But what is interesting is are two main ideas:

A) How specific the adaptation becomes.

B) How the adaptation can decrease results.

With regard to specificity, our nervous system is the master of all movement. It learns to fire muscles in a precise pattern, in a precise order, and with rather precise conditions. This is why the champion deadlifter is not also the champion at the clean and jerk, necessarily. Two different movement patterns have been practiced. No one would say that this deadlift champion is not strong, he is just not as strong at a particular movement. This applies to us as well.

This also applicable to energy systems. A winner of the marathon cannot then go and win a sprint, or even a 500m run, typically. Why? Because the marathon is lower intensity and more aerobic, and the sprint is anaerobic (without oxygen) and high intensity. The body is efficient at a specific pattern, long distance running, but not another of the same pattern, running at a sprint.

So whatever we train, we get better at.

Thus, much of our exercise program should be practice for life. Just as a baseball player practices his/her swing to get more efficient at the complex interplay of joints and muscles involved in that motion, so should we practice our movements.

Now take a look at your average gym-goer, or your own exercise program. How many of your exercises even involve these movements? How many of these fancy machines even perform these patterns?

Before you say, "I bench, which is a push, and I do the leg press machine, which is a squat kind of motion," think about this...each of the above list of movements must be done in a field of gravity in real life, while maintaining your own center of gravity over your own base of support (not falling over).

This is an entirely different animal, as anyone who has ever tried to squat the amount of weight they can lift on the leg-press machine will tell you.

So, with regard to specificity, attempt to use much of your time practicing the following fundamental movement patterns (ironically often done by infants with no problem or thought) on your own two feet, without the help of a machine bolted to the floor:

- Squat

- Lunge

- Bend (Deadlift)

- Twist (of torso)

- Push

- Pull

- Walk

- Run

In part two, the final section of this article, we will discuss 'Adaptation' and how that must be factored into one's exercise program. Have a great and healthy week!

David Younkins, M.S., CES

They’re everywhere. In our hospitals, gyms, places of work, our schools, and in our homes - the ubiquitous hand sanitizer. Certainly sanitizing the skin cannot be a bad thing, can it? That is exactly what we will examine this week!

Naturally, it makes sense that a product which kills harmful bacteria and viruses must be helpful in allowing us to prevent disease by killing any of them on the hands (our most ‘social’ body parts). Indeed some of the research supports this premise, with school age children reporting fewer gastrointestinal issues when using alcohol based hand sanitizers. Other studies report reduced student absenteeism when using hand sanitizers.

Hand washing, however, also reports similar positive results with regard to student absenteeism, and studies comparing the two sometimes find no significant differences. A relatively recent review of studies was not sure where to come down on this issue.

So now what? Yes, hand sanitizers or hand washing reduce germs on the hand, and also reduce infection. In addition, alcohol based sanitizers (if they include over 60% alcohol) can be effective in reducing germs.

However, this does not mean we need to scrub our hands with sanitizer every five minutes as if our job is ‘roadkill juggler.’ We need to keep in mind that there are GOOD bacteria as well as bad on our skin that actually help fight off disease and prevent infections. It seems that hand sanitizer in particular can kill the good along with the bad! This can lead to skin inflammation.

In addition, our immune systems, like most systems in our bodies have what are called ‘positive feedback cycles.’ The more we provide a stimulus, the more we get a response. This means that exposure to negative substances like bacteria (called ‘antigens’) actually strengthens our immune system and allow it to mount a better defense. We have cells called ‘memory B cells’ which actually REMEMBER a previous invader and how to defend against it! Pretty cool!

So, inhibiting a positive feedback cycle is a bit like never driving in traffic as a teenager because there are more cars. That is how you get better! Indeed, it seems that the young are particularly benefited by some ‘antigen’ exposure .

Let’s not suffer from paralysis by analysis. Clearly there is evidence both to support at least washing the hands, with some hand sanitizer use, and allowing some bacteria to “get past the guards,” as it were. So, let’s see what the Centers for Disease Control recommends given this information. Here are a few of the main recommendations, but the entire page can be viewed here. We should wash our hands with soap and water:

1. . Whenever dealing with food (Before eating / Before, during and after preparing)

2. . Before and after touching a wound

3. . After using toilet

4. . After touching animals or animals waste (sorry roadkill jugglers)4

5. . After blowing nose, sneezing coughing

6. . After touching garbage

7. . After changing diapers

In addition, you should hum the “Happy Birthday’ song while washing, as this is the approximate amount of time to wash (~20 seconds) in order to ensure the necessary thoroughness. Front, back, and between fingers should be covered.

