Yes, it’s true, you don’t have to exercise for hours a day to be fit. In fact, you don’t even have to exercise an hour. A slew of modern studies confirm that, for many people, about 30 minute a day of intense exercise is all you need.
Of course the media has skewed some of this research in order for it to sound dramatic, none of this worse than “30 Minutes of Exercise Better Than An Hour,” a headline that in reality is the first half of a sentence that should have concluded “for some people.” Regardless, there is good information uncovered, if less sensational, that can help you get fitter, quicker. I’ll summarize the bits you need to know.
The idea that short exercise can be more effective than long began with two studies in the 90s (Tabata and Laval, which you might have heard of) that showed high intensity intervals, or HIIT, could lead to rapid increases in fitness because it stimulated hormonal production that changed your metabolic processes.
The downside to the average Joe and Josephina was that you needed to be pretty fit to do these intervals. In the last six years, however, we’ve chipped away at the premise that these intervals need to be as high intensity as once thought. Yes, they need to be anaerobic but similar effects on hormone production have been found using a myriad of various exercise modalities, from running to circuit-style weight training and plyometric work.
In 2013, a study comparing 30 minutes of high intensity training versus aerobic training concluded: “High intensity intermittent exercise suppresses subsequent ad-libitum energy intake in overweight inactive men. This format of exercise was found to be well tolerated by an overweight population.” In other words, short bouts of intense exercise are now being recommended even to de-conditioned populations.
Your body has an emergency response to exercise. When you begin, no matter what you’re doing, you burn glycogen for fuel. Once your body figures out that you aren’t in an emergency, it begins to conserve by shifting to body tissue, primarily fat stores, for energy. It was once assumed that training during this “fat burning” period was optimal for weight loss. Now we know it’s the opposite. If you take advantage of the glycogen window by training hard (and smart so you don’t get hurt) you can alter your body’s metabolism—the key to changing your body composition—quickly and efficiently.
It is important to note that this doesn’t not mean longer exercise is bad/wrong/unnecessary. Especially athletes, who need 100% efficiency in performance, will need to train body systems that take more than 30 minutes to stimulate. But for the average time-crunched person it’s good to know that short, intense, exercise has been proven to be your ticket to staying healthy.