Heavy Snow Shoveling

brian_gunther wrote: »

Unless you have a heart rate monitor that is converting activity to calories burnt its a total crap shoot. I just use my step counter and move on. At worst I'm getting extra credit that will help me in the long run I just don't "count" it. You know?

Azdak wrote: »

AnnPT77 wrote: »

I do use a HRM when I do a bunch of it. (@Azdak , as I have great repect for your expertise, I'd be interested in why you think it's intermittent: I've been athletically active for a dozen years, using a HRM for training, and the RPE is consistent with many classic forms of cardio if you go at the shoveling with vigor. It's continuous movement.)

Last round, 1200-1500 square feet, 4-5" fairly fluffy snow with some tire-track ice and a little snow-plow slush, 96 minutes, HRM estimated 458 calories. Subjectively, this doesn't seem out of whack effort-wise with other more classic cardio activities I do (e.g., cycling, rowing) for a similar result - close enough for gubmint work, IMO.

There is an MFP exercise database entry for snow shoveling. At the same body weight, it would've given me 540 calories, about 17% more - not a whole different planet given the calorie-error range inherent in all the estimates we use during weight management.

Just my opinion.

ETA: Those estimates were for 120 pound body weight, which may be relevant given that there's a decent amount of brisk-walk/body movement involved.

As has been stated in the past, the programming for an HRM is only valid under aerobic steady-state conditions. If the activity you are doing deviates from that description, then the error factor for the HRM becomes larger.

The fact that you get a number that seems appropriate for the duration and effort of shoveling snow--for you--is more coincidental than causal. The MFP database number is derived from who knows where (likely the Compendium) and it is a rough, rough estimate as well.

Here are factors that affect HRM readings when shoveling snow:

Higher proportion of upper-body movement and effort--this will push HR and thus skew the calorie numbers higher; in addition, part of the movement also involves lifting the load to shoulder height or above, which also puts a proportionally higher load on the heart.

Isometric contraction/valsalva maneuver when picking up a load of snow with the shovel--this imposes a pressure load on the cardio system that can raise HR and RPE, but calorie burn increases at only a fraction of what would be expected.

Intermittent movement: The act of loading the shovel, lifting it up, and throwing the snow to whereever is a vigorous movement, followed by very low-level movement as you move to the next pile of snow.

Changes in posture can also cause variations in heart rate.

Lack of "training" in the shoveling movement means that HR can be disproportionately elevated as well.

Now there is going to be a LOT of variability in all of this. The weight of the snow, the layout of the walkways, one's personal style of shoveling, one's general level of conditioning.

The HRM has no idea you are shoveling snow. It is programmed to assume that the HR signals it receives are coming from someone jogging on a treadmill, riding a stationary bike, etc. It cannot account for any of the above conditions I described.

In your case, because of the way you shovel, because of your conditioning, because of the way you have your HRM set up, it just so happens that, even though the HRM thinks you have been walking on a treadmill for 90 minutes, the number it spits out and what you are actually burning coincide and are in the same neighborhood.

For someone less conditioned, shoveling with a different movement pattern, with a higher-than-age-predicted maximum heart rate, with an HRM that is not set up to match their actual physiological profile--the calorie number displayed could be radically different from reality.

So while your n=1 sample might be different, given the underlying factors, the odds are much, much higher that the majority of other people are going to get significantly skewed readings.

I usually pitch my general information to what I think is the "best fit" for the majority of people. For someone like yourself--better conditioned, more experienced, you obviously pay attention to your workouts and have amassed a large amount of observational data that is relevant to your situation--you are going to be able to see patterns and draw conclusions that will allow you to "follow your own rules" so to speak.