why is the absolute maximum Vo2 normalized by the total body weight ? If the activity is not weight bearing like cycling on flats or rowing, should the body weight of the working muscles be considered ? or at least the lean body mass ?
Well…yes…sort of. It’s just a number. It is often presented as relative VO2 max because it has most often been used by runners, a weight bearing activity. In that case,the relative number is much more relevant. You are right though, for non weight bearing activities, the relative value loses some relevance.
Not that important though. Power or pace at LT is much more important that VO2 max anyway. VO2 max is out, LT power or pace is in…
Mike
I always thought it mattered because if you have muscles even though they are not being used in the sport. like lets say biking and not using your arms you still have to supply them with O2 and the more you weigh(fat or muscle) the more weight you have to carry around. in non weight bearing cycling you still have to pump oxygen rich blood to your arms shoulders, chest and back even though they may not be doing anywork at that time, I think that is why total body weight comes into play. think of boxing as a good example the featherweight guys go in there and they throw punches the whole fight when the heavier weight categories can’t do that. the light weight guy maybe 6’ and weigh in at 130 and the heavyweight guy may be 6’ and weigh in at 225. Well if they both have the same cardio capacity their heart will have the same volume per stroke and they both pump out equal amounts of oxygen rich blood. the problem is the little guy only has to pump blood to 130lbs(we will assume all muscle) and the heavier guy has to pump same amount of blood to 225 that means the same heart has to supply O2 rich blood to another 95lbs. Well that is why those guys get tired. Even with GH the internal organs don’t grow as much as the skeletal muscles. it goes back to the marathon runners being so thin. but if you look at the sprinters they are muscular. you are limited to how much O2 rich blood your heart can pump out and that is all your body can use.
well at least that is what i was told.
so even if all the muscles use the same amount of oxygen which they obviously don’t, we should only consider the lean body mass and not fat. For a lean athlete this is about 10% difference. But again, the working muscles use the majority of the supplied oxygen…
Well You are asking the wrong guy. I am not learned(or shall I say well versed) in this subject as a matter of fact I was trying to find out the other day if the fat cells in the body actually where supplied with O2 and or anything from the blood stream. To see if just loosing a couple more lbs of fat would also help increase the VO2. But I couldn’t find a definitive answer. I think that you have to account for total weight anyway it goes. because even if you are sitting down and not doing anything you have to use your core muscle to balance your body and hold it up right. and if it is more weight that has to be balanced and held up right then it requires more energy/work to do it. i think that is why the weight is important in the Calculation.
But Like I said this is what I was told and it seems to make sense to me.
In my quest to understand my own Vo2 max results, I found papers saying that cycling on flat roads performance was correlated to V02 max in L/min, but not the relative figure (ie L/min/kg). But still, getting complete flats is rare, and there are always corners and changes of pace which mean bodyweight is still a factor, even on a flat cycling course.
why is the absolute maximum Vo2 normalized by the total body weight ? If the activity is not weight bearing like cycling on flats or rowing, should the body weight of the working muscles be considered ? or at least the lean body mass ?
Both values have their place, as others point out. Working muscles are essentially all that is of relevance, because, considering a resting person comsuming 0.25 L/min vs the same person at a high work rate might be ~4 L/min, the only big change in consumption being muscle, therefore pretty much all that is of relevance (other organs uptake is negligable, or even decreased at very high intensity - except the brain - constant).
Because of this, to make equal comparisons between people of vastly different sizes, therefore muscle masses, you revert the measure to a measure of body size. Therefore, in general, a person of given lean mass will have higher relative VO2max than another person, within reason, with less proportion of lean mass.
This obviously does not take into consideration sport specific requirements, as pointed out for rowing and cycling. Good example - Cancellara - 80kg, big absolute VO2max, but likely less relative VO2max than the small climbers, so in a flat TT is the man, but gets dropped in hills.
See Hawley and Noakes (1992 I think), can’t remember the journal off hand. Absolute cycling VO2 and power output while using a specific protocol are VERY well linearly correlated.
Well You are asking the wrong guy. I am not learned(or shall I say well versed) in this subject as a matter of fact I was trying to find out the other day if the fat cells in the body actually where supplied with O2 and or anything from the blood stream. To see if just loosing a couple more lbs of fat would also help increase the VO2. But I couldn’t find a definitive answer. I think that you have to account for total weight anyway it goes. because even if you are sitting down and not doing anything you have to use your core muscle to balance your body and hold it up right. and if it is more weight that has to be balanced and held up right then it requires more energy/work to do it. i think that is why the weight is important in the Calculation.
But Like I said this is what I was told and it seems to make sense to me.
Losing fat, talking theoretically and not accounting for all factors, will increase your relative (per kg) VO2max, but not your absolute. As mentioned above, fat tissue does not increase O2 uptake with exercise intensity. Since, for all intensive purposes, we are talking about white fat (as distinct from brown fat, which can consume much O2 in the right circumstances but adults have very little or none of), it contributes practically zero to your VO2. White fat has low mitochondrial content and activity of oxidative enzymes; it has a definite purpose that does not involve consumption of oxygen. Therefore, if you lose it, you don’t ‘gain’ extra O2 for muscle to use (that’s still dependent on your muscles!), but you can divide your absolute VO2max by a lower number. Fat generally loses a bit of blood flow with exercise, although still gets some to a point so that lipids within it can be released into the blood stream.