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What do you think the accuracy of performance metrics in the Forerunner 245 is?

A_Valens
over 3 years ago

I have been using the Forerunner 245 for a few months now, and I have to say that I am generally disappointed with the accuracy of the performance metrics, VO2 Max particularly.

To give a bit of context, I am 43 and started running quite late, ~18 months ago. I know I am not an outstanding runner, as I have always found running very painful and I also generally run pretty slow (around 6.55-7.00 minutes per k), but nonetheless I got very passionate about it.

I completed a couple of 10k programs and am now training for the half marathon.

When I started off, about a year ago, with the Forerunner 45, my estimated VO2 max was around 41-42, fitness age 32-33.

As I started running more and more, and clearly became fitter..well that's when the performance metrics just started falling dramatically (?). Just to give an idea, when I started off running I wasn't able to jog for 10 minutes in a row. I can now run 10k in about 1 hour and 10 minutes, and some days I have no problems running up to 15 k.

What I find most disappointing is the ability of the metrics NOT to reward achievements, and immediately punish weak performances. So for instance, a few weeks back I ran a 5k in 29 minutes, and was generally in a period of good shape, running faster than usual with a heart rate barely above 150 beats per minute. Considering that it took me months and months of training to be able to run my first 5k, and even more effort to be start running it at about 7 minutes per k, I think this is a good result. However, my VO2 max or fitness age didn't increase of 1 single point during that period. As soon as I went for a long run on a bad day, during which I had to stop because I was feeling tired, my VO2 max immediately dropped in the poor region, my fitness age increased. my training indicators immediately shifted in the unproductive area.

I am just wondering how is this possible, and where I can get some insights on how those metrics are computed?

I still enjoy the device and running quite a lot, but I guess understanding how those metrics are calculated would help me get over the disappointment I sometimes feel.

Thanks!

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  • 0 over 3 years ago in reply to CT-7567

    I am not using a chest strap, but I agree that HR data might be inaccurate. Originally, especially when I started running, I was noticing that every run, even if it was a light easy jog during which I was not struggling much, indicated that I was spending most of the time in Zone 5, which did not sound very realistic to me. As a consequence, I changed the HR zones based on my rest HR. This caused the HR zones to look much more accurate, in the sense that it was matching more realistically the level of effort I experienced during the run. Also, my HR has gradually decreased as I progressed in my training. Needless to say that this hasn't improved my Forerunner 245 estimated VO2 Max at all.

    I also use RUNALYZE as I read somewhere that it had more accurate estimates. In RUNALYZE, even though my VO2 Max remains generally low (around 32, 32.5), I definitely can see an upwards trend with more intense workouts in the last few months. This trend is not reflected in my 245 metrics, that just keep getting worse despite my fitness clearly improving.

    As I mentioned in the OP, when I started running I was barely able to run 5 minutes continuously. I remember training for my first 5K and getting stuck for weeks and weeks on a workout that required to run 2 sessions of 3 and 5 minutes, alternated with walking. It's worth noting that I'm not overweight, I'm 1,83 m for 78-79 kg. I can now run 6-7 miles without particular effort. That's why I simply don't get how my 245 fitness metrics keep getting worse and can be so merciless Slight smile

  • 0 over 3 years ago in reply to Aslam
    Aslam said:
    Seems like the fast stuff pushes up my v02max.

    Since you and shared some insights and thoughts about your training, maybe I can also share some useful experience.

    I am 42 years old now and running regularly for about 25 years. Right now my FR245 says my VO2Max is 54, so not too bad for my age.
    Most of the years, especially in my younger days, I did not care for training plans or HR zones and just did medium long runs in a medium tempo, because I liked it. Only when I started to prepare for my first half marathon ten years ago, I started using a running watch with HR metrics and following a training plan. Since then I did more then ten half marathons and lowered my record from 1:47 to under 1:35.

    Like Aslam says: The fast stuff will make you fitter and push your VO2Max, right. BUT (!) always keep in mind, that you should not do to much of the fast training.
    Fast things like running intervals and longer tempo runs sure will push your maximum capacity of your cardiovascular system, which can be shown in the metric of VO2Max. But also, those type of runs will be very stressful and hard for your muscles and will give you long recovery times.

    So my suggestion from years of training for endurance runs like 10km and half marathons is:
    The low intensity "Aerobic"/Zone 2 runs are the most important!
    Those should be at least 2/3 of your training, or even up to 80%. The remaining 20% to 1/3 can be intervals and long tempo runs (Both anaerobic/ Zone 4 - Zone 5).
    NONE of your training should be in the medium section of Zone 3, this is just a dead end. Zone 1 you can do as much as you like, it will not help you getting fitter, but be good for recovery.

    So why so much Zone 2 / Aerobic? This is the classic "Jogging" and can feel little to slow sometimes, but this is the basis for all stamina. Your body will learn to provide energy over a long time and your muscles and metabolism will also adapt. The good thing is, this is not such a stresser like fast runs (Zone 4/5), so you can do A LOT of it - and you should. Especially, at least once per week, you should do a long run (60 or 70 minutes at least, up to two hours) and strictly stay in Zone 2, even if it feels slow and boring. These are the runs, that will prepare you for the long distances.

    And over the time, aerobic runs in Zone 2 will also push your VO2Max. I just lifted mine from 51 in Decemer 2021 (had done less training before) to 54 in April 2022 - with 100% Zone 2/ Aerobic training! I do 3 runs with around 3,5 hours a week and additionally 2 units with 1 to 1,5 hours of rowing on a Concept2 - all in Zone 2!
    My pace did also improve much over these these 4 months. When I feel that I reach a dead end with this kind of training OR start to prepare for another half marathon or 10 km run, of course I will add some tempo runs and intervals to my training. But the basis is always "slow" runs (or lets say aerobic runs)!

    Hope this helps you. Keep on running!