High-intensity cardio, the last category is done at 80% to 100% of your maximum heart rate. This intensity level is very difficult to maintain so it is done in very short bouts. Typically this category of training is done in the form of interval training such as running intervals like 1-minute sprints followed by a 2-minute medium or low-intensity interval for recovery.
This style burns the most calories per minute but keeps in mind it can only be done in small bouts before completely exhausting your carbohydrate stores and you have to switch to a different training style. Typically, a high intensity cardiovascular training workout lasts for a maximum of 20 to 30 minutes and is usually coupled with some other type of lower intensity workout.
Medium intensity, on the other hand, is more of a stand-alone workout. Done at around 60% to 75% of maximum heart rate, medium intensity cardiovascular training is intended to be done from 30 minutes to 60 minutes; anything less than that and you would be better off switching to high-intensity cardio to burn more calories. This category represents the vast majority of most people’s actual training and is what most people think of when talking about cardio.