From Runner’s World, 2014 November Issue, PP42-43
 
Dictated by Bob Chen
Written by Wang Xiu Juan
 
Do you understanding your own running?
 
Everyone lands on his feet differently, and there are usually three kinds: overpronation, underpronation, and arch (including longitudinal arch and transverse arch collapse).  These can usually be determined by mechanical analysis of foot and ankle, distribution of plantar pressure, and changes during running.  This professional data needs professional people to obtain it through scientific analysis in a laboratory.  In order to seek a remedy, right now, the most direct checking method is to look at the degree of wear and tear on the bottom of the shoes, which can be used as one of the references to determine the running postures and technical characteristics of the runner. 
 
The normal sole wear and tear
 


Landing characteristics:  for normal runners, when they land, the lateral heels of the shoes land first.  The moment the foot touches the ground, the ankle turns slightly inward, but after landing, with the heel in contact with the ground, the ankle soon turns outward, and the foot lands gradually from heel to toe.  From the observation of foot wear, between the forefoot and the toe joints, especially near the second and third metacarpal bone joints, there is a large area of wear and tear beneath it.  The faster runners even leave shoe tip wear due to the force of the big toe (illustration: the shaded area is the friction area; this is true in the illustrations to follow as well). 
 
Risk:  this normal sole wear shows that during the process of the runner’s landing and taking off, his overpronation and underpronation are just right, and the pressure distributes evenly. 
 
Excessive underpronation
 



Characteristics of landing and sole wear: compared with normal runners, this type of runner, when landing, tends to turn the heels outward, and at the moment of landing, the angle of overpronation is even greater, but after landing, the foot quickly turns to underpronation pressing from outside to inside. 
 
Risk: during the process of overpronation to underpronation, the arch collapses too much, and the body weight rests on the inside of the foot, which can easily lead to foot pain. When the foot is in a condition of underpronation, excessive underpronation of the subtalar joint causes the ankle joint to twist inward, which can easily lead to excessive twisting of the knee, resulting in discomfort of the knee.  Excessive underpronation of the ankle during running is also the greatest cause for knee and back pain. 
 
Affected runners: people who have arch collapse, lack of muscle strength in the foot, and have poor stability in their joints. 
 
Excessive overpronation
 


Characteristics of landing and sole wear: this is seen commonly in high-arched runners because the backside of their heel lands first, with the outside of the heel gradually touching the ground.  When both feet land and take off, they pace on the outer edge, so the feet maintain the relative position of overpronation throughout. 
 
Risk: it easily causes fatigue fractures in the 4th and 5th metatarsals on the outer sides of feet. 
 
Affected runners: those who have high-arch feet or whose ankle joints are relatively hard and stiff.
 
Sesamoiditis
 


Characteristics of landing and sole wear: for these runners, when the feet thrust against the ground, much of the pressure is focused on the first metacarpophalangeal joint, and the heels land normally. 
 
Risk: those with differing size and thickness of bones in their feet, where the first metatarsal and metacarpal bones are thicker than the other four.  Because these runners’ forefeet receive uneven force, this causes strain, which easily leads to sesamoiditis. 
 
Affected runners: sesamoiditis occurs among people whose first metacarpophalangeal joints are relatively large, or those who have protruding sesamoids.
 
Anterior arch collapse
 


Characteristics of landing and sole wear: the anterior arch is also known as the transverse arch, and it is formed mainly from the first to the fifth metacarpophalangeal joints.  The transverse arch and longitudinal arch form the major point of force during landing, and eventually they form a solid triangular pressure point.  During the process of running, due to the weight and impact, the feet become deformed under pressure; the transverse and longitudinal arches are deformed accordingly, which increases the pressure on the bottom of the feet.  Sole wear and tear is concentrated in the central part of the forefoot, and its wear and tear area is smaller than in those who have normal arches. 
 
Risk: it generates pain in the front part of the soles, which makes people hesitate to step on the ground forcefully.
 
Affected runners: people who suffer from transverse arch collapse, where the pressure point is concentrated in the middle area (the second and third metacarpal joints).