The Muscle Factor Model (Read 3135 times)

Rich_


    Over the past few years it has been my observation that quite often there is a disconnect between training and physiology. Specifically, it is not at all unusual for a coach, athlete, writer, whomever, to offer a physiological explanation for a particular training method only to find out later on that the physiological explanation is inaccurate or incorrect. For example, look at the concept of "lactate threshold" and "lactate threshold training". Runners routinely train at "lactate threshold" pace with tempo runs. Training at that level of intensity is known to improve performance. The physiological explanation for why tempo runs work is that training at or near lactate threshold improves the body's ability to clear fatigue causing lactate from the muscles. However, today we know that lactate doesn't cause fatigue and there is no "lactate threshold". Of course, that doesn't mean tempo runs aren't effective - they are. It only means that the physiological explanation for why tempo runs works is inaccurate. There are other examples of this same phenomenon including aerobic base building (which doesn't build an aerobic base), recovery runs (which don't speed recovery), VO2max (which doesn't limit performance), running economy (which is about energy, not oxygen), and so on. I've spent a lot of time over the past few years working on finding answers to some of these contradictions. The answers I've come up with have led to the creation of power running, the running theory of everything, and the dynamic model of fatigue. Recently, I had a new physiological breakthrough in terms of understanding how muscles function during exercise and, more importantly, how they adapt to exercise. This breakthrough has led to the creation of a new model describing muscle activity during and adaptation to exercise. I termed this new model the muscle factor model. In terms of physiology this new model provides a much more accurate explanation for why particular training methods work. It explains why base building works (for those that base building works for). It explains why easy runs are beneficial for some runners. It explains why research consistently shows high intensity running produces better results. In short it fills in a lot of the physiological gaps we have today. I believe this new model will cause some changes in how runners train. The new model won't make wholesale changes in training, but it will make noticeable changes when incorporated into existing training methods.
    Rich World's Fastest Slow Runner
    xor


      Over the past few years, it has been my observation that you post a bunch of stuff that sounds really science-y, but actually isn't really.

       

