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what is the relative or expected difference between running and cycling FTP in watt/kg?
How do you plan on measuring watts while you're running?
Fabulousssss!
SeasonsChange wrote:
what is the relative or expected difference between running and cycling FTP in watt/kg?

There's never been a way to measure running Watts before, so the correlation has never been made.
Perhaps we will now have an opportunity?
I've seen some treadmills that show watts based on the weight that you enter at the beginning of a workout. I don't know how accurate it is, but I've usually seen running numbers about 20% higher than cycling on several different treadmills. I don't know if that's because running takes 20% more power or because they're all using the same programming with a 20% error in their formula. My HR at LT is higher running than it is cycling (which is normal), so that could be an explanation for the higher numbers, too.
im talking about the relationship between cycling ftp and running ftp in watts/kg

rchung would know this...
I've wondered about those treadmills too. I bet the calculation is just a simple weight to speed with elevation calculation.

"Power tap shoes" would be sweet because you could measure the difference between the above calculation and the actual power output in regards to speed. The difference would be efficiency. IE, bounce, foot strike, ect. Probably some stuff we don't even know that would make a difference.

You could also calculate how much drafting off someone would help.

I bet you could find a lot of similar height/build/weight people who put out the same amount of power running but go at different speeds due to running form.

So much fun stuff. I'm really excited about power meter shoes.

Co-host of the Ask a Cycling Coach Podcast
SeasonsChange wrote:
im talking about the relationship between cycling ftp and running ftp in watts/kg

I don't know with running FTP in watts/kg but, AFAIK, the relationship between your running FTP (mph) wrt your cycling FTP (watts/kg) depends on:
- The %VO2max you can sustain for 1h running vs 1h cycling

For example, if you can sustain 90%VO2max for 1h running and 85%VO2max for 1h cycling, your Running Economy is 210ml/km and your Cycling Gross Efficiency 21%, the relationship would be FTP(mph)=2.57*FTP(watts/kg).

Ale Martinez
www.amtriathlon.com
Last edited by: Ale Martinez: Jan 26, 11 18:07
Are onto some new crazy training method? What the hell is FTP running? There is no such thing as functional threshold power in regards to running. Furthermore you can have a super high FTP on a bike and be 5.0W/kg and still suck at running if you never run or don't run enough to get good at it. The only thing that matters in regards to running is pace and what the clock says. Pace is running's version of power for now until some other scientifically valid method of measuring running improvement comes along. God knows HR training is stupid and virtually useless.
I've given this some thought during a slow day at work...

Considering just the aerobic engine, what pace should you be able to run at if you can produce a certain power on the bike? If you make a couple assumptions, you can estimate this.

Assumptions:
1) You burn 1 kcal / kg body weight / km run - I know, can be way off.
2) Your efficiency running is the same as cycling (24 %) -- Again, I know, WAG

Then, you take a certain pace, say 4:00 min / km, your body weight, say 70 kg, and preform the following calculations:

4:00 min/km = 15 kph
15 (km) * 70 (kg) = 1050 kcals energy required per hour
Assuming a 24 % efficiency, Eout = Ein *0.24
1050 * 24 % = 252 kcal energy generated
252 kcal * 4.18 Joules / calorie ~= 1050 kJ -- isn't that convenient?
1 W = 1 j/s therefore 1050 kJ / 3600 s (in one hour) = 290 W

You can work out the power for other paces. It seems kind-a close for me, at least judging by my PER riding at set wattage and running at set pace.

At 70kg
3:45 min/km = 310 W
4:15 min/km = 275 W
4:30 min/km = 260 W
4:45 min/km = 245 W
5:00 min/km = 230 W

What say you?
aca_broj_1 wrote:
I've given this some thought during a slow day at work...

Considering just the aerobic engine, what pace should you be able to run at if you can produce a certain power on the bike? If you make a couple assumptions, you can estimate this.

Assumptions:
1) You burn 1 kcal / kg body weight / km run - I know, can be way off.
2) Your efficiency running is the same as cycling (24 %) -- Again, I know, WAG

Then, you take a certain pace, say 4:00 min / km, your body weight, say 70 kg, and preform the following calculations:

4:00 min/km = 15 kph
15 (km) * 70 (kg) = 1050 kcals energy required per hour
Assuming a 24 % efficiency, Eout = Ein *0.24
1050 * 24 % = 252 kcal energy generated
252 kcal * 4.18 Joules / calorie ~= 1050 kJ -- isn't that convenient?
1 W = 1 j/s therefore 1050 kJ / 3600 s (in one hour) = 290 W

You can work out the power for other paces. It seems kind-a close for me, at least judging by my PER riding at set wattage and running at set pace.

