Pace and Power Discrepancy in FinalSurge
I wanted to reach out to the Stryd users as I’ve noticed an interesting discrepancy in Final Surge between running pace and power targets.
I started using a Stryd power meter in October and collected data through RDP and the Jan OS -- I ran my workouts to pace and observed my power figures. Once it was safe to run outside I performed the 9 min/ 3 min Stryd Critical Power test and a few days later a 5k test to determine HR zones. I talked with Stryd about the results of the test and we aligned that the 5k test was a better all-out effort (apparently I sandbagged the 3 min test). That resulted in a CP of 305 watts.
I took 95% of that figure and input 289 watts into Final Surge as my rFTP. I’m doing the Bike Focused Half Ironman plan right now and uploaded two versions of the plan, so I could get both pace and power targets for the run workouts.
The issue I am finding is that the power targets for a workout nowhere line up with the pace figures. I will use this morning’s run to highlight:
Workout: 80 min TRP (70 min TRP, 1-mile Zone 2)
Goal Pace 70 min TRP: 8:14-8:24
Goal Power 70 min TRP: 232-237 watts
Actual Power at 70 min TRP Goal Pace: ~260 watts
Actual Pace at 70 min TRP Goal Power: 9:05 per mile
Goal Pace 1 mile Zone 2: 7:35-7:45
Goal Power 1 mile Zone 2: 246-254 watts
Actual Power at 1 mile Zone 2 Goal Pace: ~280 watts
Actual Pace at 1 mile Zone 2 Goal Power: 8:35 per mile
To summarize, at the goal TRP pace of 8:14-8:24 my power was ~30 watts higher than goal. If I ran to goal power my pace was 50 seconds slower per mile, 9:05 min per mile. For the 1-mile Zone effort, at the goal pace my power was ~35 watts higher and at goal power, I was roughly a minute slower.
(I should caveat, this is based on running on flat terrain. I’m in Minneapolis so there are not a lot of hills and I understand these pace and power figures would vary widely in other terrain)
When I noticed this, I had a friend of mine build a linear regression model based off the 114 runs I have done since starting with Stryd, looking at distance, time, and average watts. He was able to create an equation based off my data that, as you would suspect, nails pace and power for my current fitness; I can calculate power if I know the target pace and vice versa. I’m sure FS has created a regression based on numerous data points, but for me it’s not close.
I then went into FS and changed my rFTP to my critical power (305 watts) and that brought the power zones up some, but it’s still off. Conceivably I could continue to play around and find the rFTP that generates zones near what I actually see when I run.
Questions for the Stryd users on the team, if you’re training to run power:
1) Do you run to power in your workouts? If so, how are you calculating zones? Or are you running to pace and simply collecting power data?
2) Have you gone through and looked at your workouts in FS to see if pace and power correlate to what you experience? Are they far off? How did you address?
I like the idea of training to power on the run and will continue to do so, but I’ll type in target paces into the regression model my friend made and then determine my target watts.
I know there has been some activity in the Forums on Stryd recently with regards to CP calculation and race planning with @tim cronk @Larry Peters @Mike Westover @Rich Stanbaugh @Al Truscott @Tim Sullivan
Comments
@Jeff Phillips this makes me wonder whether your rFTP is still set too low. What power did you have in the 5k? Based on your power at TRP and z2 pace, I would think your rFTP would be around 315-320 W.
On your questions, I train by pace more than power in the flats, but with the watch pulling pace from Stryd so that it is more accurate and responsive. I will look at power when I get into the hills. I haven't analyzed pace vs. power in training, but for races it has been about right (e.g., 280-285 W for a marathon when my CP was 315-320).
@Jeff Phillips I dont think I can give you any good answers. Trying to correlate the Zones to match Power and Pace is similar to trying to match HR to Power Zones. However there is and will be some correlations and it sounds like you are working through those by collecting the data and doing the comparisons.
1) Do you run to power in your workouts? If so, how are you calculating zones? Or are you running to pace and simply collecting power data?
Yes and NO , I do mostly trail running so its hard to apply power in any form consistently. Most of my runs are RPE, easy is really easy below TRP which I find too hard for me and have little use for, when I do intervals I do them all out and look at the power later to confirm the zones equal RPE, when I race I run the RPE I think I can handle for the duration of the event whether its 30 min race or a 6hr 50k.
2) Have you gone through and looked at your workouts in FS to see if pace and power correlate to what you experience? Are they far off? How did you address?
Yes they are off for me as well , but that is to be expected on trail running, the HR zones are pretty dang close to the power zones though, although HR is generally a bit higher. I kind look forward to training for IMAZ later this year where I will spend a lot of time on a track and should be able to apply some of what you are thinking.
Have you looked in STRYD and compared zones? Here is a shot of mine and I would say they are pretty accurate for the first 4 zones. I pretty much couldnt do anything in the repetition line.
Thanks for the responses
@Mike Westover my power for the 5K test was 325.1 watts. Per the Stryd app, that led to a CP of 305. Perhaps I shouldn't have haircut again at 95% to get my rFTP?
@tim cronk thanks for the response. I can see how for you trying to connect trail running pace to power is not as relevant. Below are my Stryd zones and they are pretty close to what my analysis would equate to pace for a given power, off by 5-10 sec consistently. However, I've found the ranges to be too wide when looking at the Half IM run workouts in FS.
I'm also seeing a discrepancy with my power zones in Finals Surge (calculated using the EN formula) being much lower than my pace zones. I have done three tests to set my power (one on a track, one 5k, one 10k). The test results of these three were pretty close. The 5k was on terrain very similar to my everyday running. Power zones are off by more than an entire zone. For example, TRP pace is Z3 power.