Introduction:
Physical activity is an important environmental factor affecting skeletal remodeling and metabolism. Bone tissue reacts more effectively to dynamic loading than static loading, and the maximum effect is achieved with weight-bearing activity. Therefore, volleyball players are appropriate groups for research on the impact of dynamic loading on different skeletal regions in examined athletes.

Aim of the research:
To compare bone mineral density (BMD) and bone mineral content (BMC) and also soft-tissue composition, i.e. mass body fat (MBF) and lean body mass (LBM) between male volleyball players and physically inactive men. The relationships between selected parameters from the DXA (dual-energy X-ray absorptiometry) test and the strength of shoulder muscles were also assessed.

Material and methods:
A group of 40 men aged 20–25 years was included in the study (20 male volleyball players, 20 inactive men). Body composition tests were performed with the DXA method with a Lunar iDXA. An IDO isometer was used to assess the isometric strength of muscle groups acting on the shoulder joint.

Results:
Higher BMD and BMC parameters in almost all evaluated body parts were recorded in the group of volleyball players. There were no statistically significant differences between the MBF of volleyball players and the control group except for the trunk (p = 0.045). In the group of volleyball players, a significantly higher percentage of LBM content was observed. The presence of a statistically significant positive linear relationship between the shoulder muscle strength and BMD, BMC, and LBM of the upper limbs was confirmed.

Conclusions:
Our study highlights the importance of impact forces acting on the skeleton and the systematic development of muscle strength to increase BMD and BMC.