Tendons are tough, cord-like fibres that connect muscle to bone at your joints. They act like the guy ropes of a tent to hold the muscle in place. A tendon injury may seem to happen suddenly, but it is usually the result of many tiny tears to the tendon that have happened over time. Imagine the tendons fraying like rope, but instead of wearing at the edges, the wear occurs within the substance of the rope. This overuse injury of a tendon is called tendinopathy.
In overuse injuries, the tendon is not actually inflamed but can become painful as it is unable to cope with the load that is placed on it. In fact, tendon injuries are usually the result of overuse of the muscle as well as the tendon that anchors it to the bone (the muscle-tendon unit). Although the tendon portion (the guy rope) is injured, there may be weakness or tightness in the muscle that has contributed to this happening. If the muscle is weak and also tight, the tendon may be pulled too taut, or if the muscle is weak and loose, the tendon may have to work harder to tie it down.
The term ‘overuse’ implies that the problem results from too much activity. You have ‘over-used’ the tendon. Put differently, the muscle-tendon unit has to be strong enough to deal with the activity undertaken (the load applied to it), or injury will occur. An overuse injury occurs because the muscle-tendon unit is not strong enough to deal with the load on it.
Load can be:
- A sudden huge force, as in lifting heavy luggage.
- Smaller repetitive forces, as in starting a walking programme.
- Smaller prolonged force, as in staying in one position for a long period of time.
Once the muscle-tendon unit is unable to perform its normal function, further loading makes it harder and harder to heal without help.