Introducing the Power Running Model of Endurance Physiology
Runners discuss and debate a lot, which is perfectly understandable because there is lots of fascinating stuff to discuss and debate about. They debate really interesting physiological topics such as lactate threshold, mitochondrial density, VO2max, and muscle pH levels. And they debate important training topics like weekly mileage, base building, HR training zones, and intensity.
When you boil it all down to its very essence the reason runners discuss and debate all the above is for one simple reason – we want to run faster. That’s all it’s really about. All the debate and discussion is about the physiological constraints to performance and how to train so as to maximize your performance.
So, exactly how does all that physiology stuff fit together? What is the answer to the question, “Why can’t I run faster”? That’s what this article is about – the essence of performance. No research study dissections, no in-depth discussion of intricate physiological factors, no pH or lactate charts; just a straight forward explanation of how endurance performance is physiologically determined, all without including a lot of physiological jargon.
If you are curious about the research data supporting this explanation please see all other articles on the Power Running web site, especially those in the physiology section. In fact much of the Power Running web site consists of the data supporting the explanation I’m laying out here. The supporting research data is all there. For our purposes here, though, I’m only going to explain how it works in simple, straightforward language. So without further ado I present the Power Running Model of Endurance Physiology.
The Power Running Model of Endurance Physiology
- Performance is ultimately determined by your muscles.
You can only run as fast as you can run because your muscles aren’t capable of moving you faster. When your muscles are contracting as fast and with as much force as they are capable of contracting, then that’s it; that’s as fast as you can run. A few lucky people are born with really powerful, fast contracting muscles that are amazingly resistant to fatigue. These folks run really fast. Most of us are born with average amounts of power, strength, speed, and endurance. We don’t run especially fast. A few folks are, unfortunately, born with below average power, strength, speed, and endurance causing them to run slower than average.
Sure, there are exceptions to the above. For example, there are some people who are really fast at short distances but not so fast at long distances. We call these people sprinters. However, exceptions don’t disprove the rule. After all you wouldn’t say that just because there are some short people it proves that most people aren’t of average height.
Obviously, endurance runners don’t routinely compete at their top running speed. So, what’s the relationship between your top speed and the pace you can sustain during longer events? Your top speed determines every other pace/distance that you can hold because properly trained muscles fatigue at a known rate. If you are familiar with prediction tables you already know this to be true; you are able to predict your performance at any distance based on your performance during another event, assuming proper training. Prediction tables work because the average person’s muscles fatigue at a known rate. For example if we take your 100m sprint time to be your top speed (it’s not exactly, but it is close enough for our purposes) then with proper training you can run:
400 meters at 96% of your top speed
800 meters at 87% of your top speed
3 kilometers at 74% of your top speed
5 kilometers at 71% of your top speed
10 kilometers at 68% of your top speed
10 miles at 66% of your top speed
½ marathon at 65% of your top speed
Marathon at 61% of your top speed
How do I know this? Because it is a known fact that you fatigue – your muscles fatigue – at a known rate. And since we know that we can predict your performance at one distance from your performance at another distance. Your top speed and your performance at any other distance are linked by rate of fatigue.
The bad news is that there isn’t much you can do to speed up your muscles. Your top speed is mostly genetically determined and neither training nor science has found a way to overcome those genetic limitations. You can only marginally increase the speed of your muscles and your top speed. The good news is that most of us can dramatically improve the endurance of our muscles and the other physiological systems of the body, improving our performance at most endurance events so that it matches what the prediction tables tell us is possible.
- Other physiological systems influence how hard your muscles can work
Just because your muscles are capable of working at a particular high level doesn’t mean that all the other parts of your body will be able to withstand the same workload. Other parts of the body may prematurely limit how hard your muscles can work. For example, while running in hot weather your core body temperature is likely to reach a critical level at a much slower pace than when running in cooler weather. Even though your muscles are capable of working harder they are prevented from working at a higher level because your body will overheat prior to your muscles getting to that level of work. Similarly, your muscles may be capable of running a 10k at a faster pace, but insufficient mitochondrial energy processing capacity prevents them from working at that faster pace for the full 10k. Or your muscles may be capable of running a marathon in 3 hours, but insufficient glycogen stores may limit your performance to a 3 ½ hour marathon.
Any number of physiological systems and factors can prevent your muscles from working at full capacity. If you think about it for a moment, this isn’t particularly surprising. After all most of us know that just because a prediction table says that based on our 5k run time we can run a marathon in 3 hours it doesn’t mean we can run a marathon in 3 hours. The prediction table is telling us what our potential is in the marathon with proper training. Without the proper training our physiological systems and factors won’t be fully conditioned and prepared to work at the level required to run a marathon in 3 hours, nor will our muscles be conditioned to perform optimally and, therefore, our performance will be less than predicted.
The good news is that proper training can mostly remove these physiological limitations so that you are able to tap into the full potential of your muscles.
3. The Central Governor is the way the physiological systems of the body influence the performance of your muscles.
In your subconscious brain you have a Central Governor. This governor constantly monitors all the systems of your body and if one or more of them should approach a dangerous level the governor reduces the work rate to protect the body from catastrophe, injury, and/or death. The Central Governor’s primary role is to ensure the safety and survival of the body, a role it fulfills by preventing you from working so hard that irreparable damage or catastrophic failure occurs within any of the systems of the body.
When an event occurs that triggers the Central Governor to react, not only does it reduce the amount of active muscle fiber, thus slowing the pace, but it also sends strong signals of fatigue and distress to your conscious brain. You need not have been a runner long to recognize that during some particularly strenuous workouts you have experienced strong desires to stop exercising and/or strong signals of distress. These were signals from your Central Governor letting you know that one or more of your physiological systems was working at or close to maximum capacity.
For example, if during a workout in very hot weather your body’s core temperature should reach a too high level, your central governor reacts by slowing your running pace, increasing your rate of sweating, diverting blood to your skin to increase your cooling rate, and sending strong signals to your conscious brain to stop working out and seek shade and water. Similarly, if during a sprint workout your muscle acidity levels should reach a too high level, the central governor will de-recruit muscle fibers, slowing the pace, so that the excess hydrogen ions causing the muscle acidity can be cleared from the body, lowering the pH of your muscles to acceptable levels. Or, if you are running at a pace that utilizes all the available oxygen such that blood oxygen levels reach dangerously low levels, the central governor reacts to slow the pace so that your body’s demand for oxygen decreases to an acceptable level.
The Central Governor ties together all the different parts of your body involved in endurance exercise. It constantly monitors everything and allows you and your muscles to work only at a level and duration that does not risk severe or irreparable damage to any part of the body. It is in this way that all the physiological systems and factors are able to influence the performance level of your muscles.
The Power Running Model of Endurance Physiology teaches that:
- muscles ultimately determine your performance
- other physiological factors can have a strong influence on how hard your muscles can work
- the Central Governor links the ability of your muscles with your body’s other physiological systems
These three things – muscle, physiological systems, & Central Governor – together determine how you will perform during any endurance event.