Why is Apple Watch VO2 max dropping despite improving running fitness?

[Riverz]

I have an Apple Watch and I make sure it’s tightly worn on my wrist

I have attached a photo of my graph and I know it’s not a big decline but it’s really driving me mad because it doesnt make sense. Am I missing something?

I started running for the first time in Sept 25 and got 40.6 readings. At that time could barely run for 2 mins at a time!

I got a viral lung infection in November/December and it was cold out so I was running less hence gaps

I recovered from this viral infection and no further issues with a cough or any symptoms

6 months later after starting and getting 38.1 readings now, but I can run a 5k without stopping (slow pace mind you tbh).

I’ve also tried getting a VO2 max reading from walking to see if it’s just a glitch but I get the same reading if running or walking and it’s going down, not up?

Has anyone else had this? Is it something to be concerned about?

How often are you exercising? What other exercise are you doing? What’s your time per km?

A watch can’t measure VO2 max at all accurately, I’d just ignore it.

VO2 is best judged by fast hard slightly more prolonged exercise - for instance running a mile as fast as you can. If you incorporate some faster work it'll probably go up a bit. But bear in mind it does decrease with age too.

I don't really trust it either. Mine won't go above 35, and I've been running anywhere from 5-22km each time, four to six times a week, over the past two years. I just can't get it higher, even though I feel much fitter.

It has something to do with how high your heart rate is, and how fast it drops. So if you run super slowly, and your heart rate stays low, it assumes that you are more fit and your VO2 goes up! Even if you feel like you're working less hard. Or if you stop when you're at your highest heart rate, and then stand still for the first minute or two, so your heart rate drops quickly, that increases the VO2. But if you cool down gradually towards the end of your workout, and then stop, and maybe walk a bit as you are going home afterwards, then it calculates it from a lower heart rate to begin with, and the fact that you're still walking means it's still going to be a bit higher, so then it assumes you're not as fit. But your fitness is actually the same, but just the circumstances give it different info.

And the heart rate zones it uses aren't very individual. I think that's probably why my Vo2 is still so low, as my heart normally goes very high very quickly, even when I'm at my fittest.

I am running in zone 2 HR pretty much all the time. This is how I have managed to get the stamina to run a 5k without stopping because I had never run before and found it so so hard, I failed c25k so much because I was going too hard/fast all the time and didn’t pace myself - the walking breaks made it too hard for me to pace myself I would start off so fast and then crash out before the timer. This also means I’m getting less injured too

I will start running faster (I hope), but it’s based on my HR so my current pace is 7.23km (fastest so far) but usually around 7.45km

I run 3k 2-3 times a week and usually at least one 5k a week now

I did wonder if it’s lower because I am basically plodding the same slow pace and it’s not really seeing much variance, whereas before I was interval running

Is interval running better for your cardio health overall? I found it stressful

Watches and vo2 max is not an exact science.

mine dropped when I was injured (understandably) but when I came back it went back up quickly, even though I didn’t feel very fit. Then it dropped again as I started to feel fitter in myself again. I think I have figured out that even though I was finding it all easier my heart rate was going higher and not coming back down properly until I stopped.

I’ve pushed through as I’m marathon training and Now I’m back at my usual running level and my heart rate now recovers, after a big hill or something, without me having to stop again it’s gone back up and is now actually higher than it was pre injury. I’m not sure feel fitter than I did pre injury but also not miles different.

To really improve fitness and running you need to do a mix of easy runs, tempo runs, intervals and hills. You probably won’t notice a lot of improvement if you stick to just steady 5ks (from experience).

My Apple Watch VO2 Max was insanely high when I purely focused on cardio - HIIT, Spin and fast running, think holding zone 4/5 for half an hour solid. Two years ago I swapped to heavy weights and zone 2/3 cardio and I’ve watched my VO2 plummet. It’s reading normal fitness levels now.

I’ve come to the conclusion that zone 2/3 isn’t as good for heart health? But it’s better for cortisol and I look way better, am far stronger, so it’s a trade off I’m really happy to make.

Do you have work outs on when you walk? If so you need to set them as indoor walk workouts or it will reduce it. That worked for me. Dog walks were destroying it.

I thought it was good for you but I am unsure now although I suspect it’s easier on your joints and reduces injuries! I was having mad injuries when I was going hell for leather. I also do a lot of weights which is zone 1/2.

I will have to up my game I think, I can start running in zone 3 I just find if I do that, I can’t get to the end of a 5k

I am 46 so was hoping I’m not completely past it yet

I know the watches are not great or that scientific

I’m 43 with a V02 max of 33 and mine says above average??

To improve VO2 max you need to train both Z2 and also do faster interval training/hill sprints/strides. So if you do one of your short runs a week a faster workout it will help push it up. Your body needs to learn to keep going for a long time and make those adaptations but it also needs a bit of stress/challenge now and again. Once a week should be enough though!

For reference, I'm 37 and run 5km in under 22 mins and my VO2 is only 51, so not significantly higher than yours. As well as fast runs I run slow and steady and also do intervals and cover about 40 miles a week. So I think you'd have to be doing significantly more, recovering faster and moving at a faster pace to see any noticeable change. It's hard to increase it.

Sorry I don’t know why it says average on mine, for my age I am in the ‘high’ zone but I have noticed a drop off. I’m concluding I’m just plodding too much and need to do something more active

I am plodding 5k in 38 mins 😂
yours is amazing time I could only dream of that

I will try doing something interval style this weekend and see if that helps!

I do 5k in 31 minutes and my V02 is 33, so yours is amazing and obviously your slower pace is fine as your fitter than me still! I do think intervals help push it up, I have noticed that when I do them.

@HappyCheesyI always wondered if my walk home affected it.

I have a Garmin 255 which has a bit more data showing anaerobic, high aerobic and low aerobic load and it's happiest when they're in balance and my exercise load is at the upper end of balanced.

It's anaerobic that I struggle to get the score up on.

There are so many factors here. I’m 47 and ‘above average’ but not ‘high’ seems right to me. According to my watch, my VO2 max is 33. I occasionally do a 5k (not a regular runner) and take 27-28 mins.

I take stimulants for ADHD so my resting heart rate is pretty high (watch counts only a small fraction of the sedentary readings, ie the lowest) but my heart rate when I exercise is definitely high. Would be 140bpm plus during even a slow run. When I didn’t take the ADHD medication for a few weeks last year, my VO2 max was climbing rapidly even though I was in fact ill and not doing anything more than walking. When I recovered, took the medication again, and got fitter it plummeted.

Obviously most people aren’t taking amphetamines every day, but I assume caffeine has a similar but weaker effect. Do you drink a lot of coffee?

51 is actually pretty high, well done you!

I went for a walk yesterday and it’s dropped even more to 37.7.

I am getting a bit bothered by this now but unsure what I could do about it?