noun - Interval training for swimmers is a type of training that involves a series of low- to high-intensity exercise workouts interspersed with rest or relief periods. The high-intensity periods are typically at or close to anaerobic exercise, while the recovery periods involve activity of lower intensity. Varying the intensity of effort exercises the heart muscle, providing a cardiovascular workout, improving aerobic capacity and permitting the person to exercise for longer and/or more intense levels.
Interval training can refer to organization of any cardiovascular workout (e.g., swimming, cycling, running, rowing, etc.), and is prominent in training routines for many sports. It is a technique particularly employed by swimmers, triathletes and runners, but athletes in many disciplines use this type of training.