Quantitative research of bone tissue related to physical activity (PA) and sport has a preventive dimension. Increasing the parameters of bone tissue strength, especially reaching the maximum value of peak bone strength in childhood, adolescence, and early adulthood due to practicing sports can contribute to maintaining bone health throughout life. Practicing martial arts (tai chi, traditional karate, judo, and boxing) can effectively improve the quality of bone and reduce the risk of falls and fractures. The study aimed to evaluate the calcaneus bones among Okinawa Kobudo/Karate Shorin-Ryu practitioners using the quantitative ultrasound method as an indicator for assessing bone fracture risk. Forty-four adult martial arts practitioners with a mean age of 36.4 participated in this study. Quantitative ultrasound (QUS) with a portable Bone Ultrasonometer was used in this study. Speed of sound (SOS), broadband ultrasound attenuation (BUA), and the stiffness index (SI) were measured. Subjects were assigned to two groups of black and color belts, according to the advancement in Kobudo/karate practice. The measurements of the SI, BUA, SOS, T-score, and Z-score were significantly higher in subjects from the advanced, long-term practice (black belts) (p < 0.05). The long-term martial arts training in traditional karate and Kobudo significantly impacts the parameters of the calcaneus quantitative ultrasound measurements. Significantly higher bone density was observed among the black belt holders. Long-term practice subjects achieved results far beyond the norm for their age groups. Further studies using non-invasive methods of bone quantification are needed to determine the specific conditions for preventing osteoporosis through physical activity, sports, and martial arts, particularly the duration of the activity, the magnitude of loads, and other related factors.