corrado33

My coworker and I were recently discussing running (I know, it's bike forums, not running forums.) We were debating whether or not running faster for a set distance burned more or less calories. Instinctually, you'd say running faster would burn more calories. But, if you think about it, if you run faster for a set distance, you're running for less time. (Same goes for biking.) So, we went off to google and I found this.

Mythbusting: Running A Mile Always Burns The Same Calories | Runner's World

This article talks about running (sorry, it's not biking.) and basically says that when olympic runners ran faster their energy intake in joules/meter actually went down. Therefore they'd burn less energy for a set distance. (The study didn't take into account anaerobic energy used, a point the author of the article quickly pointed out.)

Now, I wholeheartedly disagree with this. I was a competitive D1 runner in college and I know what my legs feel like after a workout day compared to a long distance day. But, I can't find any studies that say similar things for biking as the article above, or any studies giving real data on how many more calories are burned when you run/bike faster. I guess a power meter would be perfect for these types of measurements, therefore there has to be data on this somewhere...

Anyone know of any good data for this? Anyone have any opinions about the matter?

delcrossv

the math says it all

+Crr v

As the drag force goes up, your calories per foot traveled goes up.

corrado33

What about climbing, where drag isn't an issue?

delcrossv

If you're really going slow so Fd~0, it takes the same number of Joules to climb a certain distance, so no.

PE= mgh.

Edit, but you're talking like under 6 mph.

corrado33

Ideally, yes. Practically, no. I would argue that traveling up a hill faster uses more anaerobically produced energy, which burns more calories.

delcrossv

Ideally no too, Drag kicks in at a pretty low speed.

fietsbob

Serious Headwinds and Hills can be a Lot of work done at low speeds..

RonH

If your heart rate is up and you're breathing harder it seems to me that you're burning more calories.

bbbean 

Riding/running HARDER burns more calories. Speed only loosely correlates. Same with distance. You have to take work load into account.

wphamilton

Yes. But this isn't very clear since his question is about calories and this equation is force.

it works out though because work (calories burned) is the force times distance. Distance is the same in both cases in OP's question so the relative amount of extra calories is the same as the relative amount of extra force, so the force equation says it.

How about, going twice as fast we'll burn somewhere in 2 to 4 times as many calories over the same distance.

ThermionicScott 

Soreness may not necessarily have any correlation to calories burned, either.

I would expect that for a given amount of time, riding faster/harder would burn more calories, because of the energy "wasted" due to aerodynamic drag.

More tangentially, I'm curious what the goal of this thought experiment is -- if the goal is to lose weight, diet warrants more attention than burning calories through exercise, since it's not hard to out-eat what you burn off.

Another thought is that high-intensity exercise (often done through intervals to allow bursts of maximal exertion) seems to be better for body composition than lower-intensity exercise, even when fewer calories are burned during the exercise.

achoo

I wonder if that holds for long descents?

fietsbob

mean after 21? its All, down Hill ..

achoo

If the goal is to lose weight, and time riding is not limited too much, never forget that you can ride a LOT longer at 80-90% effort than you can ride at 100% effort.

You can probably ride 4-5 hours at 80% of of the power you can ride at for one hour. If you can burn 1,000 calories in an hour of all-out riding, you can probably ride 5 hours or more at 700 cal/hour and burn well over 3,000 calories.

achoo

21?

More like 5. Having to do work starts in first grade. Before that? You got NOTHING to worry about.

fietsbob

Grow tall then get old and shorter..

ThermionicScott 

I think you missed my point, unless the subject in question has 5+ hours of free time to spare every day, and is so morbidly obese that they need to create an insane deficit every day.

corrado33

I don't have any goal, this is purely speculative. I think your second statement above isn't what I was trying to ask. Sure, you can ride slowly for a long period of time, but say you have a set distance you want to travel, a route. Would riding it at 100% burn more calories than riding it at 80%? Taking into account that you're riding longer if you're riding slower.

gregf83 

Riding faster will burn more calories per mile as it is less efficient due to wind resistance. Exactly the same effect as observed in a car travelling at 50 vs 80mph.

I've used a power meter for years and enter all the data in a spreadsheet that also tracks calls/mile. It ranges from about 37 to 50ish for a recovery vs a 'hard' ride or race.

The talk about anaerobic efforts is a bit of a red herring with respect to cycling as it's primarily an aerobic sport and no one cares how many calories they burn in a 30 second sprint at the end of a race or some hard effort in the middle of a race.

achoo

If your base metabolism is about 2,000 cal/day, not eating at all won't get you as large a deficit as burning 3,000 calories on a bike can.

wphamilton

Nope. the simple force equation is assuming that the wind speed is all from your efforts.

achoo

Yeah, but which way does it fall apart?

My gut feel is that it'd take a LOT more than 2-4 times the amount of calories to double your speed on a descent, only because first, you can go pretty fast on a descent and burn zero calories, and second, the faster return of energy from going down faster is only linear with speed while the driving force is squared with speed and the necessary driving power cubed.

But I don't care to figure out the actual equations and plot the results.

ThermionicScott 

The math works. Is riding 5+ hours to create a 3000 calorie bonk common?

mrFreel

I want to add that in the real world when I ride slow I coast and when I ride fast I am on the pedals much more. So I am sure I burn more calories riding the same distance fast


Mike

spdracr39

In the big picture zone 2 riding helps me lose more weight over time because I can ride longer and more often without as much recovery time. In the short term more work equals more energy/calories burned. If I know I will be riding a few days in a row I stick with zone 2. If I know I will be off the bike for a couple of days I do hill training, faster rides, or mountain biking.