Interval Training: An Old Methodology With Current Popularity—New Advances and Practical Applications

Interval training is a regimen that consists of systematic repetitions of high-intensity efforts (above the second ventilatory threshold [VT 2 ]) with recovery periods. Several meta-analyses have summarized the benefits of interval training for human performance and health, with an optimal time-efficient relationship compared with moderate-intensity continuous training. There are 2 effective traditional ways of implementing interval training: (a) high-intensity interval training, which consists of repeating submaximal efforts, and (b) sprint interval training, which consists of repeating supramaximal efforts. A style of interval training that has emerged in recent years is high-intensity functional training, which promotes cardiorespiratory and neuromuscular adaptations. Nevertheless, many protocols prescribe volumes that exceed the recommended minimum of 75 min/wk of physical activity—a level not reached by a large portion of the population. In other cases, regimens have induced severe fatigue and discomfort, making them unfeasible for most adults. Currently, it has been shown that low-volume interval training (≤15 min/session) that includes short efforts does not attenuate physiological adaptations (e.g., maximum oxygen consumption [V̇ o 2 max]) and is better tolerated. This review aimed to describe the acute and chronic physiological/psychological effects of different interval training styles, focusing on short efforts and low-volume sessions.