This study aims to determine hemoglobin and collagen levels in muscles before and after exercise, and over time, using Multispectral Optoacoustic Tomography (MSOT). During MSOT, a transducer is placed on the skin similar to a conventional sonography and instead of sound, energy is supplied to the tissue by means of light flashes. This leads to a constant change of minimal expansions and contractions (thermoelastic expansion) of individual tissue constituents or molecules. The resulting sound waves can then be detected by the same examination unit.

Duchenne muscular dystrophy (DMD) is one of the most common progressive childhood muscle diseases with an incidence of 1 in 3500 male newborns and is associated primarily with decreased life expectancy. Pathogenetically, there is a deficiency of dystrophin, a structural protein of the sarcolemma, which is caused by mutations (usually deletions) of the dystrophin gene (Xp21.3-p21.2). The result of dystrophin deficiency is a necrosis of muscle cells that are replaced by connective tissue and adipose tissue. Clinical scores (6-minute walk test, 6MWT) and MRI studies to characterize the degenerative changes of skeletal muscle in the early stages are available for the quantitative assessment of the disease progression as well as therapy effects, the significance of which is controversially discussed. However, the highly sensitive assessment of gene therapy effects will become increasingly important in the future. Sensitive, non-invasive methods for the detection of early muscle degeneration and muscle function in the course are of great clinical and scientific importance.

MSOT has already been demonstrated to be a potential monitoring tool in different diseases. However, it has not yet been investigated to what extent 1) previous physical activity 2) different measuring ranges at the muscle, 3) longitudinal measurements and 4) intra- and interoperative variability influences the measured results. In particular, molecular changes immediately after the 6-MWT are relevant for studies in patients with DMD.

In this first pilot study, the investigators want to investigate in healthy adults, whether increased exercise changes the hemoglobin values, whether the collagen content remains constant and whether repeated measurements at different muscle positions by different investigators provide consistent results over time. This information is indispensable for future studies of children with muscular diseases in order to be able to make statements about disease progression or even therapy response.

Inclusion Criteria:

• >18 years of age

Exclusion Criteria:

• any reference to a myopathy
• pregnancy
• tattoo in the scanning region

The data sets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request as follows:

• Individual participant data will not be available
• Study Protocol and Statistical Analysis Plan will be available
• The data will be available beginning 9 months and ending 36 months following article publication.
• The data will be available to researchers who provide a methodologically sound proposal.
• The data will be available for individual participant data for meta-analysis, only.
• Proposals may be submitted up to 36 months following article publication. After 36 months the data will be available in our University's data warehouse but without investigator support other than deposited metadata. Information regarding submitting proposals and accessing data may be found at https://www.uk-erlangen.de.

Restrictions may apply due to patient privacy and the General Data Protection Regulation.

36 months after publication

Resonable request