Does it matter how many calories you burn?
“Flatten, Shape, Tone, Lengthen, Rip, Ripped, Ripping, Burn, High Intensity, HIIT, Tabata, Metcon, Muscle Confusion, Blah, Blah Blah”
These are some of the terms used to convince us to think a workout is either going to give us those results and/or a super sexy name to make it sound cool. Often times you can’t believe the hype based purely on certain keywords. We have been literally fed this as well by “food” companies that get us to buy a products that resemble nutritious food but is just a science experiment with a catchy label.
Another thing I’ve been noticing with fitness trends are trainers, and workout programs that claim that they burn 1000 calories, in one hour. Sweet, but is this a good thing? Will this help me with my goals? Can I do this without it killing me?
Does High Intensity training burn fat better than steady state cardio? Studies have shown that shorter bursts of high intensity exercise burns a significant amount of fat compared to the traditional cardio training.
I pulled out a few pieces of the study that I found interesting.
Nevill examined the growth hormone (GH) response to treadmill sprinting in female and male athletes and showed that there was a marked GH response to only 30 s of maximal exercise and the response was similar for men and women but greater for sprint compared to endurance trained athletes. GH concentration was still ten times higher than baseline levels after 1 hour of recovery. Even after an hour of recovery from the sprint workout, Growth Hormone level was 10 times higher than baseline levels!
Twenty minutes of moderate-intensity aerobic exercise resulted in a significant fall in glycemia. However, one 10-second sprint at the end of the 20-minute aerobic exercise bout opposed a further fall in glycemia for 120 minutes, whereas in the absence of a sprint, glycemia decreased further after exercise. The stabilization of glycemia in the sprint trials was associated with elevated levels of catecholamines, growth hormone, and cortisol. In contrast, these hormones remained at near baseline levels after the 20min of aerobic exercise. Thus, one 10-second all out sprint significantly increased glucose, catecholamines, growth hormone, and cortisol of type 1 diabetic individuals for 5min after HIIE.
Such a small amount of really hard work can significantly improved glycemic stability, growth hormone and cortisol. 20 minutes of aerobic exercise had little effect on those hormones.
More recently, Trapp conducted an HIIE program for 15 weeks with three weekly 20-minute HIIE sessions in young women. HIIE consisted of an 8-second sprint followed by 12s of low intensity cycling. Another group of women carried out an aerobic cycling protocol that consisted of steady state cycling at 60% V˙O2max for 40min. Results showed that women in the HIIE group lost significantly more subcutaneous fat (2.5kg) than those in the steady state aerobic exercise program
20 minutes of High Intensity Intervals were much more effective at burning fat than 40 minutes of steady state cardio.
Well if interval training is that much more effective, why would you ever do anything else? Go hard every time for maximum results! Not quite…
Unfortunately we also have all those pesky joints and tendons that happen to get pissed off as we go too hard for too long. Also you shouldn’t neglect building muscle and strength by doing some heavier lifting work. After all, that strength is what supports your ability to do the high intensity work.
You also have this little thing called a heart that needs to be taken into consideration. Just like the other muscles in your body your heart is a muscle that needs to be well rounded. Too much of one thing doesn’t seem to be a great thing. Too much time spent in high heart rates can thicken the heart and cause problems. Long slow exercise has been shown to cause cardiac problems if done excessively.
Our bodies typically don’t like to do just one thing for a long time without some kind of break down. Most trainers that know what they’re doing already know this and plan their strength training accordingly. However I don’t think the same is true for conditioning work. So if you just rely on one form of conditioning you may be doing more harm than good. Spend time at a really low heart rate relaxing, breathing, meditating. Spend some time at a low, easy walk around your neighborhood. Get some exercise at a slightly more elevated rate a few times a week by jogging, cycling, whatever… Then depending on your goals get after it and see what you’re made of. Challenge yourself with short bursts of work to stimulate all those great benefits of High Intensity exercise.
Stress ManagementOne more little thing I took out of this study was a paragraph on what High Intensity exercise does to your Central Nervous System (CNS). Parasympathetic activation was found to be significantly impaired in a 10-minute recovery period after repeated sprint exercise and a 1-hour recovery period in trained subjects. Buchhiet have suggested that parasympathetic or vagal impairment is caused by the heightened sympathetic activity that occurs during HIIE exercise and the persistent elevation of adrenergic factors and local metabolites during recovery (e.g., epinephrine, norepinephrine, and venous blood lactate). Interval workouts seem stimulate the Sympathetic Nervous System and inhibit the Parasympathetic Nervous System. This makes sense if you think about exercise in terms of added stress rather than just purely calories burnt. Like I’ve written about several times here, here and here, you need to consider the amount of stress in your life and then evaluate whether you should add more stress too it. Sometimes you need to go hard and push the limits, while other times chill out. Train as hard as you should, not as hard as you can or your body will eventually break down.
Do Calories burnt actually matter?
I don’t personally put much stock in any claims of calories burnt during training. The body is far too complex to put a number to anything and then justify eating a
piece entire cake because you just burnt 1000 calories in spin class.
You also have to consider things like how much extra calories the body burns after your training session rather than just the session itself.
My final suggestion is to make sure you get a little of this and that when it comes to exercise, eat real foods and try not to pay attention to those fancy tag words that make the exercise program sound better than it actually is.