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In recent years, high intensity interval training has become a very popular way to perform cardiovascular activity.

High intensity interval training, or HIIT, is characterized by repeated bouts of high intensity exercise followed by recovery periods of varying intensity and time. This is very different from what people have traditionally done to increase cardiovascular endurance and attain other adaptations associated with cardiovascular training. Traditional cardio can be described as “steady-state” cardio. Steady-state cardio is considered any exercise (cycling, swimming, running, etc.) done at a consistent intensity and performed for longer than twenty minutes.

Many positive adaptations can occur as a result of cardiovascular training of any type. These adaptations include, but are not limited to, increased cardiac muscle mass, increased use of fat as fuel, increased maximal oxygen consumption (VO2max), and an increase in mitochondria, the energy factories of the cell. All of these adaptations allow us to exercise for longer periods of time at higher intensities. One might ask, “What is the best way to attain these adaptations?”

Well, recent studies show that cardiovascular and muscular adaptations to HIIT are comparable and sometimes even greater than those of steady-state training. In regards to cardiovascular adaptations, these studies show that HIIT increases stroke volume and VO2max to a greater degree than steady-state cardio (stroke volume: 10% greater improvement; VO2max: 6% greater improvement). These studies also suggest HIIT increases mitochondrial density, which allows us to create more energy, to a similar degree as steady-state but in less time and fewer days per week.

In addition to producing greater adaptations, HIIT is very time efficient. HIIT sessions can be completed in 20 minutes or less depending on the work-to-rest ratio. So you’ll be able to attain the same positive adaptations while spending much less time in the gym. So, if you’re tired of putting in hours on your cardio machine of choice, give HIIT a try!

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