Research carried out by Clifton Bradeley at the Sub-4 Human Performance lab has revealed that human asymmetry is responsible for the largest majority of repetitive injuries in runners and in many other sports.Research carried out by Clifton Bradeley at the Sub-4 Human Performance lab has revealed that human asymmetry is responsible for the largest majority of repetitive injuries in runners and in many other sports.
95% of the world’s population has a leg length inequality (one leg longer than the other) and the body deals with this in very specific ways. Humans became bipedal (walking on two legs) approximately seven and a half million years ago and for much of this time we were hunter-gatherers, who walked on natural uneven surfaces like grass, sand, forest floors and well compacted trails. In more recent times modern man has put concrete and other hard surfaces in much of our environment. Concrete has 100% energy return, which can send a shock wave back up through the feet, legs and into the lower back increasing the risk of injury. Running with a leg length inequality on concrete can increase the risk of sports injuries. However good quality running shoes help reduce this risk by absorbing shock.
Your posture can deal with the leg length inequality by compensating in the feet, legs, pelvis and upper body. The human centre of gravity is high and so to stabilise the upper body and head to maintain the eyes and a horizontal plane, the pelvis creates torsion (one side of the pelvis rotates differently to the other side) and the legs flex (bend) at the ankle joint, knee and hip joint differently to one another. By using the legs as a series of levers and allowing the pelvis to compensate for asymmetry in the body allows humans to move around their environment effectively, but can increase the risk of injury too, especially if the compensation mechanisms are too great.
If you notice any of the following signs you may wish to consult a podiatrist for a biomechanical assessment and gait analysis to check you out for a leg length inequality or other functional weakness:
• One shoe wearing more than the other.
• Recurrent, foot, knee, hip or lower back pain when you run.
• A sense of asymmetry in your posture.
• A sense of drifting to one side when you run.
• Swing one leg outwards when you run.
• Recurrent injuries on one side of your body.
• Lower back pain during activity, especially when flexing forwards.
