Interval training provides numerous benefits to your aerobic system. Perhaps the most important benefit is the increase in its ability to produce energy. This is driven by an increased ability to consume oxygen during exercise. Several experiments have produced results showing that interval training increases both VO2 peak (Perry, 2008) and VO2 max (Sloth, 2013). Oxygen is necessary for the conversion of sugars, proteins and lipids into usable energy. The chemical processes involved in aerobic metabolism are not possible without oxygen, particularly the electron transport chain, the mechanism responsible for 95% of the ATP needed to keep cells alive. Oxygen is needed to capture the large amount of energy locked in the chemical bonds of pyruvic acid, the product of the anaerobic process of glycolysis. Therefore, the more oxygen the body is able to consume, the more ATP will be produced through the aerobic system. Interval training not only increases the amount of oxygen your body can consume during exercise, but also its efficiency in delivering oxygen to key muscles. . This is attributed by researchers to the increase in stroke volume. Stroke volume is the volume of blood pumped by a ventricle of the heart in a single beat. The body can continue to perform exercise only when the performing muscles receive oxygenated blood. Therefore, it is crucial that the oxygenated blood supply continues to be open during exercise. Stroke volume may increase through increased left ventricular contractile force and/or through increased cardiac filling pressure, which increases end-diastolic volume and resulting stroke volume (Laursen, 2002). In addition to the increase in stroke volume, researchers identified an increase in b...... half of paper ......l., 1987). In a study where participants performed sprint interval training (Bayati, 2011), an increase in maximal blood lactate was found from pre- to post-workout, indicating an increased capacity for anaerobic glycolysis. This increase was found to coincide with increases in peak power, average power, and total work. Sharp et al. (1986) reported increased blood lactate concentrations and total work performed during a 45-second maximal sprint cycle after eight weeks of intense sprint training in untrained subjects. These data were reported together with an increase in the glycolytic enzyme phosphofructokinase (PFK), suggesting that the increase in lactate values ​​and total work were due to improved glycolytic production. All these studies suggest that interval training improves the performance of the anaerobic system and activates the aerobic metabolism more easily..