INTRODUCTORY NOTE

For newcomers to these Puzzles & Paradoxes (P&Ps), these P&Ps are 
Propositions, not facts or dogmatic proclamations. They are intended to 
stimulate interaction among users working in different fields, to re-examine 
traditional concepts, foster distance education, question our beliefs and 
suggest new lines of research or approaches to training.  We look forward 
to responses from anyone who has views or relevant information  on the 
topics.
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PUZZLE & PARADOX 114

The concepts of pronation and supination used to understand and manage 
problems with the lower extremities may sometimes be misleading and 
relatively unhelpful.

INTRODUCTION

Athletic footwear, injuries to the foot and overpronation (or sometimes, 
oversupination) are very frequently mentioned in the same breath in the world 
of athletic efficiency and injury.  The definitions of pronation and supination 
would appear to be accurate and universally accepted, with 'pronation' of the 
foot being used to describe the inward or medial rolling of the sole of the foot 
and supination referring to outward rolling, all relative to a neutral standing 
position.

The term 'overpronation' is taken to mean an excessive rolling inwards of the 
foot, caused either by faulty gait or stance, or inappropriate footwear, relative 
to the neutral position for a given individual.  Similarly, the term 
'oversupination' refers to excessive outward rolling. On this basis, an entire 
philosophy of sports medical care of the lower extremity and design of athletic 
shoes has sprung up.   

In the latter case, a multi-billion dollar industry has been erected on the 
foundation of a given concept of pronation/supination and shows no signs of 
abating, even though respected footwear engineers admit that the best that they 
can hope to achieve is to design a shoe which equals the capabilities of the 
unshod foot.  Nevertheless, it would appear that few coaches, scientists and 
athletes even question if these concepts of abnormality of foot action are as 
helpful and as accurate as seems to be suggested by advertisements and sports 
scientists at many conferences.

SOME COMPLICATIONS

Possibly the simplistic definitions given above are quite acceptable, but one 
still has to ask a simple question:  "Is pronation of the foot affected by the 
degree of 'toe-in' or 'toe-out' during the phase of foot contact with the ground?"   
In other words, does pronation (or overpronation) with the foot inwardly or 
medially rotated produce the same effects on the body as pronation with the 
foot outwardly or laterally rotated - or straight-ahead, for that matter?   Is 
pronation (or overpronation) equally stressful to all components of the 
musculoskeletal system irrespective of the orientation of the foot?    What is 
the effect of a high or low arch (pes cavus vs pes planus) on the nature of 
pronation?

If we probe a little more deeply  and ask if every individual produces a given 
degree of pronation with exactly the same mechanisms and tissues, then we 
have to wonder if overpronation in one person implicates greater stretching or 
range of movement of passive tissues (such as ligaments and capsule) than in 
another, whose degree of pronation is associated more with greater range of 
activity of the active muscle tissues.  Possibly, the degree and pattern of 
muscle contraction during gait is so significantly different in everyone that 
what may be regarded as overpronation in one may be within the normal range 
for another.

Possibly the alleged dangers of exaggerated pronation or supination lies not so 
much in the degree of medial or lateral rolling, but more in the rate of force 
development, the duration of the apparently hazardous contact phase and the 
rapidity of reflex processes to correct inappropriate patterns of muscle and 
joint action.

What also of the relative degree of flexion of the ankle, knee and hip joints 
during all stages of the contact phase?  Is overpronation just as stressful or 
problematic if one runs with the knees flexed more or less on average?  What 
is the effect of overpronation on patterns of pressure distribution beneath the 
foot during long striding vs fast striding running action?

Do all of these questions simply add unnecessary complications which have 
minimal bearing on the effects of pronation/supination on the lower extremities 
during running? 

PROBLEMS OF DEFINITION 

The issue does not end here.  Thus far we have been contented to analyse 
running problems of  the lower limb on the basis of pure pronation or 
supination, independent of other concurrent joint actions such as inversion, 
eversion, medial/lateral rotation, flexion/extension and so on, something that 
was hinted at in earlier questions.

In mentioning inversion and eversion, we immediately run into controversial 
territory, since some authorities use inversion as a synonym for supination and 
eversion as a synonym for pronation.  Others prefer to define inversion as a 
complex inward-turning action of the foot involving supination, medial 
rotation and plantarflexion (and varus), and eversion as a complex outward-
turning action of the foot involving pronation, lateral rotation and dorsiflexion 
(and valgus).  

CONCLUDING ISSUES

Thus, it would appear to be more logical to abandon the concept of 
overpronation or oversupination as the primary causes of injuries to the lower 
extremities and replace this with an emphasis on exaggerated eversion or 
inversion (according to the complex definition in each case).

Discuss the issues raised, using appropriate references or your personal views 
to resolve any apparent paradoxes or inaccuracies.

A practical task to close this P&P: As a simple experiment to assess how much 
pure pronation or supination of the foot is possible in the absence of concurrent 
action of other joints, try to actively pronate or supinate the foot without 
moving your knee or hip joints.  The marked difference between the degree of 
supination and pronation shows why ankle sprains occur most commonly in a 
given direction and why pure pronation cannot account for so-called 
'pronation' injuries. Your experience should guide you in responding to some 
of the above questions.  Other useful information may be gleaned from the 
book: Nigg B (ed) book 'The Biomechanics of Running Shoes'.
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Dr Mel C Siff
School of Mechanical Engineering
University of the Witwatersrand
WITS 2050    South Africa
[log in to unmask]


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