Burning Up

So it's been hot lately. I've been burning up in this heat. I've never liked the heat and humidity we have here in the south even though I've grown up with it. All the heat has made it difficult to run in the evening. It was still 85F (29.44C) at 9PM last night, so I've been running on a tread mill I purchased from Larry a couple years ago before he moved to Arkansas. It's a good, powerful, full size tread mill and it easily handles me. It has some nice features:

• digital speed and incline controls
• time and distance traveled
• calorie burned

It also allows you to set a calorie burn goal, and when you reach your goal the belt slows, and in a few seconds, stops. Since my favorite part of exercise is when it is over, I like anything that will get me to my favorite part. So I set the burn goal for a whole box of mac & cheese (2 servings, or 500 calories) and started jogging. I was surprised when the thread mill shut off in about 25 minutes, way short of the 40 minutes I was expecting.

So is the 75 calorie for 6 minutes of jogging I used wrong, or is it the calorie counter on the tread mill? Well they are both wrong, and probably for the same reason. Both assume some weight value and chances are I'm not that weight. Well there are calorie calculators all over the web. But very few provide the formula. I found a formula that most scholarly pages site is from Energy Expenditure of Walking and Running, from Medicine & Science in Sport & Exercise, Dec. 2004.

	Your Total Calorie Burn/Mile	Your Net Calorie Burn/Mile
Running (>5mph)	.75 x your weight (in lbs.)	.63 x your weight
Walking (3-4mph)	.53 x your weight	.30 x your weight

Total Calorie Burned (TCB) includes your basal metabolism (what you burn just sitting there), and the Net Calorie Burned (NCB) is just what the exercise burned and is what typically gets shown by calculators.

So just how long do I have to spend on the tread mill to burn up 500 (total) calories? Ever how long it takes me to go 3.12 miles if I run, or 4.4 miles if I walk. So 37.5 minutes based on 12 minutes per mile pace which is about right or me. When walking your center of gravity does not move (up and down) as much as when you run, so you don't burn as many calories. That is an overly simple explanation. How Many Calories are You Really Burning? is a good place to start reading if you want specifics. Also exercising on a tread mill or on a track is about the same. But a flat track and the hills in your neighborhood are of course, different. Proving once again your mileage will vary!