Calories: Run/bike

[wc1934]

Interesting and maybe debatable - for a 20 mile ride my garmin has me burning more than 620 calories.

http://drmirkin.com/fitness/run_or_cycle.html

[nmrt]

ok -- so...i get that no matter how long you take do run 1 mile, you will always burn the same amount of calories.

but cycling....? you would burn more if you rode faster? i dont get that.
why is it not the same for cycling -- which is, no matter how long you take to ride 1 mile, you would burn the same amount of calories?

what am i missing apart from wind resistance.

[pbarry]

Like the comparison, but no way the math works. 6 mile run at a 4:30 pace does not equal a 20 mile bike ride at 15mph.

[MattTuck]

I'm sure that the bigger the person, whether they are riding or running, will burn more calories than a smaller person.

As for the difference in speed, I guess it comes down to how much faster you'd have to ride to burn the same amount of calories on the bike in the same time... 6 miles @ 4:30 pace is 27 minutes. How fast would you have to ride to burn that same number of calories in 27 minutes... I'd think it would be VERY fast.

I'd like to hear more about whether this assumes near 100% aerobic respiration. Once you get into anaerobic, you start having to replace the glycogen that you burn... so that is more of a calorie deficit than the pure speed/time would predict.

[Black Dog]

I ran the numbers and for a 155 pound rider at 30km/hour (19mph) burns ~20 Calories/km or ~30 Calories/mile.

[CunegoFan]

This is the same Dr. Coyle that came up with a crack brained theory based in shoddy data to explain Lance Armstrong's improvement, so I think I will take this with a big grain of salt.

I do wonder where in America he found the average adult weighs 155 lb. Maybe somewhere that does not have a McDonald's and no way to buy an Xbox .

[Mark McM]

ok -- so...i get that no matter how long you take do run 1 mile, you will always burn the same amount of calories.

but cycling....? you would burn more if you rode faster? i dont get that.
why is it not the same for cycling -- which is, no matter how long you take to ride 1 mile, you would burn the same amount of calories?

what am i missing apart from wind resistance.

Didn't you answer your own question? On flat roads, the majority of drag (energy consumption) is wind resistance. But wind resistance does not increase proportionally to speed - it increases to the square of speed. The wind resistance at 20 mph is 4 times the resistance at 10 mph (2 times the speed = 4 times the resistance). If you go 1 mile at 20 mph, you take half the time as you do at 10 mph - but you have to overcome 4 times the drag force. So, 4 times the drag for half the time has a net result of twice the energy lost to air resistance if you go 1 mile at 20 mph vs. going 1 mile at 10 mph.

[giverdada]

this is hilarious.

i love looking at my garmin data for my rides and runs because they make absolutely no sense for calories burned. i weigh about 165.

if i got out for a 10k run and it took me 47 minutes and it was -20 C and snowing and the last bit had a hill and i was wearing a ton of clothes and cleats for the snow and icy bits, i only burned 680 calories. if i got out for a 52k ride with an average HR of 120bpm i burned 1969 calories. wha? no way. of course, this is garmin calculation and i have no idea how they run formulae.

as a graduating project in high school physics, i aimed to discern the static and dynamic coefficients of friction for two different rear mountain bike tires. it ended up being an elaborate and fascinating experiment, fraught with huge margins of error and lacks of control, but i learned a lot. i learned, most importantly, that coming up with consistent enough data to really get any kind of predictable thing takes a TON of data, and a whole lot of controls. i think there are too many variables to figure out, accurately, caloric differences between riding and running, particularly when accounting for wind in both sports, and speed in running (which i imagine has a steeper curve than cycling in terms of calories needed to produce m/hr.). i don't know. but it's totally fascinating. maybe a treadmill with wattage and a computrainer would be a better measure system?

[bobswire]

Just weigh yourself before and after the ride/run. Those numbers aren't debatable. :)

[Mark McM]

Just weigh yourself before and after the ride/run. Those numbers aren't debatable. :)

... Except that the majority of the weight change will be water, which doesn't have any calories.

[josephr]

... Except that the majority of the weight change will be water, which doesn't have any calories.

depends if you get in a good trip to the bathroom during your run, doesn't it? I once lost 4 or 5 lbs in less than 2 minutes! :eek:

I'm new to using a Garmin but I can't believe some of the numbers it comes up with sometimes --- I got to the point where I don't really pay attention to that so much. I'd suggest you're definitely better off with establishing a habit of watching intake and working towards improving your efforts than staring at a scale or computer screen. In the end, the fitness and health will take care of itself.
Joe

[Mark McM]

I'd suggest you're definitely better off with establishing a habit of watching intake and working towards improving your efforts than staring at a scale or computer screen. In the end, the fitness and health will take care of itself.
Joe

If your main interest is weight control, it is definitely better (not to mention easier) to watch calories consumed rather than calories burned. Calories consumed has a much larger influence on weight control than exercise does. Remember, even if we are serious exercisers (say, a couple of hours of intense exercise a day), the exercise only burns a fraction as much as just our basal metabolism calories (the energy our body burns to just to remain alive). Also consider this: it might take an hour and a half to burn off 500 calories - how long does it take to not eat those 500 calories to begin with?

[EDS]

I'm sure that the bigger the person, whether they are riding or running, will burn more calories than a smaller person.

As for the difference in speed, I guess it comes down to how much faster you'd have to ride to burn the same amount of calories on the bike in the same time... 6 miles @ 4:30 pace is 27 minutes. How fast would you have to ride to burn that same number of calories in 27 minutes... I'd think it would be VERY fast.

I'd like to hear more about whether this assumes near 100% aerobic respiration. Once you get into anaerobic, you start having to replace the glycogen that you burn... so that is more of a calorie deficit than the pure speed/time would predict.

I seriously doubt there is anyone on this message board running six miles at a 4:30 pace.

[MattTuck]

I seriously doubt there is anyone on this message board running six miles at a 4:30 pace.

I was using the numbers that pbarry posited in the post before mine. The more pertinent question is why people conflate the difficulty of an athletic feat with calories burned.