      Rich_


        Muscle Factor Model How muscles function during and adapt to endurance training One thing that long distance runners have long known is that the single best predictor of performance at any running distance is performance at another running distance. You are probably familiar with this fact in the form of a prediction table. Most running books and many running web sites contain a prediction table as a tool to help runners predict what they can run for some distance. Plug in a recent performance at one distance into the prediction table and it tells you what you will most likely be able to run at some other distance. The accuracy of prediction tables is very high, 90% or higher in most cases, and is significantly more accurate than anything else available to runners or physiologists to predict performance. In more recent years physiologists have discovered that sprints and other “anaerobic” events are highly correlated with endurance performance. One study of endurance runners found that a 20 meter sprint could accurately predict 5k performance. A study of 10k runners have found that 50 meter sprints, 300 meter sprints, and a modified triple jump to be excellent predictors of 10k performance. In fact, in that study the modified triple jump was the single best predictor of performance of 10k performance. Very interesting when we consider the fact that a triple jump is not even a running event. Physiologists have long struggled to explain why performance at one distance so accurately predicts performance at other distances or why sprints and leaping events are able to predict endurance performance. Runners have traditionally been taught that the body’s ability to absorb, transport, and utilize oxygen determines performance but this theory fails to explain the relationship between performance at widely varying distances. For example, the theory can’t explain why a 5k run at or very close to VO2peak is able to predict performance in the marathon, which is run at a pace significantly below VO2peak. Further, the theory doesn’t even begin to offer an explanation as to why endurance performance can be predicted from sprints or even why the modified triple jump was such a good predictor of 10k performance. In addition to being unable to explain the performance relationship between running at all distances there are some basic training methods unexplained by current wisdom. Every current training program includes long runs, tempo runs, intervals, sprints, easy runs and hill running in various combinations. Different physiological explanations are offered for why each of these specific types of workouts contributes to performance, but many of these explanations are known to be inaccurate or incomplete. Easy runs provide an example of this. Programs that include easy runs typically provide varying explanations for why easy runs are an important workout, including promoting faster recovery, building an aerobic base, increasing the number of mitochondria in muscles, or increasing glycogen storage, amongst others. But there is no real evidence that easy runs promote or speed recovery, increase glycogen storage more than other workouts of similar duration, or build an aerobic base in anyone except beginner runners. Other types of run are known to produce the same benefits attributed to easy runs but to a greater extent. For example, high intensity runs are known to increase aerobic capacity and mitochondrial density as much or more than do easy runs. If the benefits attributed to easy runs are produced to a greater extent by other types of workouts, then why include easy runs in a program? The answer is that easy runs do produce a unique benefit but the benefit and the reason are unexplainable by conventional training wisdom. Easy runs are just one example of training practices that are widely believed to be beneficial but whose physiological explanation is incomplete or insufficient. Tempo runs provide another example. Tempo runs were originally invented to improve the “lactate threshold” back when lactate was believed to cause fatigue. Today we know that there is no lactate threshold and, even if there was it wouldn’t matter because lactate does not cause fatigue. We know tempo runs work but the traditional physiological explanation for why they work is now known to be false. If traditional physiological theories are unable to explain the performance relationship between runs of any distance and are unable to explain accepted training methods, then what does explain these things? I have interpreted the relationship between endurance performance at any distance, sprinting, and even the modified triple jump to mean that there is one factor that primarily determines performance. I suggest this one factor is involved in running any and all distances, from the shortest of sprints to the longest of races, and it is this factor that more than anything else determines performance. I further suggest that this one factor offers a single, accurate explanation for the necessity and effectiveness of all the various training runs included in most programs. This factor explains why easy runs work (for those that easy runs work for), why tempo runs are so effective and how they work, why long runs are the key to marathon performance and are beneficial even for sprinters, why running uphill improves performance on both hills and flat ground, and why sprints improve marathon performance. In short, I believe this single factor answers many of the previously unanswered training observations and questions. What is this one factor? Muscle. Specifically, I believe that muscle contractility – the ability of a muscle fiber to contract – is the number one factor that determines performance in any event in which power, endurance, and/or strength are important. In support of this belief is a large body of data and research evidence ( you can find much of the data in other article I've written, especially the ones posted in the “muscle” section of the physiology page at www.powerrunning.com). In 2006 while conducting background research for an article on strength training for endurance runners I came across a strength training study whose results were quite startling. That particular study caused me to rethink some of what physiology currently teaches about the function of muscle during exercise and its adaptation following exercise. In turn, this led to a breakthrough in muscle physiology; a breakthrough I have termed the Muscle Factor Model. I believe this new model more accurately explains how muscles function during and adapt to exercise. Furthermore, this new model suggests some significant modifications in training methods for any sport in which strength, power, or endurance are important. The muscle factor model may lead to the most significant changes and refinements in training since the introduction of Periodization back in the 1980s. I realize that is a heck of a bold claim, so let's have a look at the muscle factor model in detail. More to follow.
        Rich World's Fastest Slow Runner
          Hefty?
          JimR


            Hefty?
            No, it's Richard Gibbens. Hey Rich...have you bettered your 30 minute 5k time yet?
            xor


              No, it's Richard Gibbens.
              aka 'Richard99' from coolrunning... and the famous churning threads. I never took an active role in those threads, but I certainly tried to puzzle through them and the arguments (it was rarely discussion) from various sides. All I'll say is that there needs to be a handbook written for how to deal with these threads, the weird "science", and the spirited debates. Even as an interested reader, one will probably need a map and a compass. And a raincoat. And very high boots. That's all I'll say for "Worlds Fastest Slow Runner" (... what the heck does that MEAN?)... and these threads. Goodnight and good luck.

               

                Wow, Rich sure SOUNDS like Hefty!


                Prince of Fatness

                  aka 'Richard99' from coolrunning
                  Ahh, good times they were over at CR.

                  Semi-retired.

                    I always have found Richard's posts interesting and thought provoking-by the time they run to ten pages or so there is a lot of info in the point/counterpoint of the discussion from which I am sure to learn something. (For example I got a link to an interesting Hadd website once.) I don't necessarily think his theories are correct; at best perhaps controversial, but I don't think being able to run faster than he can is a compelling counter argument. Simon.

                    PBs since age 60:  5k- 24:36, 10k - 47:17. Half Marathon- 1:42:41.

                                                        10 miles (unofficial) 1:16:44.

                     

                    Mishka


                      Are calls from a payphone still a quarter?
                        Dude. I already put my high boots on after the first post, but the next post overflowed my boots already. And yes, Teresa, it does sound somewhat like Hefty.

                        When it’s all said and done, will you have said more than you’ve done?