Interestingly, the CDC recommends that hand sanitizers be used only if soap and water are not available. Also a Harvard Health Letter seems to put soap and water first as well, due to the fact that alcohol does not kill all bad bacteria, and usually sanitizer does not cover all of the hand.

So wash your hands regularly with soap and water, but not too obsessively. Hand sanitizer should be used as an adjunct. This advice is, of course, for the average citizen, and cannot speak to those in the health care/hospital industry or those with compromised immune systems.

'Happy birthday' to you all!

David Younkins, M.S., CES

Shame on you for envisioning a bunch of your co-workers cheering you on as you guzzled a beer at work! Unacceptable. We are actually here to discuss water, as the title obviously suggests.

First of all, it is well known that water is one of the most vital nutrients for our body. We can go without food for a few weeks, even phytochemicals (per last week's blog), but we can only go without water for a few days.

This is due, in part, to the fact that our bodies are composed of around 60% water. Water is required to allow our blood to move through our bodies efficiently, it fills the discs in our spine, and is generally a vital part of every cell's processes and structure. However, we lose water every minute in the air that we exhale, the sweat we excrete, every time we go to the bathroom, and in the digestion process. If left unchecked, this will lead to dehydration, which can increase blood pressure, decrease cognition, and negatively impact joint lubrication and connective tissues like tendons .

Although our energy processes actually produce water as a part of energy metabolism, this is not enough to replenish what we lose during life, which is around 10 cups or two liters, not to mention that water lost during exercise. So we must drink.

So far nothing earth-shattering here. We all know that we need to drink water. Yet should we only drink when thirsty? How much water do we need?

Although our thirst mechanism is very sensitive, we also need an objective measure of fluid intake, given two points:

1) Our sense of thirst is not always accurate

2) Once thirst is felt, we are already somewhat dehydrated and could suffer the aforementioned decreases in performance.

Since our sense of thirst does at least tell us that we are dehydrated to some degree, we should avoid becoming thirsty. We do this by attempting to drink ~ 1/2 of your body weight in ounces every day. For instance, a 150 lb. person should shoot for 75 ounces per day. Simply drinking a 20 oz bottle of water along with all three meals (in lieu of calorie-drenched soda) would leave a simple 15 ounces throughout the rest of the day to drink for a 150 lb. person!

Keep in mind that if we ingest lots of fruits and vegetables we can decrease that requirement by a little due to the high water content of these foods.

Finally, what if we get tired of water - what about sports drinks and other popular beverages? Well, research does suggest that adding electrolytes to a beverage does improve retention of fluids and hydration. This does not mean we need to buy stock in Gatorade. Simply add a dash of sea salt (in lieu of table salt, which has more additives). Salt is an electrolyte, and works just as well as any special drink, though it has no sugar and will not taste as sweet. The sodium in salt can allow for greater hydration through more water retention - in small amounts of course.

This indicates to us that water and/or liquids with high water content and low electrolyte content (e.g. water plus pinch of sea salt or a sports drink) are best for hydration. As the number of particles, salt, and sugar increase in the drink, the hydration effect will likely decrease, as water is actually drawn out of the cells. Think about seawater. It is not the fact that salt is in the water that makes drinking seawater dehydrating and deadly, it is the amount of salinity that draws water from the cells.

Drinks containing some carbohydrate, or sugar, are not necessarily negative in all cases. During longer periods of exercise (> 1 hour), some intake of sports drinks and the sugar within them may be beneficial for performance and to replenish blood sugar, as this will provide energy for the activity. Any sport involving short bursts of activity (e.g. football), or lasting under one hour has not need for such drinks, however, as a healthy diet and plain water will supply all hydration and electrolyte requirements.

So, drink almost half your body weight in ounces while eating fruits and vegetables. Drink only watery beverages with the least amount of sugar, salt, and other additives as possible, unless the other ingredient(s) are small amounts of electrolytes.

'Water' you waiting for?

When we consider our dietary needs, we often think in terms of vitamins and minerals. Thus, many people consider a multivitamin supplement as all that is required to maintain health. However, there are more benefits in eating healthy fruits and vegetables than just the maintenance of the bare minimum vitamin/mineral intake. This is only what is needed to maintain life, not to optimize health and fitness. One example of such 'above and beyond' benefits of eating fruits and vegetables is the intake of 'phytochemicals.'

