I’m basically new at all this tri training. I was reading the “grossly underfit†thread and saw a couple of Strava fitness screen shots. It made me wonder “what does this meanâ€? Is this based on age, weight/height, past training, or…?
I can see what my numbers are, but was wondering if these numbers are something that be compared to another person, and if so, what’s the limit of this comparison?
They’re based off of some well established guidelines from a very scientific book on cycling training I forgot the name right now. They’re almost only useful for cycling if you have a power meter but I imagine they could be a good gauge of how fit you are relative to someone else. I am unsure how much faith to put in these numbers in general though as a lot of people complain about how weird they are.
Personally I’ve been getting back into training lately and my fatigue numbers have been off the charts which is slightly worrying to me, but again not sure how accurate they actually are.
Strava Fitness is really a measure of training load, rather than of fitness performance. Strava calls it “Fitness” to get around paying licencing fees to Andrew Coggan (who pioneered the concept) for the trademark terms of Performance Management Chart, Chronic Training Load and Acute Training Load.
It basically compares the training you have done over the past 7 days (how hard you are working now), versus what you have done over the past 6 weeks (as a proxy for what your body can likely tolerate). It is useful as a means of ensuring that increases in training duration and/or intensity are gradual and sustainable, and also of a reminder to taper ahead of a goal event.
Don’t compare yourself to anyone else, just look at the chart as a means of tracking your own training load over time.
I don’t know anything about the science behind the fitness numbers.
But it is about you, not about anyone else.
I use the fitness score (and fatigue and form) sometimes as a trigger to take a break.
Basically, fitness plateau + high fatigue + low form = (light bulb) stop now before something bad happens
Strava is bullshit
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The numbers are specfic to you.
Also note that Strava uses HR data (I think I read that?) to compute your fatigue/fitness numbers. I’ve found that as a result, it de-emphasizes the really important muscular endurance (non-HR) part of training.
For example, I’m riding at my highest power for 3 hr rides (significantly so) vs the past year that I’ve been religious recording the data, which means my HR is lower than it was previously for equal power. So if I go out, ride a ‘best power’ ride that really taxes my legs but doesn’t pump my HR the way it used to when I was less fit/powerful on the bike, Strava records it as my fitness slightly decreasing, when obviously it is not.
Similarly, I often run at noon-workdays, and when there the temps get hot for a week and I’m running in much hotter temps, my run HR goes up a lot. Strava records these as ‘monster’ efforts, and sure, it’s tougher on the system than cool runs, but in terms of leg beatdown, there’s no way those 45-60 minute hi-intensity hi-heat interval sessions have 5x more fatigue effect than a 90 minute run I did today at much lower HR but with a really big hill in the middle where my legs were complaining by the end.
So you def have to take with a big grain of salt (unfortunately), especially if you’re pushing the limits of your muscular endurance since that will be underballed in the Strava fatigue/fitness scores.
Thanks for the input.
If the “fitness” number is a proxy for training load, how fast of an increase is too fast? Or is this also just a personal number and no one can say that an increase of 2 per day is better or worse than an increase of 1 per day for John or Jane?
Not an expert here, but at least from looking at my personal numbers for the last year (and I was intentionally very good about using a reliable HRM for every bike/run just so I could analyze this dataset on Strava), my n=1 is that for me, the fatigue/fitness correlates with reality, but is by no means better, or even the equal of it.
I was hoping to have situations where I could say, ‘I seem to be ready for ‘A’ type efforts with a fatigue of 0-15’ or ‘I’m definitely in dangerous overtraining territory ater 80+ fatigue’, but I can’t say that about either.
The most ‘bummer’ part for me about the Strava fitness/fatigue graph is that in the past year, I’ve been doing my best, most consistent training in a decade, and expectedly, am significantly faster and putting down more power than I was a year ago. I’m dropping PRs on my Strava segments left and right, yet if you look at my Strava computed ‘fitness’, it has me peaking about 9 months ago, and has decreased by 5 points since then, implying I am now less fit than I was back then. Obviously, this fitness number is just wrong - not by a lot, but absolutely should be higher, not lower.
Again, I impute this mainly to the reality that as you get a (lot) more fit, your HR goes down for efforts, especially hard ones. And since the Strava fit/freshness data is computed entirely of HR data (I don’t think it accounts for speed or power at all), if you’re training at lower HRs, you get lower fitness scores. Even if your leg muscular endurance is hitting all-time highs.
So, is there any “fitness” app that can be used to focus on fitness gain (TP, Garmin Connect, something else)?
I know since I’m basically new, I am improving fitness in all three disciplines. What I don’t know is whether I’m improving too slowly (not enough training or not training hard enough) or improving too quickly (over training and possibly setting my self up for injury).
Do most go by “feel”? I take a rest day on Sundays. Mondays through Thursdays I feel like I’m not training very hard (even on speed days), but after 2 hours of running on Friday and 2+ hours of biking, I feel I’m ready for my rest day. So, without a lot of experience, it “feels” like I’m training pretty close to where I should be training, but I’m a numbers guy and would like some numbers to look at 
Feel first, add numbers to supplement, but not replace. I’m not throwing away all the numbers from Strava, but I’m not slave to it nor my powermeter or HRM.
You’ll know you’re overcooking it when you feel the beatdown and your training paces on what are supposed to be strong days, start slogging. It’s an art, not science, and it takes awhile and constant awareness to know what you are and aren’t capable off (including taking some risks with training when you’re feeling up to it.)
Not specific to Strava’s flavor of the classic PMC chart, but a known limitation of these types of models is that they assume that the athlete has an infinite capacity for training stress. When in reality we will all break down at some level of training stress, sometimes catastrophically.
That’s why it’s important to not just chase an ever-higher peak in “fitness” in the absence of other types of feedback.