                        Rich_


                          Muscle Fiber Contractile Properties Physiologists generally divide muscle fibers into three basic types - Slow Twitch, Fast Twitch A, Fast Twitch B - based on the contractile properties of the fibers. Slow twitch fibers are the weakest of fibers, contract relatively slow, and have very high levels of endurance. Fast Twitch A fibers are stronger than Slow Twitch fibers, contract relatively fast, and have high levels of endurance. Fast Twitch B fibers are the strongest of fibers and have the fastest contraction speed but have the least amount of endurance. The above description of the contractile properties of each muscle fiber type might lead you to believe that each type of fiber has distinct contractile properties. Nothing could be further from the truth. Muscle fibers of any type are not all alike; they don't all contract the same; they are not homogenous. Instead there is a broad continuum of contractile properties in all the muscle fibers of any type. Physiologists have measured up to a 129x range of contractile properties in muscle fibers of the same type. What this means is that in any specific fiber type you will find fibers that contract much slower or faster than other fibers of the same type; fibers that contract much more or much less forcefully than other fibers of the same type; fibers that possess much more or much less endurance than other fibers of the same type. For example, physiologists measured the time to exhaustion in a group of fast twitch fibers and found some of the fast twitch fibers fatigued in as little as 16 seconds while other fast twitch fibers were able to contract for 34 minutes before reaching fatigue. The contractile properties discussed early tell us what the average contractile properties are for each type of muscle fiber. The average Slow Twitch fiber is slower, weaker, and has greater endurance than any of the Fast Twitch fibers. The average Fast Twitch B fiber is stronger and faster but less enduring than other fiber types. But the broad range of contractile properties across all muscle fibers means that fibers of the same type do not all have the same level of strength, endurance, or speed. A very important point about muscle fiber contractile properties is that there is a strong inverse relationship between a muscle's strength and its endurance. The stronger a muscle fiber the less endurance it has and vice versa. Weaker fibers possess much greater endurance than do strong fibers. Stronger fibers possess much less endurance than weaker fibers. This point is critical to understand. Muscle Activation During Exercise Not all muscle fibers are activated during exercise because the body only activates the minimum number of fibers required in order to get the job done. Muscle fibers are activated in a very specific order, from weak to strong. Physiologists have termed this the size principle of activation. Basically, muscle fibers are recruited based on the amount of force required to complete the task at hand. Recall that there is a wide variation in the strength of muscle fibers; every whole muscle has fibers with different levels of strength, from very weak all the way up to very strong. The weaker fibers are recruited first with the strongest of fibers only being recruited during the heaviest of tasks. Fibers are generally recruited in the following order based on the level of force required to perform the task: Slow twitch - Fast Twitch A - Fast Twitch B There are 2 important points to understand about muscle fiber activation; 1) it is a team sport and 2) total force is the sum of the force of all the active fibers. 1. A team sport: Muscle fiber work together. Activation proceeds from Slow - Fast A - Fast B. It is NOT the case that Slow Twitch fibers exclusively handle the easy tasks, Fast Twitch A exclusively handle the moderate tasks and Fast Twitch B exclusively handle the heavy tasks. Instead, as the load increases from easy to moderate to heavy an increasing number of fibers are activated and all are working together to complete the task. 2. The total force produced by a whole muscle during a task is the sum of the force of all the individual fibers. All active fibers, whether Slow, Fast A, or Fast B, contribute force during movement and the total amount of force generated by a muscle is the sum of the force of every active fiber. During a really heavy lift, the active Slow Twitch fibers are producing force and helping lift the weight. In practical terms this is what it means: If you pick up a light weight, then only Slow Twitch fibers will be activated because little force is needed to pick up the weight. If you pick up a somewhat heavy weight then both Slow Twitch and Fast Twitch A fibers will be activated because more force is required to lift the weight. Note that the Slow Twitch fibers are still active during this exercise, but since they are unable to generate enough force to get the job done, some Fast Twitch A fibers are also required to help out. Pick up an even heavier weight and now you are using Slow Twitch + Fast Twitch A + Fast Twitch B fibers to lift the weight. The Slow Twitch and Fast Twitch A fibers did not possess enough strength to lift the weight by themselves, so the strongest of fibers, the Fast Twitch B fibers, were activated. The same thing applies to running. Running at a slow pace activates only Slow Twitch fibers because the force required to run slowly is small enough that the Slow Twitch fibers are strong enough to handle the job themselves. Running at a fast pace activates Slow Twitch and Fast Twitch A fibers because running faster requires more force to be generated. Very fast running (i.e. intervals and sprints) and fast or steep uphill running activate the Slow Twitch + Fast Twitch A + Fast Twitch B fibers due to the high level of force required to run at very fast paces. Muscle Fiber Activation at Exhaustion As an exercise proceeds it becomes increasingly difficult to maintain a set amount of force production because of fatigue. The first repetition of an exercise might be reasonably easy but repetition 20 with that same weight might be an all-out effort. Are all fibers activated during the hard to all-out effort that athletes routinely reach during intense workouts? Only in some cases; in most cases not all fibers are activated. During exercise as a person fatigues some inactive muscle fibers are recruited to assist those active fibers that have fatigued. However, there is a limit to the amount of additional fibers that are recruited. During endurance exercise the body does not keep recruiting muscle fibers until 100% of all the fibers in a particular muscle are activated. About the only time that all fibers are active is during the heaviest of tasks, such as during very heavy weight lifting. Less forceful tasks, such as distance running, do not result in 100% activation of all available muscle fibers, even at the end of the run when the runner is running as hard as they can for that distance. For example, one study found a little less than 70% leg muscle fiber activation while running to exhaustion on a level treadmill and a bit more than 70% activation during exhaustive running up an inclined