HIIT (high intensity interval training) is short in duration but explosive in the movement and intensity of the exercise. This includes bouts of pushing yourself as hard as you can go followed by a rest period catching your breath until the next sprint. An average HIIT session should range from 10-20 minutes. Anything over 20 minutes would not be considered HIIT as our bodies simply could not allow it if it has been executed correctly. True HIIT should feel like you can’t breathe, and just when you feel like you cant push harder- you do- and this is where the magic happens. It’s uncomfortable, and that is why the body changes. The overall effectiveness of HIIT cardio is determined by the amount of time the body spends at it’s VO2 Max (the maximum rate of oxygen consumption during exercise).HIIT cardio creates an after burn effect much like weight training does. Which also increases metabolism. EPOC (excess post exercise oxygen consumption) this is the amount of oxygen your body needs to return to its normal resting metabolic state. The more oxygen that is needed- the more calories burned. A study has shown HIIT to produce an after burn effect of up to 21 hours post exercise.
Lastly, HIIT is more beneficial for preserving muscle tissue. For example, if you look at a sprinters body compared to a distance runner you will notice the difference in muscularity. That’s because a sprinter is activating muscle fibers with more intensity in their movement.
Steady state cardio can be defined as a continuous, moderate- low Intensity pace also known as (MISS) or (LISS). This is implemented at a fixed rate of intensity and sustained for an extended amount of time. About 55-70% of VO2 Max. Steady state can increase endurance and burn calories but does not make changes in the body to improve metabolism. Steady state does not have the same muscle retention as HIIT. Muscle tissue is at higher risk for catabolic effects as muscle fibers are not engaged in the exercise like they are in more explosive movements. However, steady state cardio is beneficial when an individual is already implementing HIIT cardio up to 4 days per week and needs to create a larger energy deficit. This is when you would combine both methods during the week for further results. Some people may enjoy steady state for relaxation purposes or due to physical Injuries preventing them from implementing HIIT. Both methods of cardio have merit, but it’s important to know the facts on both to decide what kind of cardio regimen is needed for your specific goals.