Intense interval exercise induces greater changes in post-exercise metabolism compared to submaximal exercise in middle-aged adults.

Abstract

High-intensity interval training (HIIT) and sprint interval training (SIT) consistently elevate post-exercise metabolism compared to moderate-intensity continuous training (MICT) in young adults (18-25years), however few studies have investigated this in middle-aged adults. To assess the effect of exercise intensity on post-exercise metabolism following submaximal, near-maximal, and supramaximal exercise protocols in middle-aged adults. 12 participants (8 females; age: 44 ± 10years; O2max: 35.73 ± 9.97mL·kg-1min-1) had their oxygen consumption ( O2) measured during and for 2h following 4 experimental sessions: (1) no-exercise control (CTRL); (2) MICT exercise (30min at 65% O2max); (3) HIIT exercise (10 × 1min at 90% maximum heart rate with 1min rest); and (4) modified-SIT exercise (8 × 15s "all-out" efforts with 2min rest). Between session differences for O2 and fat oxidation were compared. O2 consumed post-exercise was elevated during the 1st h and 2nd h following HIIT (15.9 ± 2.6, 14.7 ± 2.3L; P < 0.036, d > 0.98) and modified-SIT exercise (16.9 ± 3.3, 15.30 ± 3.4L; P < 0.041, d > 0.96) compared to CTRL (13.3 ± 1.9, 12.0 ± 2.5 L) while modified-SIT was also elevated vs HIIT in the 1st h (P < 0.041, d > 0.96). Total post-exercise O2 consumption was elevated following all exercise sessions (MICT: 27.7 ± 4.1, HIIT: 30.6 ± 4.8, SIT: 32.2 ± 6.6L; P < 0.027, d > 1.03) compared to CTRL (24.9 ± 4.1L). Modified-SIT exercise increased fat oxidation (0.103 ± 0.019gmin-1) compared to all sessions post-exercise (CTRL: 0.059 ± 0.025, MICT: 0.075 ± 0.022, HIIT: 0.081 ± 0.021g·min-1; P < 0.007, d > 1.30) and HIIT exercise increased compared to CTRL (P = 0.046, d = 0.87). Exercise intensity has an important effect on post-exercise metabolism in middle-aged adults.