Foot Alignment: Research and Observations

A good performance plan starts with a good assessment.  One area that is often missed or misunderstood is the assessment of the foot and ankle.  The foot should be assessed while both weight bearing and non weight bearing.  The previous blog post “Different Perspectives on Foot Posture” outlines the standing foot posture of everted rearfoot, and its correlation with a non weight bearing inverted forefoot alignment.  Research indicates that a significantly inverted forefoot alignment has correlation with decreased postural stability.1

From a purely mechanical standpoint, it makes sense that a non weight bearing inverted forefoot alignment would have a correlation with an everted rearfoot that when weight bearing.  Research suggests that the inverted forefoot alignment is often an acquired soft tissue adaptation that develops because of subtalar joint pronation.2  In other words, it is the everted rearfoot posture while standing, walking, and moving that initially causes the forefoot to become inverted, and the soft tissue to adapt into that alignment.  Once the forefoot is inverted in a non weight bearing alignment, the sub talar pronated position and everted rearfoot during stance becomes more persistent.

As a former athlete and someone interested in movement, when a physical therapist gave me an assessment and told me that my non weight bearing forefoot alignment was over 10 degrees inverted, I thought that if I reduced this misalignment, I would be able to reduce my knee pain that I was having, especially while doing single leg exercises.  I used basic exercises to improve my foot posture and alignment: soft tissue work, range of motion of the ankle and forefoot, and foot and ankle stability exercises.  I had a significant reduction in my knee pain, and also significantly reduced the strains in my hip flexors, adductors, hamstrings, and quads.  It is important to note that I was also continuing to work on my hips and core, and continued to use the physical therapy exercises that I was given by my PT to recover from a knee scope.

A year after learning and researching different foot alignments, I began working as a football coach, track coach, personal trainer, and strength coach for high school teams.  My mentor was a strength coach who worked with D1 and D2 college programs.  I also was discussing foot alignment with a couple of physical therapists, and discussing the techniques for completing the assessing and how to accurately take the measurements.  On occasion, my strength coach mentor would ask for a foot alignment for one of his athletes or personal training clients.  I remember one specific assessment where the individual had a highly everted rearfoot standing posture, and the correlated non weight bearing inverted forefoot alignment.  However, his feet were very rigid and his kinesthetic sense for his feet was low.  I began to think that the potential performance plans may differ depend on the individual: what worked for me may not work for everyone: different factors such as the alignment, mobility level, age, training experience, injury history, and performance goals should be taken into consideration.  There are also times when working with a mentor or referring to a clinician may be the best option for the individual.

Initial Research

Because I had success with improving foot alignment and function, I wanted to do some of my own research to see what percent of the population had a similar foot type.  I measured the standing rearfoot posture and non weight bearing forefoot alignment of over 50 college athletes and over 50 high school athletes.  Because I was coaching track for the high school athletes and I was able to observe their athletic ability in practice and competitions, I was able to make some interesting observations.  I was initially surprised that two of the fastest individuals had high degrees of inverted forefoot alignment.  Both had a high level of success that year, but one of the individuals had minor muscle strains later in the season.  This made me think that in some cases, forefoot misalignment could be a contributing factor to injury risk, but that it was not necessarily a limiting factor to athleticism or athletic achievements.  This assessment is not meant to be a prediction tool: some individuals with a misalignment may have good durability and good overall movement.

In addition to gaining valuable information about foot types, the assessments were also useful as a coach.  There was one notable conversation between me and the head coach where the coach asked about a particular athlete’s alignment.  I noted that there was a significantly high level of misalignment in both left and right forefoot.  This individual rarely participated in practice due to shin splints.  The coach said this alignment information was helpful because she had previously wondered why the individual was so limited in practice.  The coach, who had a neutral standing rearfoot posture and non weight bearing alignment, had not experienced those types of injuries and limitations in practice as a college track and field athlete. 

Second Round of Research

A few years after measuring 100 athletes, I was invited back to the college by the head strength coach and asked to provide measurements and to also collect injury history.  The purpose of this data collection was to help the strength staff determine if they should provide extra attention and time for individuals who had high degrees of misalignment and therefore potentially lower levels of stability.  The athletes filled out an injury history survey, which I did not see until the data entry stage.  I took measurements and observations of:

1.      Standing rearfoot posture

2.      Non weight bearing rearfoot alignment (sub talar neutral)

3.      Non weight bearing forefoot alignment (sub talar neutral)

4.      Forefoot mobility (to determine whether the misalignment was rigid or mobile)

In this recent research, there were 146 athletes: 86 male and 60 female from various Division 1 sport teams. 

