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BOSS’s programming and recommendations are someone unique compared with the average international exercise physiology or strength and conditioning organization. It is also unique compared with what you’d see on the CrossFit main site or Jillian Michael’s blog. I’m often asked, when the rest of the world is saying that the best way to lose weight is aerobic exercise, why do we say high-intensity interval exercise is better? If you continue to read this blog and learn more about BOSS’s programming model, you’ll soon learn that I’m a geek. Being a geek whose job it is to advance exercise science, I am always questioning exercise programming models. In fact, that’s one of the reasons Chad and I created BOSS Strength Institute. We wanted to be examine industry trends and applicable research in order to adapt and progress with the constantly changing landscape. We believe this is what makes us different. At BOSS, we believe in HIIT as the one of the most efficient and effective method of increasing health, fitness, and, to a degree, sport performance and this is the primary focus of our programming and academic research. Not that a modest amount of aerobic training is bad for you, but there are many reasons that HIIT can be better. Besides being vastly more time-efficient (ie. bigger bang for your time-buck) and making the same cardiovascular or ‘aerobic’ physical changes in the body, it is more effective than aerobic training in increasing high-intensity work performance and potentially safer (although the data on safety are not robust enough to make concrete conclusions). Add the resistance and multimodal components to HIIT, and you have increases in muscle size, strength, power, and function that make for BOSS’s HIIT model. |
We do know that HIIT tends to be better than aerobic training for weight loss (see references below), but I’ve often been asked why. The answer is usually a bit wishy-washy because the research is not yet clear. We know that HIIT tends to increase metabolism for a longer duration after exercise than aerobic training – the so-called ‘afterburn’ – whereby more energy and calories are expended. We also know that HIIT produces the optimal hormonal balance for energy utilization and muscle growth. More muscle results in greater metabolism and greater chance of fat loss. Aerobic exercise is, by nature, designed to make the body more efficient at storing energy in the form of fat and results in muscle breakdown and a greater chance of fat storage. The research also suggests, however, that these mechanisms are quite small; too small to significantly contribute to weight loss. Until now, we didn’t really know the effects of HIIT on food consumption and hunger post exercise compared with aerobic exercise, which is most likely the biggest factor in weight loss or gain. Most research suggests that hunger levels increase after prolonged aerobic exercise, which usually results in more eating, but little was known about HIIT.
Along comes this excellent little study published in the International Journal of Obesity by an Australian research group (Sim et al. 2013) that compared hunger levels and voluntary food intake in overweight individuals after either two types of HIIT or after moderate intensity aerobic exercise. Both types of HIIT were similar to the levels of intensity that BOSS recommends in its programming for what are termed ‘aerobic intervals’ (high-intensity) and ‘fly and die burner intervals’ (very high-intensity). Here’s what they found:
Despite no differences in perceived levels of hunger between exercise trials, food intake was significantly less immediately after both types of intervals than after aerobic exercise and this was more pronounced in the very high intensity intervals. This difference persisted for up to 38 hours after exercise. Associated with the decrease in food intake was a change in the hormonal balance to support a lower hunger response despite the decreased intake. All of this and no differences in sensation of hunger.
What do we take from this? While still far from being conclusive and only using a sample of 17 participants, this study provides evidence that HIIT, particularly the very high intensity fly and die intervals that comprise most of the HIIT sessions we advocate at BOSS, reduces the amount of food intake for more than a day after exercise. Obviously, you need to be mindful of the type and quality of the food you’re eating and the hunger cues that your body is telling you; as it is becoming more and more clear that a calorie in does not equal a calorie out and you can always ‘out-eat’ your exercise program. But if you’re one who does struggle with cravings and are having difficulty with hunger, very high intensity HIIT appears to be most effective.
Happy HIITing,
Dr. Scotty
REFERENCES:
Boutcher et al. High-intensity intermittent exercise and fat loss.Journal of Obesity. 2011;ID868305. Note: this article, not by me, is available as a free open access article at: http://www.hindawi.com/journals/jobes/2011/868305/
Sim et al. High intensity intermittent exercise attenuates ad-libitum energy intake. International Journal of Obesity. 2013; online DOI: 10.1038/ijo.2013.102
Tjonna et al. Aerobic interval training reduces cardiovascular risk factors more than a multitreatment approach in overweight adolescents.Clinical Science. 2009;116:317-326.
Trapp et al. The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women.International Journal of Obesity. 2008;32:684-691.