Phytochemicals ('phyto' is Greek for 'plant') are present in all fruits and vegetables, and have important antioxidant and health enhancing properties. There are over 100 of them, and most are not present in the average multivitamin supplement (with the exception of the recently popular lycopene).

Examples of other phytochemicals (PC's) are flavonoids in fruits, which help prevent cancer, phytic acid, in whole grains and brown rice, which is helpful in combatting diabetes. Other more prevalent PC's like gallic acid, present in almost all plants, have powerful antibacterial and antifungal properties. Some combinations of PC's, specifically resveratrol (found in grapes) when combined with grape seed extract produces the "suicide" of colon cancer cells!

So optimizing our health is as easy as eating a variety of fruits and vegetables. For specific information on which foods contain which phytochemicals, this site is a good resource for some of them.

But what about preparation of fruits and vegetables​? Is there a preferred way to get the maximum access to these many life-promoting chemicals?

It would seem that eating fruits and vegetables raw is the way to go in many cases, as extensive reviews have shown. However, it is not completely settled, as other singular studies show increased absorption of beta carotene with carrots that are pureed rather than eaten raw.

Overall, the weight of the research seems to point to raw plant consumption for the prevention of cancers such as bladder cancer and breast cancer, though it is likely that some cooking does not destroy the nutrient content of most plants. What matters is the degree of heat and method of cooking.

Microwave cooking, for instance, seems to be one of the worst methods for heating vegetables or fruits with regard to phytochemical retention as seen here, here and here. The results of these studies may be due to the fact that microwaves tend to dehydrate food, and this combined with their effect on living cells (they essentially vibrate them at a high frequency), which kills much of the plant. Indeed, nurses will not microwave breast-milk anymore, if only for the easy potential to overheat the milk and kill enzymes. Faster is not always better!

Since some of the aforementioned experiments have shown that cooking vegetables at lower temperatures (e.g. not pressure cooking or boiling for too long) seem to allow for similar nutrient retention, it is likely acceptable to cook vegetables occasionally as well. Just keep in mind that the higher the heat and the longer time exposed to heat, the more nutrients will be lost, likely into the surrounding water.

If this review of preparation does not to provide a single simple answer, it is likely because the research is also very mixed. But it would seem that you cannot go wrong with eating raw vegetables or lightly cooked vegetables.

So, in summary, eat your fruits and vegetables (even if you take a multivitamin) in order to take advantage of the scores of phytochemicals, and try to keep the plant as 'alive' as possible until consumption by not destroying it with excess heat or microwave radiation. Until next week!

David Younkins, M.S., CES

As summer fast approaches in our area, many of us will be outdoors, perhaps to the beach, enjoying the sunlight. But isn't sunlight bad for us, with the possibility of skin cancer? What about the health benefits of sunlight? In this article we will attempt to answer a few of these questions.

First of all, we should understand that a certain amount of sun exposure is a vital to health and fitness. This seems to be backed by a glance at evolutionary history, where all of life came about under the rays of the sun. Experimentally it is also understood that there are indeed specific responses within the body which occur when the skin receives sunlight.

One such response is the production of vitamin D, a fat-soluble vitamin that also acts a lot like a hormone in the body, with effects in many different areas. Research supports that most Americans are vitamin D deficient. This vitamin plays an important role in bone health and strength, , as well as proper digestion of calcium and other products, immune system regulation, and even in preventing the very cancer that many are afraid of getting from sun exposure.

Though some take vitamin D supplements, it seems that this is not as efficient as sunlight, and in some cases may even cause negative effects in the body. So it seems that nature has the right idea with regard to vitamin D and sunlight exposure.

Another benefit of sunlight is mood improvement. In fact, light itself is often used to treat depression or seasonal affective disorders

So all this establishes that we probably shouldn't have 'Bram Stoker's Summer.' But, like most variables, there is a happy medium. The relationship between too much sun and cancerous melanoma is also well established. We almost intuitively know that to become burned is an inflammatory response of the skin, it indicates that damage is done, and this is supported by research as well.

So, in order to avoid too much sun in places like the beach, ensure that you use shade wisely, allowing your skin to rest, and/or using protective clothing. Also, using sunscreen is a necessity if you plan on being out in the sun for long periods of sustained time.

Therefore, along with ensuring we get adequate sun exposure for health, we also want to avoid too much. Generally, we should shoot for around ten to fifteen minutes a day of midday (10am to 4pm) sun exposure. If outdoors earlier in the morning or later in the day, it may take more time to get our appropriate amount of sunlight exposure and vitamin d.

