Last month, I attended the Pedorthic Footcare Association (PFA) annual symposium. This event is a great opportunity for me to continue to expand my knowledge and skills as well as connect with my fellow pedorthists across the country. The three-day symposium covered topics including footwear science, shoe modifications, pedorthics and podiatry, kinesiology taping, and a number of reports and functional outcomes from a variety of studies that have been conducted. In a series of articles over the next few months, I’ll share my notes from many of these topics, but in this article, I will grossly oversimplify three of the more interesting research projects and their results.
Comprehensive Biomechanical Characterization of Feet in USMA Cadets: A Comparison Across Race, Gender, Arch Flexibility and Foot Types. Jinsup Song, DPM, PhD
Dr. Song (Temple University, Gait Study Center) and his team studied United States Marine Academy recruits to try to understand rates of injury correlated with their biomechanics. To set the stage, 15% of 1.45 million soldiers experience foot/ankle injuries. 11% of all discharges from the military branches were associated with lower limb pain and “flat foot.”
The study focused on 1052 cadets at the beginning of their basic training at West Point. The research team measured the cadets arch height in both sitting and standing by gender and race. The breakdown of arch heights, irrespective of gender and race, in the cadets was:
- 7% had a very high, rigid arch with a supinated gait
- 20% had a normal arch and gait
- 73% had a lower arch with over-pronation
Regardless of arch height, 39.6% of these cadets experienced injury during their basic training. 82% of those injuries were in the foot / ankle. From a gender perspective, 33% of the injured were male and 55% were female. Women experienced nearly twice the injuries as men regardless of the arch height and Caucasians had slightly more than 2.45 times relative risk than African Americans, Hispanic, or Asian.
In a related study of 900 cadets, 5.7% of males and 19.1% of females experienced at least one stress fracture in the first 3 months of training.
There is still much to be learned, but the initial findings indicated that for these cadets, selection of running shoe and insole had virtually no impact of the rates of injury / non-injury. So, what is the root cause of injuries? Apparently, it still isn’t known but this study suggests that more than arch height and foot type is a factor.
One Foot in Front of the Other – Contributions from Foot Sole Cutaneous Mechanoreceptors, Leah Bent, RT, OTRL
This was a fascinating study focusing on the mechanoreceptors in the skin on the bottom of the foot. There are four major mechanoreceptors – vibration, skin tension, pressure and stretch. Some of these are nerve sensors while others are the more superficial skin sensors. The density of mechanoreceptors or “sensors” in the bottom of the foot are found at the toes and the lateral aspect or outside of the sole. The skin is most tactile under the medial arch, the lateral arch, the 5th metarsal (little toe), big toe and heel in that order and touch sensitivity correlates with the hardness and thickness of the skin.
Ms. Bent’s team found that activating the foot skin receptors fires both lower limb AND upper limp muscles. Meaning that they were able to stimulate different regions on the bottom of the foot and see different muscles in the leg and arm respond. The implication is that the development and wearing of textured custom orthotics, OTC insoles, and socks could have an impact on balance and gait and that there are implications for individuals undergoing rehabilitation from injuries.
Introduction to Kinesiology Taping and Pedorthic Implications, Jennifer Howey, PT, CAFCI
Kinesiology tape has proven benefits for reducing joint pain, improving muscle function and decreasing swelling. Dr. Virgin Gibney originated many of today’s taping techniques back in 1895 with his first technique focusing on taping for the sprained ankle.
Proprioception is the ability to sense stimuli arising within the body regarding position, motion, and equilibrium. Even if a person is blindfolded, he or she knows through proprioception if an arm is above the head or hanging by the side of the body.
Proprioception decreased 107% with shoes and 140% with shoes and inserts. However, kinesiology taping plus footwear only decreased proprioceptive by 58%. This is because kinesiology or neuro-proprieceptive taping is not mechanical, but rather based on skin and feedback.
So what does taping do?
- Controls muscular function by facilitating contraction of the muscle and inhibiting hypertonicity (abnormally high tension)
- Improves proprioception
- Improves local metabolism thru tissue correction
- Decreases pain by interfering with nerve inputs
- Provides joint support by improving normal joint surface position