treadmill. Overload and Intensity One of the primary principles of training is the overload principle. Exercise physiology generally defines overload like this - you must apply an activity specific overload in order to cause physiologic improvement and bring about a training response. What this means is that muscles must be trained with a sufficient level of intensity in order to cause adaptation to occur. There is nothing earthshaking in the concept of overload as it has been a principle of training for more than a century. However, we need to carry the concept of overload a bit further and apply it to individual muscle fibers; what is true for a whole muscle is also true for individual muscle fibers. In order to cause a training response in any individual muscle fiber that muscle fiber must be trained with a sufficient level of overload, with a sufficient level of intensity. This is accomplished by training a fiber reasonably close to its maximum capacity. Or said another way you must sufficiently fatigue a fiber in order for it to adapt and improve. This point is critical in understanding how muscles fibers work and adapt to training. Let’s examine this principle in training terms. You put a weight on a bar so heavy that you are only able to lift the bar a maximum of 10 times. Because the bar is heavy you will activate Slow + Fast A + Fast B in order to raise the bar. After 10 reps (about 30 seconds of lifting) you are no longer strong enough to lift the weight an additional time so you set it down. Which fibers did you overload? You only overloaded some of your Fast B fibers (those Fast B fibers that fatigued in 30 seconds or less). You have a whole bunch of fibers that you didn’t fatigue. Which ones? Those that take longer than 30 seconds to fatigue. Your Fast B fibers were tired and couldn’t lift any more weight; your Fast A and Slow fibers were not exhausted at rep 10 but lacked the strength to lift the weight by themselves. Therefore, your Fast B fibers will get stronger but not your Fast A or your Slow Twitch fibers. When your Fast B fibers adapt you will be stronger, but you will not be as strong as you could get. Why? Because lifting that heavy weight is a team effort and your Fast A and Slow Twitch fibers contribute to the total strength of the muscle but you didn’t train your Fast A or Slow Twitch fibers to get stronger. If you trained all your fibers – Slow, Fast A, and Fast B – then you would get as strong as you are genetically capable of getting You sprint nearly all-out for 200 meters. Fast sprinting requires high force output which means it activates Slow + Fast A + Fast B. Which fibers did you overload? Again, your Fast B fibers are overloaded and will adapt. What about your Fast A and Slow Twitch fibers? Again, they weren’t exhausted after 30 seconds of exercise and will not adapt much if any. After your Fast B fibers adapt you will be a faster sprinter, but not as fast as you could be. Why? Because fast sprinting requires force from your Slow, Fast A, and Fast B fibers but you only trained your Fast B fibers. Train your Slow and Fast A along with your Fast B and then you will get as fast as you are genetically capable of getting. This same thing applies at any running distance. You run a 30 minute tempo run. Which fibers are overloaded after that run? Some of your Fast A fibers (those that fatigue in 30 minutes). Your Fast B weren’t activated because the amount of force needed to run at tempo pace is not high enough to activate them. Your Slow Twitch weren’t fatigued after only 30 minutes of running. So, only some of your Fast A fibers were overloaded and will adapt. Putting it All Together = Muscle Factor Model When we put all the above facts together, we arrive at the Muscle Factor Model. In order to cause an adaptive response in a muscle fiber, that muscle fiber must 1) be active and 2) be overloaded; failure to accomplish both of these results in little to no adaptation in that muscle fiber. Recall the inverse relationship between a muscle fiber's level of strength and its endurance capacity - the higher the strength the less the endurance, the lower the strength the more endurance. If you are going to overload a muscle fiber you must work it to a reasonable level of fatigue. Considering that muscle fibers possess widely varying levels of endurance, this means that only a relatively few muscle fibers are fatigued at the end of any normally conducted exercise session. In training terms this means: In order to overload weak muscle fibers with abundant endurance requires long training sessions conducted at low levels of force production. In order to overload moderately strong muscle fibers that possess moderate levels of endurance requires moderate duration training sessions conducted at moderate levels of force production. In order to overload the strongest of muscle fibers with poor endurance requires short duration training sessions conducted at high levels of force production. If you want to maximize your performance, then you have to train all the muscle fibers that contribute to force production during your chosen activity. You have to train your weak fibers, your moderate fibers, your strong fibers, and your strongest fibers. Since force production is a team effort, then any untrained fibers detract from the overall performance of the team (in this case the team is the whole muscle). Summary The muscle factor model provides a more complete explanation for how muscle fibers work during and adapt to exercise. Only muscle fibers that are active and overloaded during exercise will adapt and grow. The only way to overload a muscle fiber is to train it to a sufficient level of fatigue. Normally performed exercise programs usually do not train all or most of the fibers in a whole muscle due to the way muscle fibers are activated during exercise and because muscle fibers have widely varying levels of endurance. The only way to maximize performance is to train all the muscle fibers that are active during the event; any untrained muscle fibers prevent the athlete from reaching his/her maximum potential.
                          Rich World's Fastest Slow Runner
                            In training terms this means: In order to overload weak muscle fibers with abundant endurance requires long training sessions conducted at low levels of force production.
                            In other words, long runs.
                            In order to overload moderately strong muscle fibers that possess moderate levels of endurance requires moderate duration training sessions conducted at moderate levels of force production.
                            Oh, so tempo runs.
                            In order to overload the strongest of muscle fibers with poor endurance requires short duration training sessions conducted at high levels of force production.
                            Intervals? Reps? Strides?
                            I believe this new model will cause some changes in how runners train. The new model won't make wholesale changes in training, but it will make noticeable changes when incorporated into existing training methods.
                            Sounds real different than what we have now.