Rearfoot Posture: Measured in Static Standing (Weight Bearing)

Forefoot Alignment: Measured in Sub Talar Neutral (Non Weight Bearing)

60 Female Athletes: Rearfoot Posture (WB) and Forefoot Alignment (NWB) Correlation

86 Male Athletes: Rearfoot Posture (WB) and Forefoot Alignment (NWB) Correlation

Foot Type and Injury History Correlations

I reviewed the alignment categories (standing posture, non weight bearing rearfoot alignment, non weight bearing forefoot alignment) in relation to the reported survey data of foot, Achilles, ankle, knee, muscle (hamstrings, quads, adductors, and hip flexors), and lower back. 

The notable correlations included:

·         Foot pain: The non weight bearing inverted rearfoot had a significantly higher percentage (45% reported) compared to inverted (17%) and neutral (26%) rearfoot alignments.

·         Ankle sprains: Low ankle sprains (rolling to the outside) are more common: the rearfoot being inverted appears to be a risk factor, both in weight bearing standing posture, and non weight bearing rearfoot alignment.

·         Knee pain: The standing posture and non weight bearing rearfoot categories did not have any significant correlations.  However, the non weight bearing forefoot appeared to have a correlation: 67% from the significantly inverted forefoot nwb, compared to the next two highest categories at 44%).  However, this was a small sample size, as only 6 individuals measured 10+ degrees of inverted forefoot non weight bearing

·         Muscle strains: the non weight bearing forefoot alignment had the highest correlation: the most everted and most inverted forefoot alignment groups had the highest correlation with muscle strains (although both were small sample sizes in those categories).

·         Back pain seemed to be spread relatively evenly across different foot posture and alignment categories.

 Observations

In addition to taking measurements and looking at the data, a few observations were made as well.

·         Individuals with moderate standing everted rearfoot posture often had a neutral rearfoot (non weight bearing) and a correlation with an inverted forefoot (as documented in previous research).  The foot appeared to change shape once it became non weight bearing.

·         However, in many individuals with significantly everted rearfoot standing posture (over 10 degrees) the rearfoot initially remained everted non weight bearing.  In some of these cases, finding sub talar neutral was more challenging: when the foot was off the ground, it did not change shape, it appeared to be stuck in the same position as when it was on the ground

·         There were different mobility levels within each foot type.  In the significantly everted rearfoot posture (weight bearing) and inverted forefoot alignment group, some of these individuals had highly mobile feet, while others had the most rigid feet of anyone in the assessment.  To me, this dispelled the myth that over pronation is a result of weak feet

·         I did not specifically measure Navicular height; however, an observation was made of one of the highest performers: this individual had a low arch, but neutral standing rearfoot posture and non weight bearing forefoot alignment.  To me, this dispelled another myth that “flat feet are the result of over pronation”: while the standing everted rearfoot posture does result in a lower arch; not all individuals with a lower arch had standing everted rearfoot posture.  In other words, excessive pronation does lead to a lower arch, but a lower arch does not always correlate with over excessive pronation.

·         Certain teams had interesting observations: many of the soccer players had a tight ankle on their kicking side: this was unintentionally discovered because it was more challenging to put their relaxed foot into sub talar neutral during the non weight bearing assessment.  This supports the theory that movement history can contribute to different compensations at the foot and ankle.

In my opinion, this assessment is valuable as a starting point to understand the individual’s foot alignment and possible risk factors.  In addition, the process of this assessment also provides data about if the athlete is hyper mobile or is very rigid in their foot and ankle.  The next post in this series will review the movement patterns of the foot and ankle. By understanding the movement of the foot, we can get closer to creating performance plans to improve overall foot function.

References

1.       Cobb SC, Tis LL, Johnson BD, Higbie EJ. The Effect of Forefoot Varus on Postural Stability. Journal of Orthopaedic & Sports Physical Therapy. 2004;34(2):79-85. doi:https://doi.org/10.2519/jospt.2004.34.2.79

2.       Evans EL, Catanzariti AR. Forefoot Supinatus. Clinics in Podiatric Medicine and Surgery. 2014;31(3):405-413. doi:https://doi.org/10.1016/j.cpm.2014.03.009