Why We Run


“If you were to ask a zoologist why we run, he or she might say we run because we are animals, and that’s what animals evolved to do. Running is essential to an animal’s life. Animals run to hunt; they run because they’re being hunted; they run to play; they run out of panic; and they even run to flirt with and show off to other members of their species. The zoologist may be right—on playgrounds across the country, human animals show off their speed, as boys and girls race each other during recess.

There are countless stories of people who run when faced with difficult circumstances. That’s not a coincidence. We all have things we run toward or away from. I’ve met runners who run toward life, toward freedom, health, and friendships, toward love, toward happiness. And I’ve met runners who run away from obesity, from family, relationships, and divorce, from drugs, from depression, from heart disease and cancer.

When we run, we are free of those things. We are free from what binds us, from what keeps us down, from what holds us back. Running helps us cope—with tragedy, with disappointment, with frustration, with sadness, with all of the negative feelings that hold us back from living a happy, fulfilling life.

Running eliminates the stress of most of life’s problems, heightening the enjoyment of the good things in life, at least for the precious moments that we run. We can literally put space between ourselves and our problems, inserting clarity in the space and developing the confidence to handle and deal with what is asked of us. The confidence and empowerment that running gives us can make every hour of our lives better. On both a large, public scale and a small, personal scale, running gives us hope for our future.”






We usually talk of energy in vague terms. “I don’t have a lot of energy today,” or “You can feel the energy in the room.” But what really is energy? Where do we get the energy to move? How do we use it? How do we get more of it? Ultimately, what controls our movements?

As you may have learned in high school biology class, the energy for all physical activity comes from the conversion of high energy phosphates (adenosine triphosphate, ATP) to lower energy phosphates (adenosine diphosphate, ADP; adenosine monophosphate, AMP; and inorganic phosphate, Pi). During this breakdown, or hydrolysis, of ATP, which requires water, a proton, energy, and heat are produced: ATP + H2O → ADP + Pi + H+ + energy + heat. Since your muscles don’t store much ATP, you must constantly resynthesize it. The hydrolysis and resynthesis of ATP is thus a circular process—ATP is hydrolyzed into ADP and Pi, and then ADP and Pi combine to resynthesize ATP. Alternatively, two ADP molecules can combine to produce ATP and AMP: ADP + ADP → ATP + AMP.   

Like many other animals, humans produce ATP through three metabolic pathways that consist of many enzyme-catalyzed chemical reactions. Two of these pathways, the phosphagen system and anaerobic glycolysis, do not use oxygen to create ATP and are therefore referred to as anaerobic. The third pathway uses oxygen to create ATP and is therefore referred to as aerobic.

Which pathway your muscles use for the primary production of ATP depends on how quickly they need it and how much of it they need. Racing 800 meters, for instance, requires energy much more quickly than running a marathon, necessitating the reliance on different energy systems. However, the production of ATP is never achieved by the exclusive use of only one energy system, but rather by the coordinated response of all energy systems contributing to different degrees. Think of three dials that are always being adjusted to optimize the production of energy. When you race 100 meters, the phosphagen dial is turned up very high, while the other two dials are turned down low. When you run a marathon, the aerobic system dial is turned up very high, while the other two dials are turned down low. When you race a 5K, the aerobic system dial is turned up high, the anaerobic glycolysis dial is turned to medium, and the phosphagen system dial is turned down low.

Simplistically speaking, running faster comes down to increasing the rate at which ATP is resynthesized so it can be broken down to liberate energy for muscle contraction.

Phosphagen System

During short-term, intense activities, a large amount of power needs to be produced by the muscles, creating a high demand for ATP. The phosphagen system (also called the ATP-CP system) is the quickest way to resynthesize ATP. Creatine phosphate (CP), which is stored in skeletal muscles, donates a phosphate to ADP to produce ATP:

ADP + CP → ATP + C

No carbohydrate or fat is used in this process; the regeneration of ATP comes solely from stored CP. Since this process does not need oxygen to resynthesize ATP, it is anaerobic, or oxygen-independent. As the fastest way to resynthesize ATP, the phosphagen system is the predominant energy system used for all-out sprinting lasting up to about 10 to 15 seconds. However, since you have a limited amount of stored CP and ATP in your muscles, fatigue occurs rapidly when you sprint.

Anaerobic Glycolysis

Anaerobic glycolysis is the predominant energy system used for all-out running lasting from 30 seconds to about two minutes and is the second fastest way to resynthesize ATP. During anaerobic glycolysis, carbohydrate, either in the form of glucose in the blood or its stored form of glycogen in the muscles and liver, is broken down through a series of chemical reactions. Every molecule of glucose broken down through glycolysis produces two molecules of usable ATP. Thus, very little energy is produced through this pathway, but the trade-off is that you get the energy quickly, so you can run fast.

