Run Faster – No Super Shoes Needed!

Run Faster - No Super Shoes Needed! 1

This expert article comes from our friends and partners at UESCA, the leading provider of Endurance Sports Education.
UESCA’s running coach and ultrarunning coach certifications are considered industry-leading, with a science-backed, zero-bias approach.

If you’re a runner, or even if you’re not, you’ve likely heard of the term ‘super shoes.’

Super shoes refer to running shoes that have a carbon fiber plate in them to decrease the metabolic cost of a runner while increasing their speed. So, what exactly does the carbon fiber plate do?

The carbon fiber plate in the sole adds stiffness, thus storing and releasing more energy. This equates to greater propulsion.

Did you know that your body has structures that also act to store and release energy and, more specifically, can be stiffened to increase performance? We call this passive energy.

The following section discusses passive energy and how it can make you a faster runner.

Elite runners.

Passive Energy

Within the body exist structures and movement patterns that allow individuals to significantly reduce muscle activation while maintaining the same, if not greater, running performance.

The two areas we will focus on in regard to passive energy are energy return and passive movement. Passive movement and energy return are interrelated.

The genesis of passive energy is that energy is absorbed by the impact when the foot impacts the ground during running.

The goal of a runner is to optimize their running form (mechanics) to convert as much of this stored energy as possible into forces that assist in the forward movement.

With regard to improving efficiency and performance, the five areas that influence passive energy are hip rotation (side to side), hip flexion, foot plantar flexion, knee flexion/extension, and foot arch compression.

By maximizing their passive energy contribution, a runner can improve their running economy. Meaning the active muscle requirement is reduced while still producing the required amount of force.

A strong runner.

Stretch Shortening Cycle (SSC)

“Energy cannot be created or destroyed; it can only be changed from one form to another” -Albert Einstein.

By definition, the SSC is representative of an eccentric contraction (muscle contraction of a lengthening muscle) of a muscle followed by a rapid concentric contraction (muscle contraction of a shortening muscle) of the same muscle.

With respect to running, the quadriceps, obliques, and calves represent the muscles most influenced by the SSC.

When the foot hits the ground, the quadriceps and calves eccentrically contract (lengthen) and then rapidly concentrically contract (shorten) during the drive phase to provide forward propulsion. 

To illustrate what the stretch-shortening cycle is, think of shooting a rubber band. The more you stretch the band, the further the band will travel in the air once released. However, if you stretch the band too much, the band could break.

Running gait.

Additionally, the more tension the band has (harder to pull back), the further it will go. With respect to the human body, muscles and tendons are the rubber band.

To recap, tendons connect bone to muscle. Therefore, in the context of the stretch reflex, muscles and tendons are often considered two parts of a working whole, the muscle-tendon unit. The variables that affect the degree of elastic return of the SSC are:

  1. Length of the stretch
  2. Speed of the stretch (loading)
  3. Stiffness of the muscle and tendon
  4. The time between the stretch and the contraction

From a running perspective, the legs act as springs. The springs compress during the first half of the support phase and rebound during the drive phase.

The stiffer a muscle is, the greater the amount of energy that can be stored and released. However, to not increase the chance of injury, a muscle must have full mobility.

Two people running trail.

Tendons

Let’s first examine tendons and their properties.

It is important to note that depending on the location of a tendon in the body, they will vary in thickness, shape, and length. These variables affect the stiffness of the tendon and, thus, the capacity for force production.

Tendons have elastic properties that allow them to stretch. The stretch of a tendon (or muscle) stores energy; when the stretch is unloaded, the stored energy is released.

Utilizing this stored energy properly can greatly minimize the metabolic cost of movement.

The optimal stretch for a tendon should be viewed as a modified bell curve – meaning too little or too much stretch is not optimal. While it is clear why too little of a stretch would not be optimal, why would a large stretch not be recommended?

If stretched beyond the end point of a tendon’s range of motion, a tendon could tear completely. However, before this point is reached, the tendon could still be overstretched.

When this occurs, structural changes occur to the tendon that effectively changes the length of the tendon and thus reduce the stretch reflex.

The degree of stretch to a tendon that elicits the ideal stretch reflex is called the elastic region. Once the stretch extends past this region, it is called the plastic region.

It is at this point that the structure of the tendon changes and therefore changes the tendon length.

The below image illustrates the elastic and plastic regions on a curve-based model (Load-Deformation Curve).

Tissue Deformation Graph

Achilles Tendon

With regard to running, the Achilles tendon has a large impact on performance with respect to passive energy.

A study that examined the link between resistance training and Achilles tendon stiffness found that a 16% increase in tricep surae tendon (gastrocnemius, soleus, Achilles tendon) stiffness via resistance training decreased the rate of oxygen consumption during running by 4%, thus increasing running economy (530).

Another study confirmed these findings by noting that differences in Achilles tendon mechanical properties were primarily influenced by muscle strength (531).

Depending on the study, the degree of energy that can be stored by the Achilles tendon and the resulting increase in running economy varies.

Therefore, the most important thing to keep in mind is that an increase in muscle strength of the tricep surae will increase Achilles tendon stiffness which results in increased running economy.

There appears to be no difference between men and women in regard to the effect of Achilles stiffness on running economy (529).

Runners on the road.

Role Of The Big Toe

Not all toes are created equal, at least not in terms of foot stabilization and forward propulsion. During running, the big toe plays a key role in the following:

  • Stabilizing the foot
  • Regulating the degree of foot pronation
  • Forward propulsion

The big toe, in relation to the other toes, is responsible for a much greater percentage of foot and body stabilization as well as forward propulsion.

