Performance enhancing substances


Given that the Tour de France is on at the moment and the Olympics are right around the corner I thought that I would address performance enhancing drugs (PES), commonly referred to as “doping”.

Two interesting facts became obvious when researching this topic. One: elite and professional athletes are not the number one users of PES, it is in fact amateur athletes and body builders; and two, due to research ethics, much of what is known comes from post-mortem data or interviews with users. However another interesting problem is that most PES became known around the 1980s and 1990s, meaning that there are very few records of long term use and their effects.

 What are the common types of PES?

There are two main types – drugs that increase muscle mass while reducing fat mass; and ‘blood boosters’, which deliver more oxygen to muscles improving endurance and recovery.

The first group includes anabolic steroids, growth hormone, insulin and beta-blockers, as well as some amphetamines.

The second group, blood boosters, includes erythropoietin (EPO).

So why are PES bad? First of all, there is the moral aspect. Having some athletes taking PES while others do not, does not make for an even sporting ground. The second, is that there can be serious side effects of PES use.

Anabolic steroids

Anabolic steroids, or androgenic anabolic steroids (AAS), refer to male sex hormones. In this case I will discuss testosterone. A hormone is a chemical that acts to induce changes in organs to regulate physiology and behaviour, and AAS promote the development and maintenance of characteristics common to men such as increased muscle mass and strength, as well as hair growth. AAS can also increase oxygen transport and neuromuscular transmission. Sounds good, right? Who doesn’t want that!

However, side effects include severe cardiovascular, neuropsychological, hormonal and metabolic problems. In the majority of cases, heart size is increased leading to a heart attack, but the hormones can also change cholesterol levels meaning that heart attacks and other cardiovascular problems can be induced by the high cholesterol.

There is tentative evidence that AAS can induce mood disorders and hypermanic behaviour (also known as ‘roid rage), but the unreliability of field studies make it difficult to confirm. Animal studies do show that there are changes in defensive and offensive aggression, dominant behaviour and anxiety.

There is evidence though, that neuropsychological effects are influenced by mental health status, age and gender. Again, most of this data comes from field studies and has its limitations.

It has also been shown that AAS can become a drug of dependence and therefore has the symptoms of withdrawal.

Other side effects include: kidney problems, liver toxicity (not common), tendon ruptures, infertility, gynecomastia (breast development in men), sexual dysfunction, hair loss, acne and testicular dystrophy.


EPO is a hormone that regulates red blood cell (RBCs) production. Therefore, with increased RBCs comes more oxygen delivery to and uptake by muscles. This improves muscle endurance and recovery.

The side effect of this however, is thicker blood. This leads to blood clotting, heart problems, stroke and renal failure.

It was the discovery of EPO use in professional cycling, in particular in 1998, that led to the formation of the World Anti-Doping Agency (WADA) and has been implicated, posthumous, in the deaths of 18 profession cyclists between 1980-1990.

The most famous doping case is that of Lance Armstrong (and his team US Postal Service), which lead to an in-depth investigation of doping in the Tour de France (TdF) including over 1000 witness testimonies. The conclusion of WADA and of other independent researchers into PES usage is that there is a ‘code of silence’ amongst athletes which means that PES use often goes  (and continues to go) unchecked.

“The USPS Team doping conspiracy was professionally designed to groom and pressure athletes to use dangerous drugs, to evade detection, to ensure its secrecy and ultimately gain an unfair competitive advantage through superior doping practices. A program organized by individuals who thought they were above the rules and who still play a major and active role in sport today.”

Statement From USADA CEO Travis T. Tygart Regarding The U.S. Postal Service Pro Cycling Team Doping Conspiracy Statement (released 10-10-12 at 9:30 AM Mountain Time).

Testing for PES

Tests are based on differences between endogenous (our naturally produced) and exogenous (produced artificially) hormones. For testosterone, this includes looking at the ratio of testosterone to epitestosterone (a metabolite that is not produced by exogenous testosterone) in the urine. Other tests can include exceptionally high testosterone levels in the blood. For EPO, urine tests are also used, as well as other small molecules that can be altered from high EPO, indicating usage.

The problems with these tests are natural deviations in levels of the hormones and metabolites between individuals, the fact that levels can return to normal within a number of days, and the increased use of masking agents.

An interesting side note is that the USPS team scandal included taking blood from cyclists during high altitude training sessions (high altitude increases RBCs), storing blood and then administering prior to the TdF. This meant that no ‘exogenous’ source could be detected as it was the cyclists own blood.

It is obvious that when sponsorship money, fame and glory are at stake, along with natural human competitiveness, there will always be a select few who are willing to use PES. It is the conclusion of researchers that in order to overcome this, the ‘code of silence’ needs to be broken, as well as improving detection methods.


Pope Jr, Harrison G., et al. “Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement.” Endocrine reviews 35.3 (2013): 341-375.

Momaya, A., Fawal, M., & Estes, R. (2015). Performance-enhancing substances in sports: A review of the literature. Sports Medicine, 45(4), 517-531. Retrieved from

Cadwallader A.B and Murray B, International Journal of Sport Nutrition and Exercise Metabolism, 2015, 25, 396 -404


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