One of the most influential recent developments in sports medicine’s understanding of human physiology has been grasping the effect that load has on tissue. When I speak of load I don’t just mean the additional pressure on you if you were carrying a pack on your back. Loading comes in many forms and affects us throughout the day in all the things we do. Loads are placed on the spine in sitting, through feet in walking, and on many structures in the legs with jumping and running. The tissue within the human body that are most sensitive to changes in load are tendons, and as a result, are often the first to fail when loads suddenly increase.
Tendons are structures that in most cases connect muscle to bone. Part of their role is to allow muscle to move a body segment, but the structure of a tendon allows it also to store and release energy. The primary tissue within a tendon is fibrous dense tissue (collagen), and when it is placed on stretch will store energy much like a spring. An example of the boost that tendons can provide is to describe the way they act in a high jumper in athletics. As the high jumper approaches the point where they jump their natural movement is to lower their weight. This lowering tenses the tendons in the knee and ankle allowing these tendons to store energy. When they then go to jump, the stored energy is released in combination with the muscle contraction, creating a more powerful movement than the muscle could perform itself.
Tendons can develop and change but due to their dense collagen fibers they don’t have much of a need for blood flow. This lack of blood to the tendon means that it is much slower to adapt to stresses and loads than the muscle tissue that it’s connected to. It is because of the slow adaptation of tendon tissue to change that any new form of exercise should be planned and structured so changes in load are gradual. If you are intending to embark on a new exercise format or wish to up your current level of exercise, we advise you speak to a trained professional before you undertake this.
Written by Mark Fotheringham (Physiotherapist)