title: Muscle-specific glucose and free fatty acid uptake after sprint interval and moderate-intensity training in healthy middle-aged men.
abstract: We tested the hypothesis that sprint interval training (SIT) causes larger improvements in glucose and free fatty acid uptake (FFAU) in lower and upper body muscles than moderate-intensity training (MIT). Twenty-eight healthy, untrained, middle-aged men were randomized into SIT (n = 14, 4-6 × 30 s of all-out cycling/4 min recovery) and MIT groups [n = 14, 40-60 min cycling at 60% of peak O2 uptake (V̇o2 peak)] and completed six training sessions within 2 wk. Pre- and postmeasurements included V̇o2 peak, whole body (M-value), muscle-specific insulin-stimulated glucose uptake (GU), and fasting FFAU measured with positron emission tomography in thigh [quadriceps femoris (QF) and hamstrings] and upper body (deltoids, biceps, and triceps brachii) muscles. V̇o2 peak and M-value improved significantly by 6 and 12% in SIT, and 3 and 8% in MIT, respectively,. GU increased significantly only in the QF, and there was no statistically significant difference between the training modes. GU increased in all four heads of QF in response to SIT, but only in the vasti muscles in response to MIT, whereas in rectus femoris the response was completely lacking. Training response in FFAU in QF was smaller and nonsignificant, but it also differed between the training modes in the rectus femoris. In conclusion, SIT and MIT increased insulin-stimulated GU only in the main working muscle QF and not in the upper body muscles. In addition, the biarticular rectus femoris did not respond to moderate-intensity training, reflecting most probably poor activation of it during moderate-intensity cycling.
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland;
authors.forename: Jari-Joonas
authors.initials: JJ
authors.lastname: Eskelinen
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland; School of Sport Science, Exercise and Health, University of Western Australia, Crawley, Western Australia, Australia.
authors.forename: Ilkka
authors.initials: I
authors.lastname: Heinonen
authors.affiliation: Department of Biostatistics, University of Turku, Turku, Finland; and.
authors.forename: Eliisa
authors.initials: E
authors.lastname: Löyttyniemi
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland;
authors.forename: Virva
authors.initials: V
authors.lastname: Saunavaara
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland;
authors.forename: Anna
authors.initials: A
authors.lastname: Kirjavainen
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland;
authors.forename: Kirsi A
authors.initials: KA
authors.lastname: Virtanen
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland;
authors.forename: Jarna C
authors.initials: JC
authors.lastname: Hannukainen
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland; kari.kalliokoski@tyks.fi.
authors.forename: Kari K
authors.initials: KK
authors.lastname: Kalliokoski
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*; D052097:Quadriceps Muscle / Q000378:metabolism* / Q000502:physiology; D013848:Thigh / Q000502:physiology
chemical_list: D005230:Fatty Acids, Nonesterified; D005947:Glucose
keywords: HIT; exercise; glucose uptake; metabolism; skeletal muscle