High-Intensity Interval Circuit Training Versus Moderate-Intensity Continuous Training on Cardiorespiratory Fitness...

High-intensity interval training (HIIT) has similar or better effects than moderate-intensity continuous training (MICT) in increasing peak oxygen consumption (VO_2max), however, it has not been studied when HIIT is applied in a circuit (HIICT). The aim of this study was to compare the effects of a HIICT versus MICT on VO_2max estimated (VO_2max-ES), heart rate (HR) and blood pressure (BP) of middle-aged and older women. A quasi-experimental randomized controlled trial was used. Fifty-four women (67.8 ± 6.2 years) were randomized to either HIICT (n = 18), MICT (n = 18) or non-exercise control group (CG; n = 18) for 18 weeks. Participants in HIICT and MICT trained two days/week (one hour/session). Forty-one participants were assessed (HIICT; n = 17, MICT; n = 12, CG; n = 12). Five adverse events were reported. Cardiorespiratory fitness, HR and BP were measured. The tests were performed before and after the exercise intervention programs. VO_2max-ES showed significant training x group interaction, in which HIICT and MICT were statistically superior to CG. Moreover, HIICT and MICT were statistically better than CG in the diastolic blood pressure after exercise (DBP_ex) interaction. For the systolic blood pressure after exercise (SBP_ex), HIICT was statistically better than CG. In conclusion, both HIICT and MICT generated adaptations in VO_2max-ES and DBP_ex. Furthermore, only HIICT generated positive effects on the SBP_ex. Therefore, both training methods can be considered for use in exercise programs involving middle-aged and older women.