Part 3-The Physiological Map
The particular model that I suggest is based on the ideas of Jan Olbrecht. Using his ideas and research, we can come up with a simplified way of looking at what physiological aspects govern performance. The challenge of putting such a model together is that we do NOT know everything about how the body works and performs. We have a better understanding now then ever before but the picture is far from complete.
To illustrate this point, you can look at the evolution of what causes fatigue. Originally it was thought to be a result of lactic acid build up or oxygen debt. This theory was then disproved and new ones emerged. The current idea is that lactate is an indirect marker of fatigue because it is the hydrogen ions that come from it that is a major cause of fatigue. But this still does not tell the entire picture. The body is so complex that there are many other sites that could be the weak link and cause fatigue. Some of these include central fatigue of the motor cortex and/or spinal cord, E-C coupling failure, reduced Calcium release, impaired cross-bridge cycling of actin and myosin, and a host of other theories. If we include all of these theories in our model, the model would do us no good because it would be too complex. We do not have the time or even the know how to sit down and figure out how every workout impacts all of these aspects.
The solution is to take what most consider the biggest or most likely cause of fatigue and let that be our primary model. The other things that do not fit directly into the model can then be “spiced” in the training system periodically to see the effects. In this case we can then see how those items affect the elements in our training model. For example, if we read research that shows that certain workouts will prevent central fatigue, then we can experiment and do those workouts and see what the outcome is to the aspects of our model (i.e. the aerobic and anaerobic capacities and powers).
The physiological map below is a simple representation of what takes place in our body when running a race. It is not all inclusive for the reasons discussed in the last chapter. It is simply used to give us a guide to be able to look at and see how different workouts affect it.
(sorry for the crappyness of the picture)
Before discussing the above model it is important to note once again that lactate does not directly cause fatigue. However, we use lactate because it can be easily measured; therefore we know more about it and what happens to it during exercise. In addition, while lactate does not directly cause fatigue, it is indirectly linked to it. It has been shown that an increase in lactate corresponds to several of the factors involved in fatigue. Most noticeably, as lactate increase, pH decreases. This is caused by the increase in Hydrogen ions that come with lactate. Thus in the model used, if we can decrease the amount of lactate, then that means less pH drop and fatigue.
Pyruvate is one of the products of glycolsis. For the purpose of our model we will ignore the steps that precede it and show how to get from a carbohydrate down to pyruvate. Remember that we are looking for a model to use in training and not a fully comprehensive explanation of the systems in our body. We will leave the complexity to the scientists.
Once Pyruvate is produced, for our purposes, it has two options. It can be converted into lactate or it can be converted into acetyl-CoA and transported into the mitochondria. In the mitochondria it will enter the Krebs cycle and eventually result in aerobically produced ATP. The muscle lactate then can either stay in the muscle, causing a decrease in pH (because of the H+), go into the blood stream, thus becoming blood lactate, go into the interstitial space, or be transported to adjacent muscles. When the lactate is in the blood, it can either stay there or be transported to other muscle fibers or to various organs, most importantly the liver.
Now that we have this model, what does it mean and how do we use it? The example on the right of the chart demonstrates this. We look at the things that affect the race and that we can train. Starting at the top of the diagram, the first thing that can be affected is pyruvate production. From this point forward, I will refer to maximum pyruvate production as Anaerobic Capacity. Aerobic Capacity can be seen in the amount of pyruvate that is taken up by the mitochondria and lead to aerobic energy. In our example, the aerobic capacity is 5 units.
Looking at these two capacities, it can be seen how the model works in diagnosing training. In order to increase energy available we can increase the Anaerobic Capacity. That will allow the athlete to produce more pyruvate. However if the aerobic capacity stays the same, then this means more lactate will be produced at that effort level. If we increase the aerobic capacity, then we can see that more of that pyruvate is shuttled into the mitochondria resulting in aerobic energy increase and less lactate at the given effort. Using this model, then lactate is an interaction of both the anaerobic capacity and aerobic capacity, not just the aerobic capabilities which is widely recognized as the only source in traditional training models.
That deserves repeating because it is so important:
The amount of lactate is a result of both the anaerobic capacity and the aerobic capacity.
The amount of pyruvate that is converted to lactate depends on the enzyme concentration in that muscle and how much the mitochondria can handle. Slow twitch muscles will have a higher concentration of enzymes that convert pyruvate to acetyl-CoA, while fast twitch fibers have a higher concentration of enzymes that convert pyruvate to lactate. Because the concentration of enzymes is highly correlated with the aerobic capacity of the muscle fiber, we simplify this and tie it into the aerobic capacity.
