Thursday, January 6, 2011
Wednesday, December 22, 2010
The Lydiard Method
Many athletes struggle with their competitive running after they graduate from high school or college. Some athletes are burned out and take a break from the sport and have to get back into shape. Others lose all motivation to run once they are away from the team environment, and some simply do not know how to develop a training schedule.
Developing a training schedule is not always an easy thing to do. Many runners simply do not know much about why they do different workouts. They may not understand exactly when in their training program they are supposed to incorporate their long runs, tempo runs, or intervals workouts. This article's goal is to discuss one method of organizing your training. The method was developed by Arthur Lydiard. Arthur Lydiard is considered by most of the running community to be the best running coach of all time.
Marathon Conditioning (10 weeks)
According to the Lydiard method the first phase of your training for any endurance race should be Marathon Conditioning. The marathon conditioning phase should be 10 weeks in length. The goals of this phase are to improve your aerobic foundation and help prevent injuries. The improved functioning of your heart and lungs increases your aerobic foundation. Marathon Conditioning also strengthens connective tissues and ligaments which will help you prevent injuries.
To develop you training schedule for the marathon conditioning phase you should start with short runs on a consistent basis. Gradually you can lengthen the distance of your runs. To lengthen the distance of your runs start with lengthening one run a week. Then you can increase that number to two runs a week. When you plan your training for this phase make sure that you follow the hard/easy principle. This principle says that you should run one day hard and then the next one or two days easy before doing another hard day. During the marathon conditioning phase a longer mileage day is considered a hard day. It does not necessarily have to be run fast or hard. Here is an example of what a Marathon Conditioning phase build-up may look like. If you can run three miles everyday without becoming overly fatigued you could start lengthening your runs. After a few weeks your weekly workout might have changed from three miles everyday to five miles on Monday, three miles on Tuesday, five miles on Wednesday, three miles on Thursday and Friday, and 8 miles on Saturday. Sunday would be a rest day. That is just an example and may not be the best way to organize a schedule for you. If you noticed on Saturday the sample schedule included an eight mile run. During the marathon conditioning phase Lydiard suggests increasing the time of one run per week until that run reaches two hours in duration. If you are a beginner in running the two hour run may be increasing your total time running too quickly in the 10 week phase. If this is the case then you should pick a shorter duration for your long run.
Hill Resistance (4 weeks)
The Hill Resistance phase should be 4 weeks in length, and it serves as a transition phase. The goal of this phase is to transition your body from the slower running in the Marathon Phase to the faster running in the Track Training phase. The Hill Resistance phase will begin to introduce anaerobic exercise to you and it will add power and flexibility to your legs.
There are several different types of workouts that can be included into your schedule during this phase. The first one is steep hill running. While maintaining good running form you can run up a steep hill that is 300 to 800 meters in length. While doing this workout your legs should be lifted up until they are almost horizontal to the ground. The second workout is hill bounding. Find a hill with a moderate grade and a length of about 200 meters. Use bounding strides to climb the hill. You should feel like a deer jumping over a fence. A third workout is Sprinting Drills. Examples of Sprinting Drills are high knees, strides, bounding, and butt kicks. You should do one of these workouts, or a workout similar to this, 1-3 times per week during the Hill Resistance phase. The rest of the week should include easy running.
Track Training (4 weeks)
The track training phase is 4 weeks in length and is a phase in which you will do intervals and/or repetitions on the track that will help you with you goal race. The workouts you choose for this phase should focus on developing the systems you will need for your goal race. Some examples of these workouts might include 400 meter repeats, 800 meter repeats, 1-2 mile repeats, and ladder workouts. The phase is called track training, but the workouts do not have to be done on the track. Finding a flat section of road and doing intervals from telephone pole to telephone pole may be your desired way of training during this phase.
This is a very important phase in your training, but when doing track training caution must be used. This is the phase in which injuries are more likely to occur because of the increased intensity of the workouts. It is better to be under-trained in this phase as opposed to over-trained. Once your body begins to become over-trained you will have a hard time fighting off illnesses and avoiding injury. This is you bodies way of telling you to take it a little easier. One way to help prevent over-training is to make sure you follow the hard/easy principle that was discussed earlier.
Coordination (4 weeks)
The coordination phase is where you start to get all your systems ready for the goal race a few weeks down the road. The coordination phase is the time for you to start incorporating sprint drills and time trials into your training.
