Gene doping in sport: what it changes
Gene doping is no longer just a lab story. It genuinely concerns sport, because gene therapy, myostatin and IGF-1 can change how fast muscle grows and how big an advantage one athlete gains.
Here we look at why WADA took this topic seriously early on, what the work by Dr. Se-Jin Lee and colleagues at the Johns Hopkins University School of Medicine showed, and why such developments put fair sport in a difficult position.
Why gene doping matters in sport
The World Anti-Doping Agency (WADA) held a conference on gene doping at the Karolinska Institute in Sweden on December 4-5 last year. Its conclusion was cautious: transferring genes for therapeutic purposes, known as gene therapy, does exist, but in human medicine it remains experimental and carries risks.
A week later, researchers led by Dr. Se-Jin Lee at the Johns Hopkins University School of Medicine published a study on a substance called ACVR2B. It suppressed the effect of the myostatin gene and increased muscle protein by 61%. Medicine saw potential help in it against muscle-wasting diseases such as Duchenne muscular dystrophy.
Sport looks at such a discovery differently. When something offers a big advantage in strength, speed or muscle mass, there is always someone who wants to try it before its safety is clear. Frankly, it’s an old pattern in the history of doping.
How gene doping affects muscle
Myostatin is a protein that restrains the growth of skeletal muscle. Before birth, it helps determine the number of muscle fibers. In adults, skeletal muscles keep producing myostatin, and it circulates in the blood and holds muscle growth back.
Dr. Lee’s research group is one of the best known in myostatin research. In experiments on rats, myostatin genes were suppressed and muscle mass increased by 100%. A later method used the activin type IIB receptor, or ACVR2B. Its advantage was simple: the gene itself was not permanently altered; instead, the aim was to temporarily switch off the effect of myostatin.
That difference is important. A temporary effect can, at least in theory, be controlled with doses. A permanent gene change, on the other hand, can lock in a change in the body whose consequences cannot be foreseen. A muscle can grow, but the body is not just muscle. Tendons, the heart, circulation and the nervous system also have to cope with the training load.
In the Johns Hopkins study, mice were injected with ACVR2B. Within a few weeks, noticeable muscle hypertrophy developed. The researchers gave the mice different doses and measured muscle size over one to four weeks. A dose of 50 milligrams per kilogram of body weight increased muscle mass the most.
The measurements showed that muscle grew mainly through hypertrophy, meaning enlargement of muscle cells, rather than hyperplasia, meaning an increase in the number of muscle cells. ACVR2B also worked in mice with different gene mutations. This hints that myostatin may not be the only brake controlling muscle growth.
Gene doping and natural genetic advantage
Anyone who has spent time on a school sports field has seen it: some kids run faster, throw farther and jump higher even though they have hardly had any training yet. At elite competitions, the same gap simply becomes more visible.
The Finnish cross-country skier Eero Mäntyranta, who competed at the 1964 Winter Olympics in Innsbruck, had a gene abnormality. His bone marrow produced 25% more red blood cells than the normal level. This helped deliver more oxygen to his tissues, and he won two gold medals.
In the last days of June 2004, German researchers reported on a child born with unusually well-developed musculature. He had a mutation in a gene that affects myostatin production. At the age of four, his muscles were measured by ultrasound, and the results showed they were twice the normal size.
The boy’s testosterone and IGF-1 growth factor levels were normal. This indicated that the exceptional muscle mass was linked to a low myostatin level. The boy was followed for almost five years, and during that time no health problem was found that could be directly linked to his large muscles or to the lack of myostatin.
What gene doping means for the future
Dr. Miguel Riviera, a professor of medicine at the University of Puerto Rico, explained in an interview with MD (Muscular Development) that athletic performance is not driven by a single gene. Genes come in variants; some work together and some act like a switch that influences processes tied to physical performance.
Riviera also noted that progress has been faster than many expected. Fewer genes seem to influence muscle hypertrophy than maximal oxygen uptake capacity, but Lee’s study showed that it is not as simple as switching a single gene on or off.
In strength sports, suppressing myostatin looks especially tempting. In bodybuilding, weightlifting, throwing events and American football, muscle mass can give a direct advantage. In theory, gene therapy could be used to block the processes that restrain muscle growth or to influence IGF-1, a potent anabolic hormone.
Dr. Geoffrey Goldspink and colleagues at the Royal Free and University College Medical School in London showed a similar trend in animal studies. They introduced a gene into rats that increased the muscle growth factor IGF-1. Within two weeks, the rats’ muscles grew by 20%, even without training.
So what is really going on? Medicine could gain valuable help from these discoveries in slowing down disease. At the same time, sport has to accept that the same tool can become a hidden weapon. Gene doping is not just a question of bigger biceps. It is a question of fairness, health risk, and whether a competition measures training or the capabilities of a lab.
Gene doping FAQ
Is gene doping the same as regular doping?
Not quite. Regular doping adds substances to the body or influences them. Gene doping tries to change how genes, or the signals linked to them, work. That is exactly why its effects can be harder to control.
Why is there so much talk about myostatin?
Because myostatin acts as a brake on muscle growth. If that brake is weakened, muscle can grow faster. Animal studies and rare human cases show why this interests athletes.
Can gene therapy also be beneficial?
Yes. Its original purpose is to help in treating diseases, for example conditions that cause muscle wasting. The problem arises when a treatment method is used to artificially boost the performance of a healthy athlete.
Translated by: Taavi Madiberk
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