The influence of winter and summer seasons on physical fitness in aged population

Epidemiological studies have described the association between physical fitness and health. Few have reported the impact of seasonal variation on fitness determinants, in elderly. We investigated the effects of summer and winter environmental conditions on physical fitness, in both exercise and non-exercise elders. 371 non-institutionalized older adults (74.1% female; 78.4 ± 5.3 years) randomly recruited from a total sample of 1338 subjects from north of Portugal, were prospectively followed during 1 year and 3 assessments were performed - April (baseline), October (summer season) and April (winter season). Four groups were defined, according to reported habits of exercising: Exercise (EG); Winter Exercise (WG); and Summer Exercise (SG); non-Exercise (nEG). Muscle strength was assessed with handgrip and isometric knee extension test, and aerobic capacity with the 6 min walking test. Repeated measures ANOVA with two between-subjects factors were run for independent variables, considering a three Time points. Significance set at p < .05. Findings show that: (1) men were fitter than women; (2) EG showed better results than nEG (p = .000), but not different than WG or SG, (3) nEG physical fitness was not significantly different from WG and SG; (4) SG and WG showed similar results; (5) there was significant group-by-time interaction for all variables in study. Among elderly, the regular physical exercise determined better cardiorespiratory fitness and levels of strength compared to individuals that were not exercising, however, no season impact was observed. Independently of exercising mode, regular, seasonal or not exercising, the pattern of changes in physical fitness throughout the year was similar.