Is there a running equivalent of watts?

Limey UK runner wrote:

Just realised that units might mess you up. An online calculator will probably give you a result in kcal. You need to multiply this by 4200 to get the answer into Joules.

Example:

I'm 140lbs. One formula I have found says that energy burned per mile is equal to 0.63 x bodymass (in lbs). NB: this is net energy burned rather than gross (gross includes basal metabolic energy).

Calories = 140*0.63 = 88 kcal (per mile)

Multiply by 4200 to get answer in Joules

88*4200 = 369600 J

Power = energy/time, so for a 5 minute (300 second) mile:

Power = 369600/300 = 1232 Watts

I actually think your calculations are mostly OK, but you forgot one BIG effect: running efficiency. The useful work (which is what wattmeters on bikes actually measure) is probably something like a quarter of this figure because humans aren't particularly efficient engines. But I don't know what a typical running efficiency is off the top of my head.

Yeah, i think the calculations he used were correct but running power must not equate to power output at all compared to cycling. Slowtwitch has an intelligent conversation on the topic

http://forum.slowtwitch.com/gforum.cgi?post=3179066

Bullet the Blue Sky wrote:

Cycling uses watts to measure effort and performance. Is there anything similar in running? What would the running equivalent of watts?

Cyclists use watts mostly because, above speeds of around 20-25km/h, pace is a poor estimator of effort (drag increases proportional to speed^3).

For most running though, speed is a good measure of effort. It is done slowly enough that wind resistance does not play a very big role (unless you are running into a strong headwind).

I found this website that might help:

http://web.archive.org/web/20080310073316/http://members.aol.com/BearFlag45/Biology1A/Reviews/energy.html

mph watts

 0  70

 2  179

 3  233

 4  286

 5  610

 6  719

 7.5  883

 10  1150

 15  1690

Running power output is higher than cycling because you can use more muscle groups more effectively. I would guess nordic skiers might get even higher.

You can't really do it in running because you can only measure work against a force like gravity. Cyclists can measure the force against the pedal and distance traveled. Rowers can do that against the handle. Runners don't have anything.

You could do it for short sprints in the acceleration phase. E.g. a 100 kg sprinter accelerates at 0.5 G's for 20 meters. That would result in, I think, 1000 watts.

Maybe you could measure the slight acceleration with each stride in support phase for a runner?

If you're interested in watts, or just love numbers, hop on an ergometer aka Concept rowing machine. It's also a tremendous conditioning tool for runners when you want to take some of the pounding off your legs.

Justin91 wrote:You can't really do it in running because you can only measure work against a force like gravity.

Yes. For all the posters who have simply plugged in "work = force X distance" using body weight to determine force... that would only apply if you were flying directly upwards into the sky, against gravity.

Running (and walking) are extremely complicated to analyze. For starters, to walk at 3.5 mph consumes 4.3 MET; for a 170-lb person, that works out to 332 kcal/hr = 386 watts.

But that 386 watts is just a (rough) measure of the rate at which you're burning energy from food. We're not very efficient at converting food's stored chemical energy into actual mechanical work -- you might only get about 80 watts of positive mechanical work from a typical stride cycle, when you're pushing off from the ground and straightening your leg.

The other wrinkle is that half of the work involved in walking/running is NEGATIVE mechanical work. When your foot lands, you then have to contract a bunch of muscles eccentrically to decelerate your leg. Since the muscles are pushing in one direction and your body is moving in the opposite direction, that's negative work. The positive and negative work in a stride cycle add up to zero (if you're walking/running at a constant pace).

All of which is to say that there isn't really a running equivalent of cycling watts. In cycling, they're measuring something that is a property of the bike itself, not of the human doing the biking. Of course, you could do a direct comparison of the total chemical energy burned, ignoring the respective conversion efficiencies of biking and running -- but that really just amounts to comparing calories burned.

I didn't forget any effect, but you are right that the result is probably very misleading due to the running efficiency factor. The formula for kcal per mile run will be an extrapolation from data gathered from trials of actual runners on a treadmill in a lab environment, where they measure O2 and CO2 aspirated and exhaled to very accurately determine the number of calories being burned. Invariably, 'well trained' runners are used in these trials. 'Well trained' runners frequently being males in their 20s/30s who run 10k in 35-40 mins. These guys will not have very high running efficiencies and as such they will use a relatively high number of calories to run a mile at whatever pace. This means that the wattage using that formula will be higher than it should for runners of greater efficiency.

