Running cadence or how many steps per minute (spm) you take is a hot topic in medical research at the moment - often looking at gait changes as rehab for specific injuries. The running form improvements that running at a higher cadence encourages are just as important, or even more important, in avoiding injury in the first place though. Retrospective research looking at injury prevention however, is strewn with issues, so most of the work taking place looks at changes post injury. Obviously as athletes we would rather avoid the injury in the first place though if possible!
So what should we be aiming for? You will often hear people say that 180spm or above is the ideal cadence, but we are talking about a highly individual thing here with a whole range of contributing biomechanical and environmental factors, so no number will ever fit everyone.
An interesting study on how changing cadence affects uninjured runners was carried out by Bryan Heiderscheit and his team in 2011. They looked at both increasing and decreasing cadence and found that a cadence increase of 5% decreased energy absorption at the knee and that a 10% increase decreased energy absorption at the hip and knee.
Looking at the data in this study, the mean baseline cadence was 172spm. Compared to most recreational and club runners that I see in clinic this is quite a high start point - so I would assume the sample was made up of experienced, decent level runners. This could mean that increasing the cadence of an average recreational runner may have an even larger effect.
Many of the benefits found from running at a higher cadence come from preventing over-striding - you simply don't have time to reach too far in front of yourself with each step. This results in landing with a softer knee, allowing you to absorb shock more efficiently, amongst other things.
If you are a health professional wanting to learn more about gait retraining then check out Kinetic Revolution, who run a fantastic weekend course on the subject.
Pt. 2 will cover how to practically and sustainably increase your cadence and integrate it into your running.