The purpose of this 4th Annual USADA Symposium on Anti-Doping Science was to discuss the implications for doping control given the advances made in understanding the molecular basis of muscle development, regulation, and recovery. The use of molecular biological techniques and models have created a number of opportunities for therapeutic interventions, such as within the myostatin system, which could give rise to sophisticated doping approaches. In order to stay abreast of these developments and to formulate priorities for future anti-doping research, presentations on recent advances in muscle hypertrophy and hyperplasia were heard and discussed. Strategies for development of methods for detection of these methods of performance enhancement were formulated.