What is High Intensity Interval Training?
High Intensity Interval Training is a form of cardiovascular exercise consisting of short durations of high intensity cardio followed by a very light rest stage, performed in intervals (sets). An example of a HIIT workout would be
30 second sprint (85-90% of Vo2 Max)
1 minute rest
Why perform HIIT Cardio?
HIIT can be implemented into a workout to boost your metabolic rate, which is simply the amount of calories your body burns in a given day. HIIT as a form of cardio has been shown to have a long term benefit of burning more overall body fat than other forms of cardio. There have also been mitochondrial effects shown in HIIT training in which there is a greater capacity to oxidize body fat when performing HIIT cardio.
How does this compare to long, steady state cardio?
Steady state cardio burns more calories in the workout. However, HIIT has been shown to provide far greater results than long, slow-state cardio. When performing HIIT in a carefully constructed workout routine, the individual’s metabolic rate will begin to rise and they will be able to burn more calories in a given day without needing to cut calories from their diet. Slow-state cardio may burn more calories in the workout, but the results speak for themselves: HIIT training is the superior form of cardio for burning body fat.
How does HIIT cardio affect muscular hypertrophy?
HIIT training has been shown to be non-catabolic. Studies show that individuals performing HIIT were able to maintain the same amount of strength and hypertrophy after performing numerous HIIT sessions per week.
What do case studies say about HIIT training?
When you think of losing body fat and doing cardiovascular workouts, you will often think of needing to spend hours in the gym each week to burn the calories required to reach your desired body composition. This is simply not the case. In a case study, 15 active women performed sprint intervals as part of their training method for a 6 week duration. They were able to decrease their fat mass by 8% and increase their fat-free mass by 1.3%¹.
In a larger study, 60 overweight female university students were randomly assigned to a non-training control group, a moderate intensity group, and a high intensity interval training group. The two exercise groups underwent 12 weeks of exercising 5 days a week. The studies showed that the High Intensity Interval Training was far superior in improving resting heart rate, maximal oxygen uptake, ventilatory threshold, and body composition².
The impact of exercise intensity was put to the test in a 20 week endurance-training program versus a 15 week HIIT program. Although the endurance-training program resulted in a substantially higher energy cost to the individual, the body composition and oxidation of body-fat was shown to be far more significant in the HIIT group³.
If you’re looking to improve body composition, HIIT has been shown to be the superior cardiovascular workout.