Physical fitness is associated with perceived quality of life and mental health among adults enrolling in a university extension program: a cross-sectional study

Abstract

Background: Overweight and obesity are chronic conditions that could be associated with poorer mental health and perceived quality of life across physical, social, and other domains. Lifestyle-related factors such as physical activity (PA) and physical fitness may influence this association. This study aimed to evaluate whether body mass index (BMI), PA level, and physical fitness are associated with perceived quality of life and mental health among adults enrolling in a university extension program.

Methods: This cross-sectional study included 149 adults (48.17±8.67 years). BMI was used as an indicator of nutritional status (31.80±7.00 kg/m²). Validated instruments were used to assess quality of life, mental health, and PA level. Physical fitness was measured using motor tests. Statistical analyses included simple and multiple linear regression with bootstrap procedures.

Results: In the univariate analysis, PA level was positively associated with perceived quality of life only in the vitality, where individuals with high PA levels had better scores (β = 10.90; [95% CI: 0.54; 20.58]). Regarding BMI, individuals with overweight showed higher scores in physical functioning (11.67 [3.37; 19.69]) and general health (8.80 [2.81; 14.97]) compared with those with obesity. Physical fitness indicators showed consistent associations with several quality of life domains, particularly outcomes related to muscular strength and agility. In multivariate analyses, no interaction was observed between BMI and PA level. However, interactions between BMI and physical fitness indicated that, among individuals with overweight compared with obesity, better chair stand performance was associated with lower risk of depression (−0.87 [−1.69; −0.15)]) and stress (−0.86 [−1.73; −0.14]), while better performance in the 6-minute walk test was associated with lower depression (−0.08 [−0.14; −0.03)] and stress (−0.08 [−0.14; −0.03]).

Conclusion: Physical fitness showed more consistent associations with perceived quality of life and mental health than BMI or PA level. Better physical fitness outcomes may have a stronger relationship with perceived well-being, particularly among individuals with overweight. From clinical and public health perspectives, these findings reinforce the importance of integrated strategies that combine improvements in physical fitness with broader lifestyle and weight management approaches. Multidisciplinary interventions may be more effective in promoting quality of life and mental health among individuals with excess body weight.