Comparison Of High-Intensity Exercise And Continuous Moderate-Intensity Exercise On Postprandial Metabolism: Pilot Analysis

Abstract

PURPOSE: Examine the effects of low-volume high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MICE) on postprandial glucose, insulin, and triglyceride (TG) concentration following a mixed meal (MM). METHODS: Recreationally active men (n = 7; age = 22.2 ± 2.1 yrs; body mass = 93.7 ± 18.0 kg; BMI = 28.3 ± 4.6; body fat% = 29.2±8.1; WC = 91.3 ± 16.5) completed a 1) rest bout, 2) MICE bout, and 3) HIIE bout in a randomized order. Rest consisted of sitting quietly for 20 minutes. MICE required 20 minutes of continuous cycling at 60% maximal work rate (WRmax). HIIE consisted of performing 20 (15-second) cycling sprints (@ 130% WRmax) followed with 45 seconds of passive cycling. Thirty minutes following the completion of each trial, participants consumed a MM in the form of a milkshake providing 5.3 ± 0.7 kcal/kg BM (body mass) with a macronutrient composition of 50% carbohydrate (CHO), 15% protein, and 35% fat. Blood samples were acquired prior to each trial and at 0, 0.5, 1, and 2 hours post-MM. Blood samples were analyzed for glucose, insulin, and TG concentration. Postprandial responses were quantified via the incremental area under the curve (AUCI) using the trapezoidal method. Significant differences (p<.05) between trials were determined using a one-way, repeated measures ANOVA and Bonferroni post-hoc test. RESULTS: The average work performed over 20 minutes was similar between MICE (120.8 ± 30.8 W) and HIIE (115.6 ± 15.7 W) (p = .63, ES = .17). Glucose AUCI was reduced following HIIE (26.4 ± 38.2mg·dl-1·2hr-1) when compared to MICE (44.8 ± 35.9mg·dl-1·2hr-1) (p = .018, ES = .51). HIIE was not different from rest (42.6 ± 66.4mg·dl-1·2hr-1) (p = .13, ES = .30). Insulin AUCI was unchanged between trials, however HIIE did elicit the lowest AUCI (32.8 ± 31.8μIU·ml-1·2hr-1) compared to rest (51.6 ± 31.7μIU·ml-1·2hr-1) (p = .17, ES =.59) and MICE (52.4 ± 30.2μIU·ml-1·2hr-1) (p =.15, ES = .63). TG AUCI was unchanged between trials. CONCLUSION: Low-volume HIIE may reduce the postprandial glucose and insulin concentration. While there was no statistical significance with insulin AUCI there was a moderate effect size with HIIE. The lack of change in TG AUCI was anticipated as previous studies have reported that exercise completed immediately prior to a mixed meal does not influence postprandial TG concentration.