Inactivity induces resistance to the metabolic benefits following acute exercise

Abstract

Acute exercise improves postprandial lipemia, glucose tolerance, and insulin sensitivity, all of which are risk factors for cardiovascular disease. However, recent research suggests that prolonged sedentary behavior might abolish these healthy metabolic benefits. Accordingly, this study aimed to elucidate the impact of an acute bout of exercise on postprandial plasma triglyceride, glucose, and insulin concentrations after 4 days of prolonged sitting (~13.5 h/day). Ten untrained to recreationally active men (n 5) and women (n 5) completed a counterbalanced, crossover study. Four days of prolonged sitting without exercise (SIT) were compared with 4 days of prolonged sitting with a 1-h bout of treadmill exercise (SIT EX; 63.1 5.2% V O2max) on the evening of the fourth day. The following morning, participants completed a high-fat/glucose tolerance test (HFGTT), during which plasma was collected over a 6-h period and analyzed for triglycerides, glucose, and insulin. No differences between trials (P 0.05) were found in the overall plasma triglyceride, glucose, or insulin responses during the HFGTT. This lack of difference between trials comes with similarly low physical activity (~3,500 – 4,000 steps/day) on each day except for the 1-h bout of exercise during SIT EX the day before the HFGTT. These data indicate that physical inactivity (e.g., sitting ~13.5 h/day and 4,000 steps/day) creates a condition whereby people become “resistant” to the metabolic improvements that are typically derived from an acute bout of aerobic exercise (i.e., exercise resistance).