The benefits of exercise are infinite. Not only do you feel better through the release of endorphins, you can most definitely end up looking better. Many people are of the belief that if they want to shed those extra kilos and be feeling their best, spending hours per week hitting the pavement is the best way to do so. I will admit I was guilty of this- running anywhere from 5 to 10km most days, battling shin splints and other injuries, as I truly thought that was the most efficient course of action. This however has been proven to not be entirely true.
In 2008, a study was published that revealed that high intensity interval exercise performed three times per week for 15 weeks was associated with marked reductions in total body fat, particularly around the abdomen compared to the same frequency of steady state exercise (1). There were similar results for another study that had one group perform steady state cardio for 30-60 minutes a day 3 times a week whilst the other group did six 30 second sprints 3 times weekly for 6 weeks. The group performing high intensity interval training lost significantly more body fat than the group in the low intensity steady state exercise group (2).
Another study looked at the benefits of both types of exercise on blood glucose levels and found the high intensity interval training had a positive impact on glucose tolerance and insulin sensitivity which is of significant importance as it could be a preventative measure against type 2 diabetes (3).
High intensity interval training is great for people who want faster results and are limited for time. One of the above studies had the steady-state group performing cardio for 90-180 minutes per week and had the high intensity group performing cardio for as little as 10 minutes per week. With the results being dramatically better with the high intensity group (2) it really makes you curse the hours spent jogging on the treadmill in an attempt to burn fat. Not only does high intensity cardio for a shorter amount of time burn more fat, studies also suggest that it can help to preserve a greater level of muscle mass then the lower intensity counterpart (3). You only have to consider the size of a marathon runner's legs compared to sprinters legs to illustrate this point.
Many people do low intensity forms of exercise such as swimming or jogging purely to keep fit, or because they find it enjoyable and stress reducing. This is absolutely fine and at the end of the day it is down to personal preference. Studies suggest that both forms of cardio are effective for increasing cardio respiratory fitness (VO2max) so it really depends on your reasons for performing cardio when choosing one over the other. (4).
Turning up the heat on your workouts with high intensity interval training will shorten the time spent performing cardio whilst also burning fat more effectively and allow you to maintain muscle mass. Hours spent pounding the pavement are no longer considered the gold standard in cardio, as there is a much more efficient kid on the block.
1. Trapp, E. G., Chisholm, D. J., Freund, J., & Boutcher, S. H. (2008). The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women. Int J Obes, 32(4), 684-691.
2. Rossow, L., Yan, H., Fahs, C. A., Ranadive, S. M., Agiovlasitis, S., Wilund, K. R., . . . Fernhall, B. (2010). Response to “High-Intensity Interval vs. Moderate Steady-State Exercise”. American Journal of Hypertension, 23(8), 813. doi: 10.1038/ajh.2010.119
3. Sloth, M., Sloth, D., Overgaard, K., & Dalgas, U. (2013). Effects of sprint interval training on VO2max and aerobic exercise performance: A systematic review and meta-analysis. Scandinavian Journal of Medicine & Science in Sports, 23(6), e341-e352. doi: 10.1111/sms.12092
4. Kessler, H., Sisson, S., & Short, K. (2012). The Potential for High-Intensity Interval Training to Reduce Cardiometabolic Disease Risk. Sports Medicine, 42(6), 489-509. doi: 10.2165/11630910-000000000-00000