Running Vo2Max climbing but Cycling Vo2Max plummeting

I re-read the DCRainmaker link (after many years), and he didn't think that much of the accuracy of the power numbers when compared with a direct force power meter.

the Powercal is probably close enough to get the benefits of training to power (rather than just HR), but it's pretty clear that it is not the precision required to "gauge your progress".

I'd always thought that where Powercal excels would be to train to power while travelling, but who does that any more? 

My opinion below is not exactly to answer your exact query.

I think giving Garmin Connect fitness tracking numbers extra thought is meaningless. Its a generic algorithm assuming you are constantly trying to build peak TSS and VO2Max. Even if you come back from injury or take a break.

I dont blame them - they are working to constantly improve their algorithms, and addition of full day stress tracking adds some value. But, at the end of it, the athlete himself 'know' the direction they are on - whether it may be maintaining base fitness or tapering or building it. 

Fretting over the watch say Unproductive or anything like that is no use. 

I practise the MAF method of training (google of MAF method/ Phil Maffetone) and the method essentially want me to work mostly in my aerobic zone (Z2 as per garmin). (MAF Method does want me to training at the higher end under certain cases, but lets say most of the season I would training in Z2). But the Garmin algorithms will keep complaining of "High Aerobic shortage" or UnProductive workout (High Load, Low Fitness).

This is just an example where I know the system doesnt recognize the intent. But, the same applies for a lot of other cases. 

vo2max calculation relies heavily on good data to make a judge of your fitness capacity.  So very key metrics are that you have a properly set maximum heart rate and good data from sensors, without that first and foremost... all info is going to be worthless.  It is comparing your workout heart rate plus workout run-pace or bike-power... versus that of your maximum HR.  

If you are using optical HR, that creates a lot of possible error.. and if you are using an estimated power meter then that creates a lot of error as well.  Strava has an estimated power as well based on elevation/weight etc... but it wind, position on bike, bike clothing all have a huge effect of your speed... which then in turn greatly effect estimated power, making it very poor for finding vo2max.  So I wouldn't read too much into the power or vo2max-cycling ... as far as it driving a lot of the 'Training Status' notes, mine was doing that as well, I recently started using Spin bike with a Stages Power meter, so every time I rode the bike it would raise my vo2max by 1, being that I had no vo2max to start from (it was just going from my manually set value a few years back).  So it would say I was improving overall, when really in reality I was just maintaining my training load and fitness.

Thanks for all the replies, I was mostly interested in why it appears to be more concerned with my cycling Vo2max changes to set training status as "unproductive" when cycling accounts for about 1/4 of my weekly running activities and running Vo2max is steadily climbing.  Seems odd and illogical.

Looking more at that review, error was very high, using that to figure vo2... just going to give bad info.  

Just one example or though looking at some of the values he was seeing, huge difference if you ride for a strong 20 minutes around avg 250w vs 280w!  Going to give you totally different vo2max (likely multiple points different!)

Again, this isn't really a question about the accuracy of the cycling Vo2max number, just that overall Training Status is focusing on that when my Running number is climbing and running activities are clearly what I am doing more of each week at a 4 to 1 ratio.

Yeah I get that.  Curious since obviously it isn't looking at your Load values as the biggest driver on status, seems like it is definitely looking at 'results' (vo2max updates), what has your Vo2max value been doing for Running generally over the past couple months or weeks?  

Yeah, that's the thing.  My running has taken off in the last 5 weeks with more mileage than any 5 week stretch in my 11 year history and Vo2Max climbing from 52ish to 55ish during that time.  Yet, a few (apparently) down cycling activities and THAT'S what Training Status decides to focus on.

Honestly, I usually view the little post-workout messages with a little humor because I know it's just an algorithm and will thus get it wrong but this one really just takes the cake.