Or, if you'd like to be even more precise, take a moment and use this calculator designed to tell you the amount of time in the sun required to get the recommended daily value of 1000 IU. It takes into account your skin tone, location, elevation, time of day, and more!

So, in closing, find the balance in your sun exposure, as sunlight is a vital component to health in the form of bone health, immunity, and cancer prevention. However, watch out if you are out in the sun with exposed skin for periods of time longer than 15 minutes. Now let's get out there and start getting that free vitamin D!

As a quick review, we want to keep in mind that the goal is to obtain not only the appropriate amount of sleep (7-9 hours), but also the necessary quality. We ensure this quality by allowing deep sleep to occur, in which much of the repair of our muscle happens.

We learned that deep sleep is reliant upon certain hormone release, like melatonin, and any light that falls upon the eyes during sleep prevents melatonin release and, therefore, deep sleep. We also learned not to take in any caffeine within about 12-14 hours of bedtime, as caffeine can prevent deep sleep as well

Now what are some more practical ways in which we can put this science into action in our preparation for bed?

Since we know that light or other sleep interruptions can inhibit deep sleep by stopping melatonin, we must try to instead facilitate it's release by 'gearing up' for sleep before actual bedtime. We can do this by making the following changes:

1. Dimming lights an hour before sleep. Melatonin takes time to reach appropriate levels in the bloodstream, and it is one of the tools by which our body 'knows' what time it is, also called the 'circadian rhythm.' Our ancestors set these internal rhythms to the sunrise and sunset, but today we have a constant barrage of electric lights, TV screens, etc. We need to reset the clock by turning those lights off!

2. Sleep in a cooler room. Since or body temperature drops while asleep, some research shows that it is better to mimic this environment in our bedrooms as well

3. Make time invisible. Along with the aforementioned reasons involving light on our faces, we want to keep our clocks (or other plugged in, electrical devices) away from our heads in order to avoid the electromagnetic fields. On a practical note, the clock may only make us worry all night about the time ("I've gotta get up in four hours, I have to get to sleep!").

4. Establish a routine. Bedtime should be the same every night, as much as possible. Our body always tries to maintain the status quo, it doesn't like constant change. Our circadian rhythm should be as reliable as possible. Avoid large fluctuations in sleep times and patterns, and if crossing time zones or working shifts a melatonin supplement may be helpful.

5. Get to bed before 10:30pm Most physical repair happens between ~1030pm and 1am. Miss that time period and miss the repair!

Finally, let's look at sleep position. We should keep in mind that some research shows decreased oxygen intake while sleeping on one's back, along with greater levels of sleep disorders (snoring, apnea, etc.). So the back seems to be the worst choice. With that in mind, we should sleep partly on the stomach, as this is the best position for digestion, with some sleep on the side, for a majority of the night. If we sleep on the side, we should consider a pillow between the legs , as pictured here, as this keeps the hips level and prevents the development of muscle imbalances.

Of course, we are not aware of our sleep position for most of the night, but if we start in a certain position each time we are awake we will at least spend a good part of the night in something close to that position.

If you are a habitual back-sleeper consider a light but bulgy 'backpack' for the night in order to prevent this position to the greatest degree possible.

Try to just make one of the above changes at a time until you have a good quality and quantity sleep, and you will achieve better results from your exercise program, as well as enjoy life more fully!

David Younkins, M.S., CES

Yoohoo...wake up. Not quite yet. We need to learn a bit about sleep first!

Although this title sounds somewhat counter-intuitive, there is good evidence that sleep deprivation is correlated with increased body fat and reduced health as well as the more obvious cognitive issues. Let's look at some of the ways in which lack of sleep can decrease one's fitness, health, and body composition.

First of all, how much sleep should we be getting? According to the National Sleep Foundation, adults need to be getting 7-9 hours a night.

However, more is not necessarily better either. Other research shows that too little or too much sleep can lead to a higher mortality rate. This seems reasonable, as too little or too much of almost any health-related stimulus tends to be bad - be it exercise, sunlight, protein, or sleep. There is some room for individual variation, but the two hours allowed under 7-9 hours is a pretty good range for any genetic or environmental differences.

Of particular importance in our busy metropolitan area seems to be sleep debt, or lack of sleep. Studies show that sleep debt is associated with higher blood sugar, along with elevated cortisol levels (a hormone that is associated with muscle wasting and body fat deposition, particularly around the waistline). In fact, lack of sleep has been empirically connected with obesity as well. If that were not enough, lack of sleep tends to alter our endocrine system such that we want to eat more calories per day, and do. So, to lose body fat we need to get the proper amount of sleep.

