High-Intensity Interval Training: An Effective Way to Get in Shape
Distance running. Cycling. CrossFit. Resistance training. Rowing. Cross country skiing are all effective ways to integrate High-Intesity Interval Training and get the most out of your workouts.
There are a multitude of ways to get in shape and improve your health and well-being. High-intensity interval training (HIIT) is another way and it has been gaining a lot of popularity lately.
High-intensity interval training is characterized by intermittent bouts of exercise and rest. The exercise bouts may range from seconds to minutes and they generally target 80-90% of one’s maximum heart rate.
Numerous peer reviewed studies cite benefits ranging from increased cardiac output to decreased insulin sensitivity and more. HIIT may delay the onset of fatigue when exercising allowing one to exercise longer. Multiple studies have demonstrated that high-intensity interval training increases the rate of oxygen delivery leading to increased maximal oxygen uptake (VO2max). Increasing VO2max is important because it not only increases exercise tolerance, but it also increases long-term health status. Specifically, a 3.5 mL per kg per min increase in VO2max is associated with a 13% lower risk of all-cause mortality and a 15% lower risk of cardiovascular event.
Cali Dunham and Craig Harms from Kansas State University found that both high-intensity interval training and endurance training were effective in increasing inspiratory muscle strength which might lead to enhanced performance due to decreased respiratory muscle fatigue. This study suggests that high-intensity interval training might be a great alternative to endurance training for those who are short on time, but wish to improve aerobic capacity and performance.
One study conducted by Todd Astorino and colleagues compared three different regimes of high-intensity interval training (HIIT+SIT, HIIT+HIIT, HIIT+PER) to a control group and it studied changes in VO2max and cardiac output. All three HIIT regimes consisted of eight to ten 60 second bouts of cycling at 90-100% peak power output interspersed with a 75 second recovery. Participants were then randomized into sprint interval training (HIIT+SIT-eight to ten all out sprints), high-volume interval training (HIIT+HIIT- repeated 2.5 minute bouts of cycling with 60 seconds of recovery leading to a total or 12.5-17.5 minute per day) or periodized interval training (HIIT+PER- three sessions of high-volume HIIT, three sessions of SIT and four sessions of low-volume HIIT leading to a total of 5 to 15 minutes of training per session) following the initial HIIT training. All three HIIT groups showed greater increases in VO2max, cardiac output and stroke volume compared to a control group indicating improved oxygen delivery. The data shows similar increases in VO2max across the three different high-intensity regimes indicating that various high-intensity interval trainings can all increase VO2max which provides options to the exercisers.
Michael Whitehurst looked at the benefits of high-intensity interval training in older adults, but the benefits can extend across all ages. HIIT promotes many of the same peripheral adaptations that traditional endurance training provides such as increased mitochondrial markers of oxidation, increased oxidative enzymes, improved insulin sensitivity, increased mitochondrial biogenesis and increased subcutaneous fat loss. It also may improve stroke volume and reduce resting heart rate. This translates to better performance and better health.
In sum, high-intensity interval training is a great, effective way to get in shape and to live a healthier life.
Astorino, T.A, Edmunds, R.M., Clark, A., King, L., Gallant, R.A., Namm, S., Fischer, A., & Wood, K.M. (2017). High-intensity interval training increases cardiac output and VO2max. Journal of the American College of Sports Medicine, 265-273. doi: 10.1249/MSS.0000000000001099
Dunham, C. & Harms, C.A. (2012). Effects of high-intensity interval training on pulmonary function. European Journal of Applied Physiology. 112, 3061-3068. doi: 10.1007/s00421-011-2285-5
Whitehurst, M. (2012). High-intensity interval training: An alternative for older adults. American Journal of Lifestyle Medicine, 6(5), 382-386, doi: 10.1177/1559827612450262