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Strava fitness calculation change this week?

Old 12-05-18, 09:09 AM
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Caliper
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Strava fitness calculation change this week?

Did Strava change their fitness/freshness calculation for anyone else this week? I've been using Summit for a bit over a month so naturally I'm still in the phase of geeking out on too many numbers to look at, but my fitness graph just dropped by over half compared to last week. I'm not talking just about todays number, the entire curve has dropped. Even numbers from weeks and months ago. Yeah, I know it's just a number but I'm curious if anyone else saw their fitness calculation change dramatically in the past week?
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Old 12-05-18, 01:45 PM
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Did you change your FTP/LTHR? Strava's fitness calculation is kind of worthless because it doesn't let your set different values for ranges of time in a season even though they fluctuate with training.
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Old 12-05-18, 03:39 PM
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Do yourself a huge favor and install the Elevate (formerly Stravistix) plug-in for your browser. So much more information made available, and the Elevate version of the Fitness and Freshness graph (Fitness Trend) is a lot easier to read.

Because Fitness and Freshness can't be refined down past a 6-month display, mine is just a slightly irregular line. The graph in Elevate does a better job of graphically displaying my fatigue.
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Old 12-07-18, 10:06 AM
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Originally Posted by redlude97
Did you change your FTP/LTHR? Strava's fitness calculation is kind of worthless because it doesn't let your set different values for ranges of time in a season even though they fluctuate with training.
I did make a small change in my FTP, but not sure why that would cause the fitness calc to go from 70-80 to mid 30's? I've tried putting it back to see if anything changes.
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Old 12-09-18, 01:29 PM
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Mine did Oct 8 this year and my fitness nosed dived for two weeks before I realized it wasn't my training, but their program. I initially had my max HR set up and let the zones fall where they may, but then I decided to set it up to use my zones and that is where the program failed. Got a service ticket on it and the guy at Strava told me to go back to max HR setting. I did, but adjusted it form 183 to 172 to get my zones to line up better. Worked like a charm, but not perfect by any stretch. But, I'm a noob so what do I know...
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Old 12-09-18, 06:17 PM
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Originally Posted by Harvieu25
Mine did Oct 8 this year and my fitness nosed dived for two weeks before I realized it wasn't my training, but their program. I initially had my max HR set up and let the zones fall where they may, but then I decided to set it up to use my zones and that is where the program failed. Got a service ticket on it and the guy at Strava told me to go back to max HR setting. I did, but adjusted it form 183 to 172 to get my zones to line up better. Worked like a charm, but not perfect by any stretch. But, I'm a noob so what do I know...
Basing your training zones on your LTHR zones instead of your max HR is better. The old calculations strava was doing were likely overestimating your "fitness" and the new number are more representative.
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Old 12-09-18, 07:48 PM
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Originally Posted by Caliper
I did make a small change in my FTP, but not sure why that would cause the fitness calc to go from 70-80 to mid 30's? I've tried putting it back to see if anything changes.
What kind of hours and intensity were you doing when it was saying 70-80?
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Old 12-09-18, 09:53 PM
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It also seems to have to do with the changes in algorithm when Strava went from "suffer score" to "relative effort." Back in 2016, in the Suffer Score days, my fitness peaked at 142, and I could see Fatigue scores all the way up into the 170s. In the past six months, I've not seen a Fitness score above 80 or below 71. On the 4th of July, I did 108 miles with 5,000ft of climbing, in 106º temps, and netted a Fatigue score of 84. I often wonder about Strava's math. I've had Move Ratios of 1.00 (moving time and elapsed time match) two days in a row, even though I stopped for signs/lights several times on each ride. Strava is just a big fan of rounding off.
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Old 12-10-18, 09:51 AM
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Originally Posted by rubiksoval
What kind of hours and intensity were you doing when it was saying 70-80?
When it reached that peak was right near the end of the warm weather here and I'd done two metrics over the course of two weeks, along with a few other shorter rides. The thing is, a few weeks ago, my score in early Nov after completing those rides read 80 or so. Now, when I look at my chart for the same day, it reads 40. It's not that my fitness score has dropped with time (it's actually trending slowly higher with trainer workouts) the weirdness is that my entire chart is now reading differently for the past 6 months. Same general shape, just much lower numbers.

I guess the main change is really switching from on bike to a trainer, which means I have a power meter now where I didn't before. Would that trigger Strava to recalculate the entire curve from the last 6 months?
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Old 12-10-18, 12:09 PM
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Originally Posted by Harvieu25
Mine did Oct 8 this year and my fitness nosed dived for two weeks before I realized it wasn't my training, but their program. I initially had my max HR set up and let the zones fall where they may, but then I decided to set it up to use my zones and that is where the program failed. Got a service ticket on it and the guy at Strava told me to go back to max HR setting. I did, but adjusted it form 183 to 172 to get my zones to line up better. Worked like a charm, but not perfect by any stretch. But, I'm a noob so what do I know...
I'm a noob to this side of things also. I have noticed that Strava picks HR zones fairly differently than other apps might based off resting and max HR. But when I put in custom HR zones, it doesn't seem to apply those settings to any of the analysis anyways.
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Old 12-10-18, 12:19 PM
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try adding the Elevate plugin for chrome that calculates TSS from your strava HR and power data as mentioned above, its more consistent in general. If you have a PM and want a mobile option, export strava to wattsboard to track TSS
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Old 12-10-18, 05:12 PM
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Originally Posted by Caliper
When it reached that peak was right near the end of the warm weather here and I'd done two metrics over the course of two weeks, along with a few other shorter rides. The thing is, a few weeks ago, my score in early Nov after completing those rides read 80 or so. Now, when I look at my chart for the same day, it reads 40. It's not that my fitness score has dropped with time (it's actually trending slowly higher with trainer workouts) the weirdness is that my entire chart is now reading differently for the past 6 months. Same general shape, just much lower numbers.

