8,153
edits
Changes
From Fellrnr.com, Running tips
no edit summary
I'm still testing GRP, but here are my initial thoughts.
* Getting your running pace from GPS is fairly useless, so it's not surprising that GRP's power estimate when using GPS as the speed source is pretty worthless. I typically see power estimates fluctuating by +/- 50 watts when maintaining an even effort.
* When I use [[Stryd]] as a Footpod to provide current pace, GRP provides a much better power estimatethan with GPS (no surprise. I)* On the flat, GRP provides a reasonable power estimate that varies with pace as you'm still gathering datad expect. * On the transition from flat to uphill, GRP seems to lag more than Stryd. So, if you keep a constant intensity/heart rate when you go from the flat to an incline, GRP will drop its power estimate in response to the slower pace, before it compensates for the incline and returns the power estimate to an appropriate level. * On uphill sections, GPR mirrors Stryd fairly closely.* On transition from flat to downhill, GRP suffers a similar lag, this time as a spike in estimated power.* On downhill sections, GRP does particularly badly, underestimating effort fairly consistently. This was a problem Stryd initially had, but they have mostly corrected the problem. I'll update expect GRP to get better at downhill power estimates, though this page with is a tricky problem to solve. While there is some research into the "U" shaped curve between V̇O<sub>2</sub> and decline angle, I strongly suspect the resultscurve is highly individual.
* I've not tested GRP with a Garmin Footpod, but this might be a more cost-effective approach then using Stryd. Of course, it will also require a lot more effort in terms of regularly recalibrating the Footpod, something you don't have to do with Stryd.
* The GRP estimate of power is much higher than the estimate I get from Stryd. Garmin [https://support.garmin.com/faqSearch/en-US/faq/content/vAzl2ne5dV6diuc2XbYZA6 claim that running power should be higher than cycling power for a given effort based on a number of research papers]. I'm still analyzing ve reviewed this researchin my [[Running Power Meters]] article and it appears completely flawed. The good news is that you can simply enter your weight into Garmin as about 2/3rds your real weight to get more useful data.* Because GRP is a Connect IQ data field, you can have it concurrently with the Stryd data field. Neither of them will record it to the standard power track in an FIT file, which means they both require some software support. Golden Cheetah supports Stryd power track natively, but doesn't yet support GRP.My workaround is to use SportTracks desktop app with the custom data tracks plugin, which allows me to copy the Connect IQ power data into the standard power data fields and then export it. [[File:GRP Hill Power Estimate.jpg|center|thumb|600px|A comparison of Garmin Running Power (GRP) and [[Stryd| Stryd's power estimate]].]]
