The discovery runs in the face of the previously held belief among physiologists and athletes that acidity, through a build up of lactic acid, is a major cause of muscle fatigue.
Professors George Stephenson and Graham Lamb of La Trobe's Muscle Research Laboratory and Mr Thomas Pedersen and Professor Ole Nielsen from the University of Aarhus, presented their findings to the scientific world in Science, the journal of the American Association for the Advancement of Science, published today (August 20).
Mr Pedersen, a Danish PhD student from the University of Aarhus, came to work for six months in the Muscle Research group to carry out the project with Professors Stephenson and Lamb using a technique developed in their laboratory by which the surface membrane of single muscle fibres--which are half the thickness of a human hair-- is peeled away, without interfering with the ability of the muscle fibre to contract normally to electrical stimulation. This enabled the researchers to change conditions inside the muscle cells and study the effects of acidity on the force response.
'We found that muscles play a "clever trick" in which they use acidosis--the build-up of acid--to help ensure that they keep responding properly to nerve signals and so avoid the fatigue that would otherwise occur,' said Professor Lamb.
Collaboration between La Trobe and Aarhus universities started in 2002 when Professor Nielsen came as a Distinguished Visiting Scholar at La Trobe's Institute of Advanced Study to work for a month in the Muscle Research Laboratory.
Professor Nielsen had recently demonstrated for the first time that acidity could be beneficial to muscle performance, although it was not clear how this occurred.