title: Metabolic and hormonal responses to isoenergetic high-intensity interval exercise and continuous moderate-intensity exercise.
abstract: This study investigated the effects of high-intensity interval training (HIIT) vs. work-matched moderate-intensity continuous exercise (MOD) on metabolism and counterregulatory stress hormones. In a randomized and counterbalanced order, 10 well-trained male cyclists and triathletes completed a HIIT session [81.6 ± 3.7% maximum oxygen consumption (V̇o2 max); 72.0 ± 3.2% peak power output; 792 ± 95 kJ] and a MOD session (66.7 ± 3.5% V̇o2 max; 48.5 ± 3.1% peak power output; 797 ± 95 kJ). Blood samples were collected before, immediately after, and 1 and 2 h postexercise. Carbohydrate oxidation was higher (P = 0.037; 20%), whereas fat oxidation was lower (P = 0.037; -47%) during HIIT vs. MOD. Immediately after exercise, plasma glucose (P = 0.024; 20%) and lactate (P < 0.01; 5.4×) were higher in HIIT vs. MOD, whereas total serum free fatty acid concentration was not significantly different (P = 0.33). Targeted gas chromatography-mass spectromtery metabolomics analysis identified and quantified 49 metabolites in plasma, among which 11 changed after both HIIT and MOD, 13 changed only after HIIT, and 5 changed only after MOD. Notable changes included substantial increases in tricarboxylic acid intermediates and monounsaturated fatty acids after HIIT and marked decreases in amino acids during recovery from both trials. Plasma adrenocorticotrophic hormone (P = 0.019), cortisol (P < 0.01), and growth hormone (P < 0.01) were all higher immediately after HIIT. Plasma norepinephrine (P = 0.11) and interleukin-6 (P = 0.20) immediately after exercise were not significantly different between trials. Plasma insulin decreased during recovery from both HIIT and MOD (P < 0.01). These data indicate distinct differences in specific metabolites and counterregulatory hormones following HIIT vs. MOD and highlight the value of targeted metabolomic analysis to provide more detailed insights into the metabolic demands of exercise.
authors.affiliation: School of Biomedical Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia; Centre of Excellence for Applied Sport Science Research, Queensland Academy of Sport, Brisbane, Australia; jonathan.peake@qut.edu.au.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Peake
authors.affiliation: School of Human Movement Studies, The University of Queensland, Brisbane, Australia; and.
authors.forename: Sok Joo
authors.initials: SJ
authors.lastname: Tan
authors.affiliation: Liggins Institute, University of Auckland, Auckland, New Zealand.
authors.forename: James F
authors.initials: JF
authors.lastname: Markworth
authors.affiliation: School of Biomedical Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia;
authors.forename: James A
authors.initials: JA
authors.lastname: Broadbent
authors.affiliation: School of Human Movement Studies, The University of Queensland, Brisbane, Australia; and.
authors.forename: Tina L
authors.initials: TL
authors.lastname: Skinner
authors.affiliation: Liggins Institute, University of Auckland, Auckland, New Zealand.
authors.forename: David
authors.initials: D
authors.lastname: Cameron-Smith
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D000596:Amino Acids / Q000097:blood; D001786:Blood Glucose; D050260:Carbohydrate Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005229:Fatty Acids, Monounsaturated / Q000097:blood; D008401:Gas Chromatography-Mass Spectrometry; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D019344:Lactic Acid / Q000097:blood*; D050356:Lipid Metabolism / Q000502:physiology*; D008297:Male; D055442:Metabolome / Q000502:physiology; D009638:Norepinephrine / Q000097:blood; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology*; D014233:Tricarboxylic Acids / Q000097:blood
chemical_list: D000596:Amino Acids; D001786:Blood Glucose; D005229:Fatty Acids, Monounsaturated; C508600:IL6 protein, human; D015850:Interleukin-6; D014233:Tricarboxylic Acids; D019382:Human Growth Hormone; D019344:Lactic Acid; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone; D009638:Norepinephrine
keywords: amino acids; exercise intensity; free fatty acids; metabolites; stress hormones; tricarboxylic acid intermediates