Pain in heel / arch
Under the foot is a tendon plate, the plantar fascia, which ensures that the arch of the foot is supported. This tendon plate is attached to the heel bone on one side and to the forefoot on the other side.
If pressure is put on the foot, eg when pedaling while cycling, the arch of the foot sags slightly. This stretches the tendon plate. This “stretching” leads to a great deal of tension, especially at the location of the attachment of the at the heel. If you do this regularly, it can lead to overload and even damage to fibers. The result is pain in the arch of the foot or at the heel. The complaints are often more severe after rest, starting pains, and with longer load.
In particular, feet that are somewhat 'kinked' inwards, or that easily sink in under load, have a greater risk of developing complaints. You can easily test how your foot reacts. To do this, stand on one leg in front of a mirror. Sink your knee and watch your foot move. Does it sink in a lot or does it stay in shape? Training stability and a (cycling) sole can solve this problem. A difference in leg length can also cause the foot to sink a bit on one side. This is usually the side of the longer leg that is shortened as it were. Compensating for the difference in length usually solves this problem.
Your saddle height is also very important. This affects the foot lining and vice versa. Do you stand 'high' on the toes or do you kick the ankle low, this puts a different tension on the tendon plate. Your footing varies from person to person. To determine a good saddle position, it is therefore advisable to do a dynamic bicycle position measurement.