Also, as someone else said, you can't compare wattage between sports as there are often other limiting factors i.e. the limiting factor is not the max wattage a human can produce, it is something else.

Incidentally, the wiki on track cycling suggests that instantaneous wattage can max out at around 2000W, and for road cyclists sprinting at the end of a long race it is not uncommon for them to be able to produce 1600W.

Back to the OPs question though, there is not really an equivalent in running primarily because we cannot measure wattage directly like in cycling with a power crank: we can only extrapolate from data from lab trials.

1200 watts? Lance Armstrong doesn't even hit that on a bike. Are you sure that's correct?

Over a miles, LA, or any professional cyclist could probably hit pretty close to that number. I imagine the really elite time trial specialist and sprinters can peak upwards of 2000 watts in a sprint.

I have hit over a thousand watts on a bike in a sprint on several occasions.

pre841 wrote:

Although not technically Watts, Compton Community College does have a nice all-weather track.

https://maps.google.com/maps?hl=en&tab=wl

For those of us who grew up around there, we referred to it as UCLA(University of Compton, Left on Artesia).

Just take calories per hour and do a unit conversion.

jdjd wrote:

Limey UK runner wrote:

Just realised that units might mess you up. An online calculator will probably give you a result in kcal. You need to multiply this by 4200 to get the answer into Joules.

Example:

I'm 140lbs. One formula I have found says that energy burned per mile is equal to 0.63 x bodymass (in lbs). NB: this is net energy burned rather than gross (gross includes basal metabolic energy).

Calories = 140*0.63 = 88 kcal (per mile)

Multiply by 4200 to get answer in Joules

88*4200 = 369600 J

Power = energy/time, so for a 5 minute (300 second) mile:

Power = 369600/300 = 1232 Watts

1200 watts? Lance Armstrong doesn't even hit that on a bike. Are you sure that's correct?

Old thread, I know, but I wanted to point out that there is a difference between "mechanical" watts and "biological" watts. Namely, on a bike, the mechanical watts are the force*cadence that you actually push the pedals with, but your body is doing a lot more internally and with other body parts so that only about 25% of your effort actually goes to the bike.

In running, it's much harder to calculate. I would guess that "mechanical" watts would end up being lower than expected because you only impart a force on the ground for a short period of time. But to roughly convert the 1232 watts here to "cycling watts", you could divide by 4, and get 308 watts. Much more reasonable, although you're never going to get a perfect match because running is so complicated (for instance, 5:00 pace is a couple levels better than 308 watts on a bike).

Just going by time solves all of those problems for either event. Who cares if you're working harder and going slower?

There are no watts and HR medals.

Watts is Joules per second. Watts per second would be a rate of change of power. Highly irregular. You had me going until that last step.

Just make some number up, so you can feel really scientific and precise. That's what bikers do.

Bullet the Blue Sky wrote:

How do you measure it for runners?

wisdom of the past wrote:

Just going by time solves all of those problems for either event. Who cares if you're working harder and going slower?

There are no watts and HR medals.

Well, particularly for cycling, different conditions can give strikingly different speeds with the same "quality" of performance. Power in cycling does a fairly good job (although not as good as some cyclists want to believe) of smoothing out performances over different conditions.

Unfortunately, it doesn't work too well in running, but this general idea *clearly* does work, if only we can figure out how to best measure it. That guy who surges and brakes the field up a hill during a sloppy cross country race may "only" be going 5:08/mile during his surge. But all the 4:20-milers that he drops will know that his surge was too much for them. The hope would be that watts would measure this bad-assery, but I don't think it works to well -- we've got to keep thinking about it.

Run Power wrote:

In running, it's much harder to calculate. I would guess that "mechanical" watts would end up being lower than expected because you only impart a force on the ground for a short period of time.

Even harder than that, because you aren't just pushing on the ground, you're also pushing the rest of your body forward in front of the trailing leg. Lots of forces moving lots of things in different directions.

Has anyone of you guys tried stryd?

Non-scientific thought...

Don't cyclists usually measure it going up a hill.

Thinking about going up a hill, and this is where it gets embarrassing, my two teenage daughters absolutely destroy me going up hills, yet I am faster on the flats.

So, measuring over a mile, if it's flat doesn't seem like a true measure of power. Or, perhaps we have similar power, but because they are lighter it is easier for them to move their mass up and over the hill. I guess that makes sense.