Garmin Fitness Age! Bit Miffed :-) - Bridge to 10K

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Garmin Fitness Age! Bit Miffed :-)


I'm 54 and have had my Garmin (Fenix 5x) for 2 weeks.

Week one was pretty exhausting with some hard hikes as well as my 3 runs Garmin tells me I have a fitness age of 64

Week 2 just the regular 3 runs and a very hard hike yesterday with a lot of exertion because of the gradient. Apparently I now have a fitness age of 71

What gives?

Another question, My Garmin tells me I'm between 93% and 96% of my Max heartrate when I'm running, does this seem high and does it adjust itself over time?

Thanks :-)

27 Replies

I wouldn't worry about the fitness age too much. I am 29, managed to get my fitness age down to 23 (started at 44!), but after a long slow run I am back up to 30. I have kind of worked it out though, usually if you just do a couple of short, fast runs it manages to pop out a nicer number :)

Probably the slow pace, high heart rate of the hike might have skewed the results for you too.

Anyway I am sure it will be back to improvements in no time :)

No idea about the max heart rate stuff though sorry......

sTrongFuseGraduate10 in reply to motherduckling

Fully agree. If I go out and smash a PB, I generally find my fitness age improves, but then if my next few runs are at a more leisurely pace, I suddenly become even more decrepit than I was before I smashed the PB. It's all being "worked out" on pace, and heartbeat and given that the readings tend to be less accurate because of things like cadence lock and simply just working up a sweat, a lot of it is simply electronic passive-aggressive guesswork for the sake of giving us numbers to worry about.


This is why I don’t much like data. Disable the function and stick with your training plan. When you’ve finished, turn it back on and no doubt you will see some really positive changes. Also, you may want to slow down. Do you feel ok running, and not pushing yourself too much?

Rigpig in reply to ju-ju-

Thanks 🙂

I’m ok running up to my 30 minutes it’s a bit more effort after that on my long run but not terrible and improving all the time. My 30 minute benchmark run is comfortable with slight increases in pace and distance covered every Tuesday. I’m watching some YouTube stuff on the settings right now and learning a bit more.


Oh dear, garmin being rude again 🥴 the watch gathers lots of data and so far only has 2 weeks worth so will take time to settle down what's right for you. For max HR I changed my HR % bands as I was running at numbers like you. It does that 220 - age x some% thing to calculate your max HR, I just changed my max HR reading to a nice high number and it recalculated each of the bands. Saw doc about it and general info was if resting HR was normal and recovery HR quick after run then nothing to worry about. All just numbers. Happy running

Seconding everything here.

I just ignore my personal Garmin data as it's only ever rude or inaccurate. Times etc useful (that's why I wear it😊) but HR & VO2 max etc are bonkers.

My watch is a hand-me-down from OH, so I suppose I'm cavalier about some functionality not being useful.

That said, if you find any useful YouTube advice let me know! Til then I know that my fitness is improving & my heart is fine, so I'll just keep running & resting as appropriate.

Happy running (but not in today's gales!)


I wouldn't worry too much; I'm 49 and the best fitness age Garmin has ever given me was 59. The heart rate thing is an approximation based on 220bpm - age, which may be pretty close, or may be wildly out depending on a number of factors that go into making you you.

The zones are a useful guide, but I can generally tell if a run has been harder or easier just by how I feel at the end of it; I don't need fancy charts to tell me I've pushed myself.

There's also the issue of cadence lock, which many wrist-based HRMs fall foul of; where they lock onto your footfall rather than your heart rate, so the faster you move your legs, the harder your heart appears to be beating.

I tend to look at the trends from run to run rather than the actual numbers. If a run felt harder, I expect to see a higher percentage of it in the red zone. If it was easier,. more of it will have been in the amber zone. If it was really easy (never happens) some of it may even have been in the green zone. I look at the relative amount of time in each zone, but don't look at the actual heart rate numbers which, if the were accurate, probably meant my heart spontaneously combusted on the pavement in front of me about 6 months ago.


Ah the joys of data. My VOX number has dropped by one since I started running regularly. Also my Garmin watch (viaactive3) shows the same number as the app, but the watch doesn't reflect my 50th birthday, so says fair while the app says good :-)

As others have said, take the fitness age with a pinch of salt. Mine says 39 today.

As for HR, I look at it the same as sTrongFuse, I ignore the numbers mostly and focus on the general zones that I end up in. I run 3 times a week, usually twice on a threadmill and once. outside. On the threadmill I try and stay below 160 not caring how fast I complete my 5k, on the road I tend to ignore the HR and try and run 5K as close to 30mins as I can, usually reaching 175 towards the end.


Where do you get that from? Is it with the VO2 max score? Mine says 20 and I'm nearly 45 🤣 Don't believe it but I'll take it 😶

TrawaGraduate10 in reply to Tasha99

I'm similar - it gives me much lower age than I am. I'm 36 but Garmin shows me 21. Pretty chaffed about it but no idea why?