You rely on anaerobic glycolysis when oxygen is not supplied fast enough to meet your muscles’ needs for ATP. When this happens, your muscles lose their ability to contract effectively because of an increase in hydrogen ions, which causes the muscle pH to decrease, a condition called acidosis. The concentration of other metabolites, including potassium ions and the two constituents of ATP (ADP and Pi) also increase. Acidosis and the accumulation of these other metabolites cause a number of problems inside muscles, including inhibition of specific enzymes involved in metabolism and muscle contraction, inhibition of the release of calcium (the trigger for muscle contraction) from its storage site in muscles, and interference with muscles’ electrical charges, ultimately leading to a decrease in muscle force production and running speed.

Aerobic System

Since humans evolved for aerobic activities, it’s not surprising that the aerobic system, which is dependent on oxygen, is the most complex of the three energy systems. The metabolic reactions that take place in the presence of oxygen are responsible for most of the energy your cells produce. Races longer than two minutes (800 meters to ultramarathons) rely most heavily on the aerobic system. However, aerobic metabolism is the slowest way to resynthesize ATP.

The aerobic system uses blood glucose, muscle and liver glycogen, and fat as fuels to resynthesize ATP. The aerobic use of carbohydrates produces 38 molecules of ATP for every molecule of glucose broken down. Thus, the aerobic system produces 19 times more ATP than does glycolysis from each glucose molecule. If that sounds like a lot, using fat gives you much more ATP—a whopping 130, give or take, depending on the specific fatty acid being used.

Running performance, whether recreational or elite, is most dependent on the aerobic system. The more developed the aerobic system, the faster a person will be able to run before he or she begins to rely on the anaerobic energy pathways and experiences the consequent fatigue.

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Training Plan



“What do you think about this workout two weeks before the marathon?” she asked me, showing me her workout.

I often get asked about workouts. Runners always want to know what workout they should do on Tuesday.

Training is not like cooking, simply mixing ingredients together in a skillet and adding a little salt and pepper. Every week and every month of training should build on what came before it, applying the precise amount of stress in a systematic way and transitioning from one type of training to another seamlessly.

The secret of training—listen closely, because this is what you came for—is how your aerobic and anaerobic fitness are developed and in the prescribed combination of workouts you do each week. When you do each type of workout matters. It’s not arbitrary.

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Choose from 12 different training programs (5K to marathon) for beginner, intermediate, and advanced runners and for endurance-type and speed-type runners that highlight runners’ different strengths. All programs include detailed instructions and a complete calendar-style training program.

“What workout you do two weeks before the marathon depends on the purpose of the workout and the week of training, what you have been doing in the weeks and months prior to that workout, and what you will do in the weeks after that workout,” I responded.

Do you get your current training from an expert?




To get faster, one or both components of the stride must increase. However, because stride rate and stride length are inversely proportional (as one increases, the other decreases), running speed can only increase if an increase in stride length is not accompanied by a similar decrease in stride rate or vice versa.

Stride length is more important than stride rate for increasing distance running speed. When you increase your pace from a jog to a run to a fast run, stride length increases more than does stride rate, until you’re sprinting very fast, when stride rate begins to dominate further increases in speed. Stride length explains much of the difference in speed among distance runners.

Research has shown that, up to about 3:50 per mile pace, running speed is increased by increasing stride length by the plantar flexor muscles (gastrocnemius and soleus) producing more force against the ground. At very fast speeds, the speed of muscle contraction is so fast that there is not enough time to produce a lot of force, and plantar flexor peak muscle force begins to decrease. (The force-velocity relationship dictates muscle force production; the faster the speed of contraction, the lower the force.) The primary strategy used to increase running speed faster than 3:50 per mile pace changes from increasing stride length to increasing stride rate. Specifically, the hip muscles (gluteus maximus, psoas, and hamstrings) become prominent players to quickly accelerate the leg forward during the swing phase.

Unless you’re a sprinter, don’t focus on increasing stride rate (unless you land with your foot far out in front of you, in which case it would be beneficial to take quicker steps), and instead focus on increasing stride length by increasing hip extension and applying greater force to the ground at push-off.



How do you decide paces for workouts? Although it’s convenient to use workout pace tables, you need to understand what’s behind the numbers before blindly following what they say.

