Stretching is widely used in sports and physiotherapy for improving flexibility and performance as well as lowering risk of injury [1]. The most common and clinically most relevant use of stretching techniques is to improve flexibility or range of motion (ROM). Both terms are often used synonymously and describe the ability to perform extensive movements in one or several joints. In the following, the term “improved flexibility” denotes an increased ROM in the evaluated joint(s).

Different methods of stretching are distinguished, the most popular ones being static and dynamic stretching as well as techniques based on proprioceptive neuromuscular facilitation (PNF) [1]. The stretching techniques differ mainly in duration and number of repetitions [1]. In recent research, the effects and underlying mechanisms of stretching have been re-evaluated, which led to changes in the understanding and interpretation of the underlying mechanisms. Stretching seems to lower muscular performance instead of improving it, injury risk is almost unchanged. In clinical settings, stretching, e.g. to prevent contractures, resulted in no relevant changes of ROM, quality of life, pain, or improvement of daily activities [1], [2]. In healthy individuals, all stretching methods may increase ROM, although these improvements were only observed for ten minutes to an hour [1]. Currently, there are two prevailing theories on the underlying mechanisms of stretching techniques and their effects on flexibility. The first theory hypothesizes changes in the viscoelastic properties of muscle tissue as the driving factor, although viscoelastic changes seem to last only for a short period of time [3]. The second theory hypothesizes altered sensation leading to a greater tolerance to stretch pain as the driving factor. Since most studies and assessments of flexibility use sensory endpoints such as the onset of stretch pain, the second theory may be of higher clinical relevance [3].

Effects of an altered pain threshold and reduced muscle activity have also been observed following relaxation therapy [4], [5], [6]. Relaxation therapy consists of a wide array of techniques ranging from physically active techniques, such as “Progressive Muscle Relaxation” [7], to mainly psychological and hypnosis-based techniques like “Autogenic Training” [8]. Besides the somatic effects, these techniques have shown psychological effects, especially on stress and stress-related symptoms. Possible correlations between psychological relaxation and muscle flexibility have not been scientifically evaluated yet.

The aim of this study was to pilot a study design to evaluate the possible effects of Autogenic Training on functional flexibility, muscle activity and muscle stiffness as well as perceived stress.