Does high-intensity interval training improve endothelial function and maximum oxygen uptake more effectively than moderate-intensity continuous training in obese adults?
HIIT and MICT produce different vascular adaptations in obese adults, with HIIT improving FMD and MICT increasing resting artery diameter, despite HIIT requiring less time and energy.
We hypothesized that high-intensity interval training (HIIT) would be more effective than moderate-intensity continuous training (MICT) at improving endothelial function and maximum oxygen uptake (V̇o2 max) in obese adults. Eighteen participants 35.1 ± 8.1 (SD) yr; body mass index = 36.0 ± 5.0 kg/m(2) were randomized to 8 wk (3 sessions/wk) of either HIIT 10 × 1 min, 90-95% maximum heart rate (HRmax), 1-min active recovery or MICT (30 min, 70-75% HRmax). Brachial artery flow-mediated dilation (FMD) increased after HIIT (5.13 ± 2.80% vs. 8.98 ± 2.86%, P = 0.02) but not after MICT (5.23 ± 2.82% vs. 3.05 ± 2.76%, P = 0.16). Resting artery diameter increased after MICT (3.68 ± 0.58 mm vs. 3.86 ± 0.58 mm, P = 0.02) but not after HIIT (4.04 ± 0.70 mm vs. 4.09 ± 0.70 mm; P = 0.63). There was a significant (P = 0.02) group × time interaction in low flow-mediated constriction (L-FMC) between MICT (0.63 ± 2.00% vs. -2.79 ± 3.20%; P = 0.03) and HIIT (-1.04 ± 4.09% vs. 1.74 ± 3.46%; P = 0.29). V̇o2 max increased (P < 0.01) similarly after HIIT (2.19 ± 0.65 l/min vs. 2.64 ± 0.88 l/min) and MICT (2.24 ± 0.48 l/min vs. 2.55 ± 0.61 l/min). Biomarkers of cardiovascular risk and endothelial function were unchanged. HIIT and MICT produced different vascular adaptations in obese adults, with HIIT improving FMD and MICT increasing resting artery diameter and enhancing L-FMC. HIIT required 27.5% less total exercise time and ∼25% less energy expenditure than MICT.
Sawyer et al. (Thu,) studied this question.
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