Monday, February 1, 2010

Training Adaptations

Adaptations to Training

If you are having trouble following these terms or the theme, please check out the previous article on lactate metabolism.

Having established the model for lactate metabolism and defined MLSS, aerobic and anaerobic, how do those things affect performance?
Lactate metabolism is the major fatigue mechanism mode for swim races from 100 to 1500 yards. As shown in the chart below, aerobic metabolism is responsible for more of the energy used the longer the race takes. Improvements in the rate of athletes' aerobic metabolism will give corresponding improvements in performance. In races shorter than 30 seconds, contractility and speed are limiting rather than lactate accumulation. In races over ~45 minutes, glycogen depletion can be a limiting factor. For masters swimming, most of the races are right in the range where adaptations to lactate metabolism will have benefits. In terms of the bathtub model, we want adaptations that will keep the tub from overflowing before the end of the race.
Time30s60s2 mins4 mins10 mins
% Aerobic Energy Supply2030506585
% Anaerobic Energy Supply8070503515
The goal is to have the bathtub overflow JUST at the very end of the race; just as you touch the wall. So in contrast to MLSS as discussed previously, swim races are not done at an effort that elicits a steady lactate level. The races are done significantly over MLSS intensity, how much over depends on the length of the race. In most swim races the bathtub is continually being filled until the end of the race, actually for a few seconds after as well.

How do we get faster?

In terms of lactate as the limiting factor in race performance, there are three different avenues to pursue
  1. Increase your lactate tolerance (get a bigger bathtub)
  2. Increase the rate at which lactate can be used by aerobic metabolism (get a bigger drain)
  3. Increase the whole thing from top to bottom, the firehose, tub, drain and even the overflow drain.

Aerobic Adaptations

What exactly happens when we pursue aerobic adaptations; how does the drain get bigger?

Central Adaptations

Central adaptations are changes that happen away from the working muscles, the ones listed here affect the heart.
Increased Plasma Volume
The first change is an increase in blood plasma volume. Plasma is the fluid part of your blood. In general terms, increased plasma volume will make your blood move around better. Better able to deliver oxygen to your working cells, better able to take excess lactate from those working cells and bring it to other parts of your body to be used for energy.
Cardiac Hypertrophy
The second central adaptation is “cardiac hypertrophy,” use it three times in a sentence and that word is yours, work it into conversations often! Cardiac hypertrophy is the term for when your heart gets bigger. Bigger as in the amount of blood it can hold at once. In healthy people, a larger heart is a more efficient heart, you can move more blood with each beat.3 That makes it even easier to get more oxygen rich blood to your working cells.
Improved Ejection Fraction
The third central adaptation is improved ejection fraction. After you stop giggling, you should know that ejection fraction refers to how much of the blood in your heart gets squeezed out with each beat. A higher ejection fraction is better, it will take fewer beats to get the same amount of blood to the working muscles. When you go to your favorite local cardiologist to get a stress test, one of the things he measures is your ejection fraction.

Peripheral Adaptations

Increased Capillary Density
The first peripheral aerobic adaptation is increased muscle capillary density. This change means more tiny blood vessels penetrating the muscle bed. In turn this means a better flow of oxygenated blood to the muscles and a better flow of lactate and CO2 away from the muscles.
Increased Mitochondrial Density
The second peripheral aerobic adaptation is increased mitochondrial density. Mitochondria are the the parts of the cell where energy generation happens. All the aerobic metabolism reactions we have discussed occur in the mitochondria of a cell. More and better mitochondria mean that your aerobic metabolism is more capable of grabbing lactate molecules and using them in aerobic metabolism. In terms of the bathtub model, this is most directly applicable to the idea of making a bigger drain. Or possibly making more drains in the bottom of the tub.
Increased VO2max
VO2max is the maximum amount of oxygen your body can use, in an all hands on deck alert for a longer period of time (6 to 15 minutes). At VO2max your aerobic metabolism is at full tilt and your other organs are are taking up lactate to the maximum extent possible. Not only are the working muscles involved in burning the lactate but also your non-working organs are burning lactate as fuel to maximum extent possible. Your heart is pumping at its max capacity and your lungs are moving oxygen into your blood and CO2 out of your blood at peak rates. This ability, the maximum ability to burn oxygen for energy is very important for races in the four to eight minute range.

Anaerobic Adaptations

Increased Lactate Production
Increased lactate production ability means that speed of glycolysis gets faster after training it. In terms of our model you are getting a bigger firehose and can fill up the tub faster. Depending on the swimmer and the goal races this can be important. In races on the shorter end of the spectrum it is foreseeable that you could finish the race before having the opportunity to fill up your bathtub. So even if it is not used, you do want the ability to create a lot of lactate in a hurry.
Increased Lactate Tolerance
In terms of our model, increased lactate tolerance means a larger bathtub. The ability for your muscles to keep working even though the lactate and acid levels in the muscle cell are high. This encompasses a few different adaptations and as pointed out earlier, the exact mechanisms are not exactly certain. Obvious adaptations would be improved acid buffering capacity and also a reset of the "stop" signal in your nervous system.
Increased Speed
This adaptation exists largely outside of our model. This adaptation is about how fast you can move, irrespective of the lactate metabolism. So assuming lactate fatigue never kicked in, how fast could you go. This is a matter of nervous system function, contractile velocity, and even how fast your body can cycle ATP (the energy currency of your cells). While not clearly covered in the lactate metabolism discussion, I mention it here because one of the types of swim sets USA swimming uses is directed at this adaptation.

What Next?

The next question, What types of sets help make these adaptations will be in the next article.
3. Diseased hearts also undergo hypertrophy, that's why we say in healthy people cardiac hypertrophy is a good thing.

No comments: