AMSTERDAM – French bicyclists who have competed in the Tour de France have a 41% lower mortality rate, compared with the age-matched male French general population, according to a first-of-its-kind study carried out on the 100th anniversary of the world’s most venerable professional bike race.

Causes of death were consistently lower across the board among the ex-racers. They had a 33% reduction in mortality owing to cardiovascular diseases, a 44% decrease in fatal cancers, a 72% reduction in deaths from respiratory disease, and a 78% decrease in deaths from digestive diseases, compared with controls. The sole cause-of-death category that was not significantly less common among the former Tour de France athletes was trauma, mostly from bike or auto crashes, Dr. Xavier Jouven reported at the annual congress of the European Society of Cardiology.

The study included all 786 French professional bike racers who competed in the Tour de France during 1947-2012. They participated in a mean 2.5 tours. By 2012, there had been 208 deaths.

The mortality advantage favoring the ex-racers was consistent across all 5-year age groups. It’s estimated that the Tour de France participants are averaging a 6- to 7-year greater longevity than do other Frenchmen, according to Dr. Jouven of Georges Pompidou Hospital, Paris.

He confessed to being surprised by the study results. He had anticipated finding an above-average mortality rate in the ex-racers because of the deleterious long-term effects of the various performance-enhancing drugs widely used over the decades, coupled with the sheer physical grind of participating in an event described as similar to racing a marathon per day for nearly 3 weeks and the crashes that are part of the job description.

"If there was really a danger in doing high-level exercise, then we should have observed an increased mortality rate. That’s actually what we’d expected to find," the cardiologist said.

The cyclists’ mortality reduction was consistent across all eras of the race: the 1950s and 1960s, when the use of amphetamines was common; the 1970s and 1980s, when anabolic steroids were the performance-enhancing drugs of choice; and most recently, the era of erythropoietin and human growth hormone, he noted.

The study was restricted to French cyclists because the investigators knew they could capture every single death through French registries.

Discussant Sanjay Sharma took issue with Dr. Jouven’s interpretation of the Tour de France data, which he said do not really address one of the hottest controversies in all of sports medicine: Is too much exercise cardiotoxic?

"I would like to have some data on comorbidities. I would like to have known how many of the surviving individuals have atrial fibrillation, compared with the general population. How many have implanted pacemakers? I would urge the investigators to go back and look at the survivors and produce [these] very important data," said Dr. Sharma of St. George’s Hospital, London.

He added that he was unimpressed by the investigators’ choice of a comparison group.

"They have compared possibly the fittest human beings in the world, people who are probably genetically, physically, physiologically, and psychologically superior to the general population, in which there is of course a much higher burden of comorbidities, a higher burden of risk factors for cardiovascular disease, a higher burden of adverse lifestyle, as well as a lower socioeconomic class. So I don’t believe that the Tour de France per se increases longevity of life; what I believe they have shown is, if you are capable of doing the Tour de France, then you may live 6-7 years longer than the average individual in the community," the cardiologist continued.

The benefits of physical exercise in the range of 40 metabolic equivalents (METs) per week spread over five or six workouts are well established. This level of exercise confers a 40%-50% reduction in cardiovascular mortality. But elite endurance athletes exercise at intensities 10- to 20-fold greater than that.

"There is emerging evidence that too much exercise may be deleterious to the heart," according to Dr. Sharma. "We know that marathon runners have high circulating markers of cardiac damage. Animal studies show increased inflammation and fibrosis within the myocardium. Recent cardiac magnetic resonance imaging studies have shown fibrosis in veteran athletes, and [electrophysiologists] continue to talk about the high prevalence of atrial fibrillation amongst veteran athletes."

Dr. Jouven’s presentation was big news in daily newspapers across cycling-crazy Europe. Simultaneous with his report on the Tour de France study in Amsterdam, the findings were published online (Eur. Heart J. 2013 [doi:10.1093/eurheartj/eht347]) with an accompanying editorial coauthored by Dr. Sharma (Eur. Heart J. 2013 [doi:10.1093/eurheartj/eht373]).

Neither cardiologist had any relevant financial interests. The study was funded by a research grant from the Sudden Death Expertise Center in Paris.

bjancin@frontlinemedcom.com

Tour de France riders live longer