Brief use of steroids may have permanent effects

Scientists from the University of Oslo (UiO) have demonstrated that even a brief intake of anabolic steroids may have long lasting performance enhancing effects. – If the biological mechanisms in humans are similar to the ones we find in mice, the effects could last for decades, says professor Kristian Gundersen.

The effects of short term steroid use may last for many years after quitting. 

Photo: Colourbox

A new study from the Department of biosciences at UiO shows that the effect of anabolic steroids may be much longer than previously thought. 

THE RESEARCH TEAM: PhD student Einar Eftestøl (left), researcher Jo C. Bruusgaard, PhD student Ingrid M. Egner and professor Kristian Gundersen. 

Foto: Tore Oldeide Elgvin

The results, published in Journal of Physiology, will likely fuel the debate on drugs and punishment in sports.

­­­­­– Our data may lead to changes in the exclusion rules for athletes testing positive, says the leader of the group professor Kristian Gundersen. 

Mice on steroids

In the study, mice were exposed to anabolic steroids for two weeks, which resulted in increased muscle mass and number of nuclei in the muscle fibers. 

The drug was then withdrawn for 3 months, a period which corresponds to approximately 15 percent of a mouse's lifespan. After the withdrawal, the mice’s muscle mass grew by 30 percent in 6 days following load exercise, while untreated mice showed insignificant muscle growth during the same period. 

MICE ON STEROIDS: Quantifications of cross sectional area. Muscles treated with steroids 13 weeks earlier (red) grew significantly faster that sham-treated animals (blue) when subjected to overload of the muscle.

Illustrasjon: Jo C. Bruusgaard

Therefore, former steroid use had a clear effect even after a long period without steroid use (see graph to the right). 

Muscle memory

The mechanism behind this effect can be described as a form of “muscle memory”, where an increased number of nuclei in muscle cells is maintained after temporary use of performance enhancing drugs.

Each nucleus can produce proteins for a certain volume of the cell. Thus, each nucleus and the associated synthetic apparatus can be viewed as a small protein factory that builds muscles. In principle, the more nuclei, the bigger muscles you can obtain. 

– There is an accumulation of nuclei when you build muscles, and these nuclei seem to promote the gain of muscle mass with future exercise, says Gundersen. 

– Nuclei accumulation gets harder as you get older. Therefore, it may be advantageous to perform overload exercise at a young age in order to counteract frailty in the elderly. Such frailty is an important health issue in the aging population of Western societies, he continues.

DOPING EFFECT: Microscopy images showing cross sections of muscle fibers with (right) and whiteout (lest) anabolic steroids. The cells that have been treated with anabolic steroids are more than twice the sizes of the untreated ones.

Foto: Jo C. Bruusgaard

Of mice and men

Even though the study was completed on mice, it is likely that comparable mechanisms are involved in human cells as basal biological mechanisms often are alike in mammals.

– The specific time aspect is of course challenging to extrapolate from mice with a lifespan of two years to humans who live for 80 years. However, the cell nuclei in humans are known to be very stable.

– If the muscle memory mechanism in humans is similar to what we observe in mice we could be talking about several decades of advantageous effects, the physiologist says.  

MUSCLE MEMORY: Big muscle cells (below) contain more nuclei than do small muscle cells (above).

Foto: Jo C. Bruusgaard

Questions related to the steroid effect durability in humans is something the Gundersen team will investigate in the future. 

Change of maximum exclusion penalty?

It is primarily in explosive sports, for example discos, weight lifting and sprint, where the effects of steroid use and muscle memory will be advantageous. 

The results of this study may lead to a new debate on the exclusion rules set by the World Anti-Doping Agency (WADA). 

WADA today operates with a maximum exclusion penalty of 2 years for athletes testing positive to performance-enhancing drugs. This may be changed to four years in 2015. The question, however, is whether this will be enough? 

– If the effect of steroids are permanent, shouldn't the exclusion be permanent as well? asks Gundersen. 


Ingrid M. Egner, Jo C Bruusgaard, Einar Eftestøl & Kristian Gundersen (2013) A cellular memory mechanism aids overload hypertrophy in muscle long after an episodic exposure to anabolic steroids. Journal of Physiology.

Tags: anabolic steroids, muscle memory, physiology, doping, sports, WADA, cheating By Tore Oldeide Elgvin
Published Oct. 29, 2013 09:21 PM - Last modified July 13, 2016 11:36 AM