Longterm Cardiovascular Adaptation

DavidM said:

How does this inform ideas about limiting factors to VO2max ? i.e. which part of the CV system is 'over-engineered' regarding aerobic performance ? I think it's accepted that the lungs are not the limiting factor. I think its predominantly cardiac output which is the limiting factor, and it's proven by the EPO phenomenon - i.e. skeletal muscle, and its O2 supply system (capillarisation) can ALWAYS utilise more oxygen, and perform harder, whether this O2 is delivered by greater cardiac output, or by greater blood oxygen load (secondary to EPO use). If O2 diffusion/utilisation in the muscle were the limiting factor, then surely an increase in blood oxygen would not produce such a spectacular improvement in performance.

I'm not 100% on this, but I understand that development of capillaries occurs at the greatest rate at intensities approaching VO2max. That would suggest to me that this is also important - it makes sense, too, that all parts of the mechanism of oxygen delivery will affect the maximal uptake of oxygen. If this is the case, you are right that the heart is very important, as is haemoglobin and the oxygen carrying capacity of the blood. However, I think you are wrong to discount the effects of capillarisation and other adaptions in skeletal muscle. If you are trying to get something (oxygen) suspended in liquid (blood) into a small space (the muscular site), it seems there are four intuitive ways to improve that process. Firstly, you could increase the concentration of the suspension - eg EPO's effect. Interestingly, this does not seem to be a common adaption to normal training. Secondly, you could change the flow characteristics of the liquid, allowing more to be pushed through the vessels and capillaries more easily - this correlates with plasma expansion and the increased cardiac output seen therewith (it is not that the heart is stronger but that the flow characteristics of the blood changes). Thirdly, you could increase the force and amount with which you push the liquid - this correlates with an increase in strength of the heart and increase in stroke volume (which is related to plasma expansion). Finally, you can change the path through which the liquid flows and provide easier access to the sites - capillarisation.

I don't think you could easily say that one adaption is more important than another as all the variables you mention are trained together, and are correlated with increased VO2max.

edd said:

at the end of the day it is your VO2 max potential x your sustainable power output that will determine your performance..

Sustainable power over different periods of time is probably the most important thing. Whether this correlates with performance or actually represents it is debatable.

I'd say all of the following heavily influence performance in differing amounts over different events and different career structures (eg professional athlete in different team/organisational structures, self-coached elite vs coached by other, etc):

VO2max
40km TT Power
LT
Psychology
Trainability
Self-management
Organisation
Discipline
Self-criticism
Maturity
Ingenuity
Tactical nous
2 minute maximal power
30 second maximal power
Fast twitch/slow twitch mix
Aggression
Type a/b fast twitch mix
Capillarisation
Mitochondrial density
Hypertrophy
Mental control
Muscular control
Technical ability (handling)
Strength
Neuromuscular resistance to fatigue

The list is endless; some things correlate with each other, some are indepent, others are directly opposed (correlate negatively).

That said, in terms of athlete ID, a vertical jump test, beep test (~VO2max) and biomorphic measures will tell you an awful lot.

A little story: 7 years ago, when I started cycling seriously (I have always cycled to some extent), my rest HR was 55. About 4 years ago, I went to see a doctor and nearly got hospitalized, since he measured my HR to be 35. I suspect that my skeletal muscles have improved as well, but nothing could be that dramatic! Still, it could be the result of my training routine, mainly based on endurance rather than strength.

ItsikH said:

A little story: 7 years ago, when I started cycling seriously (I have always cycled to some extent), my rest HR was 55. About 4 years ago, I went to see a doctor and nearly got hospitalized, since he measured my HR to be 35. I suspect that my skeletal muscles have improved as well, but nothing could be that dramatic! Still, it could be the result of my training routine, mainly based on endurance rather than strength.

Most of the skeletal muscle development I'm talking about doesn't involve strength at all - it's all to do with endurance exercise. And I'm not discounting the importance of cardiovascular adaption. In contrast, my resting heart rate (when not sick) has stayed between 48 and 55 in three years of competition whether I am off the back or off the front in races. I still would guess I have an increased cardiac output now because I am so much faster than I was. The point is that anecdotal evidence like this isn't always instructive.

Roadie_scum said:

Most of the skeletal muscle development I'm talking about doesn't involve strength at all - it's all to do with endurance exercise. And I'm not discounting the importance of cardiovascular adaption. In contrast, my resting heart rate (when not sick) has stayed between 48 and 55 in three years of competition whether I am off the back or off the front in races. I still would guess I have an increased cardiac output now because I am so much faster than I was. The point is that anecdotal evidence like this isn't always instructive.

You are right of course - this is just one case of many. I find it interseting because it's mine 🙄. I guess my skeletal muscles have adapted too, but it is much more difficult to see than the dramatically reduced rest HR (which is also accompanied by heart hypertrophy).

ItsikH said:

You are right of course - this is just one case of many. I find it interseting because it's mine 🙄. I guess my skeletal muscles have adapted too, but it is much more difficult to see than the dramatically reduced rest HR (which is also accompanied by heart hypertrophy).

True true. It's funny because my body composition, RHR, etc is all almost identical over the past 3 or more years but I'm a much better rider now. Just shows a lot happens at the micro level.

Its really interesting to read your comments. I do feel I am moving towards a better understanding now. I guess you cannot separate out any particular part of the aerobic system as being of unique importance, but I also see it is an area without clear cut answers. Thanks again !