Calories vs fitness

Today, because I had little to do and it was a nice day, I took the doggies on an extra long walk. It was pretty cold out because of the wind, and while walking I was thinking about how many calories I was burning between the cold and the long walk. I also contemplated how the 2 hours I spent walking the doggies did little for my fitness, as my breathing rate didn't increase at all during the whole walk, even up the hills.

Something I've highlighted in several posts by now is the axiom "Fitness over fatness." It's a reminder that our cardiovascular fitness (VO2 max) is more important than our weight or how many calories we burn. So, walking my doggies in the cold, though it may have burned a decent amount of calories, in the end did nothing to help improve my fitness or my over all health and longevity.

When I got back, I got on some websites to estimate how many calories I had burned. First, I looked up an estimate of my basal metabolic rate, which was estimated to be 1659 calories per day. Next, I looked up an estimate of how many calories I burned while walking the dogs, which was estimated to be 164 calories per hour. Last thing I needed was an estimate of how many calories I was burning just to stay warm, which I estimated to be 50% of my basal metabolic rate (i.e. being out in the cold, my metabolism was at 150% normal). SO: if I put those all into an equation to estimate the calories I burned during my 2 hour walk, it would be

= (1659 calories per day) * (1.5 for cold exposure) / (24 hours per day) * (2 hours of walking) + (164 calories per hour for walking dogs) * (2 hours of walking)

= 535 calories

Now that's including the calories I would have spent just standing there in the cold. For the walking, additional to just my BMR in the cold, it was only 328 calories in 2 hours.

For comparison, I used the same website to get an estimate of how many calories I would spend running continuously doing 9 minute miles, as this is what I ran last weekend (which is a pretty slow pace for me, historically, but that's what I get for blowing out my knee). The estimate is 820 calories per hour. So let me put that into the total formula again. This time, I'm going to assume that the running will mostly keep me warm, and that my BMR will only be raised 25% above normal to deal with the cold (I don't know if that's scientifically correct, I'm just making it up). Since I know I can't run for 2 hours, I'll cut this down to only 1 hour.

= (1659 calories per day) * (1.25 for cold exposure) / (24 hours per day) * (1 hour of running) + (820 calories per hour for running 9 minute miles) * (1 hour of running)

= 906 calories

Almost double the calories in half the time. To make the sessions isocaloric, using the walking as the standard, I would only need to run for 33 minutes. Versus 2 hours of walking. There's time efficiency for you. Additionally, if you just take the calories expended during the two activities and discount all my BMR and cold exposure mumbo-jumbo, you would only need to run for 12 minutes to get the same benefit as walking the dogs for an hour. PLUS, the running will actually benefit your fitness and overall health, while the walking won't.

Disclaimer: for some people, who are just starting out on their fitness goals, walking the doggies may actually be a legitimate way to improve their fitness. The poor man's way of telling is simple: are you breathing hard? If yes, it's improving your fitness, if no, it's just recreation.

Well, I hope this has been an instructive example and exercise in overly complicated formulas and beating the horse to death.