What defines 'high-intensity interval training' (HIIT)?

High-intensity interval training (HIIT) is characterized by alternating periods of vigorous activity with short recovery or rest intervals. This method is designed to push the participant to their maximum effort during the intense segments, significantly elevating heart rate and improving cardiovascular fitness. The brief rest periods allow for partial recovery, enabling the individual to perform at high intensity again, which can lead to improved metabolic conditioning, fat loss, and aerobic capacity.

In contrast, the other options describe different training methodologies or phases that do not represent the essence of HIIT. Continuous low-intensity routines do not involve the high-intensity bursts that define HIIT. Strength training primarily focuses on resistance exercises aimed at building muscle rather than incorporating interval techniques. Lastly, cool down techniques are intended for recovery and do not involve the high-intensity work characteristic of HIIT. Thus, the definition of HIIT truly lies in its structure of intense activity followed by brief rest, ensuring that the workout effectively targets both anaerobic and aerobic systems for maximum fitness benefits.