Running time trials allows your body to become familiar with the effort required during your goal race. One thing to remember about time trials is to not become discouraged with your time. Once you get to this phase of your training you should be in great shape. Many times you may set a personal record for an event during a time trial. Other times you may not run as fast as you think you are capable of. If this is the case for your time trial just remember that most people can not run as fast by themselves in a time trial as they can against competition in a race.
Sprint drills are also important to your goal race. These drills allow you to develop more leg turnover (speed) by developing muscle strength. These drills also improve your running form which improves your efficiency.
Freshening Up (1-2 weeks)
The freshening up phase (also know as a taper phase) is when everything should begin to come together. In this phase your training decreases and your body recovers from the hard work you have put in during the past 22 weeks. This is the time when you may not be able to sit still due to the extra energy your body has that you are not using due to the decreased training. Be cautious during this phase. This is not the time to go out and play a game of pick-up basketball to burn off some extra energy. This is also not the time to put in extra training because you are feeling energized. The length of the freshening up phase is usually 1-2 weeks, but it can depend on the athlete and the goal event. Freshening up for a marathon usually takes 3 weeks.
Down Time
Once you reach the end of the freshening up phase you have your goal race. If everything goes according to plan you should have ran one of the best races of your life. After this race comes a very well deserved period of your training. This is also a very important part of your training. While this period is not an actual named part of the Lydiard Method it is a part of almost all training methods. After your goal race you should have some down time. During this down time you should take a few weeks to relax and refresh yourself physically and mentally. These few weeks of relaxing should include jogging easily. Do not feel guilty if you miss a few days here or there during your down time. Be cautious not to miss too many days because you will begin to lose all the progress you made during the previous training cycle.
If you have not already done so now is the time to pick out your next goal race and begin the training cycle again, and build upon the progress you made. The Lydiard Method is a training cycle that can be followed over and over to build up for goal races. As with all training methods it takes time to improve. If you continue to follow the Lydiard Method over a long period you may set personal records in races that a few years ago you could only dream of. To quote the great coach Arthur Lydiard, "It is not the best athlete who wins; but the best prepared."
Why Running shoes do not work: Looking at Pronation, Cushioning, Motion Control and Barefoot running.
The running shoe model needs to be fixed. Pronation, Motion Control, Cushioning, and Stability shoes? Get rid of them all.
It’s not just barefoot running and minimalism versus running shoes, the either/or situation many portray it to be. It’s much deeper than that. It’s not even that running shoe companies are evil and out to make a profit. Shoe companies may be accomplishing the goals they set out for, but maybe the goals their aiming for are not what need to be done. The paradigm that running shoes are built upon is the problem.
Running shoes are built upon two central premises, impact forces and pronation. Their goals are simple, limit impact forces and prevent overprontation. This has led to a classification system based on cushioning, stability, and motion control. The problem is that this system may not have any ground to stand on. Have we been focused on the wrong things for 40+years?
I’ll start with the customary statistic of 33-56% of runners get injured every year (Bruggerman, 2007). That is kind of mind blowing when you think about it. Since there are a ton of injuries going on, let’s look at what shoes are supposed to do.
Pronation:
As said earlier, shoes are built upon the premise that impact forces and pronation are what cause injuries. Pronation, in particular has been constructed as the bane of all runners. We have become inundated with limiting pronation via motion control shoes. The central idea behind pronation is that overpronating causes rotation of the lower leg(i.e. ankle,tibia, knee) putting stress on the joints and therefore leading to injuries. Running shoes are therefore designed to limit this pronation. Essentially, running shoes are developed and designed to put the body in “proper” alignment. But do we really need proper alignment?
This paradigm on pronation relies on two main things: (1)over pronation causes injuries and (2) running shoes can alter pronation.
Looking at the first premise, we can see several studies that do not show a link between pronation and injuries. In an epidemiological study by Wen et al. (1997), he found that lower extremitly alignment was not a major risk factor for marathon runners. In another study by Wen et al. (1998), this time a prospective study, he concluded that “ Minor variations in lower extremity alignment do not appear conclusively to be major risk factors for overuse injuries in runners.” Other studies have reached similar conclusions. One by Nigg et al. (2000) showed that foot and ankle movement did not predict injuries in a large group of runners.
