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The laundry bin’s overflowing; the phone’s buzzing; and we still have yet to finish that project due first thing tomorrow morning. Before adding a long, slow jog around the park to that to-do list, consider this:
According to new research from Liverpool John Moores University and the University of Birmingham, high-intensity interval training can be a time-saving alternative to endurance training. So even though HIIT takes half the time, it can result in the same health benefits that we get from endurance activitiesSprint interval and endurance training are equally effective in increasing muscle microvascular density and eNOS content in sedentary males. Cocks, M., Shaw, C.S., Shepherd, S.O., et al. School of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, U.K. Journal of Physiology 2013 Feb 1;591(Pt 3):641-56..
What’s the Deal?
Researchers recruited 16 young sedentary males with an average age of 21 to compare the effects of endurance training and sprint interval training. Some of the participants did six weeks of endurance training, (40 to 60 minutes of cycling five times per week). The rest did high-intensity interval training, (four to six repeated 30-second “all-out” sprints on bikes interspersed with 4.5 minutes of low-intensity cycling, three times per week). In the next phase of the study, researchers took muscle biopsies before and after participants completed 60 minutes of cycling.
It turns out that both forms of exercise — five hours of endurance training and just 90 minutes of HIIT — helped reduce aortic stiffness (which affects how quickly blood travels through the arteries) and increase whole body insulin sensitivity (how efficient the body is at processing glucose). That’s important because it means HIIT and endurance training were equally effective at helping decrease the risk of heart disease, hypertension, and diabetes.
Is It Legit?
Looks like it. This study adds to a growing body of research suggesting that, in adults and kids, HIIT is a more time-efficient way to see the same health effects we get from endurance trainingSprint interval and endurance training induce similar improvements in peripheral arterial stiffness and flow-mediated dilation in healthy humans. Rakobowchuk, M., Tanguay, S., Burgomaster, K.A., et al. Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada. American Journal of Physiology 2008 Jul;295(1):R236-42.Similar health benefits of endurance and high-intensity interval training in obese children. Corte de Araujo, A.C. Roschel, H., Picanco, A.R., et al. University of Sao Paulo, School of Medicine – Division of Rheumatology, Sao Paulo, Sao Paulo, Brazil. PLoS One 2012;7(8):e42747.. Specifically, research suggests HIIT can increase skeletal muscle oxidative capacity (how efficiently muscles use oxygen) and improve exercise performanceSimilar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans. Burgomaster, K.A., Howarth, K.R., Phillips, S.M., et al. Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada. Journal of Physiology 2008 Jan 1;586(1):151-60.A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanisms. Little, J.P., Safdar, A., Wilkin, G.P., et al. Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada. Journal of Physiology 2010 Mar 15;588(Pt 6):1011-22.. We can even reap these benefits from low-volume high-intensity interval training (HIIT), which involves 15- to 60-second bursts of high-intensity cycling interspersed with two to four minute intervals of low-intensity cycling.
There’s also some evidence that people are more likely to stick to HIIT training routines than endurance regimensEvidence based exercise – clinical benefits of high intensity interval training. Shiraev, T., Barclay, G. University of Notre Dame, School of Medicine, Sydney, New South Wales, Australia. Australian Family Physician 2012 Dec;41(12):960-2.. That’s possibly because HIIT takes a whole lot less time, and packed schedules are one of the main reasons why adults don’t exercise. Even better news? Scientists say HIIT is appropriate for people of all ages and fitness levels (start sprinting, Gramps!)Low-volume interval training improves muscle oxidative capacity in sedentary adults. Hood, M.S., Little, J.P., Tarnopolsky, M.A., et al. Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada. Medicine and Science in Sports and Exercise 2011 Oct;43(10):1849-56..
On the flip side, of course, this research isn’t implying that long-distance runners can say bye-bye to longer runs. There’s a time and a place for mileage and marathoners and other endurance athletes will still have to log some distance in preparation for race (or game) day. It’s also important to note that intense sprint-based exercises can deplete the body’s energy stores, especially glycogenThe Role of Skeletal Muscle Glycogen Breakdown for Regulation of Insulin Sensitivity By Exercise. Jensen, J., Rustad, P.I., Kolnes, A.J., et al. Department of Physical Performance, Norwegian School of Sport Sciences Oslo, Norway. Frontiers in Physiology 2011;2:112.. So it’s worth mixing it up with some less intense cardio workouts so that the body can refuel.
No matter who we are, one of the most important parts of establishing an exercise routine is finding something enjoyable and maintainable. So for those who look forward to a 45-minute treadmill run at the same pace, it’s not necessary to switch to intervals immediately. But it is good to know that even when we’re in a huge rush (aka always), there’s still time to practice good health habits.
Have you tried high-intensity interval training? What’s your favorite HIIT workout? Let us know in the comments below or tweet the author @ShanaDLebowitz.