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You hit the gym early in the morning, warm-up, stretch, and then go to work. After ten minutes or twenty or an hour of intensity, you’re toast. It was the kind of workout that leaves you soaked in sweat and flat on your back, gasping for air even though you can’t help but smile. What a feeling!
When you’re ready, you peel yourself off the gym floor, pat yourself on the back, and then . . .
. . . you sit all day. Whether it’s at a desk on the weekdays or in front of a television on the weekends, your time outside the gym is all about sitting. Does this sound like you?
Numerous studies have shown that high intensity interval training (known as HIIT) is just as or more beneficial for overall health and athleticism when compared to longer bouts of lower to moderate-intensity exercise. For example, a 2008 study found that 2.5 hours of sprint interval training produced similar muscle and endurance improvements as 10.5 hours of endurance training. Another study found that HIIT’s effects stick with you long after you leave the gym, increasing the resting metabolic rate for 24 hours. The famous Tabata 1997 study (one of the foundations of CrossFit) concluded that “intermittent exercise . . . may tax both the anaerobic and aerobic energy releasing systems almost maximally.”
A recent study, however, set out to challenge some of these claims. Published last week in the peer-reviewed journal PLOS ONE, the study followed eighteen healthy individuals between the ages of 19 and 23 who were randomly assigned to three physical activity regimes for four days. They were split up into three groups and were instructed to either a) sit 14 hours per day b) sit 13 hours per day and exercise for 1 hour per day and c) sit 6 hours, walk 4 hours, and stand two hours per day. While the 1-hour workout group showed the same energy expenditures per day as the minimal intensity group, insulin levels and plasma lipids in the minimal intensity group were significantly better than the sitting group. The same could not be said for the group with 1-hour of daily physical exercise.
Does this mean high-intensity exercise is not as beneficial as we once thought?
We’ve talked about ideas suggesting that one hour (or less) of exercise a day cannot make up for 23 hours of inactivity no matter how intense you make it (see Sitting is Killing You). In fact, people who sit for most of the day are 54% more likely to die of a heart attack, regardless of exercise. So while exercising for six hours a day (whether it’s by taking long walks or going on a treadmill marathon at the gym) will help eliminate some of the problems of chronic sitting, you still may be missing out on all the benefits of high-intensity training (not to mention 6 hours of exercise a day just isn’t sustainable for everyone).
While there are benefits to HIIT over regular exercise, it alone does not make up for an extremely sedentary lifestyle. Looking at the PLOS ONE study in the context of other research, the literature seems to suggest that remaining active throughout the day (through intermittent standing in the workspace or daily walks) in addition to a HIIT routine can be the perfect combination to achieve both short- and long-term health and fitness goals.
What do you think? Weigh in below!
The posts on this blog are for information only, and are not intended to substitute for a doctor-patient or other healthcare professional-patient relationship nor do they constitute medical or healthcare advice of any kind. Any information in these posts should not be acted upon without consideration of primary source material and professional input from one's own healthcare professionals.