Monday, February 13, 2012

Calories burned per mile: What's the truth?

I'm confused.  This may be data overload, but there are some big discrepancies in readings for calories burned during my training runs.

An example:  I jogged 10.61 miles this morning at around a 10/min mile pace.  My Garmin watch is telling me that's 1,382 calories burned; when I enter the elapsed time (1:43) into My Plate with an associated 10/min mile pace, it registers 1712.

So where do we go from here?  I Googled the topic and came up with a great link from Runner's World at http://www.runnersworld.com/article/0,7120,s6-242-304-311-8402-0,00.html.  The article cites an academic study entitled  "Energy Expenditure of Walking and Running" in the journal Medicine & Science in Sport & Exercise.

Here's the bottom line:

Total calorie burn per mile = .75 times your weight
Net calorie burn per mile = .63 times your weight

Net calorie burned is considered a "true" reading as it takes into account your base metabolism burn. In my case, my net burn is a puny 101 calories a mile. So my ten-miler is only pulling 1000 calories total.

Maybe there's some wiggle room here, but 1000 or 1700 calories for a workout is a huge gap. That's a meal in itself. Guess in the end more running and less eating is the only formula that truly works.

3 comments:

  1. This is an interesting post! I like data overload. :)
    I am wondering if running efficiency plays into the numbers at all.

    ReplyDelete
  2. I tend to believe the machines without questioning their math. Anything that can calculate for me be it Garmin or treadmill must be more accurate than my own calculation. I average about 155 calories per mile.

    ReplyDelete
  3. I believe that total calorie burn is a fair measure. You are still burning those calories regardless of the "source" of that expenditure. It is also worth noting that residual caloric expenditure is increased over the hours following each run. Also, off-time expenditure is increased with muscle mass compared to adipose tissue... so as your fitness improves there are additional outputs of caloric burn not directly associated with each mile run.
    Good topic!

    ReplyDelete