If foot movement/pronation does not predict injuries or is not a risk factor for injuries, then one has to question whether the concept is sound or working...
Looking at the second premise, do shoes even modify pronation? Motion control shoes are designed to decrease pronation through a variety of mechanisms. Most choose to insert a medial post or a similar device. In a study by Stacoff (2001), they tested several motion control shoe devices and found that they did not alter pronation and did not change the kinematics of the tibia or calcaneus bones either. Similarly, another study by Butler (2007) found that motion control shoes showed no difference in peak pronation when compared to cushioning shoes. Lastly, Dixon (2007) found similar results showing that motion control shoes did not reduce peak eversion (pronation) and didn’t change the concentration of pressure.
This is sort of a double whammy on motion control shoes. If excessive pronation does not cause injuries to the degree that everyone thinks, and if motion control shoes don’t even alter pronation, what’s the point of a motion control shoe?
Cushioning:
Impact forces are the other major scoundrel of running injuries. The thinking goes like this, the greater the impact force on the lower the leg, the greater stress the foot/leg takes, which could potentially lead to injuries. To combat this fear, running shoes, particular cushioning ones, are to the rescue. Let’s take a look.
The first question is, do cushioning shoes do their job?
Wegener(2008) tested out the Asics Gel-Nimbus and the Brooks Glycerin to see if they reduced plantar pressure. They found that the shoes did their job!....But where it reduced pressure varied highly. Meaning that pressure reduction varied between forefoot/rearfoot/etc. This led to the interesting conclusion that their should be a shift in prescribing shoes to one based on where plantar pressure is highest for that individual person. It should be noted that this reduction in pressure was based on a comparison to another shoe, a tennis shoe. I’m not sure that this is a good control. Basically, this study tells us that cushioned running shoes decrease peak pressure when compared to a Tennis shoe.
In a review on the subject, Nigg (2000) found that both external and internal impact force peaks were not or barely influenced by the running shoes midsole. This means that the cushioning type does not change impact forces much, if at all. But how can this be? I mean it’s common sense if you jumped on concrete vs. jumped on a shoe foam like surface, the shoe surface is softer right? We’ll come back to this question in a minute.
Impact Forces: The picture gets cloudier:
But it’s not as simple as described above.
In an interesting study by Scott (1990) they looked at peak loads on the various sites of likely injury for runners (Achilles, knee, etc.). All peak loads occurred during mid-stance and push off. This led to an important finding that “the impact force at heel contact was estimated to have no effect on the peak force seen at the chronic injury sites,” and led to speculation that impact force did not relate injury development.
Further complicating the impact force idea is that when looking at injury rates of those running on hard surfaces or soft surfaces, there appears to be no protective benefit of running on soft surfaces. Why is this? Because of something called pre-activation and muscle tuning which will be discussed below.
Supporting this data, other studies have shown that people who have a low peak impact have the same likelihood of getting injured as those with a high peak impact force (Nigg, 1997). If you want to complicate things even further, impact seems to be the driving force between increased bone density.
As a coach or trainer this should make sense. The bone responds to the stimulus by becoming more resistant to it, IF the stimulus is not too large and there is enough recovery.
Underestimating our Body: Impact forces as feedback:
Back to the question I asked earlier: How can impact forces not change based on shoe sole softness and why isn’t running on hard surfaces lead to more injuries?
The problem is, once again, we underestimate the human body! It’s an amazing thing, and we never give it the credit it deserves. The body adapts to the surface that it’s going to strike, if you give it a chance. The body adapts to both shoe and surface adjusting impact forces via changes joint stiffness, the way the foot strikes, and a concept called muscle tuning.