One more thing that we can look at is where muscle lactate goes. As can be seen, it can go on to be blood lactate or can be reconverted to pyruvate, transported to adjacent muscles or into interstitial space. While this is not a main part of the model, small training effects can increase the amount of muscle lactate that is gotten out of the muscle by one of the above mentioned methods. This is important because if the lactate (and therefore H+) can be expunged from the muscle, then the pH will not drop as quickly and fatigue will be delayed. To get the muscle lactate to be blood lactate depends on two main things. The first is the diffusion gradient, which is the difference between the amount in the muscle and the amount in the blood. The greater the difference, the easier the lactate flows from the muscle to the blood. When blood lactate gets higher and the diffusion gradient decreases then the body provides a little assistance by the way of lactate transporters. These are the Monocarboxylate transporters (MCT’s) and are numbered 1,2,3,4, etc. (more are being discovered everyday). The different kinds of these MCTs have specific purposes. Some have been shown to transport lactate into the muscle (MCT-1) while some have been shown to push lactate out of the muscle (MCT-4). The research on these is relatively new so there is still limited information on how to train to increase either of these. However, we can make educated guesses at this point using the data that is available. Lighter Aerobic and higher intensity work has been shown to increase MCT-1 concentration, while MCT-4 concentration has been shown to increase by more intense work but not low intensity aerobic work. However, the picture is far from complete, thus these only play a minor role in our model. It would not surprise me that in the future; these will play a more prominent role.
As lactate increase, pH decreases. This is caused by the increase in Hydrogen ions that come with lactate. Thus in the model used, if we can decrease the amount of lactate, then that means less pH drop and fatigue. It is thus the amount of lactate in the model that represents fatigue. To use an example on how this applies to the model, let’s use the map above. If the amount of lactate in the muscle is three units per minute and total fatigue occurs when you reach 9 units then the athlete will reach failure at 3 minutes. The pace of the athlete can be seen by how much energy is produced. We started with 10 units of pyruvate. The Aerobic energy contribution can be seen as the number of units in the aerobic capacity, so in this example, 5. The Anaerobic energy contribution can be seen as the amount of units in the muscle lactate part, in this example, 5. Thus the athlete is producing 5 units of aerobic energy and 5 units of anaerobic energy per minute. This is a vast simplification of the real life physiological mechanisms of energy production, but remember it is the model that we are concerned with. Also, aerobic energy is more than anaerobic energy in our example. This is because in real life, the anaerobic pathway produces roughly 2 or so ATP, while the aerobic pathway produces over 30. The total energy reflects how fast the pace can be. So if we increase the total energy to 12 total units, then the athlete can run x faster. So the goal would be to increase the amount of energy while keeping the fatigue length (3 minutes) the same to run faster over 3 minutes.
Lactate Tolerance, or in this model the total lactate that can be withstood (in the above example 9 total units), is a factor that I have not touched on yet. In our model Lactate Tolerance is covered by Anaerobic Power, which is explained in depth next.
Powering up the model
Using the physiological map it is very easy to see how the Aerobic and Anaerobic Capacities fit in, but is not clear who the powers fit in. Earlier, we defined Aerobic Power as the ability to use the Aerobic Capacity that is built up (or how much you can use at a given pace). Anaerobic Power is the ability to use the Anaerobic Capacity (or to what degree you can use the capacity at a pace). The powers are a more difficult concept to grasp than the capacities so I will briefly some examples to make it clearer.
The easiest way to think of these powers is in terms of the percent of the capacity that is used at the given pace. If the capacities equal the current maximum of that system then we can use a simple example to make things clearer.
First let’s look at the Anaerobic Capacity part of the Physiological Map.
Using the above diagram it can be seen that in the model, anaerobic power equals the percent of max that is used. For distance coaches, it helps to think of Anaerobic Power as the anaerobic counterpart to % of VO2max. For example, many coaches talk about increasing the percentage of VO2max that the lactate threshold occurs at. For instance increasing the point where it occurs from 80% of VO2max to 85% of Vo2max. The situation is similar in terms of Anaerobic Capacity/Power. An athlete uses a certain percentage of his max at a given pace. For example, the shorter the race, the greater percentage will be used. An athlete can increase or decrease the amount used at a particular pace by training. This could be a good thing or bad thing based on the athlete and race. More on this will be discussed later, but an example of why an increase could be dangerous is if we increase the % used for a pace, then you are producing more units of pyruvate. This is fine, but if there is not an increase in the aerobic capacity, then that means there will be more units of pyruvate that are converted to lactate, thus causing acidosis in the athlete’s muscles at a faster rate. Which in the end means he has to stop at that pace earlier, thus he has to run slower to cover the whole distance.
