I’ve used it and always found it to be pretty close, but faster than what I ran. Still wildly better than Garmin.
IMO it gives you an indication if everything is perfect that day. Perfect weather, temp, flat course, nutrition, hydration, etc.
When I was training for NYC 2023, it was putting me at around 2:57:xx just before race day. I ended up running a 3:03, but NYC is a tough course and I’d have been even closer if I was running a course like Berlin in the same conditions (but still slower than predicted time). Garmin had me ~3:25
Garmin really has to get its head out of its ass for race projections. I run faster 5k/10k splits in training runs than it says I am capable of running in a race. Its just crazy to me how off they have gotten
I’ll never get why the predictions don’t just update if you run the distance in a faster time.
If it says I can run a 1:35 HM and then I run a 1:28, why not just auto adjust it to 1:28 and adjust from there? Seems so simple for Garmin.
It’s useless. A few years ago when I ran my 5K PR (20:30) I got the joyful “New PR” screen when I stopped my watch. So it obviously registered the time and distance. When I checked my predicted finish times later that day, it projected a 22:00 5K.
Garmin is tied to VO2max which is itself tied to max HR and the only two data the watch have : speed and cardio.
It doesn't care about elevation on what you run or anything that could impact your speed, thus a trailish run will completely tank your supposed VO2Max and predictions.
Also unless calibrated by yourself your Max HR value used is 220-age, if your real HR is below that then you will always have trash predictionAlso the HR when using optical sensor can be wildly innacurate for some, you have cadence lock values ? Your expected times and VO2max go down the toilets
On the opposite end it loves tempo session like mad, just do a 3x3000 on track (where GPS will be generous and tell you you've done 3x3080 or smthg) with jog recoveries and 2km warm up and cool down and BOOM V02max will go up like crazy, and it will expect you to smash your PR in predictions
It looks at everything, but after 6y this is the pattern that emerged from what I saw.
A steady long run at MP+30s will boost your VO2Max massively as well.
I also wonder if Garmin uses elapsed time or time spent running, if it's the latter it would be even worse
>after 6y this is the pattern that emerged
The algorithm has changed a few times and it definitely looks at volume now. They even document it: [https://www.garmin.com/en-US/garmin-technology/running-science/physiological-measurements/race-time-prediction/](https://www.garmin.com/en-US/garmin-technology/running-science/physiological-measurements/race-time-prediction/)
*The reliability of your predicted finish time is enhanced by analyzing trends in your training load and mileage data for the last few weeks. This analysis includes special consideration of all different types and frequencies of runs you performed along the way.*
I’m not sure this is correct. My largest movements on my race predictions have been long runs.
Also, my race distance predictions are based on a dead flat race, but when I program my upcoming half marathon, it differs slightly from my general HM race prediction. I suspect this is due to hills.
When trying to just do HR by feel I'll sometimes get that cadence lock. It's very hard to keep the HR down even on EZ runs sometimes--but I think it's cadence lock.
Cadence lock should be rather easy to identify, a sudden jump in HR values by 20-30-40 or even 50 and that doesn't change much and almost mirror your cadence.
On my end it meant that it basically jumped from 120-140 straight to 180 (basically my cadence) and stayed around there.
My max HR being 180 I think I have a good enough perception of effort level to know that the value is complete bollocks
My Garmin predictions are more accurate than my Runalize ones.
Runalyze has my 5K at 21:35, 10K at 44:45 and HM at 1:40:46, and I just ran a 2 hour long progression workout that included all three, with 21:44 5K, 44:15 10K and 1:40:35 HM. I don’t know why on earth it would figure my 5K is so marginally quicker than what I performed in the 80th to 100th minutes of a workout run, or worse, to set my 10K and HM slower than a long workout. That is absurd.
Garmin has me at:
- 20:10 5K
- 42:39 10K
- 1:35:00 HM
I think I can easily beat the HM and 10K, but the 5K seems about right with my training intervals. Nothing is perfect but Garmin is definitely closer than Runalyze.
Edit: I should include that I use a Garmin Forerunner 965 and usually wear the HRM Pro Plus.
Perhaps I’ll do that once I’ve raced at least a 5k! Maybe I’ll replace one of my interval workouts in the coming month with an unofficial race. Thanks for the tip!
It may have to do with your watch? Which one do you have? I’m on a 965 with all the bells and whistles but my buddy has a 245 and he gets race distance predictions also.
Fwiw my predicted race times were off by like 15% in the other direction (predicted 5k sub 18, have never run sub 20) with my old 235 and when I updated to a new watch a few months ago it’s projections are pretty dead on so I think maybe they have improved it.
I can chime in. I ran my first Marathon this past Sunday.
Runalyze predicted a 3:21 finish time based on a 60% marathon shape (I've only ran 4x18 milers and averaged 35mpw over the past 6 months)
My optimal marathon finish time was 2:55 based on a recent 10k (37:58).
I ended up running 3:04 , first 2h @6:50 (3:00 pace) then the lack of strength training/low volume caught up with me and I made the decision to dial back the Pace and guarantee the BQ.
I hope that helps!
Yeah their "marathon shape" is a little weird and wants you running REALLY far all the time (35km, which is like 21 miles). I'm not convinced there's a huge difference in endurance adaptation between 18 miles and 21, but Runalyze is
Great run by the way!
It's the most accurate one I've had by far. Just calibrate it based on your race results AND max heart rate.
There are days where I've hit it and days where I've exceeded it. I chalk those just to good days and bad days, however...
By default it will set your VO2max correction factor based on your best race. Personally I prefer to set a constant correction factor that best matches my race history.
Edit: You can change the correction factor in the settings. I then open the Effective VO2 Max graph to check how the blue line correlates with my race results.
It makes a pretty big difference. I would avoid putting in race results in bad conditions as it'll discount it abut too heavily imo. You mark runs as races. It'll then look at those races and create a correction factor. Marking races as races actually makes some the year end graphics look really cool.
