Tendon pain from excessive use is a very common injury in sport. It occurs if the cumulative strain on the tendon is greater than what the tendon can take. There is two parts to this: the first one is the collective load which means simply how much exercise is done and how often this is done. It is vital that the tendon is given time to adjust to those loads or the cumulative load may exceed that. Which is the second aspect, just how adapted the tendon would be to those loads. Being familiar with these principles is important in understanding and dealing with tendonitis.
For example, peroneal tendonitis which is an overuse injury that occurs on the outside of the ankle joint. The collective load in this tendon is increased when exercise amounts are too high or increased too quickly and not enough time is given for the tendon to adjust to those higher loads. The cumulative load can also be increased by the biomechanics of the foot. For instance, if the supination resistance of the foot is lower then the peroneal muscles on the outside of the lower limb will need to work harder. That will put an greater load on the peroneal tendons and then coupled with training errors that load could exceed what the tendon can take and it develops tendonitis.
Based on these concepts, peroneal tendonitis is treated by lessening that cumulative load. That will mean exercising amounts and frequency must be reduced somewhat to permit the tendon to adapt to the loads. The strain in this disorder will also be reduced with foot orthoses that evert the foot, which means the peroneal muscles does not need to work as hard. Then the tendon has to be given a chance to get used to the loads. This means that training quantity and frequency has to be slowing increased, with lots of rest between training loads to get the tendon to adjust to those loads.