Does playing tennis make you live 9.7 years longer?

A widely circulated claim that playing tennis can extend life expectancy by 9.7 years originates from a Mayo Clinic study of 8,000 Danish participants over 25 years. While the study utilized Cox Proportional Hazards Regression to adjust for socio-economic confounding factors—such as wealth and education—medical statistician Adam Jacobs highlights significant limitations that undermine the headline figure. The tennis-playing subgroup was exceptionally small, consisting of only 111 individuals in the adjusted analysis with just 16 recorded deaths, creating a high margin for error and potential random variation. Furthermore, 80% of these tennis players also engaged in other activities like cycling, suggesting that the observed longevity may stem from a diverse exercise regimen or general athleticism rather than tennis alone. Ultimately, while the data confirms the benefits of an active lifestyle, the specific 9.7-year gain remains statistically tenuous due to small sample sizes and overlapping variables.