So the treadmills and bikes at my gym have a chart (much like this one) that has heart rate on the y-axis and age on the x-axis. Can someone explain to me what the different ‘zones’ on the heart rate dimension actually signify. “Effective fat burning” seems to indicate that at that heart rate, fat is burned. Does this not happen at higher heart rates? Why not? And what is the difference between aerobic and anaerobic (not on the chart in the link, but it does show up on the chart in my gym)?
Also, some of the machines have a setting that shows the number of ‘METs’ associated with whatever level of exercise I have just engaged in. Would that refer to ‘metabolic equivalents’ (wiki link?). What’s a straight forward way of interpreting that as it applies to something like 10 minutes of running?
The “fat burn” area is where the most efficient burning of fat is happening. However, there is less overall exertion at this level so, while you may be burning fat more efficiently (a higher percentage of your calorie expenditure is coming from your fat stores than at higher levels), you’re burning fewer calories overall and, actually, a higher exertion level for the same amount of time will burn more fat calories.
If you burn calories, those calories have to come from somewhere. The “fat burning” zone is the conventional wisdom for using fat as the source of calories as the exercise is happening. I don’t even know if that’s true. Getting up the aerobic zone is where you get the better cardiovascular benefit–your body’s capacity to use oxygen. That is, lung capacity, heart efficiency/power, etc. Aerobic conditioning is usually measured as oxygen uptake in the form of VO[sub]2[/sub] max. But no matter how you burn the calories, they are going to eventually result in using fat unless you are in some sort of starvation mode where your muscles and organs atrophy.
Aerobic exercise is when you are exercising at an intensity where the required oxygen can be supplied real-time by the cardiovascular system, such as running. Anaerobic exercise is when the oxygen requirement is too high to be provided by the cardiovascular system and oxygen in the muscle stores is consumed, such as in intense weightlifting. Anaerobic exercise is therefore limited in duration, generally from a few seconds to a couple of minutes.
Thanks people, that’s great. I was starting to wonder whether I might start losing pounds like crazy if I managed to keep my heart rate between 120 and 140 but it looks like that is not true. Which in a way is a shame because I wouldn’t mind finding a way to lose weight like crazy, that’d be nice.
That’s the link I posted in the OP. What I’m asking is, if I run for 10 minutes and it says I ‘collected’ 25 METs, what does that mean? That I burnt the energy I would have burned during 250 minutes of sitting? How much is that?
You need a lot of exercise to “lose weight like crazy,” and even there, I define “like crazy” as a pound or so a week. The rule of thumb is 100 calories per mile of running, and 3500 calories per pound. So 35 miles a week (for me, at 165, and my level of exertion, it’s a few miles less than that, but it’s a general rule and you’re better off underestimating than over.)
Some people will tell you you can only lose 5-10 pounds of weight through exercise, the rest is from diet. My own experiences don’t quite confirm that, but the truth is diet is the easiest component of this equation to effect weight loss. (In my estimation, I would say two thirds of my weight loss was diet, one-third exercise. However, I was exercising moderately intensely. I first started with weight training, and then I moved to running 30-35 miles per week. Combined with an 1800-2000 calorie diet, this had me going at a rate of two pounds per week, according to my journals, from 205 to 165. The weight loss slowed down at the end, but that’s to be expected as your caloric requirements decrease as you lose weight.)
The one thing to be careful of is that exercise can make you hungrier than usual and/or it will give you the psychological excuse of “well, I just ran five miles, I can eat that Big Mac and Fries for dinner.” People will often overestimate the caloric expenditure of exercise and make up for it by overeating. Hence, some people starting an exercise program and gaining weight.
