Articles


Springs in the Foot

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The foot is the only mechanism for the human body to transfer strength into speed. Every ounce of strength you have for sprinting is put into the ground by the complex human spring system that we refer to as the foot. This is ground zero for Newton’s law of action/reaction and a tremendous source of unrealized potential thrust. Understanding how the feet make you run fast and how to train the feet can improve your speed greatly.

Since the game changing scientific analysis of Peter Weyand et al in 2000, there is no misunderstanding about what makes humans run fast. The key is application of strength. Weyand states, “Quite simply, fast people hit the ground more forcefully than slow people relative to their body weight.”

Unfortunately, the devil is in the details. Strength makes you go fast, but that strength must follow the rules of force application or it is useless. Speed is clearly not about raw miscellaneous force. An elephant applies the most force to the ground of any sprinting animal but the jackrabbit and its tiny amount of force results in 300% faster speed. The rabbit has the advantage of a better force to mass ratio, better angles of thrust, and spends much less time on the ground as the elephant.

The foot plays the key role in the drama of speed. In 1/10 of a second, all strength travels from the hips down through the calves to the foot’s compact spring mechanism. It starts just above the ankle joint where the Achilles tendon works like a spring, supercharging each stride of a sprint. Next, the arch stretches and contracts like a tight elastic band from toes to heel adding additional spring to each step. Finally, the big toe joint defies human anatomy by bending and straightening to support the full weight of the body as it pushes you rapidly into the air.

Unlike the elephant or horse hoof, the human foot stretches and contracts with every step to provide this magical springing mechanism that puts all of our strength to work for us as we sprint. So we honor this marvelous gift by wearing foot-action restricting shoes that look great but make us run slow.

Sprinting isn’t what we were made for. In fact, humans are really bad at speed compared to others in the animal kingdom. We are built for LSD (long, slow distance). This is how we can outrun a horse; we just keep running and running all day until our prey gives up from exhaustion. Even our toes have evolved from long finger-like appendages millions of years ago to the stubby little nubs we have now. According to Sabrina Lee and Stephen Piazza and their work, “Built for Speed” (2009), shorter toes are efficient in LSD, while bigger toes aren’t. Is it any wonder that elite sprinters tend to have longer toes and highly developed explosive toe reaction to the ground when compared to marathon runners.

The vast majority of humans evolved being real slow, but always the statistical outliers have carried the seeds of speed. The small percentage of human speedy people have significant anatomical advantages, including a higher proportion of white meat (fast twitch muscle fiber). Elite speedsters are neurologically unique, wired for speed, often have a volatile disposition, usually with a screw loose. And these same speedy humans display some highly efficient feet no matter how big. For those who aren’t so genetically gifted, it is the training the feet to be fleet that pays off with improved speed.

Foot Strike

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The downward leg punch, the angles of impact, and quick springing back off the ground make up the missing link in speed. Often referred to as the “stiff leg” principle, this means training yourself to not sag down at the hips or excessively bend at the legs on impact. Part of the stiff leg action is the “stiff ankle” which happens when the foot hits the ground nearly flat footed then like a tennis ball, springs back into the air instantly. Surprisingly, this enormous force of action/reaction has less to do with tough-guy strength and much more to do with elasticity. Both of these can be trained, but elasticity is the genesis of strength for speed.

The foot must punch the ground hard. The ball of the foot (forefoot) lands directly under the hips (not reaching out in front) on the little toe side, instantly rolls to the big toe side of the foot, then pushes off all the way through the tip-toes. Never once will the heel hit the ground, but it will come about 1/4” from the surface. All of this happens in about 1/10 of a second. Your training should be to get back into the air quick, quick, quick. Focus on running as though you are on the hot coals of a giant barbeque pit.

Typical weightroom exercises for strong calves don’t translate into fast foot action. I often see guys in the weightroom doing Donkey raises, shoes on a weight plate, heel on the ground and raising up. This is a sad misunderstanding of how the foot spring mechanism works. It isn’t a muscle system that springs the foot, its elastic bands of connective tissue. The foot is the storage unit for elastic energy; it has only a tiny amount of muscle compared to the huge backside power chain (glutes, hamstrings). It is the elastic bands of Achilles and the arch (plantar fascia) that propel you from the ground. These bands are very easily developed but completely ignored.