An example of this can be seen with barefoot running, the diminished proprioception (sensory feedback) of wearing a shoe negates the cushioning of the shoe. Studies using minimal shoes/barefoot have shown that the body seems to adapt the impact forces/landing based on feedback and feedforward data. When running or landing from a jump, the body takes in all the sensory info, plus prior experiences, and adjusts to protect itself/land optimally As mentioned above, it does this through a variety of mechanisms. Thus, you stick some cushioned running shoe on the bottom of your foot and the body goes “Oh, we’re okay, we don’t need to worry about impact as much, we’ve got this soft piece of junk on our foot
One concept that needs to be further discussed is muscle tuning. It’s a concept recently proposed by Nigg et al. in 2000. He sees impact force as a signal or a source of feedback, as I stated earlier. The body then uses this information and adjusts accordingly to minimize soft tissue vibration and/or bone vibration. His contention is that impact force is not the problem, but rather the signal. Muscle tuning is essentially controlling these vibrations via a variety of methods. One potential mechanism is pre-activation. Pre-activation is activation of the muscles prior to impact. In this case it serves as a way of muscle tuning to prepare for impact and in addition can alter muscle stiffness, which is another way to prepare for impact. Pre-activation has been established with multiple EMG studies.
Shoes not only impact this, but surface type does too. As mentioned previously, the change in running surface did not impact injury rates. Why? Probably because the body adapts to running surface. In an interesting study measuring muscle activity, O’Flynn(1996) found that pre-activation changed based on surface. To prepare for impact, and presumably to minimize muscle/bone vibration, when running on concrete pre-activation was very high, when running on a soft track, not so much.
What all of this means is that the body adapts via sensory input. It has several different adaptation methods. A shoe influences how it adapts. The shoe is not doing anything to alter cushioning, it is simply altering how the body responds to impact. It’s a significant mindset jump if you think about it. Here’s the summary:
The type of shoe and material of the shoe changes impact NOT because of alignment of the lower leg or because of changes in cushioning. Instead it changes impact characteristics because it alters the sensory feedback
In conclusion on the cushioning concept. Well, what are we trying to cushion? Heel impact forces have not been shown to relate to injuries, in fact in one study low impact runners had a 30% injury rate compared to a 20% injury rate in high impact runners. Shoe midsoles do not change, or marginally change impact forces anyway. So, not only may cushioning not be the answer, the shoes might not even be doing their job. But what about those shoe cushioning studies showing improved cushioning with their new midsole?! Well, the majority of that testing is done by using a machine to simulate the impact forces that you experience during running. That means, yes it may cushion an impact more, but it doesn’t take into account the role of the body adjusting impact based on feedback.
The reason cushioning doesn’t work? Because the body adapts based on feedback and feedforward information. These results prompted one notable researcher(Nigg,2000) to call for the reconsideration of the cushioning paradigm for running shoes.
Barefoot running?
Quickly, this topic could not be complete without a brief mention of barefoot running. An interesting thing to note is that the initial peak impact force is absent in barefoot running when compared to running with shoes. What this means is that, the impact forces look like (A) for shoes and (B) for barefoot. That initial little blip in A is the initial impact force. There is a hypothesis that this initial impact force is related to injuries.
A recent study by Squadrone et al.(2009) compared running shoes, barefoot running, and running in Vibram Five Fingers. They demonstrated reduced impact forces, shorter ground contact and stride length, but increased stride frequency while running barefoot (and in Vibrams) as compared to running with shoes. This is not unexpected, but shows that running shoes do in fact alter our normal strides. An interesting point is the reduction in stride length but increase in stride frequency. Shoes tend to promote this longer stride at a consequence of ground contact times and frequency. This happens because of changes in feedback signaling, increased likelihood to land on heel stretched out, increased weight, all of which lead to longer times on the ground. It’s interesting to note that elite runners all have short ground contacts and high frequencies (as demonstrated by the often quoted Daniels study of 180 strides per minute).
Tying this to the discussion above on the body controlling things based on sensory information, when running barefoot, there is a higher degree of stiffness in the lower leg. Increased stiffness can result in an increased SSC (stretch shortening cycle) response, resulting in greater force on the subsequent push off (2001). Dalleau et al. demonstrated that pre-activation causing increased stiffness improved Running Economy. In his study, the energy cost of running was related to the stiffness of the lower leg (1998)
Another recent study found that knee flexion torque, knee varus torque, and hip internal rotation torque all were significantly greater in shoes compared to barefoot. What does all of this mean? Potentially, this means more stress on the joints in this area. Jay Dicharry put it best when he said:
“The soft materials in modern running shoes allow a contact style that you would not use barefoot. The foot no longer gets the proprioceptive cues that it gets unshod. The foot naturally accommodates to surfaces rapidly, but a midsole can impair the foot’s ability to react to the ground. This can mute or alter feedback the body gets while running. These factors allow a runner to adopt a gait that causes the elevated forces observed above.”
