How to Run

From his book The Science of Running (2014) Chapter 22.

If you want one book on the principles of run training and some of the differences between scientists and coaches I have yet to find a better one.

Running well is a movement skill, so it’s well worth dwelling on how this is done with optimal economy. Here he goes through the running cycle.

“To go through the entire running cycle, we will start with when foot contact is made and go through the full stride. Foot contact should occur on the outside edge of the foot and depending on speed, either at the midfoot or fore-foot. The initial contact on the outside of the foot is generally not felt and instead for practical reasons should be thought of as a simple mid/whole foot landing. Contrary to what many people believe, initial foot contact should not occur on the heel even when running slow. Heel strikes result in a higher breaking force, reduced elastic energy storage, and prolonged ground contact. By hitting forefoot or midfoot the braking action is minimized, and the initial impact peak is reduced. Additionally, the landing should occur in a neutral position at the ankle, as that sets up the calf and Achilles for optimal use of elastic energy. Once landing has occurred, it is important to allow the foot to load up.

Often the mistake is made in trying to get the foot off the ground as quickly as possible, but remember it is only when the foot is on the ground that the force is transferred into the ground. While having a short ground contact time is beneficial, it should be the result of transferring force faster and not of getting quick with the foot. Loading up the foot means allowing it to move through the cycle of initial contact to fully support the body. Since initial contact is on the outside of the foot, the support will move inwardly with forefoot strikers, the heel has to settle back and touch the ground to allow for proper loading of the Achilles and calf complex. Holding the heel off the ground and staying on the forefoot will not allow for the stretch reflex on the Achilles calf complex to occur.

After the initial loading phase, propulsion starts to occur as the foot begins to come off the ground. The center pressure should move forward with the big toe acting as the locking mechanism for the foot to leave the ground. This locking ensures the foot acts as one entire unit, allowing for greater propulsion. Unlike what many suggest, do not try to get any extra propulsion out of pushing off with the toes consciously. It is too late in the running cycle to net any forward propulsion and will result in simply making the stride flatter. Instead, the forward propulsion should come from the hip, and the foot should be thought of as being along for the ride, which we will discuss shortly. Essentially, once the hip is extended, leave the foot alone.

During this entire process, the calf and Achilles tendon can utilize the stretch-shortening cycle and reflex phenomena. Upon foot contact, the Achilles calf complex goes from a neutral position to fully stretched upon mid-stance to fully constricted upon toe-off. This cycle allows for energy storage upon ground impact and release upon takeoff. In essence, the complex acts like a spring as it stores energy that comes with ground contact and then releases it when the ground contact is broken. A common mistake is to stay too high up on the balls of the feet and never let that heel touch the ground. When this occurs, the Achille calf complex is not fully stretched and thus you’re losing out on the elastic energy return. Similarly, if a runner is too quick with the foot, meaning that they try to rush it off the ground, elastic energy is lost because the foot and the Achilles are not properly allowed to store and release energy. Likewise, the arch in the foot also stores elastic energy and is initially compressed and then subsequently rebounds. This mechanism happens because of its elastic properties.

While the foot contact is occurring, the emphasis in your mechanics should be to shift to the hip. The extension of the hip is where the power comes from, not from pushing with your toes or any other mechanism that is commonly cited. The hip should be thought to work in a crank-like or piston-like fashion. The speed and degree of hip extension are what will partially control the speed. A stronger hip extension results in more force application and greater speed, thus how powerfully and rapidly the hip is extended helps to control the running speed. Once the hip is extended, the foot will come off the ground, and the recovery cycle will begin.

In coming off the ground you are trying to optimize the vertical and horizontal component of the stride. If you think too much horizontally, you’ll flatten out and not come off the ground, just losing air time and stride length. If you think too much vertically, you will be high up in the air for too long and almost bounce along, not having a very big stride length. This is important to optimize the angle and extend the hip so they have a slight bounce in your stride. A good cure for this is to look at the horizon. If it stays flat, you are too horizontal. If it bounces a lot, you are too vertical. The best analogy is to think back to your school physics class and remember how to get the greatest distance when firing a cannonball. The angle has to be optimized, not minimized.

Once the hip has extended, the recovery phase starts. When the hip is extended correctly, it will result in the working of a stretch reflex mechanism. This is best thought of as a slingshot where you stretch the slingshot back and then let it go. The result will be that it shoots forward very rapidly. The hip works in much the same way. If you extend the hip you are putting it in a stretch position. With the slingshot, If instead of letting it go, you try to move it forward, the slingshot band would come forward much more slowly. The same applies to the hip.

With the combination of the stretch reflex and the basic passive mechanical properties of the lower leg, the recovery cycle of the leg will happen automatically. The lower leg will lift off the ground and fold so that it comes close to your buttocks (how close depends on the speed you are running) and then pass under your hips with the knee leading. Once the knee has led through, the lower leg will unfold and it’s the runner’s job to put it down underneath them. Ideal landing is close to the center of your body and directly underneath the knee.

Trying to actively move the leg through the recovery phase is another common mistake and will only result in wasted energy and slower cycling of the leg through the recovery phase. Two other common mistakes are trying to lift the knees at the end of the recovery cycle and kicking the lower leg to the butt at the beginning of the recovery cycle. Neither idea is sound, as they essentially like trying to push the slingshot forward in our analogy instead of just letting it go. Active lifting of the knee lengthens the recovery cycle with no added stride length of benefits. Instead, the knee should be allowed to cycle through and left on its own. It should not be forced upwards because the cycle through the knee is a result of the stretch reflex.  Similarly, pulling the lower leg to the butt simply wastes energy, as the hamstrings have to be put to work in doing this action. Instead, the folding up of the leg should be thought of as a passive activity. How close the lower leg comes to the butt depends on the amount of hip extension.

