Cycling is one of those sports that people turn to in cases where knee or hip injuries have prevented them from running or playing sports. In seeking a lower impact hobby, cycling is often viewed as the answer to their prayers. Cyclists can often become extremely disappointed if their old pain returns or they develop a new injury that was not there before.
Knee pain can develop if there is excess rotation of the knee or if excess valgus angulation occurs. Valgus angulation is where the the lower leg moves laterally in relation to the thigh. Increased valgus angulation at the knee causes the kneecap to move laterally and increases the contact stress at the patellofemoral joint (the joint between the kneecap & thigh bone). Increased internal rotation of the femur also causes increased pressure behind the kneecap (Liao et al 2015).
The three points of consideration in bike set up are:
1) The handlebars,
2) The saddle
3) The pedal.
A saddle that is too high has been associated with increased ITB pain (Holmes et al. 1994) as well as anterior knee pain (patellofemoral pain). Increased internal rotation of the femur is known to increase pressure and stress behind the patella (Liao et al. 2015). Pain precence behind the knee occurs due to issues with body position or the bike set-up itself.The knee should reach 30° at the bttom of the pedal stroke and 110° at the top. The correct measurement of bicycle height will involve measuring the knee flexion angle with the foot pedal at the bottom (6 o’clock position). In this position the knee should be bent to 30°. In standing the saddle height should correlate the inseam leg length height.
In terms of handlebar distance, when the bars are further away this tends to improve aerodynamism and cycling speed. This can give rise to neck strain as the cyclist needs to extend the neck to look ahead. When the bars are moved closer to the body the stress on the shoulder joint is decreased while the more upright position means that the need for holding the neck in an extended position for prolonged periods is avoided. This decreases the likelihood of neck extensors muscle strain and overload of the joints of the neck (facet joints).
Saddle height: Small adjustments in saddle height can have a significant impact on forces on the patellofemoral joint behind the kneecap. Having a saddle position that is too high can be associated with iliotibial band syndrome or stress on the anterior cruciate ligament. If the saddle is too low this has also been linked to anterior knee pain (Burke & Pruitt 1996).
References:
- Liao et al. (2015). Femur rotation increases patella cartilage stress in females with patellofemoral pain. Medicine & Science in Sports & Exercise; 47(9): 1775-80.
http://www.ncbi.nlm.nih.gov/pubmed/25606814
For further information on conditions treated go to:
www.physioclinic.ie/conditions