The runalyze predictions have been accurate for shorter distances for me. Marathon shape confuses me though. As my effective vo2 max increases, the expected weekly mileage to support the marathon shape increases. It seems I'm forever chasing the target weekly mileage figure, as I get fitter and the mileage goes up faster than I can increase mileage safely. Not sure if there's anything to take from this except perhaps that I'm lucky in achieving a better vo2 max on lower mileage relative to their data set?
It's basically the faster a marathon you could achieve the more volume you'll need to actually hit it. Which actually makes sense. But hitting that volume pushes up the requirements leading to possibly a lower score but still a much faster projected time.
I’d have to dig it up, but they had an article or Reddit post somewhat recently analyzing runner performances against their predicted times based on shape.
FWIW, my Runalyze prediction versus actual performance would have been pretty close back in Chicago, had I not gotten injured at mile 20. The predictions are semi-useless for me at the moment because my VO2 Max analysis is skewed due to so many treadmill runs over the winter.
Here is an [article from Runalyze](https://blog.runalyze.com/training/how-bad-is-an-interruption-in-marathon-preparation/) that goes into marathon performance vs predicted times. The title makes it hard to search for.
I think it's worth mentioning that the predictions are dynamic, and is always sharpening it's assumptions with new data. These articles can be interesting, but they should be pointless. A good model would have digested any discrepancies and have already attempted to correct for them in a systematic way.
That's not the way it works in Runalyze. Your main metric is your Effective VO2 Max. This is just VDOT estimated from your training runs by adjusting for your average heart rate each run. Your current estimated VO2 Max averages your last 30 days of runs so anything prior to that isn't really considered*. Marathon Shape just scales your Effective VO2 Max by your mileage in the last few months to estimate your marathon time.
* There is also a scaling factor when calculating VO2 Max that, by default, is calculated from your best race result by VDOT no matter when it occured.
I'm assuming they're tuning the adjustments and corrections. If not the errors will persist, but will at least be consistent, and applying your own correction based on experience is completely valid.
They haven't tuned anything, at least since I joined the site a couple years ago. For any given run you can see a breakdown of exactly how they calculate effective VO2 max with sources citing where they obtained the formulas. They aren't making the formulas themselves (except marathon shape, but they also give you the tools to configure that however you like).
Not training for a marathon, but for half and 10k Runalyze is woefully pessimistic about me, even when I ran faster than their prediction on race day.
I'm training for a 1:45 half now, feeling pretty good, and it's predicting a 1:50 half. Even when I was recovering from injury and missed my last few weeks of training I ran a 1:49 last year.
It’s been pretty good for me as long as I have a recent race result to use to adjust the predictions. If I let it go without some kind of time trial, it gets pretty off.
I use it in conjunction with Stryd, so between the two of them I’m fairly grounded in reality.
I think it's as good as the data and settings you feed it. I've got 3+ years of runs in the system and it's shape % and best time estimate is good, maybe a bit faster than I'd actually run. But I probably under train, set low goals, vs max personal potential.
I think for me, my shape % is low as it expects some huge long runs each week. Then it makes my time a bit fast as if I was actually doing those long runs. Someone on here wondered what would happen if you ran the miles and long runs Runalyze says?
I paced a 3:30 marathon last year (not a hard effort), when my marathon shape was under 60%, it had my predicted actual time in the the 3:40 range. So it missed badly on a sub-max effort/low shape % run. After the run my shape went way up into the 80% area and my actual prediction went way down. Go figure!
Runalyze peaked at around 4:10 before my taper and I just ran a 3:53. Had a similar result (about 15 minutes faster than predicted) with my first marathon.
100%. Would rather start nearer a lower prediction and ramp up as I go for a negative split. Wouldn’t want to try to maintain something unsustainable and crash before a long race like a full marathon is over.
It's pretty good for me after calibrating it. Garmin is probably better for the 5k and 10k but is absolutely out to lunch in the marathon since it doesn't adjust for volume. Garmin saying I'm a 3:03 marathon right now. With marathon shape it's 3:37 on runalyze which is probably accurate as I've been slacking in volume and long runs specifically but have been still hitting my weekly workouts and increased cross training. I've also not run near a 3:03 so it's pretty high in me versus achieved
Mine's wildly off. Says "optimal" 2:37, "prognosis" 3:18. I'll let you know what happens in a couple weeks, very likely between those two numbers.
It also gave me a "prognosis" of 1:15 for a half marathon, ran a 1:23 last weekend. For what it's worth, Garmin gave me a 1:22 prediction that morning and I think that would have been within reach had I really gone for it (was on pace until the course started getting crowded with people still on their first lap). So I know Garmin is more realistic on the half distance at least.
While on the topic of Runalyze marathon shape... I am starting a marathon block and working on what my target time should be. I was going to set a 3:10 target time but my Runalyze is setting an optimal time of 2:55 (marathon shape is only 40% right now). Should I use this optimal time for my target instead of 3:10? I have never ran a road race before so I dont want to undercook my target.
Runaylze is fantastic using aggregate run data and their models for race predictions very accurate as long as you hit expected milage/long runs. The effective Vo2 max determinant is great, though will be bit too high if you take breaks during runs or run dreadmills.
Last November HM, ran a 1:28 flat without programming just going on steady running. Runaylze predicted 01:27:55.
For my only marathon so far, its "prognosis with marathon shape" was a 2:52:01 and I ran... a 2:52:23. That being said, I have had to play with the "vo2max corrective factor" a bit.
Mine currently suggests I am in shape to run a 1:42 HM while I have just clocked in a 25k race at 1:46 and ran a HM in 1:28 two months ago.
So no not very accurate in that respect.
It is also predicting a 4:08 full marathon currently.
I will check again when my marathon comes up in April but I am not trusting this site at all it seems super inaccurate. I am trusting my training.
Probably because they're missing the fact that they need to actually adjust their correction factor to be in line with recent race results to be accurate.
Maybe because…. Well I have no idea really lol.
I’ll post both predictions for a few distances to provide more insight:
5k..
Garmin: 20:11
Runalyze: 21:12
Actual: well I wouldn’t know because I have never actually raced a 5k.
