I would like to say that 1 out of 10 people have this issue but it’s more like 3 out of 5. It can be the source of back and neck pain and the source of inefficient cycling or running. The skeleton has to work against gravity 24 hrs a day and this applies whether you are sitting on a bike, standing or running. Our pilot research has shown that correcting for the differences (eg. small pad on one side of your bike seat, or dense foam inner sole in a shoe) can decrease the energy you use at various intensities by 3-9%. The difference between first and second in an Olympic event is 0.4%.
Brendan Roach MSc, Exercise Physiologist