Comfort. Pronation of the foot is an issue many runners suffer
from: it is when the foot angle's inwards, and as the heel hits
the ground it causes the arch of the foot to stretch and flatten.
This can result in a number of lower leg tendinitis issues. Alongside
pronation, runners can generate an impact equal to three to four
times their body weight when the foot/heel hits the ground. Gel
cushioning aims to combat these issues. Placed in the midsole -
which is between the outsole and the upper - gel cushioning helps
support the arch so that it does not collapse and provides impact
protection for the heel.
Gel cushioning was an innovation developed in the 1980's. Asics
were one of the first brands to develop a gel cushioning system
- with the intention of providing absorption of vertical impact.
Since then; Adidas, Nike, and Mizuno; are three other notable companies
who have released running shoes with some form of gel cushioning.