Monday, November 17, 2008

Get your Geek on!

Recently, I did a metabolic stress test (often referred to as a VO2max or a cardiopulmonary stress test) on a local elite athlete. The test results were outstanding for this individual. In fact, the results were some of the highest that I’ve seen on a test subject. The only other one higher was on a classmate of mine in grad school and he was a Division I cross country star. The results were also significantly higher than I’ve ever achieved.

The test got me thinking about the basic physiology of an aerobic athlete and what makes one faster or more powerful than another. Why are some individuals “natural” aerobic athletes while others struggle to hang on to the back of the pack?

WARNING! Geekdom at it’s finest approaching

VO2max is the ability to consume oxygen and utilize it for aerobic glycolysis. The muscles use oxygen in aerobic glycolysis to break down stored carbohydrates and eventually produce ATP (adenosine triphosphate). The high energy phosphate bond in ATP is what allows muscles to contract.

Man, I wish I had a syringe of ATP to inject into my legs during cross. Kinda like nitrous oxide for your legs. Unfortunately, that wouldn’t work and would probably kill you.

Anyways, back to the nerdy stuff, if the cardiovascular and pulmonary system cannot sustain the volume of oxygen required by aerobic glycolysis, the body will begin to call upon anaerobic glycolysis to help keep up with the muscle’s demand for ATP. Aerobic means with oxygen and anaerobic is without oxygen. Anaerobic glycolysis isn’t as efficient as its bro aerobic glycolysis and only provides a fraction of the ATP from the same amount of carbohydrate. So anaerobic glycolysis is kinda like the friend you call as a last resort to pick you up from downtown when you’ve had too much to drink. You really don’t want to go there, but you have no choice.

Anaerobic glycolysis results in lactic acid (actually lactate and hydrogen ions) as a nasty byproduct of producing those valuable ATP’s. That’s the familiar burn we’ve all felt on numerous occasions and especially during cross country races, crits and cross. So as the body is unable to provide sufficient volume of oxygen to the working muscles through aerobic means, the balance swings from aerobic to anaerobic glycolysis. As a result the muscles and lungs begin to suffer. Eventually if a person “red lines” for too long the muscles will shut down. The hydrogen ions from the lactic acid combine with bicarbonate ions and form carbonic acid which spontaneously dissociates into water and carbon dioxide. The increase in water isn’t such a bad thing, but the increase in carbon dioxide eventually has detrimental effects. A lot of folks don’t know this, but carbon dioxide is actually what triggers us to breath. Not a lack of oxygen.

Now there are several ways one athlete can be superior to another in various physiological systems which leads to a higher VO2max. Huge lungs help. Also a great diffusion capacity (ability to transfer oxygen and carbon dioxide to and from the lungs and the blood) is vital. Any kind of pulmonary disease (asthma, bronchitis, emphysema and smoking) can hinder the delivery of oxygen to the blood.

After the lungs come the heart and vascular system. Having a big strong and efficient pump (heart) is also critical, but if the plumbing is shitty the delivery of oxygen is hindered. Atherosclerosis (heart and vascular disease) will narrow those arteries and make them less compliant and impede delivery of oxygen rich blood. Pressure is also higher in small pipes which can lead to greater endothelial insult and subsequently more atherosclerosis. It’s a vicious cycle.

Now once at the starving muscles, AVO2difference (arterial venous difference) is the next critical physiological variable. The AVO2difference is simply the difference in the oxygen content of the arterial blood and venous blood. The arterial blood drops off oxygen to the working muscles and become venous blood (artery away from the heart and venous towards). The venous blood goes back to the heart and then the lungs to pick up more oxygen and start the cycle over again. Some individuals have higher AVO2differences than others. This was the great debate when I was in grad school. What is the deciding factor in a high VO2? There was the central theory (the big pump – heart) and the peripheral theory (AVO2difference). I personally think you gotta have both, but there really is no way to easily measure AVO2difference potential. The heart can be assessed rather easily with echocardiogram, CT and even catheterization.

