High-intensity interval exercise in the cold regulates acute and postprandial metabolism


High-Intensity Interval Exercise (HIIE) has been shown to be more effective than moderate-intensity exercise for increasing acute lipid oxidation and lowering blood lipids during exercise and postprandially. Exercise in cold environments is also known to enhance lipid oxidation, however the immediate and long-term effects of HIIE exercise in cold are unknown. The purpose of this study was to examine the effects cold stress during HIIE on acute exercise metabolism and postprandial metabolism. Eleven recreationally active individuals (age: 23±3 years, weight: 80±9.7 kg, V̇O 2peak : 39.2±5.73 mL˙kg -1 ˙min -1 ) performed evening HIIE sessions (10x60s cycling, 90% V̇O 2peak interspersed with 90s active recovery, 30% V̇O 2peak ) in thermoneutral (HIIE-TN, control; 21°C) and cold environments (HIIE-CO; 0°C), following a balanced crossover design. The following morning, participants consumed a high-fat meal. Indirect calorimetry was used to assess substrate oxidation, and venous blood samples were obtained to assess changes in noncellular metabolites. During acute exercise, lipid oxidation was 113% higher in HIIE-CO (p=0.002) without differences in V̇O 2 and EE (p≥0.162) between conditions. Postprandial V̇O 2 , lipid and CHO oxidation, plasma insulin and triglyceride concentrations were not different between conditions (p>0.05). Postprandial blood LDL-C levels were higher in HIIE-CO two hours after the meal (p=0.003). Postprandial glucose AUC was 49% higher in HIIE-CO vs HIIE-TN (p=0.034). Under matched energy expenditure conditions, HIIE demonstrated higher lipid oxidation rates during exercise in the cold; but only marginally influenced postprandial lipid metabolism the following morning. In conclusion, HIIE in the cold seemed to be less favorable for postprandial lipid and glycemic responses.

Journal of Applied Physiology