For example, the VDOT tables of Jack Daniels and his former athlete and computer programmer Jimmy Gilbert are popular among coaches and runners. Those numbers are computer-generated based on regression equations. To come up with the workout paces, it’s assumed that every runner has the same running economy (which is not true) and that every runner is equally as good at all racing distances (also not true). I have found the paces to be more accurate for very good and elite runners than for recreational runners.       

Let’s look at an example: For a runner who runs a half-marathon in 1:00:54 (4:38/mile pace), that equals a VDOT of 80 and a corresponding pace of 4:41/mile for threshold (tempo) workouts. For a runner who runs a half-marathon in 1:50:59 (8:28/mile pace), that equals a VDOT of 40 and a corresponding pace of 8:12/mile for threshold workouts.

For the runner who runs 4:38/mile pace for a half-marathon, I agree that threshold pace is 4:41/mile because threshold pace will be very close to or right at half-marathon pace for someone who runs a half-marathon in 1 hour. From my own lab research, I have seen that very good runners can maintain threshold pace for about 1 hour. However, the runner who runs 8:28/mile pace for a half-marathon will not likely have a threshold pace of 8:12/mile because that means he/she will be running for 1 hour and 51 minutes at a pace that’s only 16 seconds per mile slower than threshold. It’s difficult to imagine that someone who runs a half-marathon in 1:51 runs only 16 seconds/mile slower than threshold for 1 hour and 51 minutes, especially when someone who runs a half-marathon in 1:01 runs 3 seconds/mile faster than threshold (a 19-second/mile difference relative to threshold—16 seconds slower vs. 3 seconds faster).

Bottom line? Don’t just blindly follow a pace table. Acquire expertise about training and you can design workouts to fit your abilities and needs. Where can you acquire that expertise? I’m glad you asked. revo2lutionrunning.com  



Workout Sunday: 800-meter reps at lactate threshold pace with 45 seconds rest between reps. With the World Masters Track and Field Championships 10 months away, I’m continuing with “Project High School” (my attempt to approach my high school track times) as my Achilles tendon heals and working on my aerobic strength before doing the anaerobic speedwork I’ll need later to get into 800-meter and mile race shape. Did 8 reps today.

Training tip: Never start workouts with a number of reps in mind. Number of reps is arbitrary and not as important as causing fatigue. There’s no magic in doing 6 or 7 or 8 reps. Do as many reps as it takes to cause fatigue, until you feel that you couldn’t do another rep without breaking the bank. Fatigue is what your body responds and adapts to. Give yourself the opportunity to adapt.

The other reason to do “Unlimited Reps Workouts” (which are a tenet of my coaching training programs), is to redefine your limits. If you focus on one rep at a time without any preconceived idea as to how many reps you’ll do, you may do more than what you thought you could do. If you decide before the workout you’ll do 8 reps (us scientist nerds call that “a priori” when something is decided before an experiment), guess what happens when you get to rep 7 or 8—you feel tired, because your brain thinks you’re close to the end of the workout. If you leave the workout open-ended, you’ll be amazed at what you can accomplish. Same for tempo runs and other types of workouts. Reset your limits by not placing limits on your workouts. That’s smart training.   



Hi! I’m hemoglobin.

I live inside red blood cells and eat all the iron in the fridge. I’m very attractive (see my photo attached). My shape changes as the number of oxygen molecules attached to me changes. The more oxygen molecules bound to me, the more attractive I become to oxygen, and the more oxygen wants to bind to me. When only one oxygen molecule is bound to me, I’m not so attractive. But when 3 oxygen molecules are bound to me, the fourth one can’t bind itself fast enough, so beautiful I become. (When I have 4 oxygen molecules attached, I can’t stop looking at myself in the mirror.) This change in my affinity for oxygen is important because it facilitates the loading of oxygen in lungs and unloading of oxygen in the muscles and other organs.

This change in my shape is how doctors and nurses know when blood’s oxygen saturation is low. You know that little finger clip they put on your finger in the hospital or doctor’s office? There’s an infrared light inside of that clip. When I change shape, I change how I refract light. So, that clip is “reading” how the infrared light is refracting because of my shape. If blood’s oxygen saturation is less than optimal (98-100% at sea-level), the light refracts differently because my shape is different. Pretty cool, huh?

How saturated I am with oxygen is determined by the partial pressure of oxygen in blood. The lower oxygen’s partial pressure, the lower my saturation. When you go skiing, hiking, or running at high altitude, the partial pressure of oxygen in the air decreases, which decreases the partial pressure of oxygen in your blood. Up to an altitude of about 3,000 feet, the drop in the air’s partial pressure of oxygen is minimal, so my saturation doesn’t change; it remains at 98-100%. But when you travel above 3,000 feet, my saturation begins to drop. That’s why it’s harder to do aerobic exercise at high altitude—because I have less oxygen bound to me as I travel through your circulatory system.

