Short exposure to anabolic steroids could last for decades
Professor Kristian Gundersen, PhD, Professor of Biology (physiology) Department of Molecular Biosciences, University of Oslo and colleagues examined the effects of steroids on muscle re-acquisition in mice and discovered greater muscle mass and more myonucle, (essential components for muscle fibre function) were apparent after returning to exercise.
Based on in vivo (inside the organism) and ex vivo (outside the organism) microscopy, the researchers suggest there is a cellular memory mechanism residing in the muscle cells.
For the study, female mice were treated with testosterone propionate (fast acting anabolic androgenic steroid) for 14 days, which resulted in increased muscle mass and number of cell nuclei in the muscle fibres.
The research revealed after withdrawal of the drug (approximately 15% of a mouse's life span) their muscles grew by 30% over six days following load exercise. The untreated mice showed no significant growth.
The researchers write “Our findings might have consequences for the exclusion time of doping offenders, as brief exposure to anabolic steroids might have long lasting performance-enhancing effects.”
Professor Gundersen comments "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."
This data also 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.
This study is published in in The Journal of Physiology.