I recently tried 80:20 training,but after two months my VO2 max went down by a couple of points (and my zone 2 pace got much worse). But I wondered if that might not be due to the 80:20 training, but just the effect of seasonal variation (I only run out doors in the U.K.). Would a seasonal variation of a couple of points be normal between Summer and Winter?

Just to clarify - I am not talking about VO2 max measurements performed in a lab, where (AIUI) your absolute VO2 max will be measured and your relative VO2 max calculated by dividing by your (lean?) body mass. This is the gold standard, but not generally practical unless you are an elite athlete. I am talking about the estimate of VO2 max provided by a smart watch or e.g. the Cooper test. Both of these work by correlating (via e.g. a regression analysis) running performance and expected VO2 max from a population of runners that have lab based VO2 max measurements. These do not explicitly depend on bodyweight, so losing weight will not necessarily give you a higher VO2 max. If you loose fat, you will be able to run faster and your VO2 max estimate will likely go up. If you lose muscle mass, it is likely that you will be slower and your VO2 max estimate will likely go down. Those VO2 max estimates are a measure of performance, but one that is approximately calibrated with VO2 max. Whether they are a useful measure of performance is another matter (I think the Cooper test has definite advantages there as the smartwatch estimate needs to compensate for differences in effort level, which introduces additional sources of uncertainty/variation).

As suggested by @JohnP, this is my current training regime:

Monday - High intensity running, each week I choose one of:

  • Cooper test & continue on to 5k (at whatever pace I can manage), followed by walking recovery, followed by 5 x 500m intervals with 500m jogged recoveries.
  • 5 x 1k intervals with 1k jogged recoveries
  • 10k at threshold (heart rate reserve zone 4)
  • Half marathon in heart rate reserve zone 3
  • Very occasionally a "race pace" 10k

Tuesday - 3k easy-ish swim (HRR zone 2 and 3, ~ 2:10/100m)

Wednesday - 15k easy run (HRR zone 2), 10k if I am feeling tired

Thursday - 20 min elliptical warm up (zone 2) followed by strength training

Friday - rest day (5k walk @ ~5.5kph - not even zone 1 most of the time)

Saturday - "race pace" 5k (most enjoyable run of the week), 5k walk, strength training

Sunday - rest day (5k walk)

So that is usually somewhere 25-40 km per week.

My training only went flat when I started 80:20 training, where I was replacing the Monday run with a 10k zone 2 jog in order to make up enough zone 2 for the "80" part.

Prior to that, my training scheme was similar except that the Wednesday run would be in zone 3 rather than zone 2 and I've only recently started doing the workout starting with the Cooper test. I'd been doing that for about a year, and it was working pretty well. The need for zone 2 running is the thing I have retained from 80:20 - I don't enjoy it, but I can accept it is good for me.

However, it could be that the flattening was just a seasonal thing, so I thought I'd check here. It is the worsening of my zone 2 pace that makes me think it may be a seasonal effect as more training in zone 2 should improve that not make it worse.

It may also be relevant that my pace often tends to improve the further I run in zone 2, see Why does my pace improve during a low heart rate (HRR zone 2) 10k?

  • I'm not a big fan of VO2 max being used as a training metric. It's an indicator of potential, and not much more. You can increase or decrease your VO2 by losing or gaining a couple of pounds (respectively). Want to improve your VO2? Lose 5 lbs. :D
    – JohnP
    Jan 23 at 20:05
  • @JohnP I have reached the point where my body fat percentage is low enough that losing 5lbs is not the easiest way of improving my VO2 max and definitely not the most enjoyable. Also neither my watch, nor the Cooper test estimates appear to depend on body weight - as far as I can tell, they both estimate relative VO2 max directly (and I work out absolute VO2 max from that). Jan 24 at 7:45
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    Understood, and that's better than most I've seen. The Cooper test is a decent indicator as well. I always thought vVo2 (Velocity at VO2 max) was a much better value to look at, and if I remember my classes, the Cooper test is more an approximation of that than it is VO2 straight up. I'd have to go look again though, it's been a while.
    – JohnP
    Jan 24 at 13:49
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    One thing you can consider - Sometimes the larger universities with kinesiology departments will have "open lab" days where the students practice conducting the tests with people. It's not a regular occurrence but it does happen.
    – JohnP
    Jan 24 at 18:02
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    Ah. We are of the same age. If your goal is overall fitness, then your program looks good. There is some genetic component (~ 50%) to VO2 max, and you will notice some decline with the loss of elasticity in lungs/muscles and other age related items. Take that into account when measuring.
    – JohnP
    Jan 26 at 15:31

1 Answer 1


It's plausible, one paper shows a ~7% worse VO2 max during winter compared to summer in healthy men.

Running is a great sport where the only participate is you and the variables are, allegedly, all controllable. Truth is beyond the obvious fitness, weight, and training, there is mood, sleep, and diet.

If you have a reputable training plan and are early in it it's worth sticking it out to completion. Training can take time to bear fruit.

If you truly plateau with other factors being the same (weight, health) a coach is the only one who can tell you if you're training too hard, too easy, or just wrong. Many roads can lead to success, especially early on.

  • I don't really have a training plan, but as your last sentence mentions I don't think I really need one at this stage - I've only been running for less than 18 months. Jan 23 at 8:06
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    @DikranMarsupial - I've been running for years. What I've generally found is that new/inexperienced runners go too hard on their easy days, and not hard enough on their hard days. In a constant state of "not quite recovered". Also, if you've been doing just basic running for 18 months, probably time to start considering speedwork.
    – JohnP
    Jan 24 at 17:59
  • @JohnP cheers, I keep my weekly "long" run (only 15k) to zone 2 (mega-slow!), but I do a race pace 5k each week and the other session is either Cooper test + 500m intervals/1k intervals/10K threshold run/zone 3 half-marathon (with an occasional race pace 10k), so I am trying to run at a variety of paces and intensities. Does that sound reasonable? Jan 24 at 18:03
  • @DikranMarsupial - Put your training regimen by day for a week in your question, or start a new question with that info. I'm a little confused by what you are actually running each day, as well as total mileage. If it's what I suspect, I may know why you are "flat" in your progression.
    – JohnP
    Jan 24 at 21:08
  • Cheers @JohnP, I have set it out in an edit to the question. Any advice would be appreciated. Jan 25 at 8:58

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