Now, tell me how beautiful of a protein I am. Want to learn more about me?



When your foot lands on and pushes off the ground, it applies a force to the ground. Consequently, the ground applies a force to your foot that is equal in magnitude and opposite in direction to the force applied by your foot.
When your foot lands out in front of your center of gravity (hips), with a large lower leg (shank) angle, your foot pushes down and forward on the ground, resulting in a ground reaction force that pushes up and back on your body—the exact opposite of what you want.
To maximize the propulsive forces from the ground reaction force (and to reduce the risk of injury), you must land on the ground with a small shank angle. The shank angle at touchdown of average runners is about 16 degrees, compared to 6 to 10 degrees of proficient runners. Proficient runners land with the foot closer to underneath their hips.
To create this small shank angle, practice pulling your leg back toward you before your foot lands (like a cat or dog pawing the ground), as if you are sweeping your leg through a vertical line below your center of gravity. You can practice this while running and through specific drills.
Just over 4 months until I return to Kenya to hold the first annual Run Kenya camp! Have you signed up yet?

Riches are in the Niches


When I coached high school track and field, it was often difficult to get kids to focus on one event. With so many options in the sport, many want to run and jump and throw. I’ve tried to convince them that it’s better to be very good at one event than mediocre at multiple events. As adults, little changes. I often hear personal trainers say that they train all types of clients—weight loss clients, elite athletes, clients who want general muscle toning, seniors and so on. For their areas of expertise, they list specialties such as “weight loss,” “athletic performance,” “metabolic conditioning,” “senior fitness” and “post-injury rehabilitation” and obtain certifications for every specialty.

First of all, no one can be an expert in all of these areas. Secondly, you shouldn’t even try. That’s not the path to success. It’s tempting to train all types of clients because it seems that you could make more money with a broad focus than with a narrow one. Many of the high school athletes’ parents tell their kids to do many extracurricular activities to increase their chances of getting into college. Well, their parents are wrong. Successful people are not well-rounded. They don’t do many things. Successful people and successful businesses do one thing and do it better than everyone else. Choose a niche to specialize in and become as educated and as skilled in that niche as possible.

If you’re passionate about helping people lose weight, become a weight loss expert. Read every scientific study that has ever been done on weight loss. Open a biochemistry textbook and understand metabolism and hormones and everything that affects weight gain and loss. Volunteer for weight loss studies. Talk to scientists who have devoted their lives to researching weight loss. Learn how much, what type, and what intensity of exercise result in significant weight loss. Learn the documented habits of successful weight losers. Know the role that nutrition plays in weight loss. Know the data from the National Weight Control Registry as well as you know your parents’ names. How many trainers do you think know all this, yet still claim to be weight loss experts?

After you’ve done all your homework, become known in your community as The Weight Loss Expert. Speak to weight loss groups, give weight loss tips on TV, write a weight loss column for a local newspaper or magazine. When people ask about your services, charge a lot of money because you’re The Weight Loss Expert and they can’t get your expertise anywhere else. Riches are in the niches.

Landing Softly or Landing Hard-ly?


We’re told to do a lot of things softly. Librarians tell us to whisper in the library. Theodore Roosevelt told us, “Speak softly and carry a big stick.” Golfers are told to grip the golf club softly rather than strangle it. Even the hip hop group Fugees sing, “Killing me softly with his song.”

The advice I love the most is to run softly over the ground, like you’re running on eggshells, on ice, or on water. For some reason, runners, coaches, and writers on the subject seem to think that the best way to run is to strike the ground as softly as possible, trying not to crack the eggs. It seems logical, at first thought, that you would want to strike the ground softly, because striking it hard-ly would be bad, causing injuries from all that “pounding.”

But you shouldn’t always do things at first thought. When you dig deeper, into second thoughts and third thoughts and fourth thoughts, you begin to understand things on a different level. Better, quicker running comes from applying more force to the ground so that the ground reaction force applies more force to your foot, propelling you forward with each step. (Remember Isaac Newton’s third law of motion—for every action, there is an equal and opposite reaction). 

Running softly over eggs so as not to crack them prevents a runner from optimizing the propulsive force and increase running speed, because running speed is a function of the vertical ground reaction force—the greater the vertical force, the faster the running speed. To create a large ground reaction force, you must strike the ground with a lot of force—hard-ly instead of softly. And running hard-ly would crack a lot of eggs!      

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