So here is the gist of it:
HIIT increases the ability of your body to utilize energy in the form of carbohydrates and fat by increasing your uptake of oxygen. Oxidation (aka “burning”) of these substrates, essentially your body’s energetic currency, can only take place in an environment replete with oxygen (hence the term oxidation). The additional oxygen in your body actually stokes your metabolic fire, which is why you’ve heard that an efficient HIIT workout can increase your metabolism for hours after you’ve finished exercising!
Increasing your resting metabolic rate (the amount of calories your body needs to sustain basic body functions at rest) is a major benefit, especially considering that there is around a two percent decrease in your resting metabolic rate (RMR) per decade! Couple that with a steady decline in lean body mass, which is one of the major determinates of RMR, and you can see where people can get into trouble with weight gain as they age. While the metabolic effects of HIIT don’t actually change your RMR beyond that period post-exercise (at least on its own), losing fat and gaining or maintaining lean body mass is certainly the goal to strive for.
Which brings me to my next point: losing fat while maintaining lean body mass. This is one of the most challenging nutritional bedevilments, a seemingly elusive unicorn of sorts. HIIT provides one of the most solid solutions, at least from a cardio perspective. The fight or flight hormones epinephrine and norepinephrine surge to extreme levels during high intensity physical activities. These and other stress hormones act as keys to the process of breaking down fat stored in your muscle, below your skin, and, most importantly, the dangerous fat that some people have deposited around their internal organs.
Totally--except that the normal stress response of the body also has the tendency to break down muscle. Enter human growth hormone, testosterone, and vascular endothelial growth factor, all of which foster an environment of anabolism, or growth, within the human body. The release of these hormones during a high intensity interval type training session actually mimics their release during resistance training workouts. This doesn’t necessarily mean that you will get ‘swole’ by doing a HIIT workout, but you won’t be losing lean body mass either. Eureka!
So before you head into the studio or get one of our HIIT workouts going in your living room, here are just a couple of things to think about:
Consistency, consistency, consistency: most of the credible research out there is looking at HIIT routines for a duration of anywhere from 6-12 weeks before seeing measurable results. It isn’t about instant gratification; optimum health is created by a lifetime of the choices that you make daily. What can you do today to ensure that you are your best self tomorrow?
Always remember that you can have a killer workout schedule, but if you aren’t treating your body right with your nutrition, chances are, you aren’t seeing the results that you could. Remember: abs happen in the kitchen!
FYI: I am about to start a personal nutritional experiment using branched chain amino acids and intermittent fasting (combined with high intensity cardio and resistance training). My next post will be about one or both of these hot topics, so stay tuned!