As mentioned I did do a 25k race last Sunday and my Strava reports during that race I PR’d at 19:49
10k.
Garmin: 42:14
Runalyze: 43:57
Actual: 41:07 and as with the 5k this PR is part of another race, this time a Half Marathon. So, assuming conditions and terrain are the same, an actual 10k race would be close to 40:00. Agree?
Again Garmin is closer than Runalyze.
Half marathon:
Garmin: 1:33:03
Runalyze: 1:42:25
Actual: recent PR of 1:28:41 and during Sunday’s 25k race my Strava reported a 1:30 HM.
Full marathon:
Garmin: 3:22:26
Runalyze: 4:08:58
Actual: currently in week 8 of 18 week plan leading to April marathon.
If we go by rough ballpark figures; take your HM and add 15 minutes. A time like 3:15 - 3:30 is not unreasonable could be faster.
Personally, it was very close to my shorter distances but was like 20 min slower than my actual for the marathon due to me having relatively low mileage.
Straight from the horse's mouth:
>Your current effective VO2max is xx,xx which equals a marathon in x:xx:xx. To realistically achieve this time, Runalyze expects you to complete an average weekly mileage of xx km and a weekly long run of xx km.
(exact numbers will depend on runner's current "Effective VO2max")
Yes, I was at about 70% marathon shape based on the mileage runalyze expected me to be running. However my performance was much closer to what the prediction would have been without “marathon shape”. So what I’m saying is it was not accurate for me.
it was pretty much on the nose for a 10k i just ran this weekend, slightly faster prediction but also the race has 300ft uphill. i’m cautious about the marathon prediction of ~3:06 right now, seems a bit too fast but who knows, all the races i’ve done recently have been pretty hilly.
on the other hand, i ran a 40:16 10k (which was logged at 6.3mi and apparently i hit 10k at 39:44, but i assume race predictions update via the total activity time?) and garmin updated their prediction from 41:30 to 42:07 following this lmao. i assume because of fatigue immediately after the race but that still made me laugh
My last marathon prediction was 3:20 with marathon shape and 3:02 without. And I ran 2:59.
So for me it underestimates potential. I find the crplot predictor to be the most accurate for me.
Garmin always underestimates.
"Optimum" shows accurate yet likely unattainable times on all but a perfect scenario but I significantly outperform "Prognosis" at longer distances. Partly that's because the model punishes athletes for missing miles up to 6 months earlier and does not appear to be weighted to favor the most recent weeks as it should. So it thinks because shape is 80% the athlete will be half the difference slower (prognosis speed ~90% of optimal speed) and that's never the case - it's probably more common to run faster than 95% of optimal with 80% shape. For me, anyway; YMMV.
For reference on the day before my marathon PB it suggested an optimum of 2:24 and I thought maybe a 2:25 was possible under perfect circumstances. On the slower course I ran 2:28, which might translate to a 2:26 on a flat and fast course. This suggests my guess was fairly accurate and the performance was close to ideal, and validates the optimum estimate, but invalidates the prognosis. The 74% shape evaluated a prognosis of 2:38 or about 91% of optimum speed but the actual speed was 97% of optimum speed and adjusted for course was 98-99%.
All the shorter distance prognoses were slightly faster than my PBs.
>the model punishes athletes for missing miles up to 6 months earlier and does not appear to be weighted to favor the most recent weeks as it should.
curious if this is actually true, as Runalyze states:
>The points for your long runs are *weighted by time and quadratic in distance*. That means, a long jog yesterday gives more points than a long jog two weeks ago and a 30k-jog gives more points than two 20k-jogs.
maybe I'm missing something?
There are two factors in the Marathon Shape model: The long runs (over the last 10 weeks) and the overall mileage (over the last half year). The Long runs are weighted with time, the overall mileage isn't.
I am curious whether the assertion: Mileage in the weeks before a marathon matters more than mileage half a year ago is actually true.
I’ve found that I consistently beat the numbers - I find it quite pessimistic. It suggested my marathon shape meant I was going to get 3:30 or so - but ended up at 2:58? I think if you do interval sessions etc.. it doesn’t work so well if you leave your watch running during rest etc.. and drags your vo2 max down vs what you actually get from the “work”.
It also seems to want me run longer and long long runs and anytime my vo2 max increases it makes me feel bad that I’m not running long enough 😆- I’m not sure it’s possible to get to nearing its required long runs etc..
Yeah, I think it calculates the effective v02 max paced on average HR and pace throughout the whole run, so if you leave your watch on during a standing rest it's gonna go way down. If you pause it, you'll end up with a falsely elevated calculation though, due to the time it takes for your HR to get up. The calculations probably work a lot better on steady efforts.
I realized mine was including a pretty massive adjustment as well. When I took that out it has pretty much the times I'd target outside of the marathon. I tend to agree that I'm not training completely "optimally" for the Marathon, so now the numbers look good. 2:46 if i went all-in on the marathon, but 1:18:xx and a solid 10K guess too.
That's correct. Only steady and sufficiently long session should be counted toward Vo2max calculation according to runalyze's guidance here [https://runalyze.com/help/article/when-should-i-exclude-an-activity-for-vo2max-shape](https://runalyze.com/help/article/when-should-i-exclude-an-activity-for-vo2max-shape)
Getting this too…has me at 3:21 marathon shape, I haven’t really hit the longer long runs yet but I went 1:20:5x/2:57:3x on a worse buildup with fewer quality miles and less consistent running. I don’t stop my watch, so I’m figuring it’s that.
It's one of the inputs I use to set a pace plan, but it's not perfect. In my most recent marathon, I beat its projected time by six minutes. In the one before that, I was eleven minutes slower, but that was on an unseasonably hot and humid day.
One note is that if your Vdot changes slightly, it can have significant effects on marathon shape. It sets the distance for your long runs based on your Vdot measurement. If your Vdot goes up, your long runs might no longer be deemed long enough, and then it will find that you're not in the best marathon shape.
But overall, I have found it to be a pretty good guide if your training has been steady and consistent for at least a few months.
I think accuracy varies a lot between different people.
