Effects of Lifelong Exercise on Body Composition and Bone Density

Abstract

Objective: The purpose of this study was to compare body composition and bone density among young exercisers (YE), lifelong exercisers (LLE), and old healthy non-exercisers (OH), as well as between men (M) and women (W). Hypothesis: A hierarchal pattern will emerge (YE > LLE > OH) for healthy body composition and bone density. Both body composition and bone density will differ between M and W. Methods: Healthy adults were separated into three groups: YE (n=20, 10M, 25±1yr, 67±10kg), LLE (n=28, 21M, 74±2yr, 75±12kg), and OH (n=20, 10M, 74±2yr, 77±14kg). Daily physical activity was indirectly assessed using a pedometer (YE: ~10,000steps/day; LLE: ~9,000steps/day; OH: ~6,000steps/day). LLE individuals completed aerobic exercise regularly ~5 days/week (~7 hrs/week) for 52±1yr. Further analysis was done between men and women to investigate potential sex differences (M: n=41, 62±25yr, 80±10kg; W: n=27, 58±28yr, 62±7kg). Dual X-ray absorptiometry (DXA) was used to assess body composition (fat and lean mass) and bone mineral density. Results: There was a hierarchal pattern of beneficial body composition related to total body fat (YE: 21±6% < LLE: 25±6% < OH: 37±7%; p<0.05) and lean mass (YE: 79±6% > LLE: 74±6% > OH: 62±7%; p<0.05). In addition, there were sex differences for both total body fat (M: 24±7%; W: 32±9%; p<0.05) and lean mass (M: 75±7%; W: 67±10%; p<0.05). Bone mineral density was not different among the three groups (YE: 1.26±0.10g/cm2; LLE: 1.27±0.18g/cm2; OH: 1.22±0.14g/cm2; P>0.05) but was different between men and women (M: 1.33±0.12g/cm2; W: 1.14±0.11g/cm2; p<0.05). Conclusion: These data suggest lifelong endurance exercise was beneficial for body fat and lean mass in both men and women. Bone mineral density, generally thought to decrease with age, was not impacted by aging or exercise status in this cohort. Women had lower bone mineral density compared to men, regardless of age, which may be related to distinct hormonal regulation between the sexes. Funding Sources: This research was supported by the National Institutes of Health Grant R01-AG038576 and the Ball State University Human Bioenergetics Program. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.