Bone and skeletal muscle changes in oldest-old women: the role of physical inactivity

Background Alterations in bone and muscle parameters related to advanced aging and physical inactivity have never been investigated in oldest-old women. Aims To investigate the impact of physical inactivity on bone mineral density (BMD) and body composition at the systemic and regional levels in oldest-old (> 75 years old) women. We hypothesized that, further to aging, alterations in bone and body composition parameters are exacerbated in the locomotor limbs that have experienced physical inactivity. Methods Whole-body and regional (lower limbs and trunk) BMD and fat-free soft tissue mass (FFSTM) were measured by means of dual-energy X-ray absorptiometry in 11 oldest-old wheelchair-bound women (OIW), 11 oldest-old mobile women (OMW), and 11 young healthy women (YW), all matched for weight (+/- 10 kg), height (+/- 10 cm). Results Whole-body BMD was reduced by 15% from YW to OMW and 10% from OMW to OIW. Whole-body FFSTM was also reduced from YW to OIW (- 13%). Lower limb BMD was progressively reduced among YW, OMW and OIW (- 23%). Similarly, lower limb FFSTM was reduced among YW (12,816 +/- 1797 g), OMW (11,999 +/- 1512 g) and OIW (10,037 +/- 1489 g). Trunk BMD was progressively reduced among YW, OMW and OIW (- 19%), while FFSTM was similar among the three groups ~ 19801 g. Conclusions The results of the present study suggest that the alterations in bone and body composition parameters are exacerbated in the physical inactive oldest-old. These negative effects of physical inactivity are not confined to the locomotor limbs, and a systemic decline of bone and muscle parameters are likely associated with the physical inactivity.