By Mark Charrette DC
Excessive foot pronation, whether in one foot or bilaterally, interferes with the carefully coordinated movements during gait and causes problems throughout the musculoskeletal system. The effects of excessive pronation on the function of the spine are of particular interest to doctors of chiropractic.
With many interconnected joints, lots of connective and articular tissues, and both intrinsic and extrinsic muscles, the lower extremities are very well-supplied with proprioceptive nerve endings. Mechanoreceptors in the feet and ankle joints, along with the muscle spindles of the foot and lower leg muscles, are responsible for the positive support reflexes and a variety of automatic reflexive reactions.
The position receptors in the lower extremities, pelvis and spine (and especially the neck/head-righting reflexes) must coordinate smoothly in order to maintain postural equilibrium. Difficulty in achieving or keeping optimal postural alignment, or problems with excessive postural sway, are frequently caused by inaccurate information sent by spindle sensors in chronically strained muscles or aberrant joint mechanoreceptors in the feet.
In addition, much of the neurological coordination of the body is based on a balanced, rhythmic lower extremity movement and gait. The “cross crawl” pattern organizes many fundamental musculoskeletal functions at the spinal cord level, permitting smooth performance of daily physical activities without the need for conscious thinking about posture or planning out movements. This includes factors such as balance, stability, and centre of gravity.
When one or both feet spend too much time in pronation, many muscles throughout the body (and around the spine) don’t turn on and shut off in proper sequence. This affects posture, raises the work effort for all activities, and even increases the amount of oxygen consumed during normal walking.