Windlass Mechanism

Windlass Mechanism (foot)

As noted in the figure above, the sesamoid bones are two small (pea-size) bones that are embedded into a tendon. The bones sit under the ball of the foot at the big toe joint. The sesamoid bones act as a fulcrum to provide the foot leverage when pushing off the ground.

Big Toe Joint Facts

  • It carries 12 times more weight than the small toe.
  • It’s the only toe made up of two bones as opposed to three.
  • It has a separate set of control muscles and tendon insertions from the rest of the toes.

Mechanics

Rapid dorsi-flexion (loading – rotating the foot up) and plantar-flexion (unloading – rotating the foot down) of the ankle is what is responsible for the spring action of the Achilles tendon.

If the ankle is not dorsiflexed enough, the energy stored in the Achilles tendon will not be as high as it could be. The implication from a mechanical perspective is that the heel of the foot during the drive phase should touch the ground while the hip is extended behind the body.

If the heel does not touch the ground during this phase, potential energy is reduced, and as a result, running economy is decreased as well.

Based on the influence of dorsiflexion and the potential energy of the Achilles, it could be theorized that shoes that have a high heel in relation to the forefoot (large heel to toe drop) would reduce the amount of stored energy, as the shoe limits the amount of ankle dorsiflexion possible.

Additionally, poor Achilles tendon range of motion (flexibility) will likely limit the amount of potential energy able to be stored.

A person running on the road.

Outside Influences

In relation to passive energy, running economy is not just based on storing energy but also on utilizing it. The interface of the foot and the ground influence the amount of energy that can be utilized.

The more solid the interface is, the more efficient the runner will be.

If the running surface is very soft (e.g., sand) and, or a shoe has a lot of cushioning, this will reduce the amount of energy that can be used by the runner, as a large portion of the energy is being dissipated via absorption of the ground and shoe, respectively.

Some absorption, however, is likely a positive thing in relation to running economy and decreasing the chance of injury.

For example, studies have shown that there is a higher metabolic cost to running barefoot than with minimal shoes due to the increased muscular demand (532).

Shoe selection plays a large role in the Achilles tendon’s flexibility and range of motion.

It is commonly understood that sitting for long periods of time influences an individual’s posture – primarily due to the hamstrings and hip flexors being in a chronically shortened position.

Akin to this is wearing shoes that have a high heel in relation to the forefoot, as this places the Achilles tendon and calf muscles in a shortened position.

Therefore, from the standpoint of increasing Achilles tendon range of motion, spending time walking indoors without shoes on or in shoes with a small heel-to-toe drop is helpful.

A group of runners.

Trainability

Many distance runners do not perform strength and sprint training due to the perceived lack of specificity.

While there are many benefits to distance runners, if they only did sprint training for the purpose of stiffening the Achilles tendon and the longitudinal arch (pictured below) to utilize elastic energy return more efficiently, it would be well worth the effort.

Foot Arch

The primary functions of the foot in regard to running are shock absorption and propulsion. The foot plays a large part with respect to passive energy, specifically, the longitudinal arch.

The muscles and connective tissue of the foot, including the plantar fascia (the horizontal line below the longitudinal arch in the image above), which affect the longitudinal arch, act as a spring to provide passive energy during the running gait.

The above image denotes how the foot acts as a spring in relation to the plantar foot muscles and connective tissue. 

Longitudinal arch.

Muscles

Like tendons, the stiffer a muscle is, the greater the elastic return will be.

Pre-activation of leg muscles when running prepares the body and leg musculature for foot impact. Pre-activation of leg muscles is theorized to decrease stress on leg muscles and increase cushioning upon landing.

Think about this for a second – if the leg muscles did not contract before and during landing, the body would collapse upon foot strike.

Leg muscle ‘stiffness’ can be controlled consciously or unconsciously.

The degree of leg stiffness directly affects the amount of knee flexion. With regard to conscious control of leg muscle stiffness, an individual is able to control their stride rate and stride length.

Leg stiffness is also influenced by the geometry of the leg at impact. This is because, depending on the angles of the leg at foot impact, there will be varying loads on the leg that the muscles must counteract.

A runner's gait.

Lastly, and as noted previously, on the topic of leg stiffness, the type of surface that the foot lands on correlates to the degree of muscle stiffness.

When running, the body looks to maintain the same degree of total vertical stiffness (surface stiffness + leg stiffness) at all times. Therefore, when running on different surfaces, such as pavement and sand, the degree of leg stiffness will change to maintain the same degree of total vertical stiffness.

For example, if running on sand, the legs must become stiffer to compensate for the decrease in surface stiffness.

It is critical to note that while muscle stiffness elicits a higher SSC, the muscle must have full mobility (range of motion).

A runner.
Photo of author
Rick Prince is the founder and director of UESCA, the leading provider of Endurance Sports Education. UESCA's running coach and ultrarunning coach certifications are considered industry-leading, with a science-backed, zero bias approach. Rick holds a BS in Kinesiology from Springfield College and is a certified corrective exercise specialist through the National Academy of Sports Medicine (NASM), as well as a certified UESCA running and triathlon coach. Rick is a competitive runner and cyclist, having raced bikes nationally and internationally and run collegiate track and cross-country. Rick competes in running races and tries in vain to keep up with his 4-year old son.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.