PURPOSE: Sprint interval training (SIT) has gained popularity as a time-effective alternative to moderate-intensity endurance training (END). However, whether SIT is equally effective for decreasing cardiometabolic risk factors remains debatable, as many beneficial effects of exercise are thought to be transient, and unlike END, SIT is not recommended daily. Therefore, in line with current exercise recommendations, we examined the ability of SIT and END to improve cardiometabolic health in overweight/obese males. METHODS: Twenty-three participants were randomized to perform 6 wk of constant workload SIT (3 d/wk, 4 to 6x30 s approximately 170% Wpeak, 2 min recovery, n = 12) or END (5 d/wk, 30 to 40 min, approximately 60% Wpeak, n = 11) on cycle ergometers. Aerobic capacity (VO2peak), body composition, blood pressure (BP), arterial stiffness, endothelial function, glucose and lipid tolerance, and free-living glycemic regulation were assessed pre- and posttraining. RESULTS: Both END and SIT increased VO2peak (END approximately 15%, SIT approximately 5%) and glucose tolerance (approximately 20%). However, only END decreased diastolic BP, abdominal fat, and improved postprandial lipid tolerance, representing improvements in cardiovascular risk factors that did not occur after SIT. Although SIT, but not END, increased endothelial function, arterial stiffness was not altered in either group. Indices of free-living glycemic regulation were improved after END and trended toward an improvement after SIT (p = 0.06 to 0.09). However, glycemic control was better on exercise compared with rest days, highlighting the importance of exercise frequency. Furthermore, in an exploratory nature, favorable individual responses (VO2peak, BP, glucose tolerance, lipidemia, and body fat) were more prevalent after END than low-frequency SIT. CONCLUSION: As only high-frequency END improved BP and lipid tolerance, free-living glycemic regulation was better on days that participants exercised, and favorable individual responses were consistent after END, high-frequency END may favorably improve cardiometabolic health.

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