Running Patterns Change as Shoes Wear Out
Researchers at University of Texas and Nanyang Technological University investigated the biomechanical effects of running using new versus worn out shoes, as well as comparing three types of cushioning footwear – air, gel and spring.
Dr. Kong and his team studied 24 runners (14 men and 10 women) who were asked to run 200 miles in the same pair of shoes with assigned cushion consisted either of air, gel or spring. They were tested on a 20m laboratory runway, running at 4.5ms-1 (16.2 kph or approximately 3.7 minute kilometre pace) using a force platform and a motion capture system
Pre and post reading of the stance time by using force data, external loads by maximum vertical force and loading rate and kinematic changes on angles of the torso, hip, knee and ankle were calculated during the run.
The results showed that for worn-shoes there was an increase in stance time. Additionally, there were also decreased torso leaning forward (running more upright) and less forward lean during toe- off, decreased maximum ankle dorsiflexion and increased in ankle plantarflexion during toe-off.
But there was no change in knee and hip angles found in all three types of cushioning footwear or either between new or worn shoes.
The researchers suggested that runners modify their running pattern to adapt to the condition of the shoes (decrease in cushioning during wearing out process) to maintain constant external loads. The adaptation changes among different types of shoes cushioning in running were similar. Therefore, types of shoes cushioning should not be the main factor to consider when choosing a pair of running shoes.
Running in new and worn shoes: a comparison of three types of cushioning footwear, P W Kong, N G Candelaria, D R Smith, British Journal of Sports Medicine 2009;43:745-749