A new study has found that American runners are getting slower—in the 5K, 10K, half-marathon and marathon. Led by Jens Jakob Andersen and Ivanka Andreeva Nikolova from RunRepeat.com, the team looked at data from 24,763,389 race results between 1996 to 2016.
According to NPR, based on their research, results from 2015 and 2016 are the slowest in history. Andersen and Nikolova were quick to dispel three possible answers: 1) the increase in women racers; 2) the boost in participants who choose to sign up and walk the race versus run; 3) slow runners are getting slower.
So if these aren’t the case, what is? They believe it is the decline in health among Americans.
The authors told NPR:
“We correlated the average race finish time with each of those parameters and saw clear trends. These correlations proved to be strong, 99 percent statistically significant, consistent, plausible, coherent and replicable in different circumstances.
Nevertheless, these are just correlations. We cannot infer from the national statistics the health condition of the race runners. Is it deteriorating or improving? Also, in no way we argue that these are the only possible explanations and reasons for the observed effect.”
NPR hopes the team will repeat the study among runners in other countries—especially those without rising health epidemics such as obesity—to find out if this is truly the answer.