Now that the amount of sleep is understood, what about the quality? After all, simply lying on a platform for eight hours will not make one feel rested. We understand that the body goes through five distinctive stages of sleep in a cycle, each phase with it's own focus of repair. Each complete cycle of stages lasts an average of 90 minutes, which is why it may feel better to get 7.5 hours of sleep (1.5 hours x 5 cycles) then 8 hours, as your body is just finishing a sleep cycle and is not in the midst of deep sleep. It may take some experimentation to discover your exact sleep cycle length.

Each of the cycles involve a trip through five stages of sleep, one being REM sleep (rapid eye movement) in which we tend to dream and the body is paralyzed. Stage 1 and 2 sleep are lighter sleep levels as well.

However, of greater importance for our current discussion are stages 3 and 4 sleep, or slow wave sleep. This is also called deep sleep, and it is during this phase that much of the muscular and tissue repair and growth occurs, in part due to an increase in HGH, or growth hormone, release. Since we know the benefits of HGH (just look at Sly Stallone), how do we make sure we are reaching a stage of deep sleep in order to maintain or build muscle?

This brings us to one more hormone - melatonin, released from the pineal gland in the brain. This hormone is essentially the 'deep sleep hormone.' Melatonin creates deep sleep and deep sleep releases HGH. Thus we should not antagonize the release of melatonin. Unfortunately, some of our current lifestyle habits do just this. Specifically, the presence of light inhibits melatonin release, particularly light in the eyes. This means we must sleep in dark rooms, without a TV on and minimal nightlight. Also, ensure bright alarm clocks are not facing towards you.

Finally, avoid any caffeine intake within a much as 14 hours of sleeping , as caffeine antagonizes deep sleep .

Since that's a lot of information, let's try to first initiate these changes:

1. Get 7-9 hours of sleep per night

2. Sleep in a dark room

3. Do not take in caffeine later than around 10am, if possible.

Then in part two of this article we will look at even more practical strategies to help get the most out of a night's sleep, to include preparation and even body position.

David Younkins, M.S., CES

The DC/VA/MD area is replete with gyms and fitness centers, and in any given gym you will see at least 50% of the people either about to do crunches, finishing crunches, or thinking about doing crunches. Turn on the television and see advertisements for ab exercising tools to make crunches easier to do, and so forth. We, as a nation, and certainly in the D.C. area, are 'absessed.'

Certainly having a strong set of abdominal muscles is very gratifying aesthetically, and they absolutely help prevent injury and improve performance. This next series of articles will focus on abdominal training in the form of little known 'secrets.' These are little 'fun facts' that have been collected over the years that will help improve your abdominal training such that your body functions better as well as looks better. We will look at the proper way to perform common exercises, suggest better exercises, and critique some popular gimmicks and even more common 'wisdom.'

Crunches, done in moderation, can be one minor tool in a 'tool box' to help strengthen one particular set of muscles in the abdominals, the rectus abdominus. There are four different sets of abdominal muscles, of which the 'rectus' is only one, but this is the muscle on which we focus when performing a crunch. Like all exercises, there is an optimal technique for the crunch that allows the body to function as it should, and does not sacrifice function or injury prevention on the altar of vanity or comfort.

This article will focus on neck function during the crunch with a focus on tongue position. "David, what does the tongue have to do with crunches?" you may ask. Good question!

First of all, we must establish that the neck, or cervical spine, tends to work with the lumbar spine during human motion. This relationship is well established via reflexes which ties together the eye and head motion with pelvic motion. One key point of these reflexes is that looking down is associated with activation of the abdominals and front neck muscles, looking up with activation of the spinal muscles, which antagonize the abdominals (work in the opposite direction). For instance, imagine trying to lift a really heavy couch with your chin tucked into your chest, and looking down. You'd probably feel weaker. We tend to naturally look up and lift our chins when lifting with our lower back. And the opposite applies for abdominal recruitment

Why, then would we allow the neck to 'relax' on some pillow or head support (including your own hands) usually while looking up at the ceiling, as is so common in gimmicks and gyms today? We should, instead, allow the head to 'nod' and curl along with the rest of the spine, while looking down with our eyes in order to avoid antagonizing the movements of the spine.

