Started a thread in the main forums, but it turned into a thread of people explaining me why GPS is accurate and how to calibrate a foot pod.
So I'll try a similar thread here, hoping that people will share their thoughts, findings and ideas about the usefulness of power in running.
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Leg Spring Stiffness (LSS) a useful metric?
https://www.trainingpeaks.com/coach-blog/using-leg-spring-stiffness-to-measure-running-economy/
In its simplest definition, LSS measures the stiffness of the muscles and tendons in your leg. As a result, LSS is a measure of how well a runner recycles the energy applied to the ground in each stride.
...
Trends in LSS/kg for specific speeds should be the focus of any analysis.
The most striking result is the strong and statistically significant correlation (even at the 0.001 level) between Running Effectiveness (RE) and LSS.
As explained before, the LSS represents the stiffness of the leg muscles and tendons. Based on the the assumption that stiff muscles and tendons are able to recoil more elastic energy upon landing, runners with a higher LSS would use less energy and oxygen lowering their RE.
Leg Spring Stiffness (LSS) a useful metric? https://www.trainingpeaks.com/coach-blog/using-leg-spring-stiffness-to-measure-running-economy/ In its simplest definition, LSS measures the stiffness of the muscles and tendons in your leg. As a result, LSS is a measure of how well a runner recycles the energy applied to the ground in each stride. ... Trends in LSS/kg for specific speeds should be the focus of any analysis. ... The most striking result is the strong and statistically significant correlation (even at the 0.001 level) between Running Effectiveness (RE) and LSS. ... As explained before, the LSS represents the stiffness of the leg muscles and tendons. Based on the the assumption that stiff muscles and tendons are able to recoil more elastic energy upon landing, runners with a higher LSS would use less energy and oxygen lowering their RE.
What is a "good" number? what is the scale? and what is yours?
It says in the article that it can't be compared between runners.
Mine varies depending on a few variables. Pace is definitely one of them, and I think fatigue is another one.
The article says we should track the evolution for a given pace, so not compare our numbers at different paces. But here's a few random observations:
6:00-6:20ish pace:
- last week 2 x (3200m / 2min), was very tired... last workout before my current break: 11.8 kN/m, 12.2 kN/m efficiency 2nd split was faster
- nov. 28th 6 km Tempo : 12.2, 12.4, 12.5, 12.6, 12.8 kN/m ... LSS was getting better and better, but pace was also getting faster and faster
- nov 13th 3 x (2km / 1min) 12.4, 12.7, 12.8 kN/m each split was faster than the one before
When running easy, on my commutes, I get numbers looking in the high 9s to low 11s kN/m
When doing the Monas, I get up to low 14s
(example here: https://www.stryd.com/powercenter/run/5554408573960192 Change Lap Selection to "Splits")
Still new to the technology but thinking it might help for racing marathons. Right now I see myself close to the 200 number for many runs and I know if I'm in the 215-220 I'm either going uphill or it's windy, so if I see that number in a run and it's neither, then I can assume it means I'm working harder and should slow down. Maybe that will help during racing.
Damaris
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It says in the article that it can't be compared between runners. Mine varies depending on a few variables. Pace is definitely one of them, and I think fatigue is another one. The article says we should track the evolution for a given pace, so not compare our numbers at different paces. But here's a few random observations: 6:00-6:20ish pace: - last week 2 x (3200m / 2min), was very tired... last workout before my current break: 11.8 kN/m, 12.2 kN/m efficiency 2nd split was faster - nov. 28th 6 km Tempo : 12.2, 12.4, 12.5, 12.6, 12.8 kN/m ... LSS was getting better and better, but pace was also getting faster and faster - nov 13th 3 x (2km / 1min) 12.4, 12.7, 12.8 kN/m each split was faster than the one before When running easy, on my commutes, I get numbers looking in the high 9s to low 11s kN/m When doing the Monas, I get up to low 14s (example here: https://www.stryd.com/powercenter/run/5554408573960192 Change Lap Selection to "Splits")
For my last 2k workout (not too far off your 2k paces), mine ranged 8.9-9.1 (the 6:15 paced ones were 9.0).. so what does that mean if yours is in the 12's at the same pace? you are more efficient? what is your form power? Mine resides in the lower 50's for most runs). And that was ~250 watts for the 6:15/mile pace reps
I weigh more than you, so it might be about the same? (or not). Also I don't know if we should compare between runners. The article says we shouldn't.
The way I see it, is that for me, at a constant weight (therefore I don't need to divide by my weight), I should aim at increasing my LSS for a given pace (all paces, actually, but you only compare paces that are the same).
The ways to do that now... running form? plyometrics? hills? Anything that will increase my muscles and tendons' ability to recycle energy applied to the ground.
how is your triangle looking?
So I looked at today's numbers and my leg spring stiffness was 10 and thereabouts.
From the Internet.
BAH I'm in the new beta and I don't get the triangle as an option!
Still just accumulating data and waiting for it to become useful. I need some longer tempos and longer race efforts to really get critical power dialed in, I think, and unfortunately I don't have much of that planned for a while. Oh well.
What? No!
I don't see a triangle either, but not sure if I'm missing it. Is it because I have the modern power center (is that the beta?)
Yeah, eventually everyone will be moved over and then nobody will have the triangle
I thought the triangle was so cool at first, but now that I know how Stryd comes up with the 3 numbers, I find it pretty useless.
Each of the three percentages is actually how your number scores compared with all the other Stryd users that are on the same "plan" as you. I chose marathon. Maybe it's also grouped by gender, and maybe by age, but it's you against the others.
3 percentages and they put that into a triangle.
I used to think there was some complex algorithm analyzing my training as a whole and showing me my strengths and weaknesses.