Somatic Structure and Ultrasound Parameters of the Calcaneus Bone in Combat Sports Athletes in Relation to Vitamin D Levels.

: Physical activity is widely recognized for its beneficial effects on bone density during adolescence, which could lead to enhanced bone density in later life, thus acting as a health-promoting activity with long-lasting implications. However, not all studies are conclusive regarding the type, intensity, duration, and frequency of the most effective physical activities. This study focuses on combat sports athletes and examines the relationship between their somatic build and heel bone parameters using ultrasound (USG) and their vitamin D3 levels. : The study included 40 male athletes specializing in various combat sports. The measurements of body height, body mass, skinfold thickness, and bone widths at multiple sites were performed to estimate the somatic build. The USG parameters of the heel bone and the blood levels of vitamin D3 were also recorded. Statistical significance was determined using one-way ANOVA, with differences among sports disciplines also examined. : The study found significant differences in the body composition and USG bone parameters among athletes from different combat sports ( ≤ 0.05). The calcaneus stiffness index (SI) and speed of sound (SOS) were significantly higher in athletes with normal vitamin D3 levels compared to those with below-normal levels ( = 0.0015 and = 0.001, respectively). These findings suggest that vitamin D3 may influence bone stiffness and density. : The study underscores the importance of maintaining adequate vitamin D3 levels to support bone mineralization in athletes, particularly those training indoors with limited exposure to sunlight. It also highlights the potential of using USG as a non-invasive method to assess bone health, aiding in the optimization of training programs to prevent injuries and improve performance.