Multiple short bouts of exercise over 12-h period reduce glucose excursions more than an energy-matched single bout of exercise

Objective: Long, uninterrupted bouts of sedentary behavior are thought to negatively influence postprandial glucose and insulin concentrations. We examined the effects of a 1-h bout of morning exercise versus intermittent walking bouts of short duration on glucose excursions and insulin secretion over 12-h.

Materials/methods: Eleven young, obese individuals (18-35 years, BMI>30kg/m(2)) with impaired glucose tolerance were studied on three 12-h study days: 1) sedentary behavior (SED); 2) sedentary behavior with 1-h morning exercise (EX) at 60%-65% VO2peak; and 3) sedentary behavior with 12-hourly, 5-min intervals of exercise (INT) at 60%-65% VO2peak. Meals (1046kJ/meal) were provided every 2-h. Blood samples were collected every 10 min and measured for glucose, insulin, and c-peptide concentrations.

Results: Glucose iAUC (12-h) was attenuated in the INT and SED conditions compared to the EX condition (P<0.05). Glucose concentrations were higher in the EX compared to the SED condition for ~150min (20% of the study day), and comparison of the EX-INT study days revealed that glucose concentrations were greater for~240min (~1/3 of the 12-hday). In the SED condition, the 12-h insulin iAUC was ~15% higher (P<0.05) compared to the INT and EX conditions. Insulin production rate was found to increase ~20% with INT exercise vs. the SED and EX condition (P<0.05).

Conclusions: Short, frequent periods of exercise attenuated glucose excursions and insulin concentrations in obese individuals to a greater degree than an equal amount of exercise performed continuously in the morning.