Tendons are the structures that connect muscles to bones and their job is to transmit force that produces movement and stability across joints. But tendons don't just act like passive ropes. Tendons are able to store energy, which when released makes movement more efficient. For example, it has been estimated that the Achilles tendon provides about 40% of the effort it takes to hop on the spot from stored “elastic” energy (1). Tendons also play an important role in controlling movement as they contain nerve endings that respond to tension. These nerve endings send vital information to the nervous system about the position of the body, that is used to control the muscular system.
Tendon pain is a common complaint. One study estimated that tendon pain constituted 30% of the workload in muskuloskeletal treatment centres (2). Tendons can become painful for a number of reasons with the most common being linked to how they are loaded. An example is when a tendon is exposed to significantly more load than it is accustomed to, over too short a time. This could be a runner who adds in some hill running routines too quickly to his programme and ends up with a sore Achilles tendon. Another example is the over exuberant home DIYer who decides to decorate the whole house in a weekend and ends up with a sore shoulder. These short term overload scenarios are relatively easy to deal with, if appropriate action is taken at the time. This is simply a case of reducing tendon loads and then gradually phasing back to an appropriate level of loading. The types of tendon pain that are more difficult to treat are those that come on gradually. This often happens to tendons that are exposed to sub maximal loads over a long period of time. Initially the discomfort isn’t too limiting, so no action is taken. It maybe several weeks or months before the tendon pain becomes so bad that activities become compromised and help is finally sought. By this time, structural changes in the tendon have occurred, and the issue is more difficult to treat.
Successfully managing persistent and long term tendon pain should be based on load management. This basically involves removing painful activities and replacing them with loaded activities that help to reduce pain and then improve the structure and function of the tendon. The use of isometric loads to a painful tendon have been shown to produce pain relief (3). Isometric exercises can be performed in a number of ways and in many different positions. However, they all involve tensioning muscles and therefore tendons without any angular joint displacement. This coupled with the fact that isometric force can be built up gradually, means that exercise loads can be introduced at relatively low levels and this helps to prevent any pain flare ups caused by excessive loading. The pain relieving effect of isometric exercise is thought to come about by modifying central nervous system responses that are involved when pain is experienced. Once some pain control has been achieved, higher loads should be introduced to the rehab work. A large amount of research has been done, particularly on eccentric exercise, which shows that this type of progressive tendon loading is an effective way of restoring pain free function. The results of one study demonstrated that this approach was superior to surgical management (4).
1 Types and epidemiology of tendinopathy. Maffulli N, Wong J Clin Sports Med 22 (2003) 675–692
2 Assessing health needs in primary care. Morbidity study from general practice provides another source of information. McCormick A, Charlton J, Fleming D BMJ 310: 1534. Jun 1995.
3 Isometric exercise induces analgesia and reduces inhibition in patellar tendinopathy
Ebonie Rio, Dawson Kidgell, Craig Purdam, Jamie Gaida, G Lorimer Moseley, Alan J Pearce, Jill Cook Br J Sports Med doi:10.1136/bjsports-2014-094386
4 Surgical Treatment Compared with Eccentric Training for Patellar Tendinopathy (Jumper's Knee)
A Randomized, Controlled Trial. Roald Bahr, MD, PhD; Bjørn Fossan, PT; Sverre Løken, MD; Lars Engebretsen, MD, PhD J Bone Joint Surg Am, 2006 Aug; 88 (8): 1689 -1698