The one thing that non-barefoot/heel strike proponents use to dismiss midfoot striking/barefoot running is the Achilles tendon. They say, correctly, that the load on the Achilles is higher in midfoot striking runners. The Achilles is meant to take a large load. The problem is we’ve weakened the Achilles through years of wearing shoes with their elevated heels. Essentially, we’ve created the Achilles problem with the shoes meant to prevent it. The Achilles is designed to operate in a rubber band like fashion. . During impact such as the braking or contact phase of running, the achilles tendon stores energy and then subsequent releases that energy via recoil during the take off phase of running. The Achilles, can store and return approximately 35% of its kinetic energy (Ker, 1987). Without this elastic storage and return, the oxygen uptake required would be 30-40% higher! So, in terms of performance why are we trying to minimize the tendonous contribution? It’s like giving away free energy.
Running shoes do not utilize the elastic storage and return as well as barefoot or minimal shoes. More energy is lost with shoes than with barefoot running (Alexander and Bennett, 1989). In addition, in some models of shoes, the arch is not allowed to function like a spring. The arch of the foot can store around 17% of kinetic energy (Ker, 1987). Given these results, its not surprising that running barefoot when compared to running with shoes is more efficient. Several studies have shown a decreased VO2 at the same pace with barefoot running, even when weight is taken into account. This should be no surprise as I mentioned above, without elastic recoil VO2 requirement would be 30-40% higher. Running in a minimal shoe allows for better utilization of this system.
So, the take away message is that shoes change natural mechanics to one that creates mechanical changes that are not optimal for running fast (decreased stride frequency, increased ground contact, decreased stiffness of the system, decreased elastic contribution, and on and on).
Tying it together with elites:
Looking at elite athletes, when racing and training, they generally have higher turnover, minimal ground contact time, and a landing that occurs closer to their Center of Gravity. Since the majority of elites exhibit these same characteristics while racing, it makes sense that this is the optimal way to run fast. So, why are we wearing footwear that is designed to increase ground contact, decrease turnover, and promote footstrike out in front of the center of gravity? I have no idea.
Conclusion:
In conclusion, I’m not some fanatic saying everyone ditch shoes now. Chances are you’ve been running in shoes for 20+ years. Your bodies done some adapting during that time. You’ve got to gradually change if you want to undue some of the changes.
The purpose of this article wasn’t to talk about the benefits of barefoot running. Instead it was to point out the problems with Running Shoe classification. It’s based on a cushioning/pronation paradigm that simply is not as true as they want us to believe. That paradigm needs to be reevaluated. It’s not founded on good science but rather initial ideas that made sense with no science behind them, but upon further review may not stand up to testing. A recent study found that using the good old shoe classification system that everyone uses, had little influence on injury prevention in a large group of Army Basic Training participants (Knapik, 2009). They concluded that selecting shoes based on arch height (like all major running magazines suggest) is not necessary if injury prevention is the goal. I guess that means the systems broken…
Where do we go and how do we fix it? I have no idea. Sorry, no genius answers here. My inclination is that we aim for letting the foot function how it is meant to function, or at least come up with some shoe that may alter foot mechanics but while still allowing feedback/functionality of the body. The first step is looking at the foundation on which running shoes are built upon, the motion control, stability, and cushioning paradigm. My take is that it needs to be reevaluated. I’m going to end with something I’ve already said, but it’s an important concept to get across:
The body is more complicated and smarter than we give it credit.
The type of shoe and material of the shoe changes impact or stride characteristics NOT because of alignment of the lower leg or because of changes in cushioning. Instead it changes impact and stride characteristics because it alters the sensory feedback. The brain is a wonderful thing.'
It’s not just barefoot running and minimalism versus running shoes, the either/or situation many portray it to be. It’s much deeper than that. It’s not even that running shoe companies are evil and out to make a profit. Shoe companies may be accomplishing the goals they set out for, but maybe the goals their aiming for are not what need to be done. The paradigm that running shoes are built upon is the problem.
Running shoes are built upon two central premises, impact forces and pronation. Their goals are simple, limit impact forces and prevent overprontation. This has led to a classification system based on cushioning, stability, and motion control. The problem is that this system may not have any ground to stand on. Have we been focused on the wrong things for 40+years?
