MECHANICAL STIFFNESS OR RESOLVED INFLAMMATION: WHAT IS MORE IMPORTANT FOR TENDON REHABILITATION?

Abstract

As high incidences of tendinopathies are observed particularly in those who intensively use their tendons, we assume that pathological changes are caused, at least partially, by mechanical overload. This has led to the so-called overload hypothesis, explaining the development of tendinopathies by structural failure resulting from excessive load. At the same time, tendon loading is an important part in tendon rehabilitation. Currently, exercise treatment approaches such as eccentric training or heavy load resistance training are widely applied in tendinopathy rehabilitation, with good clinical results such as an improvement in function and a reduction in pain. Particularly those rehabilitative approaches which impose high strains on the tendon may induce an adaptation of the tendon's mechanical properties such as increased tendon stiffness. An increased tendon stiffness is often interpreted as desirable, as it may protect the tendon from overloading and thus prevent future strain injuries. However, the tendinopathic tendon is not necessarily less stiff than the tendon in the contralateral leg and an improvement in tendon stiffness is not necessarily accompanied by an improvement in tendon pain or function. In addition, metabolic factors, resulting e.g. in low-level systemic inflammation, may contribute to pathological tendon tissue changes and are not necessarily affected by an exercise program, while nutritional interventions or dietary supplements may potentially affect tendon cell metabolism. Indeed, dietary supplements have been introduced as an additional therapeutic approach in the treatment of tendinopathies in recent years, and their positive curative effects have been reported for both the general population and athletes. In the management of tendinopathies, it may thus be advisable if therapeutic approaches aim to address both tendon mechanics and tendon metabolism for better treatment effectiveness and a sustainable improvement in pain and function.