Garmin/Firstbeat Performance Condition Metric Observations

Hi all,

TL;DR: Does anyone use / track this metric against their life style?

So I know my biggest hindrance is recovery, or more precisely adequate sleep (both quality and quantity). Work and commutes have me out of the house for usually around 13hrs a day, a family with little kids leads to lots of interruptions at night, either directly due to some incident or indirectly, like last night, when I had a vivid nightmare of one of my kids burning themselves in the shower…but I digress.

I try to stick to a sleeping rhythm which suits me and the rest of the family and allows me to train in the early morning hours before the rest of them wake and it usually works well. I feel alert and awake enough throughout the week and good about myself if I get my scheduled workout in in the morning before heading into the office.

Ok, stage set, here is what I want to talk about: I’ve been monitoring the performance condition metric on my Garmin device for the past few months and with very few exceptions I almost always start out with a negative value, which generally (not always though) only gets worse throughout the workout / ride. I suspect this is due to lack of quality sleep as described above and it tracks well, when I feel particularly down or fatigued. However on many days I feel “normal” (for lack of a better word). Sure I could sleep, but tired is not the word I’d use. As an example. I’m currently in what I’d call my pre-season and am doing some of the Traditional Base 1 Low Volume workouts (Virginia today). I could probably ride at that effort level all day, however the watch said -5 at the beginning of the ride. I suspect corporate life has led me to be unable to recognice how my body feels and when it needs more rest. Or better, corporate life has me ignoring it.

This is not looking for recommendations on how to improve my situation (although if you have any let me have it), but more about others and what their experiences are. I keep telling myself that this merely informs RPE but does not dictate what I should or shouldn’t do. And for the most part this seems to work, I’m not sick every two weeks but seem to get on with life just fine, so long as I catch up on sleep a bit every weekend. So I’m just curious what, if any, others thoughts are on this.

Input appreciated! Thanks


Performance Condition basically compares your heart rate (as a % of max) with your power output, for a person with your VO2Max. It is entirely normal for your PC to decline as fatigue gradually accumulates over a ride.

Because it is based on heart rate, anything that affects your heart rate will also affect PC. So high temperatures, fatigue from previous workouts, poor sleep, illness can all affect PC. Although it can sometimes be hard to narrow down which factor is applying at what time.

Personally, I find that I often record negative PC numbers on Z2 endurance rides, but positive (at least initially) on higher intensity rides. I am not sure whether this is normal, or because of inconsistency of L/R power balance (I use a single-sided power meter).

One thing I would suggest is keeping an eye on your Resting Heart Rate, as it may provide some clues as to when your HR is likely to higher (and therefore PC lower) due to lack of recovery, sleep etc.

1 Like

As I understand the information provided on

Firstbeat’s performance condition is just a real-time version of their VO2max fitness level detection minus your base-line VO2max. You get some insights on their VO2max fitness level detection in

Especially, page 3, calculation step 4) should explain some of @mcalista’s observations.

That said, if your performance condition reading is negative throughout each workout, it should update your estimated baseline VO2max, unless you deactivated its auto-detection. At least this is my understanding.

I read the Garmin docs up and down and think I understand what it means, as well as the offset performance condition provides. Auto detection for VO2max is enabled and the estimates for both bike and run are hovering at around 55±1. This has ramped up from there over the months from 48, however I like the idea of manually adjusting it down by 5 points and see what happens. Most of my rides, but not all have a consistently negative baseline and an increase of my VO2 max estimate typically comes only after particularly grueling rides, as you would imagine. I’ll probably lower it by 5 points and see what happens. As I go properly into base I expect it to creep up to ~54 again relatively quickly though. But in the meantime it’ll be interesting to observe Performance Condition.


1 Like

Here’s an unexpected observation (I have to go back through my other rides to see if this matches): last night’s fast group ride which had me nudge into HR Z5, ride at IF 1.08 and inspire the watch to detect a higher FTP also incidentally had a positive PC throughout. Which you would expect given the effort level… something went right yesterday. In any case, I will continue to give little value to it.