Effects of a high-intensity interval training compared to moderate-intensity continuous training on maximal oxygen consumption and blood pressure in healthy men: A randomized controlled trial

Introduction: Aerobic exercise generates increased cardiorespiratory fitness (CF), which results in a protective factor for cardiovascular disease. High-intensity interval training (HIIT) might cause higher increases on CF in comparison with moderate-intensity continuous training (MICT); nevertheless, current evidence is not conclusive. Objective: To compare the effects of a low-volume HIIT and a MICT on maximal oxygen consumption (VO2max), systolic blood pressure (SBP), and diastolic blood pressure (DBP) during a period of eight weeks in healthy men between 18-44 years of age. Materials and methods: A randomized controlled trial was conducted. Fortyfour volunteers were randomized to HIIT (n=22) or MICT (n=22). Both groups performed 24 sessions on a treadmill. The HIIT group completed 15 bouts of 30 seconds [90-95%, maximal heart rate (HRmax)], while the MICT group completed 40 minutes of continuous exercise (65-75% HRmax). Results: Intra-group analysis showed an increase in VO2max of 3.5 ml/kg/min. [confidence interval (CI) 95%, 2.02 to 4.93; p=0.0001] in HIIT and 1.9 ml/kg/min. (CI 95%, -0.98 to 4.82; p=0.18) in MICT. However, the difference between the two groups was not statistically significant (1.01 ml/kg/min. IC 95%, -2.16 to 4.18, p=0.52). MICT generated a greater reduction in SBP compared to HIIT [median 8 mmHg (p<0.001)]. Finally, no statistically significant differences were found between the groups for DBP. Conclusions: Results indicate no significant change in VO2max was observed with a low-volume HIIT protocol versus MICT after 24 sessions. In contrast, MICT provided a greater reduction in SBP compared to HIIT.