Unless you were born with the genetic package of Usain Bolt, your foot must be instructed how to behave. That instruction must be something the brain comprehends, something very similar to the way you perform at top speed. Most of the training must be fast acting, like jumping rope or skipping. Lots of drills you already do need to be altered to put more focus on the foot. Much more of your work needs to be barefoot inside and out to gain the tremendous benefits of letting the foot interact with the ground naturally.

Resistance training in the weightroom is mandatory, very hard-to-lift weights to develop the backside chain, and done in very low volume to maintain neurological integrity. But lifting must be something you can translate into high speed action on the ground. When training on the field for speed, you’ve got to run full speed bursts every week or you fail to teach the foot how to transfer leg extension into foot extension. Outdoors, the higher the resistance, the worse the outcome. Train for speed by running at top speed regularly.

There is a very simple and refreshing method to this madness. Use contrast training (potentiation of performance) where you use moderate resistance for a few high intensity seconds then go full speed without resistance. The classic model of this is short burst sprinting in the sand (such as a long jump pit) followed by full speed sprinting on the grass or the track. The foot will instantly translate the powerful burst effort resisted by the sand into a powerful burst on hard surface. A waist belt resisted by a rope for a few steps then released for a full speed burst works even better.

Ankle Springs

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For speed development, the ankle is sadly misunderstood. The bodybuilding culture has us thinking of big calf muscles, all oiled up with veins popping out. Unfortunately, big calves have little to do with running fast. Its the elasticity of the ankles that lets us spring.

There is an astounding elastic capacity of the Achilles tendon for instant springing action off the ground. With the toes pulled up (dorsiflexed) at about 90°, the ankle is “cocked” like the hammer of a pistol. Calf muscles (gastroc and soleus) are pre-stretched and ready for action. But it is the elastic band we call the Achilles that provides the speed. The fastest people on the planet tend to have significantly shorter Achilles tendon than normal folk. This makes for a tightly drawn elastic cord, made for higher reactive forces operating is less time. Having a powerful Achilles that performs in 1/10 of a second is the opposite of slow stretching or plodding in a parking lot pushing a truck.

Elite sprinters on average have an Achilles 25% shorter than non-sprinters (Lee and Piazza, 2009). This means that the ankle is tighter and more loaded for spring than non-sprinters. A tighter Achilles is of great advantage until misunderstanding sets in with counterproductive activities such as static ankle stretching exercises. Furthermore, typical speed training involves dorsiflection drills that are carelessly administered and incomplete. Unfortunately, not much is done for rapid push down (plantarflection) resulting in tens of thousands of sprinters who get very little full push-off from the foot.

Conversely, ballistic and dance like motions develop ankle springs. Skipping and Ladder exercises are ballistic, even jumping jacks are ballistic. Every athlete I train is under strict orders to jump rope barefoot every day, even if only for 5 minutes. Ballistic exercises can be very light or very intense. The ankle needs to be trained to spring fast and powerfully and ballistic movements fit the bill.

Up-down toe lift exercises more like tapping the foot to music is needed, and these are very easy to do. It’s called skipping. Skipping teaches the ankle to be stretched up to 90° followed by a snap back down to push off the ground. This is especially useful as you start and accelerate the first 10 yards. Lack of ankle ROM (range of motion) inhibits the ability to get the shin angle low enough to allow you to lean (straight “broomstick” back, not bent over). Lack of ankle drills will lead to “sitting” in your sprint; a sprint that is squatting down with the toes pointing out in a slow and inefficient push-off.

Ankle drills will help solve this, and the drills can be incorporated into everyday training with no additional time. Just change your focus. Warm-up with a series of skipping drills, never jogging. Teach the feet to land dorsiflexed and spring off plantarflexed with each step. Jump rope daily, not for conditioning, but for firing the Achilles in real fast bursts. Mini-hurdles are great to teach proper use of the ankle. The old Russian Short Hops are great here, doing 30 fast low hops within 5 yards. Keep boxes around for a broad range of foot-activation drills. Trot to a box, stomp on it and push off fully, land, then the other leg. Stand on a box, drop off the back of the box, both feet spring off the ground instantly and back up. Do eagle hops with one foot planted on the box, the other out in front hopping 4 x left, 4 x right. Bounding is a great foot activation exercise.

