Exercise training is widely recommended in health and some conditions diseases. It is well established that physical active behaviour is related to decrease in cardiovascular diseases and consequently longer life expectancy. Talking about exercise training involves some methodological approaches such as type of exercise, volume, duration, frequency and intensity; and intensity is exactly what this review is focused, especially high-intensity intermittent exercise training, also known as interval training. Prescribing this model of training according to literature makes it difficult to reach a consensus about the methodology and true effects of it, especially for cardiac patients. For that reason, the aim of this review is to present the current context about the different types of high-intensity intermittent exercise training, its benefits and risks compared to endurance training in some diseases such as coronary artery disease and chronic heart failure.