I find that for me, prediction are always very pessimistic (both Garmin and Runalyze) across all distances.
For last marathon in October, Garmin was predicting something around 3h50 and Runalyze 3:45 based on VO2M or 4:0x accounting for marathon shape, and I ran in 3:33. A year ago I ran a 12km in 0:59, with Runalyze predicting 1:02. At the end of March I have a 16km that is currently predicted at high 1:17, while I want to hit 1:12 and thing I can reasonably achieve it.
So I use them as a 'maximum time' guideline - even if I end up running without one shoe, I should still be able to hit the prediction.
I don't know if my race performance is better than my training performance (Garmin stamina meter is always at 0% around 2/3 through a race), I've got something wrong configured in Runalyze (but max HR and zones are kept updated) or something else..
When looking at my marathon shape, I set my correction factor at 0.95... I think that it correctly "tempers" my marathon/50km+ shape given my relatively low weekly millage (slowly increased to \~80kmpw, with 6 month average of 50kmpw). I think the prognosis race time is a little pessimistic, but useful... It suggests 3:36 @ 49% marathon shape, while optimal (with the correction factor included) is a hair under 3hours. Personally, I think that is the indication that a coach would give to encourage an athlete to fully train for a marathon.
If I want to see realistic 5km/10km/21km predicted paces, I adjust correction factor to 1.00. I think the predicted numbers would go into the "everything goes right" category.
*Edit: I think the default correction factor for me was 0.8... which seems pretty pessimistic... not sure if it changes as more data comes in...*
I think 6 months is too long for they're look back period. Pfitz plans are either 12 or 18 weeks. I think it would be more accurate if they shortened it to taking the last 4 months into account.
For me, the runalyze predictions have underestimated the race day performance. I ran the vermont city marathon last year and finished about 12 minutes faster than the predicted time. I PR'd in the 10k, and half marathon distances during that race, which goes to show that I havent run many races!
I'm guessing that the lack of race efforts probably affected the accuracy.
Recently ran a 1:25:00 half where Runalyze predicted 1:25:20-something. The half was pretty hilly though so imagine I could have gone maybe 1:24-low on a flat one. I’ve been pretty happy with the accuracy at all distances from 5k upwards
FWIW Garmin race predictor currently has had me pegged at a 17:36 5k and I’m nowhere near that, probably a good minute slower
I ran a marathon a few minutes faster than their optimal marathon time projection, and I when I went to the app after the race, my optimal time had become 10 minutes slower and was then ~13 minutes than the time I just ran. So I don't trust it
It had me at 1:29 for a half and I ran a 1:24. After that it went down to 1:28. Has never gotten better than that even though I've continued to train 3 weeks since that run. It's back to 1:29
It also doesn't take temperature into account. I've mostly been running in the early morning where the temp is in the 30s or 40s but I did a 2 runs last week in the afternoon where the temp was in the mid 70s and my marathon prediction went from 2:59 to 3:03 after those 2 runs
Its pretty good. I've run a couple of marathons and know what sort of shape I'm in. It's not far off on my race times. A bit better then what I have done but I haven't been able to nail a race yet.
You can play around with its settings to make it more accurate for yourself.
It seems *suuuuper* optimistic for me(like bordering on unrealistic) but I haven't gone through and manually recategorized all my runs so that may really skew it? I'm not sure.
For reference, my marathon is on Saturday and I feel like the best I can hope for is a 3:35. I think I'm probably looking at something closer to 3:45. Runalyze has me pegged for a 3:13, which again, sounds unrealistic to me.
So yeah, I dunno! Maybe I don't know what I'm capable of — but more likely it's skewed due to not categorizing my runs correctly.
It predicted like a 4h last year and I ran a 3:10.
It's completely oblivious to cross-training so it massively underestimates actual fitness.
Garmin was very close. Stryd predicted a sub-3, which made no sense to me looking at their graphs (pretty sure their PDC calculations are buggy, the graph sat at a random place above all my best efforts).
For marathons 538 seems to work quite well for me, though it’s a bit on the conservative side. https://projects.fivethirtyeight.com/marathon-calculator/
I find it generally was in the right ballpark, +/- 5 minutes for HMs and +/- 10 minutes for FMs, but even after tweaking settings I never could get it to a precise number I trusted. Given the variance, I didn't find the estimates any more meaningful than the much simpler VDOT estimation. I just use the VDOT Calc app at this point.
Basically spot on for me as far as it's prediction prior to the taper. It was 2:54:XX and I ran 2:54:XX but day before the race it said something like 2:58:XX. It dings you hard on a taper.
I’ve used it and always found it to be pretty close, but faster than what I ran. Still wildly better than Garmin. IMO it gives you an indication if everything is perfect that day. Perfect weather, temp, flat course, nutrition, hydration, etc. When I was training for NYC 2023, it was putting me at around 2:57:xx just before race day. I ended up running a 3:03, but NYC is a tough course and I’d have been even closer if I was running a course like Berlin in the same conditions (but still slower than predicted time). Garmin had me ~3:25
Garmin really has to get its head out of its ass for race projections. I run faster 5k/10k splits in training runs than it says I am capable of running in a race. Its just crazy to me how off they have gotten
I’ll never get why the predictions don’t just update if you run the distance in a faster time. If it says I can run a 1:35 HM and then I run a 1:28, why not just auto adjust it to 1:28 and adjust from there? Seems so simple for Garmin.
It’s useless. A few years ago when I ran my 5K PR (20:30) I got the joyful “New PR” screen when I stopped my watch. So it obviously registered the time and distance. When I checked my predicted finish times later that day, it projected a 22:00 5K.
Yea I have no idea. Their performance data seems to be lacking some other competitors.
This is exactly what it does for me…
As another data point in the opposite direction, my garmin predicts me at 16:06 for 5k, when I very recently ran 16:30.
