Tendon injury from too much use is a common issue in sport. It occurs in the event the cumulative strain on the tendon exceeds what the tendon can take. There is two parts to this: the first one will be the collective load which means the amount of exercise is done and just how frequently this is done. It is essential that the tendon is given time to get accustomed to those loads or the collective load might go beyond that. Which is the second part, just how adapted the tendon is to those loads. Being familiar with these principles is important in understanding and treating tendonitis.
For example, peroneal tendonitis that is an excessive use injury that occurs on the outside of the ankle joint. The collective load in this tendon is greater when activity levels are too high or increased too quickly and not sufficient time is provided for the tendon to adjust to those high loads. The cumulative load can also be increased by the biomechanics of the feet. As an example, if the supination resistance of the foot is low then the peroneal muscles on the outside of the leg will need to work harder. That could place an increased force on the peroneal tendons after which in addition to training errors that load may exceed what the tendon can take and it develops tendonitis.
Based upon these principles, peroneal tendonitis is treated by reduction of that collective load. That can mean training volumes and frequency should be reduced somewhat to permit the tendon to adapt to the loads. The stress in this condition will also be decreased with foot orthoses that evert the foot, which means the peroneal muscles does not need to work as hard. Next the tendon needs to be given an opportunity to get used to the loads. This implies that exercising amount and frequency ought to be slowing increased, with lots of rest between training loads to give the tendon to adapt to those loads.