This phenomenon may seem strange and is sometimes a hard concept to grasp. After all, who has the patience not to do anything during the recovery phase? However, research has demonstrated that both muscle activity during the recovery phase and the energy use (the recovery phase only uses 15% of the whole strike energy) show that the leg is largely cycling through entirely because of the reflex-like phenomena and passive mechanics. Research on patients with spinal lesions has demonstrated the effect of the stretch reflex and passive dynamics on gait. Even though the patients have lost the use of their legs, if put on a treadmill their legs will work in a walking motion as long as the hip extension is initiated by someone. If a therapist simply manually extends the hip and lets it go, the leg will have a slight fold-up as it cycles forward automatically. The forward movement unfolding up of the leg is a result of the stretch reflex on the hip and passive mechanics. The fact that the leg folds up at all shows that it is a simple mechanical issue and does not occur due to active muscle contraction. As a simple experiment, play around with a simple two-jointed object, push the top joint forward, and see what the lowest joint segment does. If it’s moving forward at sufficient velocity, it’s going to fold up because of simple physics and mechanics.

Once the knee has cycled through, the lower leg should drop to the ground so that it hits underneath your knee and close to your center of gravity. When the foot contact is made, it should be made where the lower leg is 90° to the ground. This puts it in an optimal position for force production. The leg does not extend forwards like is seen in most joggers and there is no reaching for the ground. Reaching out with the lower leg results in over-striding and creates a braking action. Another common mistake is people extending the lower leg out slightly and then pulling it back in a paw-like action before ground contact. In using this paw-back technique, the idea is to try to get quick with the foot and create a negative acceleration. This is incorrect and does not lead to short-to-ground contact times or better positioning for force production. Instead, the paw-back motion simply engages the hamstrings and other muscles to a greater degree than necessary, just wasting energy. The leg should simply unfold and drop underneath the runner.

This paw-back phenomenon was originally taught because of the idea of trying to create backward acceleration. This concept does not hold up as the braking forces are still the same upon foot contact. Moreover, the paw-back was created through misinterpretation of scientific data. Coaches saw that the hamstrings were active during the later proportion of the in-flight recovery phase and assumed that that meant the hamstrings were contracting, thus pulling the lower leg back. Instead, the hamstrings were active during the stiffening of the muscle-tendon unit in preparation for ground contact and in aiding the slowdown of the unfolding of the lower leg. Muscle stiffness manipulation occurs for two reasons; first to absorb elastic energy as a stiff system can utilize elastic energy better, and second because of a process called muscle tuning. Muscle tuning is the body’s way of preparing for landing. In essence, it acts as a built-in cushioning system to minimize the muscle vibrations that occur during landing. The body uses feedback and sensory information to tune the cushioning so the ground reaction forces are essentially the same whether in a cushion shoe or running barefoot. When running Barefoot, muscle tuning takes place so the built-in cushioning can absorb more of the force.

So far we’ve only talked about the lower body, but the lower and upper body all link together as one unit. The interaction between the upper and lower body plays a very large role. First, you should run with an upright body posture and a very slight lean forward from the ground, not from the waist. The arms and legs should work in a coordinated fashion. When the left leg is forward, the right arm should be forward, and vice-versa the left arm and leg. But it goes beyond just the arms and legs working in opposition; when they both stop, forward and backward motion is also coordinated. When the arm stops moving forward and is about to reverse direction, the opposite leg should reach its maximum knee height before starting its downward movement.  Similarly, when the arm reaches its maximum backward movement before switching directions and coming forward, the opposite leg and hip should be the maximum extension backward.

The arm swing occurs from the shoulders, so the shoulders do not turn or sway. Is a simple pendulum-like forward and backward motion without shoulder sway or the crossing of the arms in front of your body. On the forward up swing the arm angle should decrease slightly with the hands in a relaxed fist. On the backswing, they should swing back to just above and behind your hip joint for most running speeds. As the running speed increases, the arm will swing back more, eventually culminating in going back and upwards in sprinting.

The integration of the arms and legs is critical. Often we see something happening with the leg that is incorrect and immediately work on fixing the problem by adjusting how that particular leg is working. For example, if an athlete extends out with the lower leg, we immediately try to correct them by having them put their foot down sooner. Instead, the problem seen with the leg could simply be the symptom. The real cause could be in the arm swing. A delayed arm swing or a swing with a hitch in it causes a delay or a hitch in the opposite lower leg. If you watch someone run, the arms and legs are timed up so they work perfectly in sync. If the runner has a problem with the arm swing that causes a delay in the typical forward and backward motion, such as turning it inwards or shoulder rotation, then the opposite leg must compensate for this delay. In many cases, the opposite leg extends outwards as a form of compensation. Therefore, it is important to look at the whole body and understand that the arms and legs are synced together and interact, so a problem in one of them may simply be a way of compensating. We need to figure out if the issue in the arm or leg movement is coming from that spot or if it is a result of the body attempting to counterbalance itself.”

Summary of running form:

1. Body Position – upright lean slightly from the ground. Head, face and shoulders relaxed.

2. Feet – as soon as the knee comes through, put the foot down underneath you. Land midfoot or forefoot underneath the knee, close to the center of the body.

3. Arm stroke – controls rhythm. Movement from the shoulder without side-to-side rotation.

4. Hip extension – extend the hip and then leave it alone.

5. Rhythm – control rhythm and speed through arm stroke and hip extension.