An interval type workout may be significantly more beneficial than a slower, steady-state type workout.
In a new study, half of the subjects were instructed to perform low-intensity, steady-state cardio for 45 minutes three times per week for 12 weeks. The other half of subjects performed 10 minutes of high-intensity interval training. By the completion of the experiment, both groups had lost roughly two percent body fat, increased maximal oxygen uptake by 20 percent, and boosted insulin sensitivity and citrate synthase activity to similar levels.
Considering that both groups saw very similar benefits but the interval group performed only 30 minutes of exercise per week compared to 135 minutes in the steady-state group, this suggests that interval training may be a superior use of time.
Low-intensity, steady-state cardio can sometimes be useful; clearly, this study found that the subjects who engaged in this cardio did experience benefits by the end of the study. However, there may be reason to believe that interval training accomplishes the same benefits in significantly less time, which would make it overall more favorable. Although low-intensity training may definitely have its place, it should not be surprising that so many experts have chosen to drop this type of cardio in favor of more high-intensity intervals.
Gillen, J. B., Martin, B. J., MacInnis, M. J., Skelly, L. E., Tarnopolsky, M. A., & Gibala, M. J. (2016). Twelve weeks of sprint interval training improves indices of cardiometabolic health similar to traditional endurance training despite a five-fold lower exercise volume and time commitment. PloS one, 11(4), e0154075.