High Intensity Interval Training is a training method used to bring about increases in cardio-respiratory performance in shorter sessions of higher intensity. The concept revolves around alternating bouts of light-to-moderate intensity with bouts of high intensity. A typical HIIT session will include warm-up, several short, maximum or near-maximum intensity bursts punctuated by lower-intensity recovery increments, followed by a cool-down. HIIT sessions normally range between 12 and 15 minutes, but can last upwards of 20 minutes.