The Arch: Untapped Elastic Force

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Train so that the arch of the foot can spring you off the ground harder and faster. The arch and its complex spring system produces great vertical force if it is put to work. Since we now know that speed’s number one component is how rapidly force can be applied through the foot to the ground, its time to learn how to optimally utilize the arch for faster running. Think of this as the load/explode principle. Here is the power of connective tissue.

Try this drill to understand the spring potential of your arch. Open your hand and touch the middle finger to the palm; do it as hard as you can. Now cock the finger like when you snap your fingers to the sound of music. Feel the difference that load/explode connective tissue can make? This is what you get by utilizing your arches optimally.

Unfortunately, well over 99% of the human race never even triggers this spring mechanism — it isn’t used by walking and not by jogging. Back squatting doesn’t trigger it and static stretching does nothing for it. In practical terms, heel contact with the ground does the opposite, as it puts the body back into the human evolutionary reliance on LSD.

You can teach yourself that arch load/explode action just like when you snap your fingers. Teach yourself to bounce off the ball of the foot with the heel almost touching ground. Force your foot to interact with the ground by landing with the heel just off the ground then springing back up all through the ball of the foot and the toes. This is the way to trigger the Plantar Fascia, the strings of connective tissue between the heel and the toes. The ligaments connecting the heel to toes trigger the arch’s spring-like tissue, providing great elastic strength that fires extremely fast. The arch of the foot is supported by this tissue.

You’ll hear it called “mid-foot plant” and “running on your toes”; both definitions are far from what happens. Your arch never touches the ground as you sprint and you actually run “off your toes.” It causes less confusion by calling it the ball of the foot. Working properly, the harder you punch the ground, the more you activate the Plantar Fascia for the foot’s elasticity. About 4-5 times your weight can be supported and thrust back into the air in 1/10 of a second by this portion of the foot.

The arch isn’t built up like muscle nor does it have a muscle’s built-in time delay to fire. It is more like a compressed spring. The arch spring action comes from forced stretching and contracting elastic tissue found within the three arches of the foot. These arches work optimally when the foot hits the ground and pushes at a right angle, and work inefficiently when the foot strikes ground at a bad angle. The only way to teach the foot to strike ground perfectly with enormous force is with concentration as you practice. You’ve got to think about the sensation, you’ve got to feel the action.

Get comfortable with training barefoot: jump rope barefoot, skip barefoot, run in the sand barefoot, sprint barefoot. Get on a well groomed grass field and sprint full speed bursts. Do mini-hurdle drills on the grass, get used to utilizing your foot in a sprint by regularly doing 15 minutes of barefoot grass sprint work. This is a great way to teach your foot how to optimally use the arches.

The Toes: Ultimate Push

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Speed is about the application of force to the ground, and the toes are a major part of this application process. Evolution has done us no favors by shrinking our toes into the stubs they are now, but its quite easy to highly develop whatever toes you have. The work of University of Calgary’s Campbell Rolian clearly shows the imperative of strong and efficient toe action for speed. He states, “Long toes provide more power for propulsion.” Longer toe bones allow for more efficient ground contact as the angles help provide greater force. But long toes that are underused don’t help, while shorter toes that are trained to be a active offer great advantage. Stronger toes generate more shock than untrained toes, and shock is what jolts you back into the air. (Lee and Piazza, 2009).

Toes function as a last moment source of push-off from the ground. When you consider that you only have 1/10 second on the ground, the toes can provide critical vertical thrust (the bouncing ball) and also aid in reducing the amount of time the foot stays on the ground. Toe-off in sprinting completes the job of the foot, springing the body back in the air like a bouncing ball.

Athletes tend to be apprehensive about all the emphasis that I place on barefoot work and toe activation. My standard argument is “If the toes aren’t important why is turf-toe so devastating to speed?” The first problem with training toes as well as the entire foot mechanism for speed is to overcome bias. Its time to quit making excuses, take your shoes off and get to work.

