Original ArticleBody composition changes over 9 years in healthy elderly subjects and impact of physical activity☆
Introduction
Body composition changes with aging. Our previous cross-sectional study showed that in white subjects > 65 years, weight and fat-free mass (FFM) decreased, while fat mass (FM) tended to increase in men and stabilize or decrease in women.1 Body cell mass (BCM) which is the metabolically, oxygen-consuming compartment of the FFM also decreases with age in cross-sectional studies, although to a lesser extent than FFM.2 Most longitudinal studies confirmed the loss of FFM but could not detail at which age it occurred and showed conflicting results regarding FM.3, 4, 5 However, clarification of body composition changes with aging is essential as they are related to health status and physical function.
The decline of FFM with aging and the associated physical impairment, termed sarcopenia, results from loss of appendicular skeletal muscle mass (ASMM).5 The features of sarcopenia are a loss of motor unit number, an atrophy of muscle fibers and a decline in protein synthesis. Its complex etiology encompasses decreased anabolic hormones, specific nutritional deficiencies (protein and vitamin D), changes of mitochondrial function of muscle cells, as well as increased pro-inflammatory cytokines, apoptotic activities in the myofibers and oxidative stress.6 Whatever the origin of FFM loss, it is associated with a high risk of disability, balance disorders and falls, immune and muscular dysfunctions, and impaired quality of life.7
In contrast, an increased FM is related to overweight and obesity, which in turn increases risk of cardio-vascular disease, certain type of cancers, osteoarthritis, liver and gallbladder diseases, sleep apnea and respiratory problems. Furthermore, gain in abdominal fat, which can be roughly evaluated by increased waist circumference or waist to hip ratio, increases the risk of functional limitations and disability.8 Thus, neither the loss of FFM nor the gain of FM is beneficial for health.
The fact that evolution of body composition with aging has not yet been clearly defined probably relies on confounding factors, as physical activity and diseases. In many studies, physical activity did not prevent loss of FFM or gain of total FM with aging3, 9 but frequency, type, intensity and duration of physical activity as well as length of follow-up may have been insufficient to lead to any effect. Furthermore, numerous diseases, such as malignancies, infections or decubitus ulcers are associated with decreased FFM.10
This study aims at determining, in healthy elderly subjects at baseline and follow-up, 1) the 9-year longitudinal changes of anthropometrics and body composition measured by bioelectrical impedance analysis (BIA) and K40 total body potassium (TBK), and 2) the influence of daily energy expenditure through physical activity on these changes. We have hypothesized that this prospective study will confirm our previously described cross-sectional changes of body composition and that maintenance of energy expenditure through physical activity limits the loss of FFM.
Section snippets
Subjects
In 1999, 213 healthy white subjects aged ≥ 65 years (108 women, 105 men) were recruited through advertisements in newspapers and leisure clubs, as part of a cross-sectional study which validated the Geneva BIA formula against dual-energy X-ray absorptiometry (DXA).11 Exclusion criteria were acute heart, lung, kidney or liver failure, symptomatic neurological disorders, known active cancer or infectious diseases, significant mental impairment, involuntary weight loss and hospitalization in the
Results
Of the 213 subjects included in 1999, 112 were measured again in 2008. Compared to non returnees, women returnees were younger (73.2 ± 5.5 vs. 77.0 ± 6.4 years, p = 0.01) and had higher PA (1545 ± 581 vs. 1275 ± 428 k cal/d, p = 0.08) but similar anthropometric characteristics and body composition. Men returnees were significantly younger (71.7 ± 5.3 vs. 77.5 ± 6.6 years, p < 0.001), had higher FFM (57.5 ± 5.6 vs. 55.0 ± 5.8, p = 0.03), ASMM (24.1 ± 2.7 vs. 22.9 ± 2.8, p = 0.02) and PA
Discussion
This 9-year longitudinal study showed that loss of body weight and lean tissues was higher in subjects aged ≥ 75 years at baseline compared to those aged 65–74 years. Plotting of age at baseline against changes of FFM suggested the loss of FFM to occur around 70 years. Increased energy expenditure through physical activity limited the loss of lean tissues and was associated with increased weight and FM in men while it did not alter body composition in women.
This study included subjects who were
Conclusion
This 9-year longitudinal study showed that loss of body weight and lean tissues occurs exponentially around 70 years in healthy older subjects. Increasing daily energy expenditure through physical activity limited the loss of lean tissue in men but not women. Further research should confirm these changes of body composition in subjects over 80 years.
Statement of authorship
We hereby certify that it is an original publication and the manuscript has not been previously submitted or published elsewhere. LG participated in the concept and design of the study, data acquisition, interpretation of data, and preparation of the manuscript. VLK participated in the concept and design of the study, data acquisition and interpretation of data. TC participated in interpretation of data and critical revising of the article. MPK participated in analysis of data and critical
Conflict of interest
None of the authors has declared a conflict of interest.
Acknowledgments
We thank the Public Foundation Nutrition 2000Plus for financial support.
We thank all the dietetic students who helped with the assessment of the questionnaires and the measurements of bioelectrical impedance analysis, Karine Jeandet and Sophie Namy for the measurements of total body potassium, as well as Didier Hans for his critical input.
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Conference presentation: Part of this article was presented at the ESPEN conference in Vienna, 2010.