Earlier this week one of my master instructors shared an interesting article with me on the relationship between foot strength and stiffness in those who chronically wear minimal footwear.
For those who study barefoot movement and integrated foot mechanics, the association between minimal shoes and stronger feet may seem like an obvious finding but I wanted to delve into this article a little bit more for those readers who may not be as adept to some of the terminology.
Foot strength and stiffness are related to footwear use in a comparison of minimally- vs. conventionally-shod populations – February 2018
Concept #1 – Foot Stiffness is a Positive Characteristic
I want to start off by explaining that anytime you read about foot stiffness or leg stiffness in relation to barefoot running or minimal footwear – this is a GOOD thing! The term stiffness does not mean rigid or non-flexible and is not synonymous with how we may say “I woke up stiff this morning”
During dynamic movement, the concept of stiffness is actually a fascial response that is used to help efficiently load and unload impact forces. Think off stiffness as transient rigidity as a means to increase stability. This stability is achieved through integrated isometric contractions which influence the surrounding fascial tissue and muscle compartment pressures.
In the above-referenced article, Holowka et al. found that those that chronically wear minimal footwear have higher arch stiffness upon foot contact. This can be interpreted to mean that in minimal footwear the intrinsic foot muscles are more responsive and adapted to help stabilize the foot and absorb impact forces.
This finding further demonstrates that traditional footwear can actually make our feet weaker and less responsive to impact forces, quite possibly to the point that eventually we become dependent on the footwear to absorb impact forces.
Concept #2 – Minimal Footwear Increases Intrinsic Muscle Size
Repeated use of any muscle will result in hypertrophy of that muscle, this includes the intrinsic muscles of the feet. If the chronic use of minimal footwear is associated with increased foot stiffness this means that those feet are engaging and strengthening their intrinsic foot muscles with every step they take.
In the above study, Holowka et al. demonstrated that in those that chronically wear minimal footwear there was a noted 2mm increase in abductor hallucis diameter. Now, 2mm may not seem like a lot but when you are dealing with small muscles of the feet, 2mm is considering statistically significant.
If you are unfamiliar with the abductor hallucis muscle, this is the intrinsic foot muscle that is responsible for controlling the lateral longitudinal arch. Originating on the plantar medial calcaneus and inserting on the medial aspect of the proximal phalynx of the hallux, the abductor hallucis runs under and supports the navicular bone.
In the picture to the right, you can appreciate that the navicular bone is the highest point of the medial longitudinal arch. By strengthening the abductor hallucis and controlling how much that bone drops during dynamic movement is essentially saying there is control of the medial arch.
Chronic use of minimal footwear and the strengthening of the abductor hallucis muscle is demonstrated to be an effective way to build foot control and resist the stress of flat feet and over pronation.
Concept #3 – There Are Exceptions to Every Finding
As a Functional Podiatrist, I must end by saying that the findings of the Holowka et al. study are very exciting and definitely do build the support for the use of minimal footwear. Having said that, there are exceptions to every finding.
As we take these findings and use them to make footwear recommendations for our clients and patients we cannot forget that there are still a few patients who minimal footwear may not be appropriate for.
Some of these may include:
– Accessory navicular
– Posterior tibial tendinitis or PTTD or post tib tear
– Hypermobility of the 1st Ray
– Flexible flatfoot with symptomatic post tib tenditis, plantar fasciitis, sinus tarsi syndrome
– Rigid flat foot with arthritic changes to the midfoot or rearfoot
All feet should be assessed by a qualified professional before transitioning to minimal footwear and all transitions to minimal footwear should be coupled with a barefoot foot-strengthening program, such as that created by EBFA and our Barefoot Training Specialist® Team
Dr Emily Splichal
Founder EBFA Global & Naboso Technology