Previously, re-acquisition of muscle mass -- with or without steroid use -- after periods of inactivity has been attributed to motor learning. However, this new data from the University of Oslo suggests that there is a cellular 'memory mechanism' within muscle of brief steroid users.
The team investigated the effects of steroids on muscle re-acquisition in mice and discovered greater muscle mass and more myonuclei -- which are essential components for muscle fibre function -- were apparent after returning to exercise.
The findings might have consequences for the exclusion time of doping offenders as brief exposure to anabolic steroids might have long lasting performance-enhancing effects.
Prof Gundersen says: "The results in our mice may correspond to the effects of steroids lasting for decades in humans given the same cellular 'muscle memory' mechanism. The new results might spur a debate on the current World Anti-Doping Agency (WADA) code in which the maximum exclusion time is currently two years."
Additionally, the data suggests that strength training when young might be beneficial later in life since the ability to generate new myonuclei is impaired in the elderly.
Future studies should include human muscles and further investigation into the cellular and molecular mechanism for muscle memory.