High intensity interval training & fat loss

High Intensity Interval Training, also known as “HIIT”, has received a lot of attention in the strength and conditioning industry. And for good reason: It’s effective. But what exactly is HIIT? What are the effects of HIIT? And is HIIT for everyone? As your trainer, I will do my best to educate you on this trendy acronym.

HIIT is exactly what it sounds like: intervals of short but very intense bursts of activity followed by intervals of rest (or “recovery”). The most commonly studied protocol involves the usage of a cycle ergometer. Unfortunately not a lot of research has been done on the usage of other forms of exercise such as running, rowing, or skipping (1).

The Wingate test is the most popular of all the protocols. It involves a 30 second full out sprint against a hard resistance followed by 4 minutes of recovery, usually repeated 3 to 4 times. I have performed this protocol for various lab assignments throughout my schooling, and let me tell you it is anything but easy! This is by far one of the hardest tests out there because it involves extreme self discipline to push for those 30 seconds. By the last 5 seconds your legs feel like jello, and it’s not uncommon to feel nauseated. A gentler protocol involves 4 to 6 second sprints followed by 12 seconds of rest repeated for 60 rounds total. Alternatively, for the novice, perhaps a slightly easier option would be a 2 minute sprint (obviously not at the same resistance as the Wingate) followed by a 3 minute recovery for a period of 20 minutes (1).

There are numerous physiological effects, but I will focus specifically on how HIIT aids with fat loss. There is a significant catecholamine response to HIIT. What does that mean? That means that there is an increase in epinephrine and norepinephrine. In other words, your adrenaline gets going. This is important because epinephrine in particular has been shown to release fat from subcutaneous tissue for lypolysis (1). (That’s the scientific way of saying that HIIT burns fat!) A decrease in post-exercise appetite has also been observed which could be another reason for the increase in fat loss with this type of training (1).

A study by Trapp et al. compared the effects of HIIT (using the Wingate protocol) to steady state aerobic training and to a control group among healthy but inactive nonsmoking women aged 18 to 30 years all with healthy BMI levels (2008). The study found that the woman in the HIIT group lost more weight overall, specifically due to a greater loss in fat mass (2)! If that’s not good enough news then keep on reading: Where was the greatest fat loss? In the abdomen and in the legs! We all know that you can’t spot reduce fat, but this article seems to be proving otherwise.

As I have already mentioned, HIIT is not for those faint of heart. It is an extremely demanding form of exercise both physically and mentally, and is not recommended for those who are brand new to fitness. Be smart when you train. Just because everyone is talking about the latest trend does not mean it’s appropriate for you yet. Here are a few of my personal tips for anyone looking to start their fat loss journey.

Kat’s HIIT Tips:

• If you are brand new, it is imperative that you build your aerobic capacity before delving into HIIT. Build the habit of exercising first, build your tolerance, then slowly start incorporating HIIT into your workout schedule. Stay focused and positive. You will eventually be able to work up to the Wingate!

• HIIT is like cayenne pepper. You can sprinkle it in throughout your workout to add some intensity, but if you do too much, everything else will suffer. I suggest that you start with only one session per week, and eventually work up to 3 non-consecutive sessions per week MAX. Remember, this form of training is extremely taxing, and your body needs rest in order to recover.

• Periodize your training schedule. Incorporate HIIT into your program for no more than 12 weeks at a time. Studies have shown that anything more than this and you stop reaping the benefits of it (1)! Once your 12 weeks of HIIT are up, let your body recover from it before starting it up again. I recommend incorporating HIIT into your summer plan!

If you have any questions or comments, please feel free to email me: trainwithkat@gmail.com. 

(1) Stephen H. Boutcher, “High-Intensity Intermittent Exercise and Fat Loss,” Journal of Obesity, vol. 2011, Article ID 868305, 10 pages, 2011. doi:10.1155/2011/868305

(2) Trapp, E.G., Chisholm, D.J., Freund, J.J., & Boutcher, S.H. (2008) The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women. International Journal of Obesity, 32(4), 684-691. doi:10.1038/sj.ijo.0803781