Some folks just have better genes for dropping off oxygen. If you got Norwegian genes, consider yourself lucky. The highest ever recorded VO2max results were from Norwegian cross country skiers. Records for VO2max are 96 ml/kg/min for men (Bjorn Daehlie) and conflicting records for females, but most state 80’s. Greg Lemond was 92.5 ml/kg/min at his peak and I’ve read that Lance was near 94 ml/kg/min. Just to put it into perspective, dogs used in the Iditarod can be as high as 240 ml/kg/min. Just think how fast you would be if your Mom was a canine. Maybe Dr. Moreau was on to something.

Bottom line is the really great aerobic athletes are the ones who were given great genes from their parents. A lot of one’s ability is predetermined at birth. Training can dramatically improve initial performance, but once an athlete is trained it is very difficult to increase the VO2max.

Now once the VO2max is determined, the one thing that can be shaped to increase performance is anaerobic threshold. I’ll save that discussion for another day.

26 comments:

dale said...

Nice explanation. I've never heard of the AVO2 difference before. Wouldn't the ratio of 02/CO2 inhaled vs 02/CO2 exhaled measure it?

I'm looking forward to your discussion on anaerobic threshold since it is more moldable than VO2max and AVO2.

I think even more important than genes/physical side is the mental side: goals, passion, motivation, following structured training, and cordination - how well one responds to the sensory inputs of sight, touch, and hearing (balance).

Cornbread said...

The ratio of 02/CO2 inhaled vs. exhaled is the most important variable measured by VO2max testing equipment. Since we're measuring that through inhaled/exhaled air, the processes at the muscular cellular level (AVO2difference specifically) can only be estimated. The only true way to measure AVO2diff that I know of is placing a swan catheter into the vascular system next to a myocyte (muscle cell). That is very invasive and would probably hurt like a mofoe.

I'll try to put together an AT post soon.

CJ said...

Damn you are a smart cookie Cornbread...or maybe I should say you are smart bread..ok...probably not that funny.

Great post...I found it to be really nicely written.

sydney said...

Excellent write-up. I feel like I understand this so much better. I've been breathing more consciously, focusing and deeper and simply remembering to do it regularily. Yeah, I know, how can you forget to breath? Try some highly intense short intervals. I think it's helping.

Keep sharing your hard-earned grad knowledge.

Coach said...

Can't help but stick in a few cents. I've been lucky or unlucky enough to have had my V02 measured a few times. First time @ OTC around 1986- I think I was 65, the second time early 1990 was around 70. Can it change...it did. I've given you all my secrets now. But that's just a small part of the story I want to convey.

When I was at the OTC one of the fellow campers from Kansas,was measured at 82. Wow! High hopes were piled on this guy. But you know what...He sucked at bike racing. Never came close to winning a race. Why? desire maybe?

This is my message and it ties into Dales comments above...Good genetics help, but Desire and Ability to Suffer can make a huge difference between winning and losing.

This IS one of the great things about bike racing...it allows you to be crafty, conserve energy -be crafty, plot attacks, use different energy systems, recover, read a race...

Cycling unlike Running or Xcountry Skiing allows for the smartest to win, not necessarily the most genetically gifted.

Cornbread said...

I hear what you're saying Coach and agree 100%. Some folks have all the tools, but don't know how to ride or race. Others are physiological over-achievers by using their wit. But when it comes to pure physiological might with all other variables equal, the 70 ml/kg/min athlete will have a distinct advantage over a 50 or even 60 individual.

Marc said...

how age affects VO2? I know the older I get the less of a heart I have = less energy = less compassion.

Coach said...

Marc, Are you asking a question of Corn Bread? Of the studies I've seen the unfortunate side effect of ageing is that our hearts become less efficient.

I however, have witnessed a increase in the number of aged peoples participating in edurance sports...and some are very successful.

I for one am tired of people that say O' I'm 45 I can't compete with those younger peeps. Not true. I see it all the time. In fact it frustrates the hell out of me when people use this excuse. Really most people never tap into their bodies full potential. (I partially blame poor physical education programs...especailly these days. Do you know they consider throwing the frisbee a phyiscal activity in school PE now.) The general population without a coach telling them what to do can barely get out of bed in the morning. What it takes to be fit is not being taught or pushed...which is probably why we have so many obese children these days...that and "can you biggie size that please?" Jeeezzzz.

