Sedentary Lifestyle Attenuates Positive Metabolic Effect of Regular Physical Exercise

Background: The aim of the study was to evaluate the influence of the duration of sedentary time on blood lipids and anthropometric parameters in people practicing resistance training in leisure time. Methods: Our study included 213 subjects without any history of cardiovascular disease. The target group (169 subjects) had at least two 90-min sessions of resistance training per week for at least 12 months prior to study commencing. The target group was divided into four groups according to their sitting time per week. There were no significant differences in physical activity between groups. The control group included 44 subjects without a history of cardiovascular diseases and without any regular physical activity. Anthropometric parameters, body composition, blood pressure, blood lipids and glucose levels were assessed. The International Questionnaire on long Physical Activity was used to assess physical activity and sedentary time. IBM (R) SPSS (R) Statistics 19 was used for statistical analysis. Results: Patients were divided into four groups according to their sitting time. In the first group, the median of sitting time of 21.05 (14.00 - 21.25) h per week was spent seated; in the second group, 28.0 h (25.0 - 28.7); in the third group, 38.5 h (35.0 - 42.0) and in the fourth group, 56 h (49.0 - 56.7). After adjustment for age, sex and physical activity level, we observed a statistically significant association between sitting time and high-density lipoprotein cholesterol (HDL-cholesterol) and blood glucose levels. HDL-cholesterol progressively decreased with a prolonged sitting time (first group: 1.62 (1.45 - 1.75) mmol/L; fourth group: 1.31 (1.12 - 1.38) mmol/L) and blood glucose level increased (first group: 4.27 (3.90 - 4.63) mmol/L; fourth group: 4.63 (4.24 - 5.26) mmol/L). Conclusions: Even in the subjects who are engaged in an appropriate time of resistance training, the total sitting time may exceed 56 h per week and attenuates positive effects of resistance training on HDL-cholesterol and blood glucose level.