I’ll start with the customary statistic of 33-56% of runners get injured every year (Bruggerman, 2007). That is kind of mind blowing when you think about it. Since there are a ton of injuries going on, let’s look at what shoes are supposed to do.
Pronation:
As said earlier, shoes are built upon the premise that impact forces and pronation are what cause injuries. Pronation, in particular has been constructed as the bane of all runners. We have become inundated with limiting pronation via motion control shoes. The central idea behind pronation is that overpronating causes rotation of the lower leg(i.e. ankle,tibia, knee) putting stress on the joints and therefore leading to injuries. Running shoes are therefore designed to limit this pronation. Essentially, running shoes are developed and designed to put the body in “proper” alignment. But do we really need proper alignment?
This paradigm on pronation relies on two main things: (1)over pronation causes injuries and (2) running shoes can alter pronation.
Looking at the first premise, we can see several studies that do not show a link between pronation and injuries. In an epidemiological study by Wen et al. (1997), he found that lower extremitly alignment was not a major risk factor for marathon runners. In another study by Wen et al. (1998), this time a prospective study, he concluded that “ Minor variations in lower extremity alignment do not appear conclusively to be major risk factors for overuse injuries in runners.” Other studies have reached similar conclusions. One by Nigg et al. (2000) showed that foot and ankle movement did not predict injuries in a large group of runners.
If foot movement/pronation does not predict injuries or is not a risk factor for injuries, then one has to question whether the concept is sound or working...
Looking at the second premise, do shoes even modify pronation? Motion control shoes are designed to decrease pronation through a variety of mechanisms. Most choose to insert a medial post or a similar device. In a study by Stacoff (2001), they tested several motion control shoe devices and found that they did not alter pronation and did not change the kinematics of the tibia or calcaneus bones either. Similarly, another study by Butler (2007) found that motion control shoes showed no difference in peak pronation when compared to cushioning shoes. Lastly, Dixon (2007) found similar results showing that motion control shoes did not reduce peak eversion (pronation) and didn’t change the concentration of pressure.
This is sort of a double whammy on motion control shoes. If excessive pronation does not cause injuries to the degree that everyone thinks, and if motion control shoes don’t even alter pronation, what’s the point of a motion control shoe?
Cushioning:
Impact forces are the other major scoundrel of running injuries. The thinking goes like this, the greater the impact force on the lower the leg, the greater stress the foot/leg takes, which could potentially lead to injuries. To combat this fear, running shoes, particular cushioning ones, are to the rescue. Let’s take a look.
The first question is, do cushioning shoes do their job?
Wegener(2008) tested out the Asics Gel-Nimbus and the Brooks Glycerin to see if they reduced plantar pressure. They found that the shoes did their job!....But where it reduced pressure varied highly. Meaning that pressure reduction varied between forefoot/rearfoot/etc. This led to the interesting conclusion that their should be a shift in prescribing shoes to one based on where plantar pressure is highest for that individual person. It should be noted that this reduction in pressure was based on a comparison to another shoe, a tennis shoe. I’m not sure that this is a good control. Basically, this study tells us that cushioned running shoes decrease peak pressure when compared to a Tennis shoe.
In a review on the subject, Nigg (2000) found that both external and internal impact force peaks were not or barely influenced by the running shoes midsole. This means that the cushioning type does not change impact forces much, if at all. But how can this be? I mean it’s common sense if you jumped on concrete vs. jumped on a shoe foam like surface, the shoe surface is softer right? We’ll come back to this question in a minute.
Impact Forces: The picture gets cloudier:
But it’s not as simple as described above.
In an interesting study by Scott (1990) they looked at peak loads on the various sites of likely injury for runners (Achilles, knee, etc.). All peak loads occurred during mid-stance and push off. This led to an important finding that “the impact force at heel contact was estimated to have no effect on the peak force seen at the chronic injury sites,” and led to speculation that impact force did not relate injury development.
Further complicating the impact force idea is that when looking at injury rates of those running on hard surfaces or soft surfaces, there appears to be no protective benefit of running on soft surfaces. Why is this? Because of something called pre-activation and muscle tuning which will be discussed below.
Supporting this data, other studies have shown that people who have a low peak impact have the same likelihood of getting injured as those with a high peak impact force (Nigg, 1997). If you want to complicate things even further, impact seems to be the driving force between increased bone density.