I digress

Granted our bodies ability to respond, and ability to recover is dimished as we age...But I do think our bodies do become more efficient over time with regular intensive training that can make up for a little of the loss assocated with our aging bodies.

Oh, and Compassion does equal heart.

Cornbread said...

Marc, VO2max does decrease with age as the cardiopulmonary system loses function. Maximum heart rate declines with age which in turn reduces the maximum ejection fraction (amount of blood pumped by the heart). Also the lungs lose function every year. I've read that lung function decrease 10% per decade after 30 years of age. I've also seen that figure for VO2max reduction with age.

A lot of folks have the ability to sustain our VO2max as we age due to our rigorous training/riding, but the eventual decline is inevitable.

Passion is something that can't be quantified, but it is priceless.

Marc said...

Since heart rate decreases and cardiac output thus decreases and thus VO2 decreases I might say that and older individual can train at a less intensity than a younger individual.

Crap, lung function decrease also? Since oxygen delivery is really important to get power this is likely why older athletes can't perform as well as younger athletes.

Here's my disclaimer: it all depends.

At the level we're at the playing field is pretty level. It's just when you enter higher category races that things become unequal.

So I can use the " i've got 15% less lung capacity and decreased oxygen delivery" in a race. If I can get all that blurted out I shouldn't of got lapped.

Coach said...

Marc, you need to rely on your cunning and experience to make up for you 15% diminshed performance...just not on me...

Here's a twist from the running world. I did the Buffalo run this year and based on results they can grade your performance into this;

The meaning of the performance percentage as given by
World Association of Veteran Athletes:
100% = Approximate World-Record Level
Over 90% = World Class
Over 80% = National Class
Over 70% = Regional Class
Over 60% = Local Class

OK so the question is if you were to take the folks in each of the above levels, would their corresponding V02 also rank in the same percentage?

And...if we were to do the same thing for cycling, but base it on results and fields sizes could we come up with something comparable? Would VO2 follow that pattern?

Would it in fact be the same as our Categorization used by USA cycling? IE 1-2-3-4?

I think that cycling allows for much greater latitude.

Marc said...

So what are the %'s relating too? Is it VO2? Some other performance?

If I relied on you I'd be 16% in the hole.

Coach said...

No, I meant don't use your cunning and experience on me...

If I'm not mistaken, the percentages are calculated on peformance for that distance in comparison to how others (nationally) in your age group performed at same distance.

You could easily do this for TTing. Not sure about other cycling events.

Marc said...

Dang, I'm almost about to give away the best secret in the world if we keep talking like this. The answer to this big age/VO2 dilemma. Well I guess that depends on how you look at it if it's the best answer but it's a really sweet answer.

Cornbread said...

Lemme guess...the answer is...EPO!

Marc said...

Close.
An enclosed skinsuit and helmet that delivers nothing but pure oxygen. Like a space suit.

McG said...

Corey, long time, hope all is well with you. Just had VO2 max and LT testing done at CTS here in Co Springs. Would I have a better result at sea level as opposed to 6000 ft?

Cornbread said...

Hey there McG. Definitely long time. Hope all is well out west.

Very good question. The short answer is yes.

The reason your VO2max will likely be lower at altitude is air pressure. The weight of the atmospheric pressure at 1000 feet above sea level is much greater than 6000 feet and higher elevations. The higher the elevation, the less atmospheric pressure. Kinda like a stack of pancakes. The bottom pancake feels the weight of the whole stack while the top buttery one only supports it's own weight (and the weight of the syrup). Another way to think of it is we live under a huge ocean of air that is miles deep.

The lower air pressure at 6000 feet means less oxygen present in the ambient air. Now the percentage of oxygen in the air is still the same at 21%, but there are just fewer molecules. The lower air pressure causes a lower diffusion capacity (less oxygen being transferred to hemoglobin in the lungs). Less oxygen transferred to hemoglobin results in less oxygen being delivered to your working muscles and a lower VO2max.

This is why the "live high, train low" philosophy is so popular.

McG said...