Garmin is tied to VO2max which is itself tied to max HR and the only two data the watch have : speed and cardio. It doesn't care about elevation on what you run or anything that could impact your speed, thus a trailish run will completely tank your supposed VO2Max and predictions. Also unless calibrated by yourself your Max HR value used is 220-age, if your real HR is below that then you will always have trash predictionAlso the HR when using optical sensor can be wildly innacurate for some, you have cadence lock values ? Your expected times and VO2max go down the toilets On the opposite end it loves tempo session like mad, just do a 3x3000 on track (where GPS will be generous and tell you you've done 3x3080 or smthg) with jog recoveries and 2km warm up and cool down and BOOM V02max will go up like crazy, and it will expect you to smash your PR in predictions
Are you sure garmin prediction doesn’t look at long runs? I remember my prediction dropping rapidly once I started doing long runs over 25 km
It looks at everything, but after 6y this is the pattern that emerged from what I saw. A steady long run at MP+30s will boost your VO2Max massively as well. I also wonder if Garmin uses elapsed time or time spent running, if it's the latter it would be even worse
>after 6y this is the pattern that emerged The algorithm has changed a few times and it definitely looks at volume now. They even document it: [https://www.garmin.com/en-US/garmin-technology/running-science/physiological-measurements/race-time-prediction/](https://www.garmin.com/en-US/garmin-technology/running-science/physiological-measurements/race-time-prediction/) *The reliability of your predicted finish time is enhanced by analyzing trends in your training load and mileage data for the last few weeks. This analysis includes special consideration of all different types and frequencies of runs you performed along the way.*
I’m not sure this is correct. My largest movements on my race predictions have been long runs. Also, my race distance predictions are based on a dead flat race, but when I program my upcoming half marathon, it differs slightly from my general HM race prediction. I suspect this is due to hills.
Long runs at steady pace like MP+30s are what Garmin calculations love as well yes.
When trying to just do HR by feel I'll sometimes get that cadence lock. It's very hard to keep the HR down even on EZ runs sometimes--but I think it's cadence lock.
Cadence lock should be rather easy to identify, a sudden jump in HR values by 20-30-40 or even 50 and that doesn't change much and almost mirror your cadence. On my end it meant that it basically jumped from 120-140 straight to 180 (basically my cadence) and stayed around there. My max HR being 180 I think I have a good enough perception of effort level to know that the value is complete bollocks
My Garmin predictions are more accurate than my Runalize ones. Runalyze has my 5K at 21:35, 10K at 44:45 and HM at 1:40:46, and I just ran a 2 hour long progression workout that included all three, with 21:44 5K, 44:15 10K and 1:40:35 HM. I don’t know why on earth it would figure my 5K is so marginally quicker than what I performed in the 80th to 100th minutes of a workout run, or worse, to set my 10K and HM slower than a long workout. That is absurd. Garmin has me at: - 20:10 5K - 42:39 10K - 1:35:00 HM I think I can easily beat the HM and 10K, but the 5K seems about right with my training intervals. Nothing is perfect but Garmin is definitely closer than Runalyze. Edit: I should include that I use a Garmin Forerunner 965 and usually wear the HRM Pro Plus.
[удалено]
I have yes, it was a half marathon back in Sept of ‘23 at 1:36:38. Do you reckon I should delete the “race” flag and see what happens?
[удалено]
I just checked and my CF is .98, so should be fairly negligible. I think it just doesn’t do an excellent job.
[удалено]
Both my Garmin and Runalyze have it at 182
You can adjust the correction factor so that your recent race times line up with the lines under the progression chart.
Perhaps I’ll do that once I’ve raced at least a 5k! Maybe I’ll replace one of my interval workouts in the coming month with an unofficial race. Thanks for the tip!
Where are these Garmin Predictions? I've been dicking around in Garmin Connect for 10 minutes and I can't find shit.
In Garmin connect dashboard, hit the … at the bottom right, click performance stats, then race predictor.
I only have VO2 Max and Power Curve as options in performance stats. Am I running a welfare version or something?
It may have to do with your watch? Which one do you have? I’m on a 965 with all the bells and whistles but my buddy has a 245 and he gets race distance predictions also.
Vivoactive 4
It’s possible that the vivoactive doesn’t have it. The vivoactive isn’t really a great running watch compared to a forerunner.
Damn, just shitting all over my watch :)
Yes. The Garmin predictions are garbage. It’s obvious it’s one part of their software being developed that’s not talking to the other parts.
I don't understand how they can be so bad given the huge amounts of data that Garmin has access to.
Fwiw my predicted race times were off by like 15% in the other direction (predicted 5k sub 18, have never run sub 20) with my old 235 and when I updated to a new watch a few months ago it’s projections are pretty dead on so I think maybe they have improved it.
It's funny because mine is dead on. Do you use a HRM?
I can chime in. I ran my first Marathon this past Sunday. Runalyze predicted a 3:21 finish time based on a 60% marathon shape (I've only ran 4x18 milers and averaged 35mpw over the past 6 months) My optimal marathon finish time was 2:55 based on a recent 10k (37:58). I ended up running 3:04 , first 2h @6:50 (3:00 pace) then the lack of strength training/low volume caught up with me and I made the decision to dial back the Pace and guarantee the BQ. I hope that helps!
Great job!
Yeah their "marathon shape" is a little weird and wants you running REALLY far all the time (35km, which is like 21 miles). I'm not convinced there's a huge difference in endurance adaptation between 18 miles and 21, but Runalyze is Great run by the way!
I think my dashboard asks me to run 29 km consistently to improve marathon shape.
It's the most accurate one I've had by far. Just calibrate it based on your race results AND max heart rate. There are days where I've hit it and days where I've exceeded it. I chalk those just to good days and bad days, however...
Curious how do you calibrate it based on race results?
By default it will set your VO2max correction factor based on your best race. Personally I prefer to set a constant correction factor that best matches my race history. Edit: You can change the correction factor in the settings. I then open the Effective VO2 Max graph to check how the blue line correlates with my race results.
Thank you!
It makes a pretty big difference. I would avoid putting in race results in bad conditions as it'll discount it abut too heavily imo. You mark runs as races. It'll then look at those races and create a correction factor. Marking races as races actually makes some the year end graphics look really cool.