As a coach or trainer this should make sense. The bone responds to the stimulus by becoming more resistant to it, IF the stimulus is not too large and there is enough recovery.
Underestimating our Body: Impact forces as feedback:
Back to the question I asked earlier: How can impact forces not change based on shoe sole softness and why isn’t running on hard surfaces lead to more injuries?
The problem is, once again, we underestimate the human body! It’s an amazing thing, and we never give it the credit it deserves. The body adapts to the surface that it’s going to strike, if you give it a chance. The body adapts to both shoe and surface adjusting impact forces via changes joint stiffness, the way the foot strikes, and a concept called muscle tuning.
An example of this can be seen with barefoot running, the diminished proprioception (sensory feedback) of wearing a shoe negates the cushioning of the shoe. Studies using minimal shoes/barefoot have shown that the body seems to adapt the impact forces/landing based on feedback and feedforward data. When running or landing from a jump, the body takes in all the sensory info, plus prior experiences, and adjusts to protect itself/land optimally As mentioned above, it does this through a variety of mechanisms. Thus, you stick some cushioned running shoe on the bottom of your foot and the body goes “Oh, we’re okay, we don’t need to worry about impact as much, we’ve got this soft piece of junk on our foot
One concept that needs to be further discussed is muscle tuning. It’s a concept recently proposed by Nigg et al. in 2000. He sees impact force as a signal or a source of feedback, as I stated earlier. The body then uses this information and adjusts accordingly to minimize soft tissue vibration and/or bone vibration. His contention is that impact force is not the problem, but rather the signal. Muscle tuning is essentially controlling these vibrations via a variety of methods. One potential mechanism is pre-activation. Pre-activation is activation of the muscles prior to impact. In this case it serves as a way of muscle tuning to prepare for impact and in addition can alter muscle stiffness, which is another way to prepare for impact. Pre-activation has been established with multiple EMG studies.
Shoes not only impact this, but surface type does too. As mentioned previously, the change in running surface did not impact injury rates. Why? Probably because the body adapts to running surface. In an interesting study measuring muscle activity, O’Flynn(1996) found that pre-activation changed based on surface. To prepare for impact, and presumably to minimize muscle/bone vibration, when running on concrete pre-activation was very high, when running on a soft track, not so much.
What all of this means is that the body adapts via sensory input. It has several different adaptation methods. A shoe influences how it adapts. The shoe is not doing anything to alter cushioning, it is simply altering how the body responds to impact. It’s a significant mindset jump if you think about it. Here’s the summary:
The type of shoe and material of the shoe changes impact NOT because of alignment of the lower leg or because of changes in cushioning. Instead it changes impact characteristics because it alters the sensory feedback
In conclusion on the cushioning concept. Well, what are we trying to cushion? Heel impact forces have not been shown to relate to injuries, in fact in one study low impact runners had a 30% injury rate compared to a 20% injury rate in high impact runners. Shoe midsoles do not change, or marginally change impact forces anyway. So, not only may cushioning not be the answer, the shoes might not even be doing their job. But what about those shoe cushioning studies showing improved cushioning with their new midsole?! Well, the majority of that testing is done by using a machine to simulate the impact forces that you experience during running. That means, yes it may cushion an impact more, but it doesn’t take into account the role of the body adjusting impact based on feedback.
The reason cushioning doesn’t work? Because the body adapts based on feedback and feedforward information. These results prompted one notable researcher(Nigg,2000) to call for the reconsideration of the cushioning paradigm for running shoes.
Barefoot running?
Quickly, this topic could not be complete without a brief mention of barefoot running. An interesting thing to note is that the initial peak impact force is absent in barefoot running when compared to running with shoes. What this means is that, the impact forces look like (A) for shoes and (B) for barefoot. That initial little blip in A is the initial impact force. There is a hypothesis that this initial impact force is related to injuries.
