Running with power

running
run-with-power

#1

So, I have been using a Stryd power meter since late December of 2016, and I really like it. Now, I know that there are people who complain that it is not a direct force PM, meaning that the numbers are not accurate. I am not going to get into that argument; however, I can say that the numbers seem to be consistent for me. Since arriving in the DC area earlier in the month, I have had the opportunity to do some runs along the Mt. Vernon trail. It’s a great trail with a good amount of foliage cover.

That cover, though, messes with my GPS watch and the accuracy of the pace metric. I did a little non-scientific test yesterday evening, and here it is:

I held a fairly constant power output, but my pace changed dramatically when I left the cover of the trees into open area. Same power, but up to 30 seconds/mile of difference on similar grade. You can see that my VI was 1.01, meaning that I had a pretty steady power output range.

Anyway, to me this validates previous experiences I have had with running with power versus pace or HR. If my watch isn’t accurately depicting how fast I am running, then my stress score will be off. Plus, pace doesn’t take into account wind or gradient. You can also see that it was about 90 degrees during my run, which left me with a higher than normal running heart rate for this type of effort. I’m curious to hear about anyone else’s experience running with power. I know @MitchD is now playing with it. Anybody else?


#2

@Coach_Ian is so kind to start this thread.

I’ve been using the stryd for over a year but took some time off running for a hamstring issue.

I’ve been building up some data and recently did an FTP test to set my running power zones. The goal for me is to run with power to ensure my easy runs are truly zone 1 / zone 2. I hope
To have enough data built up to allow me to use power during upcoming half marathons in the fall. The goal there is to target a power range for the race where I know I can maintain it for 1:40:00.

For the FTP test I warmed up for 15 minutes, did an all out 3 minute effort, jogged and walked off and on for 30 minutes and then finished with an all out 9 minute effort. I felt like I paced the 9 minute effort very well as I was about to puke at the end of it. Stryd then computes your FTP. Alternatively, I could have ran a 10k or 5k race to compute the FTP.


#3

@Coach_Ian - Quick question - how often do you update your weight in Stryd app. My understanding is it impacts power calculations. Website says change infrequently. Thoughts?


#4

Just downloaded Jim Vance’s Run with Power book for my upcoming vacation. Anyone else read it?


#5

I don’t update it very often, @MitchD. My weight does not fluctuate that much, a few pounds either way, so I just keep it steady.


#6

So, I’m giving this a little bump. As running has become more popular on Zwift, especially with the brutal weather, has anyone else jumped on the running with power band wagon? Is there any interest from those who use it to have the multi-sport plans available with running power targets? Let me know.

I have more thoughts on running with power that I will put down in more developed prose in the near future.

Ian


#7

I’d be interested in using power as a target on my run workouts. I’ve been gathering the data for a while now but haven’t put it to much use yet.


#8

Yeah, it’s actually one of those things that I tell people to ignore until we have a good amount of data. Otherwise, we tend to chase numbers or expect them to mirror our bike numbers, which may or may not be the case.


#9

One of the things I have been looking at over the last 12 months is determining critical power (CP), or FTP for running. Stryd has a few different tests, all of which have their own weaknesses. That is not any different than FTP tests on the bike.

The preferred Stryd method is doing the test on a track, using a 6-lap and 3-lap test. There is also a variant based on time for those that may not have a track or known distances. Still, you can also use a 5K or 10K race or run (all out effort) to determine your critical power.

The reason I bring this up is so that we all understand what our CP is and is not. CP is a guide or tool that can be used to determine training and racing zones, but it is not 100% accurate. Of course, your FTP on the bike can change from day to day, but in general your power zones are the same going uphill, downhill, or on different surfaces. It’s different on the run.

As you fatigue, your form changes. As you run on different surfaces, your form changes, and the energy returned to your body from the ground changes. So, when you are planning for an event, it’s best to perform a CP test that has similar terrain and topography as the event. That will help you determine how to attack the race. Or, you can do what I do and perform some mental jiu-jitsu on the numbers and approximate the difference. It’s not quite as accurate but generally gets me in the ballpark. Besides, I only follow numbers for the first 3/4 of any race. After that, it’s all about tactics and perceived effort for me.