Long-term effects of sport on segmental body composition: a study in adult and elderly subjects.

Research investigating the effects of sport in the elderly has demonstrated that physical exercise contributes to maintain muscle mass and to contrast the increase of fat mass. However, the effects of long-term sport on body composition, in particular on segmental body composition, and the effect of different sports have been less investigated. The objective of this research was to study the long-term effects of physical exercise on physiological and psychological well-being in the elderly. For this purpose, a first section of the thesis concerned methodological aspects related to body composition assessment: 1) the comparison of specific bioelectrical impedance vector analysis (specific BIVA) with reference techniques; 2) the association between specific BIVA and self-perceived body image; 3) the comparison of results among widely used impedance devices. Different samples and techniques were used for each objective. 1) 202 athletes (139 men and 63 women; 20.6 ± 5.1 years of age) for the total body composition study, and 50 young active students (25 men and 25 women; 24.3 ± 4.6 y) for the study on segmental body composition. DXA was used as the criterion method to assess fat-free mass (FFM), fat-mass (FM), and %FM; dilution techniques were used to assess total body water (TBW) and extracellular water (ECW), respectively. 2) 632 young adults (238 men and 394 women; 22.8 ± 2.3 y) and 162 middle-aged and elderly adults (96 men and 66 women; 61.4 ± 7.6 y). The Williamson’s figure scale was used to evaluate current body size. 3) 31 adults (8 men and 23 women; 39.8 ± 14.2 y). Three different bioimpedance devices. Specific BIVA showed to be accurate in the assessment of %FM and ECW/ICW ratio. The segmental approach showed a good agreement with DXA too. The analysis of the relationship between current body image and body composition showed that young and elderly normal weight individuals of both sexes recognise themselves correctly, and consider their silhouettes mainly associated with %FM. The comparison among bioimpedance devices showed systematic differences in the measure of reactance. The bias was amended by a correction factor. Following these results, the second section of the thesis investigated total and segmental body composition, muscle strength, morphological and functional symmetry, degree of depression and body image perception in middle aged and elderly individuals. A sample of 106 active subjects (72 men and 34 women; 60.9 ± 7.5 y), involved in three different sports (Tennis, Tai Chi, Running), and a sample of 105 age-matched controls (49 men, 56 women) were considered. The results showed that active individuals had better nutritional status with respect to the controls, lower values of %FM and higher muscle mass in the total body, in the arms and, particularly, in the trunk. Runners and tennis players showed lower values of %FM and higher values of muscle mass than Tai Chi subjects, both at the total and the segmental level. Tennis players exhibited the highest values of muscle mass in the total body, and runners in the trunk. Active subjects as a total and in each sport separately were more symmetrical than controls. Finally, the active sample exhibited better body image satisfaction and psychological well-being than controls. In summary, specific BIVA demonstrated to be a suitable tool for monitoring total and segmental body composition changes. The long-term practice of sport positively influences total and segmental body composition, with more accentuated effects among runners and tennis players than Tai Chi subjects. Active men and women were less affected by the age-related process of %FM increase, muscle mass and strength reduction, are more symmetrical and hence are further away from the emergence of sarcopenia, sarcopenic obesity, risk of falls and frailty. They were also more satisfied about their body image. All this concurs to maintain health and mental well-being and promotes successful ageing.