The right shoes or the wrong shoes can be the make or break for foot action. If you’re serious about getting fast, you need to regularly train barefoot and to get out of your normal “sport” shoes. Get out of your cleats and put on a cheap pair of track shoes to train on the grass. Wake up to faster action by wearing track spikes to sprint as fast as possible, or you can train indoors with race flats. Lose the clunky shoes.

Training must be done to fine tune your toe-off. This is basically a series of quick drills such as jumping barefoot in the sand or skipping that teach the athlete to actively engage the toes in push off. Right away you’ll find that the drills for Achilles spring, arch spring, and toe spring overlap. This is because they work as a unit, the foot spring mechanism.

Jump a lot. Use a sandbag on shoulders and do jump springs. Shock a lot. Reverse lunges and bounce back to position to stretch reflex.

Things That Ruin Foot Springs

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Heelplant

Front lunges are horrible for speed. Training (especially running) in standard flat soled exercise shoes should be outlawed as they teach the opposite of speed. How can this be allowed. You teach day after day to change a humanoid that wants heelplant for LSD running, then exercises allow it. It reminds me of soccer coaches teaching athletes to never let their hands touch the ball, then having a bunch of drills where the hands freely slap the ball.

Treadmills

It amazes me that treadmill training enters the conversation of speed development. Treadmills absolutely interfere with the essential interaction of the foot with the ground (Nigg 1995, Kivi 2002, Frishberg 1983). The unpowered variety of treadmills seem to be the flavor of the month in treadmill training, but the impact of the foot on the surface is different from ground contact. Its absurd to think that the foot interacts with a moving belt surface anywhere close to the interaction with earth. When the Achilles spring action is trained on a moving surface it dissipates most of the elastic force. The arch spring action is dissipated, and the toe push off is nowhere near the same as on solid surface sprinting. The foot learns the wrong action on the ground. Treadmill training for speed is the same as preparing for a spelling test by allowing the words to be spelled wrong but doing it real fast.

LSD

Humans are wired for long slow distance. It takes an enormous amount of training to change the genetic pull of an ultra-marathoner into an fast sprinter. Speed is unnatural as we are anatomically averse to sprinting, this is why speed is so unusual as a human characteristic. Why teach the opposite of speed?

It is highly unnatural to use the foot for speed. The Achilles tendon serves to soften the load of impact, but to run fast it must be used as a coiled up spring. The arch of the foot was designed to protect us from the weight of the body as we walk and jog, now it is asked to stretch and contract like a tightly strung elastic cord. The toes were never intended to support human weight, but in sprinting this is what they must do for about a few hundredths of a second each step.

Never un-teach the lessons of speed. The way to get fast is to run as fast as humanly possible week after week. This puts the body at great stress, crossing into the danger zone regularly. Don’t un-teach this by allowing the feet to interact with the ground like a marathoner.

Foot Spring Activation Drills

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Resources

Clark, Kenneth, and Peter Weyand. Are running speeds maximized with simple-spring stance mechanics? Journal of Applied Physiology, July 2014.

Clark, Kenneth, Laurence Ryan, and Peter Weyand. Foot speed, foot-strike and footwear: linking gait mechanics and running ground reaction forces. Journal of Experimental Biology, April 2014.

Frishberg, B.A. An analysis of overground and treadmill sprinting. Medicine and Science in Sports and Exercise, January 1983.

Ker, R.F., et al. The spring in the arch of the human foot. Nature, January 1987.

Kivi, D.M., et al. A kinematic analysis of high-speed treadmill sprinting over a range of velocities. Medicine and Science in Sports and Exercise, April 2002.

Lee, Sabrina, and Stephen Piazza. Built for speed: musculoskeletal structure and sprinting ability. Journal of Experimental Biology, October 2009.

Nigg, B.M., et al (1995). A kinematic comparison of overground and treadmill running. Medicine and Science in Sports and Exercise, January 1995.

Rolian, C., et al. Walking, running and the evolution of short toes in humans. Journal of Experimental Biology, March 2009.

Weyand, P., et al. Faster top running speeds are achieved with greater ground forces not more rapid leg movements. Journal of Applied Physiology, November 2000.

© Randy Smythe, 2016