                            When it’s all said and done, will you have said more than you’ve done?

                            Rich_


                              Training in accordance with the Muscle Factor Model So far we have discussed the basic physiological premise of the muscle factor model. We can sum up the physiological premise this way: Only those individual muscle fibers that are sufficiently overloaded will adapt. You overload individual muscle fibers, not an entire muscle. If you don't sufficiently overload an individual muscle fiber it won't adapt. This physiological fact has tremendous training implications. In short, it tells us that to maximize performance requires optimally training all (or as many as is reasonably possible) the fibers that are active during the chosen event. Imagine for a moment that you were the coach of a competitive 8 person rowing team. As the coach of the team your responsibility is to get maximum performance from the team. It appears obvious that the only way to get maximum performance out of the team is by each member of the team producing maximum performance. The overall performance of the team is dependent on the combined performance of each member of the team - a poor performance of one or more team members results in a sub-par performance of the team. How do you get maximum performance out of all 8 team members? You train all 8. You wouldn't train just 4 of the team members and then expect the team as a whole to excel, would you? If you don't train all the members of the team, the overall performance of the team will be less than they are capable of. Think of your individual muscle fibers as being part of a team, because that's what they are. Fibers work together as a team. If you don't train all of your fibers then your overall performance will be sub-par. Optimally train all your fibers and your performance will as good as is possible for you. The question that needs to be asked is "How do I train all the individual muscle fibers that are active during my event?"
                              Rich World's Fastest Slow Runner
                                JK's Muscle Factor Model Theory: Count the word in the theoretical explanations posted above. Whatever number you come up with - don't actually read them. Just count. Then run that number of miles in each of the next two years. I guarantee dramatic improvement - or your money back.
                                E-mail: JakeKnight2002@aol.com
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