenic” sports, such us football, can augment BMC at the loaded sites of the skeleton.9, 10 However, participation in “non-osteogenic sports”, such as swimming and cycling, may have a negative or no impact on bone outcomes,¹¹ which may compromise the achievement of a higher PBM and increase the risk of osteoporotic fractures in adulthood. From a public health perspective, understanding how the most popular sports worldwide among youth affect bone development is of great importance.

Cross-sectional studies have evaluated differences in BMC between adolescents engaged in different sports in comparison to a control group.¹¹ Specifically, footballers were found to have higher adjusted-BMC and BMD at most sites of the skeleton compared with age-matched controls.⁹ In contrast, previous evidence found that adolescent male swimmers had lower adjusted-BMC and BMD at several sites compared to controls,¹² but a recent systematic review concluded that swimmers have similar bone mass compared to sedentary controls.¹³ Similarly, in a cross-sectional analysis we found that adolescent male swimmers and cyclists had lower bone outcomes compared to footballers.⁸ However, other studies showed that cycling during adolescence may negatively influence bone health.11, 14 To date, there are only a few longitudinal studies on this topic and it was found that 3 years of football participation increased femoral neck BMD by 10% and improved femoral neck and intertrochanteric BMC twice as much compared to age-matched controls in prepubertal males.¹⁵ Previously, 8 months of football training significantly improved bone outcomes at total body, intertrochanteric site, lumbar spine and femoral neck in female adolescent footballers, whereas 8 months of swimming training had no effect on bone outcomes in female adolescent swimmers.¹⁶ Research investigating the longitudinal effects of the most popular sports on bone development in adolescent males is scarce. In a recent study we showed the effect of these sports on clinically relevant sites, including hip geometry estimates and trabecular texture, as well as biochemical markers.¹⁷ It should be noted that a comprehensive analysis of potential confounders, such as lean mass and objectively measured moderate-to-vigorous PA (MVPA) should be used to control for important predictors of bone status in these sports.¹⁸

In addition to Dual energy X-ray Absorptiometry (DXA), quantitative ultrasound (QUS) can indicate the risk of osteoporotic fractures at the calcaneus site that is particularly important for adolescent athletes due to their high prevalence of injuries.19, 20 In a cross-sectional study, it was shown that swimming had no effect on bone stiffness compared to age-matched controls in adolescent males and females.¹² Also, in a cross-sectional analysis it was found that footballers had higher bone stiffness than controls but there were no differences in swimmers and cyclists compared to controls.⁸ However, there is lack of longitudinal studies comparing the effects of osteogenic and non-osteogenic sports on QUS bone outcomes in adolescent males athletes.²¹ Therefore, the purpose of this study is to investigate the effect of 12-month participation on BMC and bone stiffness in osteogenic (football) and that non-osteogenic sports (swimming and cycling) compared to an active control group after controlling for baseline bone outcomes, age, height, lean mass and MVPA.