Workout of the Day:
Three rounds for time of:
10 Front Squats (60-70% of today’s 1-RM)
The Myth of the Fat-Burning Zone
Written by Mark Riebel
An old article from the CrossFit Journal has this same title, and I’d like to give a quick synopsis here if you’re not a subscriber (which you should be).
How many times have you heard that in order to really burn fat, you’ve got to work in heart rate range of 50-70% of your maximum for at least 30 minutes? There’s even convenient charts posted on nearly every piece of cardio equipment in all the traditional gyms you go to (if you’re cheating on us here at Invictus), so it must be true. Fortunately for us, it’s not.
Yes, it is true that fat makes up the bulk of your body’s fuel for most of your daily activities and in low-intensity aerobic exercise where you’re either working for long periods of time or not breathing exceptionally hard. This fact is where the idea comes from that you must be in a certain sub-maximal heart rate range to maximally burn fat. The problem is that this is a misunderstood point.
If I work at a slow and steady pace for my prescribed 30 minutes on the stairmaster while I watch TV, I might burn, say, 100 calories, approximately 50% of which are from fat. Now, if I do that same 30 minutes at a much higher heart rate (and therefore intensity level), I could burn about 300 calories, of which maybe only 30% are fat, with glucose and glycogen making up the bulk of the rest (a small amount of protein gets burned as well). “See, you burn more fat at an easier pace!” the exercise magazines will tell you. But anyone with some basic math skills can see that more total fat was burned in the high-intensity workout (90 calories vs. 50) than the lower one, and the first workout merely had a greater percentage of calories burned from fat.
Most of you will be thinking at this point, “But our workouts aren’t that long, so there’s no way we can burn this many calories!” This is a forthcoming post in itself where I’ll tell you a bit more about geeky science things like exercise post oxygen consumption and why you get much more bang for your buck with the style of workouts we do instead of watching television on the stairmaster for 30 minutes. For now, though, trust in the programming and try to hold back your snickers when someone tells you about weight loss and the fat burning zone.