title: A 3-year longitudinal study on body composition changes in the elderly: role of physical exercise.
abstract: BACKGROUND
  Cross-sectional data have shown that sarcopenia and fat accumulation are associated with aging and can be limited by structured physical training. However, it is often difficult to maintain a long-term compliance to training programs. It is not clear whether leisure-time physical activity is effective in preventing sarcopenia and fat accumulation.
  
  
  OBJECTIVE
  (i) To investigate longitudinal body composition changes in a population of elderly people in good apparent health. (ii) To evaluate the impact of leisure-time physical activity on muscle mass and characteristic as reflected by total body potassium per fat-free soft tissue (TBK/FFST), and on fat accumulation.
  
  
  METHODS
  Longitudinal evaluation over 3 years, of body composition changes in 74 healthy men and 66 women, over 65 years old. Body fat and FFST were analyzed by dual-energy X-ray absorptiometry and TBK by whole-body (40)K counter. Physical activity was analyzed by a specific questionnaire.
  
  
  RESULTS
  Despite a stable total body weight, FFST and appendicular skeletal muscle mass slightly decreased (-0.3+/-1.4 and -0.2+/-2.2 kg, P<0.01, respectively) as well as the TBK/FFST (-4.1+/-6.3 mmol/kg, P<0.001), over the 3-year period. Body fat increased significantly (0.6+/-2.2 kg, P<0.0001), and it accumulated mainly in the abdomen (0.4+/-1.5 kg, P<0.01). Multiple regression analysis showed that body composition changes were related mainly to body weight changes. Nevertheless, positive linear correlations were observed between the degree of engagement in leisure-time physical activity and FFST (P<0.01), appendicular skeletal muscle mass (P<0.05), TBK/FFST (P<0.05), whereas negative correlation was observed with total and truncal fat (P<0.01).
  
  
  CONCLUSIONS
  Mild but significant decline in muscle mass and its TBK content, and body fat accumulation were observed over a 3-year period in healthy elderly subject: leisure-time physical activity does not seem to prevent them. However, a higher level of physical activity is associated with higher muscle mass and TBK content, and less total and truncal fat.
authors.affiliation: Geneva University Hospital, 1211 Geneva, Switzerland.
authors.forename: Comasia Addolorata
authors.initials: CA
authors.lastname: Raguso
authors.forename: Ursula
authors.initials: U
authors.lastname: Kyle
authors.forename: Michel Picard
authors.initials: MP
authors.lastname: Kossovsky
authors.forename: Catherine
authors.initials: C
authors.lastname: Roynette
authors.forename: Ariane
authors.initials: A
authors.lastname: Paoloni-Giacobino
authors.forename: Didier
authors.initials: D
authors.lastname: Hans
authors.forename: Laurence
authors.initials: L
authors.lastname: Genton
authors.forename: Claude
authors.initials: C
authors.lastname: Pichard
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000273:Adipose Tissue / Q000033:anatomy & histology / Q000378:metabolism* / Q000473:pathology; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001823:Body Composition / Q000502:physiology*; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology*; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D007899:Leisure Activities; D008137:Longitudinal Studies; D008297:Male; D009133:Muscular Atrophy / Q000453:epidemiology / Q000473:pathology*; D010349:Patient Compliance; D011795:Surveys and Questionnaires