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Running Economy and Barefoot vs. Shod Footstrike | Boddicker Performance

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Running Economy and Barefoot vs. Shod Footstrike

by on Mar 25th, 2010

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In yesterday’s post we discussed briefly the three general foot strike patterns.  If you recall, the habitually barefoot athlete most frequently strikes the ground with a FFS or MFS, whereas the shod runner most often makes contact ahead of his center of mass with a RFS.  This differentiation is critical for a number of reasons, and particularly energy return and increased economy.

It seems that prior to foot strike, the barefoot athlete “pre-activates” the triceps surae to increase the stiffness of the ankle, which is the primary means of developing lower extremity stiffness and ultimately contributes to greater running economy (Nigg, 2001; Hobara, 2007; Albracht, 2006).  This pre-activation leads to a greater return of elastic energy via stretch-shortening cycle, and with other things, ultimately leads to a more powerful and efficient stride.

The lower leg is rife with muscles that are reasonably short, with relatively long tendons, and it is believed that these muscles are better suited for efficient energy return than any other set of muscles in the lower extremity (Bosch, 2005; Sawicki, 2009).  The Achilles tendon is capable of returning upwards of 35% of the stored elastic energy, making it the most efficient of all.  Shoe designers over the years have added an elevated heel to “protect” the Achilles from excessive strain, but maybe at the cost of effective use of the spring mechanism.  Additionally, the medial longitudinal arch has the capacity to return upwards 17% stored elastic energy, but a MFS or a FFS are far better at translating this energy into motion than a rearfoot strike.

To gain a full appreciation of the differences, we must first understand that the subtalar joint is capable of translating rotational forces that contribute to economical locomotion.  Pronation leads to a relative internal rotation at the tibia, which places a torsion on the elastic structures within the IT band, helping to load the hip during stance (Oatis, 2004).  In RFS patterns, athletes strike directly below the ankle and with uncertain levels of plantar flexion (with the collision taking up a great deal of translational energy), thus limiting the ability to convert translational energy into rotational energy.  In FFS and MFS patterned athletes, strike the ground forward of the ankle and often with the lateral aspect of the forefoot, and though stance progressive, controlled dorsiflexion and pronation results in greater torques converted into rotational energy (Lieberman, 2010).

Additionally, with pronation, the medial longitudinal arch “flattens” and stores elastic energy.  Rearfoot strikers are at a disadvantage in using this mechanism because the medial longitudinal arch is unable to “pre-load” until both rearfoot and forefoot are on the ground.  Barefoot athletes who are midfoot or forefoot strikers have the luxury of MLA loading during the entire first half of stance as well as in the latter half when the Windlass Mechanism reaches full levels of function.

Given that 70-80% of today’s distance runners heel strike as a potential result of shoes (Hasegawa, 2007), this may limit efficiency.  Additionally, today’s shod runners often run with orthoses and “arch supporting” shoes that limit the downward deflection of the MLA and ultimately lead to a less efficient mass-spring component of gait further (Robbins, 1987).

Of course, one must also consider the foot intrinsic musculature’s response to footwear.  Many suggest that, like during immobilization, atrophy of the small plantar muscles occur as a result of wearing “supportive” shoes, which in turn reduces efficiency further.  When these muscles do not function strongly or exhibit appropriate motor control, excessive pronation is often a result.  Interestingly, these muscles fight harder during pronation to protect the plantar fascia from excess strain, but it is a losing battle., which may lead to bigger problems down the line.  Of course, when the intrinsics are unable to convert the foot from a force absorber to a force transducer through stance, efficiency and power is lost so the body must look for other ways to gain speed.  The result is often “muscling” it from the anterior musculature of the hip, that is often overactive as is.

From an efficiency standpoint, barefoot running is probably far superior to shod.  That said, before you go and start running entirely barefoot, however, I’d suggest you pay close attention to the posts to follow that involve the Boddicker Performance assessment, warning signs, and progression advice to determine if you are prepared to run unshod.

Best regards,

Carson Boddicker

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Leave a Comment »7 Comments
  • Dave C. March 25, 2010

    Great synopsis and compilation of the relevant research on the topic. Being able to explain to people that there are performance benefits to barefoot running, not just an intangible spiritual experience, is a great way to increase utilization of it as a training tool.

  • Thomas Lee, M.D. March 26, 2010

    Great summary. As you’ve explained well, barefoot runners seem to rely more on eccentric contraction of running muscles as opposed to us plodders who rely mostly on concentric contractions. Eccentric contraction accounts for greater economy, greater force/power, but also greater lactic acid build up.

    Perhaps one reason elliptical machines are now so popular is because it is mostly concentric contractions which allows for safer motion with less lactic acid and an easier perception of exertion.

    Finally, recall that most ruptures occur during its eccentric phase. Achilles ruptures occur when the knee rides over the foot as it eccentrically contracts to check the forward progress of the tibia; not during push off as many athletes think. Quad and Ham ruptures occur during rapid decelerations. Sprinter injuries may be one of the few exceptions.

  • Carson Boddicker March 26, 2010

    Dave,

    I think you are right. I also think that with respect to barefoot training, there are considerations that should be made to ensure adequate preparedness before beginning barefoot running. Too often my athletes will tell me that they have decided to go minimal and start doing full volume in racing flats or barefooted.

    Right now we seem to be experiencing that common overreaction in the short term, but it is my goal to ensure that there is not an under-reaction in the long term. I hope by providing a better understanding of the tool we have at our disposal.

    Best regards,
    Carson Boddicker

  • Carson Boddicker March 26, 2010

    Dr. Lee,

    I appreciate your insight into the matter. I’ve recently learned of some of the things you’ve mentioned as I prepare my “Caveats of Minimalism” and “Transition to Minimalism” posts scheduled for next week.

    We definitely need to be sure that our athletes are capable of a number of things in barefoot or minimally shod conditions before we begin running in like conditions. One of those that we use is the ability to eccentrically lower a load of well over body weight in both straight and bent knee positions to ensure adequate tensile strength and resiliency of the tendons.

    Have you noticed any repercussions in your practice in barefoot running? Good, bad, or ugly?

    Best regards,
    Carson Boddicker

  • Thomas Lee, M.D. March 30, 2010

    You’ve started a lot of activity on twitter with this great blog. But notice how some of these great assumptions can be misconstrued by some researchers. http://bit.ly/bU8EDb.

    Here the researchers use some of the barefoot assumptions and apply them to arthritic patients and conclude that its better for their knees. Its true because of the greater preactiviation of their gastrocs, hams, and quads as they walk in flip flops but it neglects to note if these older arthritic patients can tolerate this type of continuous activation. In addition, it neglects the consequence of increased ground reaction forces to the foot and ankle.

    But good athletes or a member of the Tarahumara may be able to sustain these forces and perform well. I wonder how many of us weekend warriors will easily sustain this constant eccentric loads.

    If it catches on, I would anticipate a higher rate of Achilles injury, prepatellar bursitis and possibly more ITB.

    But here’s a more interesting thought: would stretching help or hurt these phenomena? Not a simple answer.

  • Alex December 18, 2010

    Excellent article thank you. My progression to barefoot is just started and involves a treadmill. Softer landings, shorter stride, etc.

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