Growth pattern of lumbar bone mineral content and trunk muscles in adolescent male soccer players

Introduction: Previous studies have reported that the peak in lean body mass (LBM) precedes the peak in bone mineral content (BMC). However, it is unknown whether the trunk region growth is similar. Materials and methods: We investigated the difference between pubertal peak age in the increase of LBM in the trunk (trunk LBM) and pubertal peak age in the increase of BMC in the lumbar spine (lumbar BMC) in a longitudinal study of 201 Japanese male adolescent soccer players. The age of peak height velocity (PHV) and the developmental age were calculated. The participants were followed over a 2-year period, with height and dual-energy X-ray absorptiometry scans taken every 6 months. Results: The trunk LBM (ρ = 0.732, p < 0.0001) and the lumbar BMC (ρ = 0.621, p < 0.0001) significantly correlated with the developmental age. The increase of trunk LBM and lumbar BMC was significantly different according to the developmental stages (Kruskal–Wallis test; p < 0.0001 and p < 0.001, respectively). We used a cubic spline to estimate the developmental age, when the increase reached its peak: the peak age of the increase in trunk LBM was estimated to be – 0.08 years (approximately – 1 month) prior to PHV age, whereas the peak age of the increase in lumbar BMC was estimated to be 0.42 years (approximately 5 months) after the PHV age. Conclusions: The maximal increase in trunk LBM occurs just before PHV age and approximately 6 months before the maximal increase in lumbar BMC during the pubertal growth spurt in the Japanese adolescent male soccer players.