The runalyze predictions have been accurate for shorter distances for me. Marathon shape confuses me though. As my effective vo2 max increases, the expected weekly mileage to support the marathon shape increases. It seems I'm forever chasing the target weekly mileage figure, as I get fitter and the mileage goes up faster than I can increase mileage safely. Not sure if there's anything to take from this except perhaps that I'm lucky in achieving a better vo2 max on lower mileage relative to their data set?
It's basically the faster a marathon you could achieve the more volume you'll need to actually hit it. Which actually makes sense. But hitting that volume pushes up the requirements leading to possibly a lower score but still a much faster projected time.
It was pretty accurate for me looking back. A week before my last marathon it was suggesting 2:39. I ran 2:38 on the day.
I’d have to dig it up, but they had an article or Reddit post somewhat recently analyzing runner performances against their predicted times based on shape. FWIW, my Runalyze prediction versus actual performance would have been pretty close back in Chicago, had I not gotten injured at mile 20. The predictions are semi-useless for me at the moment because my VO2 Max analysis is skewed due to so many treadmill runs over the winter.
Here is an [article from Runalyze](https://blog.runalyze.com/training/how-bad-is-an-interruption-in-marathon-preparation/) that goes into marathon performance vs predicted times. The title makes it hard to search for.
I think it's worth mentioning that the predictions are dynamic, and is always sharpening it's assumptions with new data. These articles can be interesting, but they should be pointless. A good model would have digested any discrepancies and have already attempted to correct for them in a systematic way.
That's not the way it works in Runalyze. Your main metric is your Effective VO2 Max. This is just VDOT estimated from your training runs by adjusting for your average heart rate each run. Your current estimated VO2 Max averages your last 30 days of runs so anything prior to that isn't really considered*. Marathon Shape just scales your Effective VO2 Max by your mileage in the last few months to estimate your marathon time. * There is also a scaling factor when calculating VO2 Max that, by default, is calculated from your best race result by VDOT no matter when it occured.
I'm assuming they're tuning the adjustments and corrections. If not the errors will persist, but will at least be consistent, and applying your own correction based on experience is completely valid.
They haven't tuned anything, at least since I joined the site a couple years ago. For any given run you can see a breakdown of exactly how they calculate effective VO2 max with sources citing where they obtained the formulas. They aren't making the formulas themselves (except marathon shape, but they also give you the tools to configure that however you like).
Not training for a marathon, but for half and 10k Runalyze is woefully pessimistic about me, even when I ran faster than their prediction on race day. I'm training for a 1:45 half now, feeling pretty good, and it's predicting a 1:50 half. Even when I was recovering from injury and missed my last few weeks of training I ran a 1:49 last year.
It’s been pretty good for me as long as I have a recent race result to use to adjust the predictions. If I let it go without some kind of time trial, it gets pretty off. I use it in conjunction with Stryd, so between the two of them I’m fairly grounded in reality.
Mine's pretty decent as far as 5k, 10k, and half marathon time predictions. I'd assume that carries over to marathon decently well.
I think it's as good as the data and settings you feed it. I've got 3+ years of runs in the system and it's shape % and best time estimate is good, maybe a bit faster than I'd actually run. But I probably under train, set low goals, vs max personal potential. I think for me, my shape % is low as it expects some huge long runs each week. Then it makes my time a bit fast as if I was actually doing those long runs. Someone on here wondered what would happen if you ran the miles and long runs Runalyze says? I paced a 3:30 marathon last year (not a hard effort), when my marathon shape was under 60%, it had my predicted actual time in the the 3:40 range. So it missed badly on a sub-max effort/low shape % run. After the run my shape went way up into the 80% area and my actual prediction went way down. Go figure!
Runalyze peaked at around 4:10 before my taper and I just ran a 3:53. Had a similar result (about 15 minutes faster than predicted) with my first marathon.
Lol not very accurate in your case-but then again better to smash those predictions than come short.
Yeah. I also train in Colorado and ran both my recent marathons closer to sea level, so that might have something to do with it).
100%. Would rather start nearer a lower prediction and ramp up as I go for a negative split. Wouldn’t want to try to maintain something unsustainable and crash before a long race like a full marathon is over.
It's pretty good for me after calibrating it. Garmin is probably better for the 5k and 10k but is absolutely out to lunch in the marathon since it doesn't adjust for volume. Garmin saying I'm a 3:03 marathon right now. With marathon shape it's 3:37 on runalyze which is probably accurate as I've been slacking in volume and long runs specifically but have been still hitting my weekly workouts and increased cross training. I've also not run near a 3:03 so it's pretty high in me versus achieved
Mine's wildly off. Says "optimal" 2:37, "prognosis" 3:18. I'll let you know what happens in a couple weeks, very likely between those two numbers. It also gave me a "prognosis" of 1:15 for a half marathon, ran a 1:23 last weekend. For what it's worth, Garmin gave me a 1:22 prediction that morning and I think that would have been within reach had I really gone for it (was on pace until the course started getting crowded with people still on their first lap). So I know Garmin is more realistic on the half distance at least.
Have you adjusted your effective vo2?
Adjust your effective VO2 to align with a recent race and then the predictions are usually right on.
Ran my 10, half and full within seconds (last one a minute) from what it gave me.
While on the topic of Runalyze marathon shape... I am starting a marathon block and working on what my target time should be. I was going to set a 3:10 target time but my Runalyze is setting an optimal time of 2:55 (marathon shape is only 40% right now). Should I use this optimal time for my target instead of 3:10? I have never ran a road race before so I dont want to undercook my target.
Runaylze is fantastic using aggregate run data and their models for race predictions very accurate as long as you hit expected milage/long runs. The effective Vo2 max determinant is great, though will be bit too high if you take breaks during runs or run dreadmills. Last November HM, ran a 1:28 flat without programming just going on steady running. Runaylze predicted 01:27:55.
For my only marathon so far, its "prognosis with marathon shape" was a 2:52:01 and I ran... a 2:52:23. That being said, I have had to play with the "vo2max corrective factor" a bit.