Thanks for the explanation. Would like to retest in the spring. Could you shoot me your email address. Might try to squeeze it in when I come home.

Carp said...

Good discussion. The genes that God gave you are critical for getting results. How hard you have trained and how bad you are willing to hurt are paramount!

Cornbread said...

McG, my email address should be linked off my profile. Shoot me an email.

Carp, you hit the nail on the head. Pain tolerance is key to cycling success. Unfortunately, I don't like hurting so much, but really enjoy hurting other people. A little more S and a little less M. BTW, gonna miss you at Nationals this year.

Coach said...

I've always thought that training philosophy "live high, train low" was a little bass ackwards. It makes much more sense to train high and recover low. In other words train where you are struggling to get oxygen @ whatever...7000 ft...or for us anything over 1300 feet and recover and sleep low where you body can recover and retreive more O2 out of the air during rest.

Anyone who has spent multiple days in a row punishing oneself @ altitude and sleeping at altitude (say 8000 or over) soon realize a huge deficit especially our flat-lander bodies because they can not recover and overtraining syptoms set in quickly. This is why those guys living on the front range get so fit. They sleep at 5200 feet and can train up to 10,000 feet.

Just my thoughts...

What would be interesting is would there be any recognized benefit for us flatlanders to go out to Ogallala @3200 feet or Scottsbluff @4000ft for a couple of weeks...is that enough of an elevation change to force the body to adapt?

Cornbread...I guess the bottom line is to train - trick your body into creating more red blood to carry more O2 as it adapts to less O2 in the atmosphere?

Marc said...

This whole altitude thingy just depends.

Train high on endurance type days.
Train low on interval days.
Live low for maximal recovery.

Try just breathing through your nose when working out. Talk about difficult. Also, something that will block the passage of O2 while your breathing, multiple ski masks? Filter mask? You could wear an oximeter to check your 02 % during these tests then convert it to altitude.

Cornbread said...

Training low allows one to push themselves to maximal exertion. Maximal efforts have numerous performance enhancing benefits such as increasing oxidative enzymes, enhancing buffering capabilities, and increasing vascularization of skeletal muscle.

Conversely, living in a higher altitude allows the body to pump out more red blood cells. That's the body's way of acclimating to the hypobaric environment.

A lot of pro's enjoy the benefits of both by living at a higher altitude and going down to lower altitudes for harder training days. Living on the front range in Colorado with mountains one direction and lower altitudes the other would be very advantageous.

Kev, I'm not sure if living and training at 4000 would make a dramatic difference in performance. I'll see if I can find any research regarding elevation thresholds for performance enhancements.

A hypobaric chamber (altitude tent) would be something a Lincolnite could utilize to get the benefits of both worlds. The cheapest ones run around $4K!

Marc, I've tried to ride while only breathing through my nose. It's a lot tougher than I thought. I'm not sure if there is a performance enhancement to it. I've done it out of necessity in very dusty conditions.

Marc said...

At 7400ft there's a 12% decrease in VO2 max (Exercise Fizz: Theory and Application to Fitness and Performance 6th ed pg502). I think it's around that altitude where you'll get more bang for you time.

Check this out http://www.higherpeak.com/index.html
Do it yourself altitude tents. Basically, a decent sealed up enclosure and use an oximeter to check blood O2%.

I tried this at superweek one year http://store.pharmapacific.com/index.html
Dang it was tuff. They had a booth. I sat down and so did another dude. He literally turned blue trying to beat me. I was watching the oximeter just plummet. Pretty cool.
I started asking the guy questions on how it was made. He didn't give up much. He probably new I was up to trying to make my own. Can you say PVC?

Doing short intervals, less than 2 min, are not affected by altitude as much. More of a dependency on phosphagen system (without O2). A lot of short distance records are set at altitude. Less air resistance.

Then there was Moser at altitude. How'd he do that? The best trainer at the time, Conconi, and the revolution of the heart rate monitor. OOOOOOH! I could go on and on about these two but......

Shim said...

Coach, you got a lotta balls making a post on a Lincoln blog belittling the benefits of frisbee as a serious physical activity. You better just lay low for a while "Dude".