Earlier I mentioned that Anaerobic Power is directly tied to lactate tolerance. Now that how the Anaerobic Power contributes to the model has been covered, it can be seen that an increase in lactate tolerance would increase the Anaerobic Power. In our original Physiology Map, I stated that the lactate tolerance was a total of 9 units in the muscle. If we increase that to 12, then over a race distance we could increase the amount of anaerobic energy we can use because we can handle more lactate units. This is accomplished by increasing the Anaerobic Power because an increase in Anaerobic Power would increase the amount of pyruvate produced, thus returning our muscle in the lactate to a level that will equal 12 units in the 3 minute race. Thus an increase in lactate tolerance is directly related to an increase in Anaerobic Power.
Aerobic Power is easier to grasp because most coaches are already familiar with the idea of it. As mentioned above, the best way to think of it is in terms of VO2max and % Vo2max. The VO2max would represent Aerobic Capacity, while the percentage of VO2max that a runner ran some certain pace at would represent Aerobic Power. Just like in the anaerobic example, capacity represents the max, while power represents the % of this max used at a certain pace. An improvement in Aerobic Power would be when an athlete can increase the percentage used over a race. In the example in the diagram, that would be an increase from 13 units to 13.5 units going into the mitochondria and being aerobic energy. If the pyruvate is the same then that would mean less would be converted to lactate, thus delaying the drop in pH and fatigue.
Putting it all together:
In the examples already mentioned it should be clearer on how the model is used. You can use it to both design and evaluate training. Both of which will be covered more in depth in later sections.
Using the model, the effect of the capacities and powers can be seen. To summarize, an increase in Aerobic Capacity will allow more of the pyruvate to be turned into aerobic energy. Using the diagram, if the amount of pyruvate produced stays the same for that pace/effort then less lactate will be in the muscle. This would delay fatigue as less lactate in this model means less acidosis.
Aerobic Power can be seen to decrease the amount of lactate produced too and increase the amount of aerobic energy produced at a given pace. This is accomplished by allowing the athlete to use a higher percent of his aerobic capacity during the race. That is due to either being able to race at a higher percent, or decreasing the amount of time it would take to reach that percent of aerobic capacity in a race. This happens because at the start of the race the aerobic capacity has to go from a rested state to a high percentage. To get to that percentage, it takes up to 90 seconds or more. Thus decreasing this time would mean the aerobic capacity is “revved up” faster and can contribute more energy.
Anaerobic Capacity can be seen as the max rate of pyruvate production. This is seen as the number of units at the top of the Physiology Map. By looking at this diagram it can be seen that an increase means there are more units of potential energy available. Whether this energy goes into the mitochondria for aerobic energy or is turned into lactate is important. In some cases increasing the total energy rate would be desirable. For example, if an athlete has a low anaerobic capacity, then in mid distance races he might not be reaching his potential. He might not be able to produce enough total pyruvate (and thus “energy” units) to run at a fast pace. Most of this would go into the aerobic pathway and therefore there would not be enough energy to supplement the aerobic system and reach fast enough speeds.
Another example would be if an athlete runs a 9 minute two mile with an aerobic capacity of 10 units and an anaerobic capacity of 20 units, that means the athlete can “handle” 10 units of lactate in that race. If the athlete then works to increase his aerobic capacity to 12 units, then he now produces 8 units of lactate at that pace. So increasing the anaerobic capacity to 22 units, would put him back at the 10 units of lactate for 2miles. Thus making the athlete an 8:50 2 miler for example because he is producing more energy for that race because of the concurrent increase in aerobic and anaerobic capacities. A decrease in Anaerobic Capacity could be beneficial for someone who produced too much pyruvate and not a strong enough aerobic capacity to deal with it. The large amount of lactate that would be produced would cause a rapid reduction in energy production and in turn race pace. Decreasing the Anaerobic Capacity would result in less lactate build up.Anaerobic Power is similar to Aerobic Power, only it refers to the anaerobic pathway. To refresh, it refers to the percentage of the capacity that you can use over a race. This would be a beneficial adaptation to supply more energy in a race as long as it does not overwhelm the athlete by causing premature acidosis.
Anaerobic Power is similar to Aerobic Power, only it refers to the anaerobic pathway. To refresh, it refers to the percentage of the capacity that you can use over a race. This would be a beneficial adaptation to supply more energy in a race as long as it does not overwhelm the athlete by causing premature acidosis.