THE EFFECT OF HIGH-INTENSITY EXERCISE AND MACRONUTRIENT-SPECIFIC ENERGY REPLACEMENT ON POSTPRANDIAL LIPEMIA IN HEALTHY MALES

PURPOSE: The purpose of this investigation was to determine the effect of high-intensity aerobic exercise with energy replacement in the form of glucose or lipid on the postprandial response to a high-fat test meal. METHODS: Ten healthy, recreationally active men (Age: 26.8 + 5.3 years, BMI: 23.0 + 1.4 kg/m2, Body fat %: 16.2 + 4.3, VO2peak: 52.8 + 4.3) completed four trials in randomized order: non-exercise control (CON), exercise without refeeding (EX), exercise with calorie (kcal) replacement from fat (EXFAT) and exercise with kcal replacement from carbohydrate (EXCHO). Exercise sessions were isocaloric and conducted at 75-85% of VO2 peak, resulting in a 600 kcal energy expenditure. CHO and fat were replaced immediately following exercise with glucose monohydrate (100% CHO) or heavy whipping cream and ice cream (86% fat). The high-fat test meal (1.2 g/fat/kg) was consumed 1-hour following exercise. Blood samples were taken in the fasted state, prior to the meal, and at 1, 2, 3, and 4 hours postprandially and analyzed for triglycerides and other lipid variables (CV% range: 8 -15). Total (AUCT) and incremental (AUCI) were calculated for triglycerides and glucose. RESULTS: There were significant differences in fasting TG values between the conditions (p = 0.018), with EXFAT significantly lower than EX and EXCHO (p = 0.021 and 0.034, respectively), but no significant differences between pre-meal values (p = 0.680). At 1- hour, EXCHO was significantly lower than CON and EXFAT (p < 0.01). At 2 and 3 hours EXCHO was significantly lower than CON, EX, and EXFAT (p < 0.05). There were no differences in conditions 4 hours postprandially (p > 0.05). The TG AUCI was 57, 61, and 69% lower following EXCHO when compared to CON, EX, or EXFAT, respectively (p < 0.01), and was significantly greater in EXFAT when compared to CON (p = 0.01). Findings for AUCT were similar, with no significant difference between EXFAT and CON (p = 0.17) CONCLUSIONS: In healthy young men, expending 600 calories at 75-85% of VO2 peak one-hour before a high-fat meal was only effective at reducing the lipemic response when exercise energy expenditure was refed using CHO. Replacing energy expenditure with fat immediately following the session resulted in a significantly higher TG AUCI when compared to non-exercise control.