A single session of low-intensity exercise is sufficient to enhance insulin sensitivity into the next day in obese adults

Abstract

Objective: The purpose of this study was to determine the effect of a relatively modest session of exercise on insulin sensitivity and fatty acid uptake the next day in obese adults.

Research design and methods: Eleven sedentary obese adults (male/female: 3/8; BMI 37 ± 1 kg/m(2); peak oxygen uptake [VO2peak] 20 ± 1 mL/kg/min) completed three experimental trials. On two of these occasions, subjects exercised to expend 350 kcal in the afternoon. These two exercise trials were identical except for the exercise intensity (50% VO2peak [EX50] and 65% VO2peak [EX65]) and the duration of exercise necessary to expend 350 kcal (EX50 = ≈ 70 min; EX65 = ≈ 55 min). Subjects also completed a control trial (CON), without exercise. The next morning, we measured insulin sensitivity (hyperinsulinemic-euglycemic clamp) and whole-body fatty acid uptake (palmitate rate of disappearance from plasma [Rd]).

Results: Exercise increased insulin sensitivity the next day, but whereas the 35% improvement after EX50 compared with CON was statistically significant (P = 0.01), the 20% improvement after EX65 was not (P = 0.17). Despite nearly identical values between CON and EX65 (P = 0.88), systemic fatty acid uptake was lower after EX50 compared with EX65 (P = 0.02), but not quite significant compared with CON (P = 0.07). Importantly, the change in fatty acid uptake after exercise compared with CON was negatively correlated with the change in insulin sensitivity for all trials (r = -0.60, P = 0.003).

Conclusions: A relatively modest single session of exercise in obese adults improved insulin sensitivity the next day, and a reduction in systemic fatty acid uptake in the several hours after exercise may be important for this effect.

Figures

Figure 1

Timeline of experimental events. Subjects participated in three separate 2-day trials. On two occasions, subjects expended 350 kcal during an exercise session in the afternoon of the first day. These two exercise trials were identical except for the intensity of exercise performed (50% VO2peak [EX50] and 65% VO2peak [EX65]). Subjects also completed a control trial in which they remained sedentary. CLAMP, hyperinsulinemic-euglycemic clamp; 13C-FA Inf, [1-13C]-palmitate isotope infusion; MTT, meal tolerance test; RMR, resting metabolic rate.

Figure 2

Plasma concentrations of glucose (A) and insulin (B) measured during the meal tolerance test conducted 1 h after exercise or remaining sedentary. Inset figures are calculated as mean area under the plasma concentration curve for each trial. A: For plasma glucose concentration, the two-way (treatment × time) repeated-measures ANOVA, P = 0.17, and the main effect AUC, one-way repeated-measures ANOVA, P = 0.09. B: For plasma insulin concentration, the two-way (treatment × time) repeated-measures ANOVA, P = 0.15, and the main effect AUC, one-way repeated-measures ANOVA, P = 0.07.

Figure 3

A: Insulin sensitivity measured via hyperinsulinemic-euglycemic clamp the day after exercise. Data are expressed as clamped whole-body glucose disposal (Rd, µmol/min) per steady-state plasma insulin concentration (SSI, µU/mL). *P < 0.05 EX50 vs. CON (P = 0.17 for EX65 vs. CON). B: Basal fatty acid rate of disappearance from plasma (Rd) measured the day after exercise. #P < 0.05 EX50 vs. EX65 (P = 0.07 for EX50 vs. CON).