We are seeing more and more problems with tendons at the clinic, in shoulders and elbows particularly. Most tendon injuries are down to repetitive use with a lack of recovery time for the tendon.
The tendons that allow us to click a mouse and type on the keyboard attach into the outside of the elbow (1) and can be an important factor in tennis elbow. In some working environments, both the office and at home, it seems that these tendons don't actually get much rest at all!
What happens to the tendon?
Figure adapted from Cook and Pardum.
As you can see here, tendon injury and change is complex, but in most cases can be reversed.
An acute high load (orange arrow), like the use of a hammer in an occasional DIY task, causes ‘reactive tendinopathy’. This is where there are changes in the tendon cell actions and chemicals which result in it being very painful. These changes are an attempt to adapt quickly to the high load the tendon has been put under. Load management allows the tendon to return back to its normal functioning state.
Repetitive loads from repetitive motion or pull of gravity (red arrow) causes the cells to continue to change causing altered cell activity and production of different proteins making the tendon stiffer.
The longer this goes on for the less adaptive capability the cells have, leading to a tendon in dysrepair. If the loads are continued the cells reach exhaustion and there is a complete change in the make-up of that part of the tendon; these areas are classed as degenerative tendons .
These changes make it less likely to adapt to loads. It is important to remember though that these degenerative sites are small and often do not cover the whole of a tendon.
Other factors
Vulnerability to tendon injury and recovery is affected by many factors, most commonly an older age, male sex but also it is associated with menopause. Other lifestyle risk factors include obesity, hypothyroidism and diabetes as they are thought to reduce the capacity of the tendon to tolerate load.
Previous injury also makes one more susceptible to tendon reaction, but this can be reduced by regular strength training.
Lack of use of tendons is also a big risk factor. When you add a normal load to a poorly conditioned tendon the tendon is likely to react.
Managing loading
The key word here is management. This involves reducing or avoiding activities that aggravate the tendon to allow it to adapt over the healing time, which is often a long time when it comes to tendons. Care usually will include an exercise program focusing on gradual strength and functional training to match your needs. The important thing to remember is that this is a slow rehabilitation process.
References
(1) Moore, K.L., Dalley, A.F. and Agur, A.M.R. (2010) Upper Limb. In Moore, K.L. (6th ed) Clinically Orientated Anatomy. Philadelphia, USA: Lippincott Williams and Wilkins, pp 750-752
Photo's by Karolina Grabowska and Yan Krukov from Pexels