Osteoporotic fractures constitute a global public health challenge, particularly as their incidence rises with age, transcending gender, and racial boundaries.1,2 Within the context of the aging Mexican population, osteoporosis has emerged as a prominent concern, with a substantial prevalence among individuals aged 50 and above, notably affecting the femoral region and lumbar spine.3 The economic burden associated with osteopenia and osteoporosis in Mexico underscores the urgency of addressing this issue, with projections indicating a significant increase in costs by 2050.3

The imperative for early-life interventions to optimize bone health is underscored by the recognition of optimal bone mass acquisition in adolescence as a pivotal determinant of long-term bone health, potentially reducing the risk of osteoporotic fractures later in life.4,5 Aspects of bone health are intricately influenced by both metabolic and mechanical factors, including sex hormones, diet, medication usage, and bone modeling, which collectively shape bone geometry.6,7

The acquisition and maintenance of bone health are significantly influenced by the mechanical environment of the skeleton, with physical activity emerging as a key factor. While the link between physical activity and bone accretion is established, the specific impact varies based on the type, frequency, intensity, duration, and mode of physical activity.8,9 The mechanostat theory emphasizes the interconnectedness of muscle and bone, suggesting a need to analyze them as a unified unit.10,11

However, within the existing body of knowledge, there is a conspicuous gap in our understanding of the epidemiological implications of different types of leisure-time physical activities (LTPA) specifically in adolescents and body composition. The need for a nuanced exploration of the impact of physical activity on bone health in this demographic is evident. In Mexico, two previous studies12,13 of our research team have assessed the relation between bone mineral content (BMC) and lean mass (LM) among boys and girls (considering their sexual maturation Tanner stage), while in adults, we have evaluated the association of LTPA and both bone and lean mass. Despite this, no previous studies have assessed the influence of Tanner stage and type of physical activity on the relationships between BMC and LM in Mexican adolescents.

Thus, this study seeks to address this gap by focusing on a crucial marker of pubertal development—Tanner stage—and its potential influence on the relationships between BMC and LM assessed by Dual-Energy X-ray Absorptiometry (iDXA)- for whole-body and limbs of apparently healthy Mexican adolescents.

Our primary objectives are to conduct a comprehensive assessment using iDXA, evaluating BMC and LM values in the whole-body and limbs, and examining the intricate relationships between these two variables. Furthermore, we aim to categorize adolescents based on the type of physical activity they engage in and analyze how these diverse activities impact bone mass and muscle-bone relationships. Importantly, this study integrates the influence of Tanner stage, exploring potential variations in the impact of LTPA on bone health across different pubertal stages.

By bridging the existing knowledge gap, this research will contribute valuable insights into the influence of LTPA on bone and lean mass health in adolescents. Moreover, the examination of the interplay between Tanner stage and LTPA on iDXA-estimated BMC and LM relationships holds implications for optimizing bone health strategies in this critical demographic. Our hypothesis proposes that high-impact LTPA improves BMC vs LM relationship in healthy adolescents depending on gender, pubertal maturity and skeletal location.