Tying this to the discussion above on the body controlling things based on sensory information, when running barefoot, there is a higher degree of stiffness in the lower leg. Increased stiffness can result in an increased SSC (stretch shortening cycle) response, resulting in greater force on the subsequent push off (2001). Dalleau et al. demonstrated that pre-activation causing increased stiffness improved Running Economy. In his study, the energy cost of running was related to the stiffness of the lower leg (1998)
Another recent study found that knee flexion torque, knee varus torque, and hip internal rotation torque all were significantly greater in shoes compared to barefoot. What does all of this mean? Potentially, this means more stress on the joints in this area. Jay Dicharry put it best when he said:
“The soft materials in modern running shoes allow a contact style that you would not use barefoot. The foot no longer gets the proprioceptive cues that it gets unshod. The foot naturally accommodates to surfaces rapidly, but a midsole can impair the foot’s ability to react to the ground. This can mute or alter feedback the body gets while running. These factors allow a runner to adopt a gait that causes the elevated forces observed above.”
The one thing that non-barefoot/heel strike proponents use to dismiss midfoot striking/barefoot running is the Achilles tendon. They say, correctly, that the load on the Achilles is higher in midfoot striking runners. The Achilles is meant to take a large load. The problem is we’ve weakened the Achilles through years of wearing shoes with their elevated heels. Essentially, we’ve created the Achilles problem with the shoes meant to prevent it. The Achilles is designed to operate in a rubber band like fashion. . During impact such as the braking or contact phase of running, the achilles tendon stores energy and then subsequent releases that energy via recoil during the take off phase of running. The Achilles, can store and return approximately 35% of its kinetic energy (Ker, 1987). Without this elastic storage and return, the oxygen uptake required would be 30-40% higher! So, in terms of performance why are we trying to minimize the tendonous contribution? It’s like giving away free energy.
Running shoes do not utilize the elastic storage and return as well as barefoot or minimal shoes. More energy is lost with shoes than with barefoot running (Alexander and Bennett, 1989). In addition, in some models of shoes, the arch is not allowed to function like a spring. The arch of the foot can store around 17% of kinetic energy (Ker, 1987). Given these results, its not surprising that running barefoot when compared to running with shoes is more efficient. Several studies have shown a decreased VO2 at the same pace with barefoot running, even when weight is taken into account. This should be no surprise as I mentioned above, without elastic recoil VO2 requirement would be 30-40% higher. Running in a minimal shoe allows for better utilization of this system.
So, the take away message is that shoes change natural mechanics to one that creates mechanical changes that are not optimal for running fast (decreased stride frequency, increased ground contact, decreased stiffness of the system, decreased elastic contribution, and on and on).
Tying it together with elites:
Looking at elite athletes, when racing and training, they generally have higher turnover, minimal ground contact time, and a landing that occurs closer to their Center of Gravity. Since the majority of elites exhibit these same characteristics while racing, it makes sense that this is the optimal way to run fast. So, why are we wearing footwear that is designed to increase ground contact, decrease turnover, and promote footstrike out in front of the center of gravity? I have no idea.
Conclusion:
In conclusion, I’m not some fanatic saying everyone ditch shoes now. Chances are you’ve been running in shoes for 20+ years. Your bodies done some adapting during that time. You’ve got to gradually change if you want to undue some of the changes.
The purpose of this article wasn’t to talk about the benefits of barefoot running. Instead it was to point out the problems with Running Shoe classification. It’s based on a cushioning/pronation paradigm that simply is not as true as they want us to believe. That paradigm needs to be reevaluated. It’s not founded on good science but rather initial ideas that made sense with no science behind them, but upon further review may not stand up to testing. A recent study found that using the good old shoe classification system that everyone uses, had little influence on injury prevention in a large group of Army Basic Training participants (Knapik, 2009). They concluded that selecting shoes based on arch height (like all major running magazines suggest) is not necessary if injury prevention is the goal. I guess that means the systems broken…
Where do we go and how do we fix it? I have no idea. Sorry, no genius answers here. My inclination is that we aim for letting the foot function how it is meant to function, or at least come up with some shoe that may alter foot mechanics but while still allowing feedback/functionality of the body. The first step is looking at the foundation on which running shoes are built upon, the motion control, stability, and cushioning paradigm. My take is that it needs to be reevaluated. I’m going to end with something I’ve already said, but it’s an important concept to get across:
The body is more complicated and smarter than we give it credit.
The type of shoe and material of the shoe changes impact or stride characteristics NOT because of alignment of the lower leg or because of changes in cushioning. Instead it changes impact and stride characteristics because it alters the sensory feedback. The brain is a wonderful thing.'
Source: www.scienceofrunning.com
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