Secondly, the muscles on the front of the neck have a tendency to lengthen and get weak. This allows the head to migrate forward into the ubiquitous 'forward head posture.' This posture allows the increased probability of neck pain, headaches, and shoulder dysfunction. Crunches, then, can also help train these muscles by forcing the neck to lift one's own head while during a crunch. In effect, we should think about 'nodding' as we crunch upward ('Yes, I love crunches'), then reversing the nod on the way back down. This will help promote neck stabilization and good posture. However, we want to avoid 'jutting out' the chin, but should instead focus on a pure nodding motion, tucking the chin into the neck. So what if your neck gets tired? Good. Let it catch up to the strength of your abdominals.

All of this being said, what about the tongue? Well, it is interesting to note that some of these front neck muscles, which help us 'nod' our head and look down, have an attachment at the tongue, specifically the supra and infrahyoid muscles. With that in mind, a 'loose' tongue, or a tongue that is hanging loose in the mouth, provides a poor foundation for this muscle attachment. This can be illustrated by protesters who go limp at demonstrations to make the police exert more force in moving them. A stable, or tense, foundation would be much easier to move!

Similarly, we want to have a solid base of motion for these all- important front neck muscles, making it easier for them to move the head. Research supports this notion as well.This begs the question as to proper tongue position.

First, try a simple test. Swallow...what happened to your tongue? If you have proper neurological function, it should have gone to the roof of your mouth.

This is called the physiological rest position of the tongue. It is here where you should secure your tongue during crunches, or any other motion in which you need a stable neck (shrugs, shoulder presses, etc.). Obviously, we should then breathe through the nose in order to maintain the natural tongue position.

So, in closing, don't support the head. Nod with every crunch. Note tongue position.

The next article in the series will go about the optimal technique for the performance of the crunch.

David Younkins, M.S., CES

The outdoor hiking and running season approaches in the D.C. area. As the Cherry Blossom Festival get closer, along with the first day of spring, there are increasing numbers of people stepping out for that first hike and/or run of the year. Along with this natural increase in running/walking interest, it is incumbent upon us to take a look at the 'equipment' for such activity: shoes.

This is not as easy as it seems, for at this time in history there are almost as many shoes as there are feet! There are running shoes, trail shoes, 'butt toning' shoes, motion control shoes, Masai shoes, and barefoot shoes. Which are best? Which are most supported as effective by research, science, and even simple logic? This next series of articles will focus on exactly that. In order to understand what a covering for the foot should do, we must first understand how the foot was designed to work. Part one of this article will look at some of the science regarding how the feet function most optimally. In what environment do they thrive?

Let's take a look at a diagram of the foot. First of all, we notice that it has a great number of bones and joints (26 bones, 33 joints). In fact, it looks a lot like a hand with regard to it's structure. Now, one thing we learn in anatomy and physiology is that structure often defines function. For instance, a large, solid bone is not meant to promote much mobility (i.e. the skull), whereas a series of small bones and joints show that an area was meant to allow for motion to a greater degree.

Next, we can examine the muscles of the foot. There are over 100 affecting each foot directly, and many more that affect the feet indirectly in the hip and lower back. In addition, the muscles of the foot and hand, among others, have a larger number of motor units, or nerves, per gram of muscle tissue (MacinTosh, Gardiner, McComis, 2006, p.176). Since the nerve is akin the 'brain' of the muscle (it tells it when to turn off or on and to what degree), we can conclude that more motor units = more brains = more fine control of an area. The quadriceps of the thigh, by contrast, have a lower number of units per gram of muscle tissue since it is a large group of muscles used for gross movements like squatting and running.

Finally, the sole of the foot is highly important from a sensory standpoint with regard to muscle activation throughout the body, particularly in standing posture. So it seems best for the sole of the foot to have a sensory role in the surface upon which the foot rest, pushes from, and so forth, if we are to optimize muscular function and posture of the whole body while walking, running, or standing.

Armed with this information, we should take another look at the a potential 'perfect shoe.' Indeed, some research supports the idea that footwear alters muscle activation patterns. It seems that, if we are to allow the body to function as it was designed for survival, a shoe should: a) Allow for motion of the joints of the foot b) Maintain strength and stability in the muscles of the foot c) Avoid inhibiting the foot's ability to adapt to changing surfaces via fine motor control d) Elicit sensory feedback from the sole of the foot such that posture can be maintained properly.

In part II of this article we will examine some of the different models of shoes, the research supporting each, and try to figure out which best fulfills our requirements of the foot with an eye towards it's physiology and biomechanics.