I guess the main change is really switching from on bike to a trainer, which means I have a power meter now where I didn't before. Would that trigger Strava to recalculate the entire curve from the last 6 months?
I'd expect 9-10 hours for a CTL of ~80 with a decent amount of intensity in there. Two 62 mile rides wouldn't cut it in my experience.

A few months with 10 hour weeks with 5-6 harder rides each week ( so nearly every ride) usually puts me around 90 or so.

So anyway, sounds like now it's more accurate than it previously was, though why is a good question.
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Old 12-11-18, 09:30 AM
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Originally Posted by DrIsotope
It also seems to have to do with the changes in algorithm when Strava went from "suffer score" to "relative effort." Back in 2016, in the Suffer Score days, my fitness peaked at 142, and I could see Fatigue scores all the way up into the 170s. In the past six months, I've not seen a Fitness score above 80 or below 71. On the 4th of July, I did 108 miles with 5,000ft of climbing, in 106º temps, and netted a Fatigue score of 84. I often wonder about Strava's math. I've had Move Ratios of 1.00 (moving time and elapsed time match) two days in a row, even though I stopped for signs/lights several times on each ride. Strava is just a big fan of rounding off.
Thing is, this was all relative effort. Or at least I thought so? I've only seen relative effort on any of my activities since joining Summit this fall.

Originally Posted by redlude97
try adding the Elevate plugin for chrome that calculates TSS from your strava HR and power data as mentioned above, its more consistent in general. If you have a PM and want a mobile option, export strava to wattsboard to track TSS
I've added that on my laptop, but the problem is there is no way to go back in time a few weeks to see what it would have read when Strava was showing me the higher numbers.

Originally Posted by rubiksoval
So anyway, sounds like now it's more accurate than it previously was, though why is a good question.
I guess that's the root of it all. Good to know that it's more on track now, even if I liked the older number better. I don't personally know anyone else using Summit, so never had an idea what the numbers should read for a given fitness level. The only change I can think is that before it was using only HR data and recently I've got mostly HR and PM data from my trainer?
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Old 12-11-18, 11:50 AM
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Strava "fitness" or elevate "fitness" is not real fitness, so it doesn't matter what the numbers say. TSS and relative effort are just training metrics. Measure fitness in terms of increases in FTP or times on a repeatable segment of road. There are lots of ways to create the same TSS/RE but not all add to your performance capability in the same way.
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Old 12-11-18, 12:34 PM
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Originally Posted by redlude97
Strava "fitness" or elevate "fitness" is not real fitness, so it doesn't matter what the numbers say. TSS and relative effort are just training metrics. Measure fitness in terms of increases in FTP or times on a repeatable segment of road. There are lots of ways to create the same TSS/RE but not all add to your performance capability in the same way.
The tricky part of your assertion, which is quite correct IMO, is that measures of fitness depend on what you're trying to do. FTP or segment times might not be perfect metrics either. Maybe one needs to watch one's times on a 40k TT or maybe on a 60 mile road course or performance in a pack sprint. IME if one's training mimics one's goal rides, watching CTL does seem to work in that too high is unsustainable, too low = poor performance. Whether one can modify one's training within the same CTL parameters to produce higher performance in one's goal rides I think is your point and a good one. IME that requires experimentation and expert advice. I keep fooling with that but haven't come up with anything firm other than "ride hard, make your legs and lungs hurt, then recover less than you'd think."
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Old 12-11-18, 03:44 PM
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That's the main caveat, not all fitness is the same and not all fitness is created equal. My peak CTL for the season was pretty high, but I wasn't particularly fast, and got faster in the cyclocross season by decreasing my CTL and increasing my amount of intensity for my race specific fitness required.
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Old 12-11-18, 04:22 PM
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Originally Posted by redlude97
That's the main caveat, not all fitness is the same and not all fitness is created equal. My peak CTL for the season was pretty high, but I wasn't particularly fast, and got faster in the cyclocross season by decreasing my CTL and increasing my amount of intensity for my race specific fitness required.
Good to know. How long are your CX races?
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Old 12-11-18, 04:35 PM
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Originally Posted by Carbonfiberboy
Good to know. How long are your CX races?
45 mins of essentially pegged HR, which is the extreme opposite of most of my other riding.
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Old 12-11-18, 04:48 PM
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Originally Posted by redlude97
45 mins of essentially pegged HR, which is the extreme opposite of most of my other riding.
Oh, what fun! We're a weird bunch.
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Old 12-12-18, 02:10 PM
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It would be interesting to compare metrics from Strava with Training Peaks.

The exact numbers might not agree but the graphs should be roughly the same in terms of trending.


-Tim-
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Old 12-12-18, 03:04 PM
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Originally Posted by TimothyH
It would be interesting to compare metrics from Strava with Training Peaks.

The exact numbers might not agree but the graphs should be roughly the same in terms of trending.


-Tim-
If your FTP changes throughout the season(as it should) the shapes won't match since strava only allows 1 value and recalculates all your rides on that, so its pretty much worthless. Depending on where you are in the season, it'll underestimate the early season fitness/fatigue and underestimate the peak season work later in the season if your FTP drops
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