A research article published 5 December describes a new light-based technology for measuring oxygen content in muscles while underwater, valuable information for competitive swimmers as well as patients using water-based therapies to recover from muscle injuries. Authored by researchers from the University of Essex and Artinis Medical Systems, the open-access paper appears in the current issue of the Journal of Biomedical Optics, published by SPIE, the international society for optics and photonics.