This longitudinal study examined whether bone mineral density (BMD) of the lumbar spine and proximal femur is maintained in premenopausal caddies (n = 6; mean age 37.8 years) in comparison with desk workers (n = 6; mean age 40.8 years) at the same golf club. BMD was followed for 12 months using dual-energy X-ray absorptiometry (DXA) and bone metabolic markers and athletic ability were also examined. Longitudinally, for caddies, the change per year in BMD of the lumbar spine was +0.009 g/cm2, while that of the proximal femur was +0.022 g/cm2, showing significant differences (P < 0.05 by signed-rank test). Their athletic ability, in terms of leg-press power, also significantly increased, whereas bone metabolic markers, such as serum alkaline phosphatase, 1,25-(OH), vitamin D3, parathyroid hormone and the deoxypyridiniline/creatinine ratio, did not show significant changes. For desk workers, the change per year in BMD of the lumbar spine was +0.011 g/cm2, while that of the proximal femur was -0.006 g/cm2. Their BMD, athletic ability and bone metabolic markers did not show significant changes. These findings support the results of our previous study, that premenopausal women can achieve continuous gain in femoral neck BMD by regular intense athletic activity, and suggest that this is also true by the continuous extensive walking of golf caddies.