Longevity

Longevity in Olympic Medalists: Competitive Edge?

Abstract and Commentary

By Nancy Selfridge, MD, Associate Professor, Department of Clinical Medicine, Ross University School of Medicine, Commonwealth of Dominica, West Indies. Dr. Selfridge reports no financial relationships relevant to this field of study.

Synopsis: Using a retrospective cohort study with passive follow-up and relative conditional survival analysis, authors demonstrated that Olympic medalists from nine major country groups live longer than the general population, regardless of country, medal, or sport.

Source: Clarke PM, et al. Survival of the fittest: Retrospective cohort study of the longevity of Olympic medalists in the modern era. BMJ 2012;345: e8308. doi: 10.1136/bmj.e8308.

Evidence suggests that regular physical exercise is a habit that confers health benefits, including reduced all-cause mortality. Several studies have suggested that higher exercise intensity and volume may correlate inversely with mortality risks. For example, in an observational study involving more than 250,000 men and women aged 50-71 years, vigorous exercise at least three times weekly combined with regular moderate exercise most days of the week was associated with a 50% decreased mortality risk.1 The Framingham Heart Study has shown that moderate and high levels of physical activity, compared to low levels, increase life expectancy for both men and women.2 In a meta-analysis of 33 observational studies (102,980 participants) analyzing risk of all-cause mortality related to cardiorespiratory fitness (CRF), subjects with low CRF had an increased risk of all-cause mortality compared to those with high CRF (relative risk [RR], 1.7; 95% confidence interval [CI], 1.5-1.9) and intermediate CRF (RR, 1.4; 95% CI, 1.3-1.5).3 These data certainly beg the question whether a longevity advantage exists in the most elite of athletes. Clarke et al analyzed a remarkable database to determine whether Olympic medalists live longer than the general population.

The authors constructed a retrospective cohort study using a database created in the 1980s by an international consortium of Olympic historians and statisticians, called OlyMADMen, which has been collecting data on all Olympians. OlyMadMen is stated by the authors to be regarded as the most authoritative source of information on Olympians. Resources for this database include official Olympic records, other official public records and sources, books, newspaper and magazine articles, interviews, obituaries, and international professional sporting organizations. The OlyMADMen database contains information on 118,442 athletes who participated in 27 summer and 21 winter games held between 1896 and 2010. The authors chose to analyze data from nine country groups (United States, Nordic countries, Russia, Germany, United Kingdom, France, Italy, Australia and New Zealand, Canada), accounting for 63.8% of Olympic medalists during this time period. They excluded medalists with missing birthdates. Those medalists who represented more than one country or won more than one medal were classified based on their status when they won their first medals. Survival among medalists was calculated using an actuarial technique by Tallis et al, which removes bias in survival estimates occurring because of missing data due to unidentified loss of follow-up. In the article, these authors demonstrate that if a conditional variable is chosen for their formulas that is greater than median survival, their formulas will yield data uncontaminated by lost information, as long as unidentified loss to follow-up does not exceed 10-15%.4 For this reason, Clarke et al chose 60 years for their conditional variable. Estimated loss to follow-up was made on OlyMADMen data before 1928 and was determined to be about 8%, well within the acceptable range for these analyses. Relative survival, then, was calculated using publically available life tables for the general population from each country group, matched by birth year, sex, and age. After overall relative conditional survival was calculated, relative survival by country group, medal, and sport was determined.

Being an Olympic medalist appears to confer a longevity advantage in this study. At 10 years, 2% more of the medalists were alive compared to the general population, which is a relative conditional survival of 1.02 (CI, 1.01-1.02). At 30 years, 8% more of the medalists were alive (1.08; 95% CI, 1.07-1.09). Medalists lived, on average, 2.8 years longer than the general population. Survival advantage occurred in all country groups except Canada. There was no difference in survival advantage when medalists were grouped according to medal won, nor was there any difference in survival advantage when medalists were grouped by sport category (endurance, mixed, power).

Commentary

Though these findings support the notion that being an elite athlete confers a survival advantage, they do not tell us why. The authors offer a few hypotheses. Assuming that the physical activity and fitness levels of elite athletes are at the extreme end of the spectrum, they at least should enjoy the statistical advantage, noted previously, for vigorous physical activity. The 2.8 year average survival increase noted in this study is consistent with the Framingham Heart Study findings that high levels of physical activity increase life expectancy for men and women at age 50 by 3.7 and 3.5 years, respectively.2 It might be assumed that athletes continue a higher than average level of physical activity throughout their lifetime, even though their time in intense training and competition is a relatively small proportion of the lifespan. The genetic advantages that predispose to high levels of sports performance may confer a longevity advantage, irrespective of training and exercise activities. Athletes may have better health habits in general: lower smoking rates, better diets, more effective stress management. Finally, the fame and fortune that success in competition confers on many elite athletes may elevate socioeconomic status, a condition associated with lower mortality. However, there were no survival differences between gold, silver, and bronze medalists, even though celebrity status certainly differs between them in modern society.

This study has to be applauded for its large scale and the comprehensiveness of the OlyMADMen database it used. Loss of follow-up data was estimated as relatively low by the authors, but if it was indeed higher, the conditional survival results for the medalist cohort could be significantly overestimated. An oversight in the reporting occurred: Although the authors stated that survival advantage was present in all country groups except for Canada, they failed to include U.S. medalists in their relative conditional survival statistics in the results section of the article. An “Olympic effect” could not be isolated in this study design, as the comparison group was the general population rather than a non-competitive group of elite athletes. Despite these limitations, this study reinforces the existing evidence that higher levels of exercise and fitness confer a survival advantage. This information may not affect our exercise recommendations for the majority of our patients, but it can be a bit of ongoing encouragement for those individuals who wish to initiate or continue athletic training and competition.

References

1. Leitzmann MF, et al. Physical activity recommendations and decreased risk of mortality. Arch Intern Med 2007;167:2453-2460.

2. Franco OH, et al. Effects of physical activity on life expectancy with cardiovascular disease. Arch Intern Med 2005;165:2355-2360.

3. Kodama S, et al. Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women: A meta-analysis. JAMA 2009;301:2024-2035.

4. Tallis GM, et al. The analysis of survival data from a central cancer registry with passive follow-up. Stat Med 1988;7:483-490.