Relationship between bone strength and the items of physical fitness, motor-related fitness, physical activity in sports in university students. The purpose of this study was to examine association between bone strength and items of physical fitness, motor-related fitness as well as the present- and past- physical activities in sports among university students. We measured tibial ultrasound velocity (SOS, meters per second) as an indicator of bone strength using Soundscan 2000 Compact (Myriad Ultrasound Systems Ltd.). The performance of the SOS studied in 10 university students. Coefficient of variation (CV) and standardized CV (SCV) of the SOS were 0.40% and 3.69%, respectively.<br>The subjects of this study consisted of 409 students (155 males and 254 females) at Okayama University, Japan. The components of the physical fitness were measured using the new physical fitness test established by the Japanese Ministry of Education, Culture, Sports, Science and Technology. A questionnaire survey was conducted to evaluate the physical activities in sports in the past (e.g., at the period of primary, junior high and senior high-school) and in the present. The average of SOS measurements was 4002±98m/sec in males, and 4040±100m/sec in females (mean±SD).<br>The subjects were classified into three levels by SOS. Results in ‘Fifty meters run’ and ‘sit and reach’ in males and ‘Handball throwing’ in females was significantly different among these levels. Conversely, when the subjects were classified into three levels according to the result of the new physical fitness tests, the subjects in the higher level in ‘Fifty meters run’ (in males) and ‘Handball throwing’ (in females) showed higher SOS. Above results indicated that ‘Fifty meters run’ in males and ‘Handball throwing’ in females (both of them are indicators of motor-related fitness) were closely and positively associated with SOS. Moreover, ‘Fifty meters run’ in males and ‘Handball throwing’ in females had positive association with the present- and past- physical activities in sports. We concluded that motor-related fitness in the university students and bone strength had significant association.