Researchers at the University Hospital of Heidelberg are investigating the effect of signalling substances on muscle development. If mice are missing a gene for a certain muscle protein, they become "marathon runners". In running tests, they have significantly more stamina than normal mice and the ability to run faster and further. Scientists at the University Hospital of Heidelberg have been able to show this effect in genetically modified mice whose muscles did not form the protein calsarcin 2. The work represents an important contribution towards understanding muscle development and is significant for research into and the possible treatment of cardiac weaknesses.