Influence of sedentary behavior and physical condition on health related quality of life in older adults: a 4 year observation of changes in fitness levels, health related quality of life and sedentary time

Abstract

The present thesis analyzes the effect of sedentary behavior (SB) and fitness level on the Health-Related Quality of Life (HRQoL) in older adults. The work is framed within the EXERNET project. This doctoral thesis examines the influences of SB and fitness on HRQoL with 2 different perspectives: cross-sectional and longitudinal. The EXERNET study began in 2008 as a cross-sectional research to study physical condition and body composition in older adults. In 2012, the project was prolonged and a longitudinal study was carried out. Therefore, 3 different studies are included in this thesis. The first study is a descriptive analysis of the fitness changes occurred between the two phases of the study in those subjects who could be recuperated. A total sample of 1,064 was included in this study. The second study consisted in a cross-sectional research with the initial sample at phase one about the effects of SB and fitness on HRQoL. A total of 3,136 individuals from different regions of Spain were included in this study. The third study analyzes the effects of variations in SB in the period between both phases, by different fitness levels, on the HRQoL. This study includes 1,064 subjects. The main findings of this thesis are: 1) Physical capacities involute differently over time. To remain active could contribute in maintaining or reducing the decline in fitness level during a 4-year period of time in older adults. 2) Higher sitting time seems to be related to poorer scores in HRQoL tests in older adults. High levels of fitness may help attenuating the negative effects of sitting time in the subjective perception of HRQoL. Thus, sitting time is negative related to quality of life in general but more specifically in subjects with low a fitness levels. 3) Independently from fitness, a reduction of the total sitting in a 4-year period could lead to greater HRQoL in older adults. High fitness levels were also related to greater HRQoL. More longitudinal studies that help clarifying the interaction between SB and fitness are needed, especially in older adults due to the tendency of this sector of the population to high levels of sedentary time and low fitness.