Heart Rate Monitors: does VO2 max affect calories burned?

marathinnerwinner
marathinnerwinner Posts: 2 Member
edited February 24 in Fitness and Exercise
I bought the Polar RCX3 GPS-compatible watch to focus on my training zones, etc, and just took it out for its first run! I've never had a heart rate monitor before so I blindly plugged in my information and it gave me a VO2 max estimate of 47. I had a great run, covering over 9.5 mi in 71 minutes, but afterward my results popped up: Avg heart rate 172 (I'm young.) Time 1:11. Calories burned 632.

632!? I'd been estimating waaaaay more in my diary (the calculator I use gave me 802--and I'm a fairly short, small person!). At first I thought oh well, I guess I'll know to be accurate now, but then I found the "fitness test" feature and was given a VO2 max of 64. I did some research and this seems more accurate due to my experience level. My question is, does VO2 max affect the calories burned reading on Polar watches? Would a jump from 47 - 64 change it a lot, in terms of the calculations?

Replies

  • bwogilvie
    bwogilvie Posts: 2,130 Member
    632 calories seems low for 9.5 miles at a 7:28 pace. My Garmin Edge 620 estimates about 110-115 calories/mile when I'm running at 7:45-8:15, and I'm a 5' 10", 160-lb. guy.

    It does look as if the RCX3 uses VO2max in its calorie calculations: http://www.polar.com/us-en/support/OwnCal
    An inaccurate VO2max would affect the reading, and if the estimate is too low, I think it would underestimate calories used.

    172 is a pretty high heart rate; I imagine that the Polar algorithm thinks that it's pretty close to your lactate threshold, and that if your VO2max is 47, you must not be putting out that much energy. If VO2max is actually 64, you'll be putting out a lot more energy at the same heart rate. Of course pulse isn't the only factor involved in oxygen consumption; the size of your left ventricle also matters, as does the number of capillaries in your leg muscles. Some HRMs take that into consideration by asking how frequently you exercise and whether you have been a lifelong athlete.

    The best way to figure out how much the VO2max setting matters is to try a similar run with the new VO2max estimate. Let us know how it goes! (You could do a shorter run at the same pace; cardiac drift means that your HR does gradually increase over time as you continue to exercise at the same intensity, but that shouldn't make a huge difference.)
  • SKME2013
    SKME2013 Posts: 704 Member
    I have the RCX5 and I did the fitness test with it, by lying still on my bed. Not sure whether the RCX3 can calculate your very own VO2max, but if it can you should do that first. My calorie burn is pretty much spot on.
    Stef.
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