Higher insulin-sensitizing response after sprint interval compared to continuous exercise
Ortega, Juan Fernando
Fernández-Elías, Valentín Emilio
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This study investigated which exercise mode (continuous or sprint interval) is more eff ective for improving insulin sensitivity. 10 young, healthy men underwent a non-exercise trial (CON) and 3 exercise trials in a cross-over, randomized design that included 1 sprint interval exercise trial (SIE; 4 all-out 30-s sprints) and 2 continuous exercise trials at 46 % VO 2 peak (CE LOW ) and 77 % VO 2 peak (CE HIGH ). Insulin sensitivity was assessed using intravenous glucose tolerance test (IVGTT) 30 min, 24 h and 48 h postexercise. Energy expenditure was measured during exercise. Glycogen in vastus lateralis was measured once in a resting condition (CON) and immediately post-exercise in all trials. Plasma lipids were measured before each IV GTT . Only after CE HIGH did muscle glycogen concentration fall below CON (P < 0.01). All exercise treatments improved insulin sensitivity compared with CON, and this eff ect persisted for 48-h. However, 30-min post-exercise, insulin sensitivity was higher in SIE than in CE LOW and CE HIGH (11.5 ± 4.6, 8.6 ± 5.4, and 8.1 ± 2.9 respectively; P < 0.05). Insulin sensitivity did not correlate with energy expenditure, glycogen content, or plasma fatty acids concentration (P > 0.05). After a single exercise bout, SIE acutely improves insulin sensitivity above continuous exercise. The higher post-exercise hyperinsulinemia and the inhibition of lipolysis could be behind the marked insulin sensitivity improvement after SIE.