If you're having problems with your knees and back then it's natural to look for the solution somewhere on your bike - but the source of the problem may be elsewhere. Some knee and back problems in cycling can be solved by looking at and correcting running or walking action.

Human bodies have taken millions of years adapting to walking and running. Cycling has only been around for a tiny fraction of that time. This means that there has been no human evolution to bike riding. It is therefore all down to how each individual adapts to riding a bike. Unfortunately there is little we can do about the basic structure of our bodies, what muscles and ligaments attach where, and how the bones and joints are structured. They are all designed for walking and running, not cycling.

We pedal at between 80 and 100 rpm most of the time. This means that in an hour of riding our legs go up and down 5000 times. That can be 5000 times correctly and giving only beneficial effects, or 5000 times wrongly and causing repetitive damage and pain.

In 1988 I (Bob Hayward) was asked to coach a team to take part in the Challengers' Trophy which was over five days and included various activities but mostly running. Whilst riding behind them on a bike during their running training I noticed that 3 out of 5 had a foot- strike problem. This means that as the foot hits the ground it either twists or rocks over to one side more than normal. We were easily able to find an athletic shoe shop in Belgium which could measure the effects and provide the correct shoes and inserts.

In the early 90s there was a promising bike rider who had a history of knee problems. We tried all the usual things like saddle position, cleat alignment, checking for bent pedal spindles and cranks, and videoing pedal action.

We were getting short of ideas when it dawned that the 1988 experience might be relevant. Jo Tym our physio on the team found a local podiatrist (or specialist in foot-strike) Debbie Kaye. We set off with turbo and bike to see what Debbie could do.

Debbie asked our rider to run on a treadmill and took a video from all directions. Then the rider did the same on the bike and it became clear that the rider's problem was in the way he walked and ran which was carried through to his pedalling on the bike. It could not be adjusted by anything on the bike. He was provided with the correct inserts to his shoes to correct his walking and running and he used the identical inserts in his cycling shoes.

After six weeks of gentle riding he resumed normal intensity training and racing and found the knee problem had completely disappeared. It reappeared 18 months later when the inserts seemed worn out and he threw them away. We must not be too critical - we all think we are invincible and believe in magic when we get on the bike.

Since that time Jo and I have both been alert to the effects of walking and running foot-strike on cycling performance. We work together, combining our different mechanical and physio perspectives whenever either of us notices problems. In addition to being a practising physiotherapist Jo is also an ABCC coach.

As with all things which are merely down to quietly thinking through the logic, many people will have independently come to the same conclusions. There is now a USA company which sells plastic angle wedges to fit under the different makes of cleat.

So why should how we run and walk affect our foot position on the pedals? Legs, knees and feet are designed to move up and down and rotate but not move sideways (see figure 1). Any sideways forces at the knee can cause internal rubbing to either side of the knee. The kneecap runs up and down in a groove. If it is forced to one side of the groove it will also cause problems.

A small abnormal rocking or twisting movement at the foot is amplified into a bigger sideways and rotating movement at the knee. That movement can sometimes be escalated to a sideways tilting movement at the pelvis causing the back to sway from side to side which can show up as lower back pain from a variety of sources.

As a foot touches the ground (footstrike) in walking or running it twists and rocks and is often able to compensate for minor misalignments such that there is no appreciable sideways force at the knee or above.

The original pedal clips and straps allowed almost complete freedom for the foot to rock and twist. The addition of shoe plates to clips and straps still allowed a small amount of twist but retained complete freedom to rock.

The first clipless pedals allowed no twist or rock, so knee problems became more frequent even if the alignment was set similarly to the old shoe plate. When a foot is attached to a modern pedal it still cannot rock even though some pedals do allow a small amount of twist. Modern pedals are still less forgiving than clips, straps, and plates.

This means that if you have gone through all the usual checks on leg length, cleat alignment, saddle position, bent pedal spindles or cranks, and are still in trouble, then there is always footstrike to consider. Since a foot cannot rock on a modern pedal, then any walking or running anomaly needs to be corrected by inserts in the shoes which compensate for that anomaly. If the inserts are correctly positioned then the foot will not need to rock from side to side and problems at the knee and above are less likely to arise. Angled packing under the cleat will have a similar effect but is no substitute for having a footstrike specialist providing accurate inserts.