High-intensity interval training involves performing a series of short, intense bouts of exercise followed by rest. It has been popular with athletes for nearly 100 years. Recently, scientists have found that (HIIT) also builds aerobic capacity quickly in recreational athletes, older adults and patients with metabolic disorders. The Newcastle University study found that 12 weeks of HIIT lasting 30-40 minutes workout reduced liver fat and improved body composition and cardiovascular function in the middle-aged adults with fatty liver disease. Fatty liver disease, characterized by fat accumulation in the liver, is usually due to obesity or excessive alcohol consumption. High-intensity interval training is an effective way to treat this health problem.