Viagra For Athletic Performance

A bout a year ago, Chicago Bears receiver Brandon Marshall set off a firestorm of speculation, expert opinions, and laughs when he told a reporter, “I know guys, it’s such a competitive league, and guys try anything just to get that edge. I’ve heard of guys using Viagra, seriously, because the blood, it’s supposed to thin.. I don’t know. Some crazy stuff.” Questions arose as to whether football players or other athletes actually used Viagra as a performance enhancing drug. But the bigger question, regardless of whether or not athletes used it, was whether or not Viagra even had the potential to enhance athletic performance.
Several studies have been performed to determine just that. Some show improvements in performance (but only at high altitudes) while others show no improvements at any altitude, casting a doubt on the benefits of Viagra in sports.
What’s the Science?
Sildenafil, the active ingredient in Viagra, works by expanding and relaxing the blood vessels in the penis. This allows an increased blood flow to the penis and results in an erection. Sildenafil has also been shown to have similar effects on the blood vessels in the lungs. For this reason, it is sometimes used to treat pulmonary arterial hypertension, or high blood pressure in the lungs. It was approved for this use in 2005. By expanding the pulmonary blood vessels, sildenafil reduces the pressure and allows for better blood and oxygen transport within the lungs.
Could this beneficial effect on the lungs help athletes perform better? That’s what scientists at Stanford University and the University of Miami decided to investigate. Both research teams used similar study protocols, but came to different conclusions.
Potential Benefits at High Altitude.
The team from Stanford studied the effects of sildenafil on cycling time trial performance among trained male cyclists and triathletes at either sea level or simulated high altitude. In high altitude conditions, when there is less oxygen in the air, blood vessels in the lungs constrict and less blood (which carries oxygen) is circulated through the arteries to the heart and working muscles. The authors hypothesized that under these conditions, sildenafil would have the greatest effect. They believed that sildenafil would help the pulmonary blood vessels expand and relax, and allow greater blood and oxygen to circulate to working muscles, therefore improving exercise performance.
The participants in the study performed both moderate exercise and a time trial (10k at sea level and 6k at high altitude) after either taking no pill, a placebo pill, or sildenafil. At sea level, no differences in performance were seen between taking sildenafil and not taking it. At high altitude, however, four of the men showed increased oxygen content of the arteries and great improvements in their time trials when taking sildenafil. The remaining six men showed no improvements. The four men who did see improvements were the same men who had been most negatively affected by the high altitude to begin with. This indicates that for athletes strongly affected by high altitude, sildenafil may counteract some of these negative effects and improve athletic performance. The authors concluded that sildenafil may improve athletic performance for certain people at high altitude, but not at sea level, where most athletic competitions take place.
No Benefits at Any Altitude.
Researchers at Miami performed a very similar follow-up study a few years later. They too used trained cyclists and triathletes of a similar age but included women. The participants performed moderate exercise and a 15k time trial this time, at either the same high altitude as the Stanford study, or a more moderate altitude. While the authors expected to see performance improvements with sildenafil at high altitude, the results showed no improvements in time trial performance at either altitude among participants taking sildenafil. Under high altitude conditions, the participants did have increased oxygen content in their arteries, but this did not translate to faster times. The authors concluded that sildenafil does not appear to have a performance enhancing effect, even among athletes at high altitude.
Conclusions.
You may be wondering how studies of cycling time trials at high altitude can be applied to football players at sea level. Kevin Jacobs, one of the researchers from Miami, admits that these types of studies haven’t really been done using football players. However, high altitude conditions are where the effects of sildenafil are most likely to be apparent. In addition, middle-distance cycling time trials were used because this kind of submaximal exercise performance is more dependent on oxygen delivery than shorter bursts of high intensity exercise, such as seen in football. If cyclists performing middle distance time trials at high altitude don’t even see reliable performance enhancements from sildenafil, it is very unlikely that football players who typically play at lower altitudes would see any benefit from sildenafil. In the same article, Jacobs told reporters that “whatever benefit they think they’re getting is probably more psychological than anything.”
And what about the obvious questions: wouldn’t we be able to see if athletes were using Viagra? And how much could they expect to improve their performance if they have to play football with erections? While neither of the studies reported the incidence of erections during the trials, Mark Stoutenburg, another Miami researcher, told the Miami Herald that none of his subjects had gotten erections during testing. Apparently, sexual stimulation is necessary for sildenafil to have an effect on blood flow to the penis.
While Marshall’s statement definitely created a buzz in the sports world, the credibility of Viagra as a performance enhancing drug hasn’t been proven. There is a chance that for some athletes who are particularly negatively affected by high altitude, sildenafil could help them when competing at high altitudes. But for the majority of athletes, who compete at altitudes much lower than in these studies (the highest point of the Tour de France is still below the simulated high altitude conditions), Viagra will likely have no positive effect on performance (at least not athletic performance). This conclusion is echoed by the World Anti-Doping Agency, which does not include sildenafil on the Prohibited Substances List.