Cycling and the Foot

The activity of bike riding has been present for centuries, a skill once taught and never forgotten. With all activities, there is the prospect of being able to complete said task; and then there is being able to do it well. As mentioned in the previous blog, the foot is a very unstable structure of 26 bones and 33 joints, in the sport of cycling – whether for elite sportspeople or the average weekend punter, the body, and in particular the lower limb is asked to move more like a machine than the multi-directional and dynamic creature it is.
In true road cycling, where the foot is latched to the pedal via cleats or a strap and both a push and pulling motion is created in conflict to the opposing limb, the legs are asked to act as levers or pistons to generate optimal force upon the small area of contact. With the foot being a highly maneuverable item, the ability to act as a stiff lever is difficult while cycling. Certain cycling shoes do have a carbon fiber sole which is in place to stiffen the shoe itself, however, this does not account for the movement inside the shoe which can then affect the angles of the knees, hips and body as a whole.
In any case of injury, irritation or performance altering ailment a full assessment should be complete to identify areas of weakness, equipment failure or technique problems associated with that particular activity. In the case of cycling this happens to be the bike and the cyclist themselves.

Road bike set-up is broken down into a number of parts:
The seat height has the ability to change power output by disrupting the length-tension relationship of the lower limb. If the seat is too high it can cause increased stretch from muscles of the posterior chain and decrease core stability as the hip drops to compensate for the extra length required to pedal. Alternatively, having the seat too low can increase knee flexion placing the muscles of the posterior chain into a position of shortening which not optimal either. When seated the cyclist should have stable hip alignment, while one leg is extended with only slight knee flexion and the pedals sit close to 0 and 180deg . The best way to measure this is to place a thick book between the legs of the cyclist while in a standing position and measuring from in-seam of their bike shorts to the ground, then multiply this number by 0.88 – the measurement found is then transferred to the bike measuring from the base of the crank to the top of the seat. Using a book between the legs aims to separate the legs to just inside hip width and provide a base to measure from.
The seat height can be adjusted from this position depending on a number of different factors including; flexibility, crank length, comfort, cleat position and shoe thickness.

The fore/aft or saddle position contributes to how much load is place through the knee joint as well as glute-hamstring length and the amount of hip flexion available. Increased patella-femoral compression forces occur if the saddle sits too far forward. Additionally, the more upright a cyclist becomes the less aerodynamic they become, this also results in the increased flexion of the knee and further extension of the hip creating a less than optimal length-tension relationship.  If the saddle is in a position too far back then the glute-hamstring length will be in excess and reduce force, similar to that if the seat post was too high.  To find the best saddle position the Plumb bolt method is used, where the bolt is dropped from the tibial tuberosity of the cyclist while the cranks are leveled at 90 and 270deg respectively. The aim is to have the bolt sit behind the pedal or in line with it to decrease the chances of patella-femoral load. Once again this method can be altered depending on a number of factors affecting the rider including; personal preference, hip flexibility and race type.

Deciding on cyclist’s reach ability (bar position) is a completely subjective task based on how the rider feels in a particular position and what appears to be safest from developing a structural injury.
Bar reach and drop is focused on the cyclist’s available flexibility and past experience. The overall desired look of the cyclist should include relaxed upper limbs which sit with unlocked elbows, retracted scapula and an anterior pelvic tilt.

Cycling technique seems easy enough to write about but mastering it is a whole other story. The pedaling motion of a cyclist needs to do exactly that…CYCLE. A smooth and continuous repetition which does not have an upstroke, which would destabilize the pelvis and decrease the available power generated. The combination of drive from the descending leg and carried on flow from the ascending limb should create a moment which pulls the ascending limb through the top stroke moment.

Cycling and Orthotics
As mentioned earlier the foot is a very unstable structure. Despite the carbon fiber sole of the shoe attempting to stiffen it to act as a lever, the millimeters of room available in the shoe still allow for the natural movements of the foot which are trying to be prevented for best transfer of energy. There are a number of items available out there for cyclists but the better quality devices are those which are rigid, supportive and able to advance the locking mechanism of the subtalar joint by pronating the rearfoot and supinating the Midfoot to created a stiff ever and reduce movement of the foot. Creating a stiff lever in theory will help increase power output during cycling, however a recent systematic review completed by Yeo and Bonanno in 2014, found that the current available evidence provided no justifiable conclusions about how cycling orthotics and wedging effect the lower limb.

Despite these findings it is important to understand that just because current evidence is not supportive of custom orthotics for power output; it should not be extrapolated to the effectiveness of the device for issues which can reduce the performance or enjoyment of cycling in a person. Complaints such as “hot foot”, knee pain, ankle pain and metatarsal head discomfort can all be addressed with the use of an insole off-loading device or adjustment to bicycle set-up.
When trying to design a custom orthotic for a cyclist which is not affiliated with a particular specialist brand, it should be recognized that the foot adjustments will have the greatest effect where the foot makes contact with a surface. In the case of road cyclists this is limited to a 20-50mm point of contact, unlike traditional orthotics which operates in a way which facilitates natural motion and reduces pathological movements at the foot through the full range of gait.

Jackson McCosker
Director /Chief Editor

References

Brukner, P., & Khan, K. (2007). Clinical Sports Medicine. McGraw- Hill Education Pty Ltd

Yeo, B. K., & Bonanno, D. R. (2014). The Effect of Foot Orthoses and In-Shoe Wedges During Cycling: A Systematic Review. Joural of Foot and Ankle Research , 1-11.

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