['Osteoporotic fractures represent a growing economical burden to society, not only because of fractures in women, but also because of an increasing number of fractures in men.', 'In this cross-sectional study we aimed to investigate the association of muscular and cardio-respiratory fitness with BMD at the spine and hip in men.', 'The association between independent variables maximal aerobic capacity (VO(2max)), leg power and hand grip strength, and dependent variables BMD at the spine and total hip was explored in a series of linear regression models successively adjusted for age, weight and height, smoking, alcohol intake and leisure time physical activity level. In the fully adjusted model we found a significant association of VO(2max) with BMD at the lumbar spine, p<0.0089. Furthermore, we observed significant associations of VO(2max) (p<0.0022) and leg power (p<0.011) with BMD at total hip.'] Are muscle strength , power and cardiorespiratory fitness associated with bone mineral density in men aged 31-60 years?