My VO2 max is 38, my pace is usually around 7:30min/km, distance about 4-6km 3x week. So why? 🤪

Tasha99Graduate10 in reply to Trawa

I do have quite a low RHR. Could be that? Average of 40-44. Once last week it dropped to 28 🤣

TrawaGraduate10 in reply to Tasha99

Yes I do indeed! Around 55 per minute. Could it be that?

Bladerunner2049Graduate10 in reply to Tasha99

On the app (at least the iPhone app) go to Health and Performance and choose VO2 Max. You’ll see a number in a circle and underneath you’ll see a fitness age. These two numbers can be the same but most likely will be different. They are not the same thing.

Tasha99Graduate10 in reply to Bladerunner2049

Yes thanks got that. Wondered if there was something else somewhere.


Sorry but it made me laugh 😂 totally not the “result” you wanted. It’s clearly lying to you, ignore it


For the Garmin stats to be useful it needs proper data to start with. As sTrongFuse says, the formula for a default value is more likely to be wrong than right. It came from a bit of research where a straight line was drawn through a wildly varied set of results. It was never intended to be used for fitness tracking.

Assuming you have input your age, gender, weight etc. you need to input your average resting HR (awake, not sleeping) and your MaxHR. Your MaxHR must be at least the highest you have ever recorded. If you want a decent estimate, do a warm up then three hill repeats at max effort. Once you set that up and give it a couple of weeks to get a better VO2Max estimate, you should get some more meaningful data.

Cadence lock is unlikely on a decent Garmin. It's fairly obvious from the graphs if it does occur.

GranspeedGraduate10 in reply to SlowLoris

Hmm. This sounds useful. Hope I can remember it if I ever decide I want it all to work. Thanks. 😊

Rigpig in reply to SlowLoris

Thank you, I’lll do a bit of research on how to do this, I’m still finding new tricks with the Garmin all the time 🙂


As others have said I think it takes a little while for the data to settle down. And also similar to others I find my longer Monday run which is slower, sometimes knocks my V02 Max down a point, and then after a quicker run or two it ticks back up again.

In general I must say I love my Garmin for the way it helps me gamify running. There's always some stat I am trying to improve.


Oh I hope you ignore those stats! The way Ifelt on my run this morning I'm sure it would tell me I'm about 90!

Awwww, my Garmin Connect just gives me VO2 max, not fitness age. I do love a number (depending on the number 😂)

I do think a large pinch of salt must be taken when looking at the stats. They aren’t useless - a lot of us aren’t as fit as we would like to be and I know I find it difficult to look the scales (aka the ‘sad step’) straight in the face sometimes! But if the numbers demotivate you rather than inspire change, there is the option of switching them off - or don’t look.

It sounds as if you are doing great. Maybe have a fiddle with the user manual and make your Fenix work for you 😊


Also make sure your watch is a nice snug fit Rigpig, can't have your watch moving around when it's trying to study your blood flow. I shave my arm a bit where my watch goes figuring that if the sensor is trying to find it's way through a mass of hairy arm it might not get a good enough look at my blood flow.

Garmin calculates VO2Max etc from algorithms developed by a third party called 'firstbeat' and they measure heart rate variability

I've found my VO2Max to be pretty stable. When I started out it was about 42, a month later it went to 43 and has been gradually climbing steadily, I'm now at 46.

I'd like to say it's extremely accurate too! But I doubt very much that my fitness age really is 20 haha I'm 52.

ForbiddenPlanetGraduate10 in reply to Brian-P6

Snap on the V02 Max. Mine started on 44 but dropped to 42 after I spent 3 weeks on the IC. Currently it pings around between 46 and 47. For my age bracket the watch only reads up to 50 - so I am determined to get it to 51, just to see what happens. 🤣

It's all just a bit of fun.

What I find with the watch, as I wear it all the time is that it often starts "recording a run" as it presses against my wrist.

GranspeedGraduate10 in reply to ForbiddenPlanet

Mine did this until I figured out how to lock it. Simps, but different for models, so check the manual. Mine turned off during a run, so I searched out the lock!

ForbiddenPlanetGraduate10 in reply to Granspeed

Thank you Granspeed - that's a good tip! 👍

If it thinks you’re in your 70’s then it probably thinks your max heart rate should be about 5 and is telling you to sit down and have a Worthers.

I keep hearing that wrist-tech is sometimes hilariously off the mark.

Hey? Here’s a thought. Can you start drawing your pension off the back of that? I might have to invest in one.


Well, Rigpig, by now I hope you are reassured. Just to give you some perspective: I wondered for ages why no matter how hard I worked on a run, my Garmin always said I had “maintained” or “slightly improved” my cardio fitness with “this easy aerobic activity.” 😳🤔 And there I was, gasping at the end of a big effort up the hill! Then I found the various heart rate zones and VO2Max. Oh. It’s all an algorithm. I’ve left it all alone for fun, because the fitness age loves me - I am a fit 20 year old! (Not for 50+ years!). And my VO2Max is 36 and rising. 🤣🤣 It’s all a good laugh unless you do more tweaking than I ever want to. But there’s good stuff in those answers above if you really want to make it work. Have fun. 😊

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