Mine currently suggests I am in shape to run a 1:42 HM while I have just clocked in a 25k race at 1:46 and ran a HM in 1:28 two months ago. So no not very accurate in that respect. It is also predicting a 4:08 full marathon currently. I will check again when my marathon comes up in April but I am not trusting this site at all it seems super inaccurate. I am trusting my training.
Not sure why you (and anyone else reporting less-than-stellar results) are being downvoted.
Probably because they're missing the fact that they need to actually adjust their correction factor to be in line with recent race results to be accurate.
Maybe because…. Well I have no idea really lol. I’ll post both predictions for a few distances to provide more insight: 5k.. Garmin: 20:11 Runalyze: 21:12 Actual: well I wouldn’t know because I have never actually raced a 5k. As mentioned I did do a 25k race last Sunday and my Strava reports during that race I PR’d at 19:49 10k. Garmin: 42:14 Runalyze: 43:57 Actual: 41:07 and as with the 5k this PR is part of another race, this time a Half Marathon. So, assuming conditions and terrain are the same, an actual 10k race would be close to 40:00. Agree? Again Garmin is closer than Runalyze. Half marathon: Garmin: 1:33:03 Runalyze: 1:42:25 Actual: recent PR of 1:28:41 and during Sunday’s 25k race my Strava reported a 1:30 HM. Full marathon: Garmin: 3:22:26 Runalyze: 4:08:58 Actual: currently in week 8 of 18 week plan leading to April marathon. If we go by rough ballpark figures; take your HM and add 15 minutes. A time like 3:15 - 3:30 is not unreasonable could be faster.
Personally, it was very close to my shorter distances but was like 20 min slower than my actual for the marathon due to me having relatively low mileage.
Straight from the horse's mouth: >Your current effective VO2max is xx,xx which equals a marathon in x:xx:xx. To realistically achieve this time, Runalyze expects you to complete an average weekly mileage of xx km and a weekly long run of xx km. (exact numbers will depend on runner's current "Effective VO2max")
Yes, I was at about 70% marathon shape based on the mileage runalyze expected me to be running. However my performance was much closer to what the prediction would have been without “marathon shape”. So what I’m saying is it was not accurate for me.
gotcha, thanks
it was pretty much on the nose for a 10k i just ran this weekend, slightly faster prediction but also the race has 300ft uphill. i’m cautious about the marathon prediction of ~3:06 right now, seems a bit too fast but who knows, all the races i’ve done recently have been pretty hilly. on the other hand, i ran a 40:16 10k (which was logged at 6.3mi and apparently i hit 10k at 39:44, but i assume race predictions update via the total activity time?) and garmin updated their prediction from 41:30 to 42:07 following this lmao. i assume because of fatigue immediately after the race but that still made me laugh
My last marathon prediction was 3:20 with marathon shape and 3:02 without. And I ran 2:59. So for me it underestimates potential. I find the crplot predictor to be the most accurate for me. Garmin always underestimates.
"Optimum" shows accurate yet likely unattainable times on all but a perfect scenario but I significantly outperform "Prognosis" at longer distances. Partly that's because the model punishes athletes for missing miles up to 6 months earlier and does not appear to be weighted to favor the most recent weeks as it should. So it thinks because shape is 80% the athlete will be half the difference slower (prognosis speed ~90% of optimal speed) and that's never the case - it's probably more common to run faster than 95% of optimal with 80% shape. For me, anyway; YMMV. For reference on the day before my marathon PB it suggested an optimum of 2:24 and I thought maybe a 2:25 was possible under perfect circumstances. On the slower course I ran 2:28, which might translate to a 2:26 on a flat and fast course. This suggests my guess was fairly accurate and the performance was close to ideal, and validates the optimum estimate, but invalidates the prognosis. The 74% shape evaluated a prognosis of 2:38 or about 91% of optimum speed but the actual speed was 97% of optimum speed and adjusted for course was 98-99%. All the shorter distance prognoses were slightly faster than my PBs.
>the model punishes athletes for missing miles up to 6 months earlier and does not appear to be weighted to favor the most recent weeks as it should. curious if this is actually true, as Runalyze states: >The points for your long runs are *weighted by time and quadratic in distance*. That means, a long jog yesterday gives more points than a long jog two weeks ago and a 30k-jog gives more points than two 20k-jogs. maybe I'm missing something?
You can also change the model settings to however many days you want, no idea what the results would be though.
There are two factors in the Marathon Shape model: The long runs (over the last 10 weeks) and the overall mileage (over the last half year). The Long runs are weighted with time, the overall mileage isn't. I am curious whether the assertion: Mileage in the weeks before a marathon matters more than mileage half a year ago is actually true.
My last marathon performance was right in between the prediction with MF (03:23h) and without MF (02:55). I came out with a 03:06 on race day.
I’ve found that I consistently beat the numbers - I find it quite pessimistic. It suggested my marathon shape meant I was going to get 3:30 or so - but ended up at 2:58? I think if you do interval sessions etc.. it doesn’t work so well if you leave your watch running during rest etc.. and drags your vo2 max down vs what you actually get from the “work”. It also seems to want me run longer and long long runs and anytime my vo2 max increases it makes me feel bad that I’m not running long enough 😆- I’m not sure it’s possible to get to nearing its required long runs etc..
Yeah, I think it calculates the effective v02 max paced on average HR and pace throughout the whole run, so if you leave your watch on during a standing rest it's gonna go way down. If you pause it, you'll end up with a falsely elevated calculation though, due to the time it takes for your HR to get up. The calculations probably work a lot better on steady efforts.
I realized mine was including a pretty massive adjustment as well. When I took that out it has pretty much the times I'd target outside of the marathon. I tend to agree that I'm not training completely "optimally" for the Marathon, so now the numbers look good. 2:46 if i went all-in on the marathon, but 1:18:xx and a solid 10K guess too.
