Vo2 Max / Race prediction times way off???

But what if you set your Running MaxHR to the max corresponding to your current fitness ? When I started running I could easily hit my max in a 10k race, now with a lot of marathon training under my belt in a full out VO2Max test I'm 15 bpm below!

Anyway the VO2Max shown by the watch is really of a "trending" tool so it's best to keep the MaxHR constant, regardless of what you've set it at. I suppose I feel better getting predictions that "make sense" and having a VDot/Garmin VO2Max/Runalyze VO2Max that are consistent.

Thanks guys, that’s good information, I’ll give it a couple more weeks and bare in mind the variation in accuracy. It’s good to be the right side of wrong at least, gives me something to aim for!
I have just recorded a 190bpm max which was fairly stable for a short while, though on the wrist hrm, now do I need a chest hrm......??

My advise is to make a maximum hr field test, is simple but hard:)
How to calculate your own MAX HR.

You’ll need a heart rate monitor for this method. I would recommend either choosing a stationary bike or treadmill for this test. Bike is the safest modality.

• Warm up thoroughly. I suggest spending about 10 minutes until you break a light sweat.
  
• Run or bike for 4 minutes. You should be too out of breath to talk.
  
• Active rest - walking or easy cycling for 3 minutes.
  
• Run or Bike for 4 minutes. You should be too out of breath to talk.
  
• Active rest - walking or easy cycling for 3 minutes.
  
• Run or Bike for 2 minutes at which point run or bike as fast as you can until you reach exhaustion and can’t continue.
  
• Immediately take your heart rate. This is your MAX HR.
  

http://www.maxworkouts.com/articles/entry/is-the-maximum-heart-rate-formula-sabotaging-your-workout-and-your-results

Here's the link https://cicerunner.wordpress.com/2014/07/11/garmin-fr620-race-times-from-vo2-max/

Could someone share a link to the table/webpage where you can get race estimates from VO2 max please? Googling "coopers running prediction" gets me lots of info on the test, but not the speed table!

Sorry for the misleading chart info. I wasn't sure where the chart I saw linked in the past came from and knowing that Garmin does reference some other things from the Cooper Institute and speculated that's what I saw.

The last two weeks I have been using both my 620 and my 935 to see how they compare when it comes to the advanced training features. In 2014 the 620 was the first Garmin watch to incorporate the FirstBeat stuff. I was wondering if there have been any changes in the algorithms after reading somewhere the VO2max estimate is lower on the 935 than on previous watches. I set the 935 to broadcast HR data so that both watches work on exactly the same HR data.

After about 10 runs I can see that the Training Effect reported by the 620 equals the Aerobic Training Effect on the 935 to within 0.1 unit and the two recovery adviser results don't differ more than an hour. The VO2max reported by the 935 however is 2 points lower than the 620 making the race predictions from the 935 somewhat more realistic than those from the 620 (but still fairly optimistic).

I think you have to take into consideration that for instance to run a 3 hour marathon you need to have a certain minimum VO2max which can probably be determined rather precisely. However, having that VO2max doesn't guarantee a 3 hour marathon as other factors come into play, like running economy, nutrition, training history and mental strength.

In other words the watch tries to quantify your fitness level by calculating your VO2max and giving you race prediction times based on that VO2max. It's up to you to undertake the appropriate and specific training to make those times happen. At least the times reported by my 935 are not completely out of my reach (unlike the 620).

That's interesting, are both watches set to the same MaxHR (the one under Running for the 935) ?

They use the exact same user profile. Max running HR on the 935 is set to the same value as maxHR.

I have done three more runs since and still the same 2 points difference in VO2max.

Only real way of telling for sure is to reset both watches then run with both paired to same HR strap for the next week or so.

By and large I ignore the race predictions (as they are pretty "impossible" for everybody) but a positive movement in VO2 Max does provide some reassurance that a period of good training is having some effect.

One of the reasons though I think the predictions can be wrong as that if you are unfit you can typically get very high HRs. As you get fitter I find it becomes very hard to reach those levels but of course you don't typically "downgrade" your HR max.

Take this AM - did my best 5K in the last few months but topped out a max HR of just 145. About a month ago on a treadmill when less fit got to 164 and my HR max is set to that. I could get higher than 145 on a "warm" treadmill for same effort I am sure. I ran 20:22 but the watch says I can do 17:22 largely as the algorithm thinks I was going "steady" with a 19 bpm "cushion". I have run 17:22 in recent years and a lot quicker besides before that but that is not happening any time unless do some huge training in and don't injured or and stop getting older!