At 70kg
3:45 min/km = 310 W
4:15 min/km = 275 W
4:30 min/km = 260 W
4:45 min/km = 245 W
5:00 min/km = 230 W

What say you?
Re-do your table with these three changes:
1. Assume gross efficiency is 23.9% instead of 24%.
2. Convert pace from minutes/km into m/s.
3. Rather than get wattage, divide by 70kg to get watts/kg.
ah there you are! i vaguely remember you posting a graph about power between cycling and running in duathletes. something like running performance and cycling performance are similar if adequately trained?

BTW, the correlation between the run and bike legs in Kona in 2009 was also about .75.
When I am doing around 4W per kilo ftp (252W) at 63 kilos, I am usually running right around 38 min 10K's. I can an almost predict how fast I will run at races, based on some bike hillclimbs that I have locally. The faster I climb, the faster I run (no rocket science). To Seasonschange, I'll let the smart guys provide actual conversions....this is what applies to my N=1

Dev
A couple of years ago Dr. Phil Skiba came up with a nifty software piece that uses GPS data and Topofusion to calculate running training stress
and as part of that power in watts. http://www.topofusion.com/govss.php

It generates higher power values for running than cycling though as the cycling values show what you're outputting to the cranks or rear wheel while
the running values of GOVSS also take into account the wasted vertical motions of a runner. It also generates weighted GOVSS values that are analogous
to TSS values from Andy C's cycling system. A one hour all out pace run = 100 GOVSS

How about looking at Daniels' VDOT compared to W/kg?

Hugh

Genetics load the gun, lifestyle pulls the trigger.
RFXCrunner wrote:
How do you plan on measuring watts while you're running?

You can measure it indirectly with Skiba's Race Day Apollo. It uses GOVSS metric to quantify your running work which in essence uses running power. Running power in short, he takes from GPS pace device, using your height, weight and slope of the surface. Downside is, it does not account for say headwind/tailwind.
I can define an interval where I ran threshold pace, the software will have power calculated to that defined interval, I can than manually convert it in W/kg. You can quantify near exact power to run any hill on any course and than convert that into pace........Pretty nifty little feature.
devashish_paul wrote:
When I am doing around 4W per kilo ftp (252W) at 63 kilos, I am usually running right around 38 min 10K's. I can an almost predict how fast I will run at races, based on some bike hillclimbs that I have locally. The faster I climb, the faster I run (no rocket science).
38 minute 10K is around 4.3 m/s, so the rule of thumb isn't bad.
Honestly, I'm not sure what you are asking. However, I remembered seing this article by Jim Martin where he very broadly correlated 10k running times to cycling FTP see table 1: http://www.owascoveloclub.com/...%20and%20Cycling.pdf If that is not what you are talking about, sorry. Phil
Wow, that's a lot simpler that what I've been doing, thanks! At least there's some agreement to my calculation.
aca_broj_1 wrote:
Wow, that's a lot simpler that what I've been doing, thanks! At least there's some agreement to my calculation.
Well, note that the simplification depends on the efficiency assumption and the kcal=kg*km assumption. That's why the scatterplots are useful: they remind us that these are simplifications and although the relationship between running and cycling is pretty strong, it's not perfect.
As another poster pointed out, there are individual variations, but overall for a multisport athlete with a solid base and several years of racing in both sports, there is probably a high correlation barring injury. Some individuals will be more efficient in running vs biking, but for a given athletes usually when their watts per kgs improve, you end up with much faster run times at short distances. I can't say that it works entirely over longer distances for the run. There are just so many variables.

It would be great if someone smart took a stab at equating watts per kg to Vdot ranges!!!
devashish_paul wrote:
As another poster pointed out, there are individual variations
Sure. But we can get a handle on the ranges. We know that gross efficiency ranges between maybe 20-24%, so the assumption above of 23.9% is on the high side of the range. We also know that running economy ranges between maybe .8 - 1.1 kcal/kg/km. So if you knew those things exactly you could improve the estimate but otherwise you can see how big the "wiggle bounds" are on that conversion. As we saw from that duathlon plot above, the correlation between run and bike times is around .77, while the correlation between the two run times was "only" .88. All in all, pretty promising.
RChung wrote:
That's why the scatterplots are useful: they remind us that these are simplifications and although the relationship between running and cycling is pretty strong, it's not perfect.
But, performance on the bike and run on the same day will have an element of inverse correlation, as the more you put into the bike leg, the less you have left for the run. So the correlation between potential performance if each were done in isolation may well be better than the scatterplots suggest.
Steve Irwin wrote:
RChung wrote:
That's why the scatterplots are useful: they remind us that these are simplifications and although the relationship between running and cycling is pretty strong, it's not perfect.

But, performance on the bike and run on the same day will have an element of inverse correlation, as the more you put into the bike leg, the less you have left for the run. So the correlation between potential performance if each were done in isolation may well be better than the scatterplots suggest.
Possibly. We see almost the same bike-run correlation for triathlons up to full IM distance when conditioning on completion of all three legs so their pacing strategies can't be way out of whack.

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