This study evaluates the effect of physical activity on the bone content (BMC) and density (BMD) in 51 girls (14.2+/-0.4 yr). Twenty-four were placed in the handball group as they have been playing handball for at least 1 year (3.9+/-0.4). The other 27 who did not perform in any kind of regular physical activity other than that programmed during the compulsory physical education courses comprised the control group. Bone mass and areal density were measured by dual-energy X-ray absorptiometry (DXA). The maximal leg extension isometric force in the squat position with knees bent at 90 degrees and the peak force, mean power, and height jumped during vertical squat jump were assessed with a force plate. Additionally, 30-m run (running speed) and 300-m run (as an estimate of anaerobic capacity) tests were also performed. Maximal aerobic capacity was estimated using the 20-m shuttle-run tests. Compared to the controls, handballers attained better results in the physical fitness tests and had a 6% and 11% higher total body and right upper extremity lean mass (all P<0.05). The handballers showed enhanced BMC and BMD in the lumbar spine, pelvic region, and lower extremity (all P<0.05). They also showed greater BMC in the whole body and enhanced BMD in the right upper extremity and femoral neck than the control subjects (all P<0.05). As expected, total lean mass strongly correlated with total and regional BMC and BMD (r=0.79-0.91 P<0.001). Interestingly, 300-m running speed correlated with BMC and BMD variables (r=0.59-0.67 and r=0.60-0.70, respectively; all P<0.001). Multiple regression analysis showed that the 30-m running speed test, combined with the height and body mass, has also predictive value for whole-body BMC and BMD (R=0.93 and R=0.90, P<0.001). In conclusion, handball participation is associated with improved physical fitness, increased lean and bone masses, and enhanced axial and appendicular BMD in young girls. The combination of anthropometric and fitness-related variables may be used to detect girls with potentially reduced bone mass.