Jughed

If I understand correctly:

VO2 max goes up with a reduction in body weight if power remains constant - per online VO2 calculators.

Example
300w for 6 min @82kg = 46.5
@72Kg = 52

Shouldn’t power output go up with a higher VO2? Or is my data skewed because I’m only changing weight in the formula - and your power output will go up as weight goes down?

terrymorse 

The VO2 units are:

volume of O2 per unit time per unit body mass

Power at VO2max is a different thing. There are some conversions that are accurate-ish.

I made a thread with some conversions: Converting Between Power VO2 METs

Jughed

Thanks. I need some coffee before reading that thread!

PeteHski

VO2 max is like W/kg ie you can increase your VO2 max by increasing your power and/or reducing your weight.

Your power is certainly not guaranteed to increase with a reduction in weight. It depends on what sort of weight you are losing.

Jughed

I'm just trying to wrap my head around the numbers (and I've not yet played with the formulas in the other thread)

I equate VO2 max with your max sustained 4-6 min power - if you are training, fit and have the strength to push the power.

If you are losing weight while training, the right kind of weight - using the formulas with everything constant except weight - VO2 max increases. If you don't lose strength - your potential 4-6 min power should increase simply because of the weight loss.

PeteHski

You are getting confused between VO2 max (eg. a value of say 50) vs VO2 max power in Watts, which is independent of your weight.

If you lost weight and your strength stayed the same, then your VO2 max power output would stay the same, but your VO2 max would increase because it is measured in units per kg of body weight.

Jughed

It's more likely that I'm not forming my questions correctly vs being confused - or a bit of both! So I will do the ole - ask the same question a different way and expect a different answer!

Is it a fair statement that for a fairly fit individual, VO2 max is essentially one of, if not the main limiting factor of power output in the 2-6 min range?

Say that number is 300W & the rider has much more actual pure power available, but VO2 is what limits them from maintaining more than 300W for that duration.

If VO2 thru training, regardless of weight, goes from 48 to 52, wouldn't theoretical 2-6 min power increase as well? I would expect the power numbers to increase with the improved VO2 max.

I'm just wondering if an improvement in VO2 from weight loss would translate to better 2-6 min power, and if not - why?

Sorry if I'm being obtuse!!

PeteHski

VO2 max is dependent on your weight. So your VO2 max can go from 48 to 52 with no increase in your 2-6 min power output. All you have to do is lose enough weight and maintain your power. It's a simple formula.

Your VO2 max can only go from 48 to 52 by losing weight and/or gaining power. I don't know how else to put it!

To answer your specific question, an improvement in VO2 max from weight loss may or may not translate to better 2-6 min power. It depends on loads of other factors. You can see an improvement in VO2 max while actually losing power if the weight loss is high enough to compensate. I have seen this first hand while training for a mountain event, where I lost 10 kg of weight and lost about 15W at VO2 max power.

Iride01 

It is pretty disappointing to see my estimated Vo2 max change when I update the numbers for my actual weight after having many rides with my weight not accurately accounted. <grin>

PeteHski

While VO2 max is a good raw indicator of potential aerobic athletic performance, it has little practical use once you actually start measuring your aerobic power directly. Why even bother trying to estimate your VO2 max when you know what your actual W/kg power output is?

Iride01 

It's for the good feeling we get when Garmin says we compare to the Vo2max of a 20 year old as opposed to the Vo2max of a 40 year old. <grin>

Jughed

I was sent an article or two about VO2 and longevity, so I went down the rabbit hole... and my Garmin barks at me every so often about new VO2 max numbers.

Garmin, online calculators, interweb test videos all seemed to relate VO2 or test for VO2 using power and HR.

Most of the sources claim the easiest way to increase the number was by losing weight.

Do hard intervals to raise VO2 max - for gains. Lose weight to raise VO2 max - for gains?? And that is my question.

So, my thinking, higher VO2 from weight loss would allow for higher power output, resetting training zones and such -apparently that may not be the case, but I'm still not sure why.

PeteHski

Unless you measure it directly in a lab, VO2 max is just an estimate from your 4-6 min power measurement, HR and weight. If your 4-6 min power goes up then so does your estimated VO2 max. If you lose weight then your estimated VO2 max also increases.

You appear to think that simply losing weight will automatically increase your power output at VO2 max, which is not necessarily true. It might well do if you are just losing fat and getting fitter in the process. But as I said I have lost weight and lost power simultaneously, while still raising my estimated VO2 max. I just lost more weight relative to my loss in power. In other words I had a higher W/kg number at VO2 max. I lost a little VO2 max power from the weight loss. Interestingly my power came back up when I went back to my normal weight after the event I was training for. For reference I went from 185 lbs down to 165 lb at 6'1" tall.

Jughed

OK, so I think I found the answer I was looking for.

VO2 max and performance isn't necessarily based on VO2 max related to total body weight, rather VO2 max in relation to lean body mass.

Losing fat weight, has little impact on the efficiency on the aerobic albitites of the lean mass system.

PeteHski

VO2 max will correlate more directly with your 4-6 min power expressed in W/kg rather than absolute power, simply because they are both normalised by unit mass.

They are basically measuring the same thing, but the power measurement accounts for your efficiency in converting raw aerobic potential into pedalling power at VO2 max. The VO2 max number that Garmin is churning out is just an estimate based on your 4-6 min power/kg. It has no clue about your individual pedalling efficiency.

So if you lost only fat, both your VO2 max and W/kg at VO2 max would automatically increase without any change in power. In reality, if you are training on the bike and losing fat then you will also improve your VO2 max power.

MoAlpha

The weight term is there for comparing different size people. It's essentially irrelevant to longitudinal comparisons within individuals who aren't adding or subtracting lots of leg muscle and, as this thread illustrates, can be confusing.