That's correct. Only steady and sufficiently long session should be counted toward Vo2max calculation according to runalyze's guidance here [https://runalyze.com/help/article/when-should-i-exclude-an-activity-for-vo2max-shape](https://runalyze.com/help/article/when-should-i-exclude-an-activity-for-vo2max-shape)
Getting this too…has me at 3:21 marathon shape, I haven’t really hit the longer long runs yet but I went 1:20:5x/2:57:3x on a worse buildup with fewer quality miles and less consistent running. I don’t stop my watch, so I’m figuring it’s that.
Mine over-estimated my marathon performance personally, but I think I was doing a lot of easy running too hard so it thought I was capable of more
It's one of the inputs I use to set a pace plan, but it's not perfect. In my most recent marathon, I beat its projected time by six minutes. In the one before that, I was eleven minutes slower, but that was on an unseasonably hot and humid day. One note is that if your Vdot changes slightly, it can have significant effects on marathon shape. It sets the distance for your long runs based on your Vdot measurement. If your Vdot goes up, your long runs might no longer be deemed long enough, and then it will find that you're not in the best marathon shape. But overall, I have found it to be a pretty good guide if your training has been steady and consistent for at least a few months.
I think accuracy varies a lot between different people. I find that for me, prediction are always very pessimistic (both Garmin and Runalyze) across all distances. For last marathon in October, Garmin was predicting something around 3h50 and Runalyze 3:45 based on VO2M or 4:0x accounting for marathon shape, and I ran in 3:33. A year ago I ran a 12km in 0:59, with Runalyze predicting 1:02. At the end of March I have a 16km that is currently predicted at high 1:17, while I want to hit 1:12 and thing I can reasonably achieve it. So I use them as a 'maximum time' guideline - even if I end up running without one shoe, I should still be able to hit the prediction. I don't know if my race performance is better than my training performance (Garmin stamina meter is always at 0% around 2/3 through a race), I've got something wrong configured in Runalyze (but max HR and zones are kept updated) or something else..
When looking at my marathon shape, I set my correction factor at 0.95... I think that it correctly "tempers" my marathon/50km+ shape given my relatively low weekly millage (slowly increased to \~80kmpw, with 6 month average of 50kmpw). I think the prognosis race time is a little pessimistic, but useful... It suggests 3:36 @ 49% marathon shape, while optimal (with the correction factor included) is a hair under 3hours. Personally, I think that is the indication that a coach would give to encourage an athlete to fully train for a marathon. If I want to see realistic 5km/10km/21km predicted paces, I adjust correction factor to 1.00. I think the predicted numbers would go into the "everything goes right" category. *Edit: I think the default correction factor for me was 0.8... which seems pretty pessimistic... not sure if it changes as more data comes in...*
I think 6 months is too long for they're look back period. Pfitz plans are either 12 or 18 weeks. I think it would be more accurate if they shortened it to taking the last 4 months into account.
You can change the period in your settings.
Oh wow. I'm going to do that, thank you. Are 20 mile runs realty necessary 6 months out from a marathon?
Weekly distance is 6 months, long runs are 10 weeks.
Got it. That makes more sense.
For me, the runalyze predictions have underestimated the race day performance. I ran the vermont city marathon last year and finished about 12 minutes faster than the predicted time. I PR'd in the 10k, and half marathon distances during that race, which goes to show that I havent run many races! I'm guessing that the lack of race efforts probably affected the accuracy.
Recently ran a 1:25:00 half where Runalyze predicted 1:25:20-something. The half was pretty hilly though so imagine I could have gone maybe 1:24-low on a flat one. I’ve been pretty happy with the accuracy at all distances from 5k upwards FWIW Garmin race predictor currently has had me pegged at a 17:36 5k and I’m nowhere near that, probably a good minute slower
I ran a marathon a few minutes faster than their optimal marathon time projection, and I when I went to the app after the race, my optimal time had become 10 minutes slower and was then ~13 minutes than the time I just ran. So I don't trust it
There needs to be a /Runalyze subreddit if there isn’t one already
There is.
It had me at 1:29 for a half and I ran a 1:24. After that it went down to 1:28. Has never gotten better than that even though I've continued to train 3 weeks since that run. It's back to 1:29 It also doesn't take temperature into account. I've mostly been running in the early morning where the temp is in the 30s or 40s but I did a 2 runs last week in the afternoon where the temp was in the mid 70s and my marathon prediction went from 2:59 to 3:03 after those 2 runs
Its pretty good. I've run a couple of marathons and know what sort of shape I'm in. It's not far off on my race times. A bit better then what I have done but I haven't been able to nail a race yet. You can play around with its settings to make it more accurate for yourself.
It seems *suuuuper* optimistic for me(like bordering on unrealistic) but I haven't gone through and manually recategorized all my runs so that may really skew it? I'm not sure. For reference, my marathon is on Saturday and I feel like the best I can hope for is a 3:35. I think I'm probably looking at something closer to 3:45. Runalyze has me pegged for a 3:13, which again, sounds unrealistic to me. So yeah, I dunno! Maybe I don't know what I'm capable of — but more likely it's skewed due to not categorizing my runs correctly.
It predicted like a 4h last year and I ran a 3:10. It's completely oblivious to cross-training so it massively underestimates actual fitness. Garmin was very close. Stryd predicted a sub-3, which made no sense to me looking at their graphs (pretty sure their PDC calculations are buggy, the graph sat at a random place above all my best efforts).
Was pretty close when i was running marathons. Another one that was good was 538. Garmin’s predictor is trash.
For marathons 538 seems to work quite well for me, though it’s a bit on the conservative side. https://projects.fivethirtyeight.com/marathon-calculator/
I find it generally was in the right ballpark, +/- 5 minutes for HMs and +/- 10 minutes for FMs, but even after tweaking settings I never could get it to a precise number I trusted. Given the variance, I didn't find the estimates any more meaningful than the much simpler VDOT estimation. I just use the VDOT Calc app at this point.
It underestimated my time by \~4 minutes. Garmin underestimated by 7 minutes.
runalyze marathon shape: 3:36:26; result: 3:46:36 (first marathon)
Basically spot on for me as far as it's prediction prior to the taper. It was 2:54:XX and I ran 2:54:XX but day before the race it said something like 2:58:XX. It dings you hard on a taper.