Seniors who run regularly are able to maintain their "fuel economy," according to the study.
Harold Bach only started seriously running in his 70s.
He started running for stress relief.
Leo Lightner started running in his 50s and now competes in marathons and ultramarathons.
One AARP blogger says it comes down to non-strenuous workouts.
He's nearly 40, but that doesn't mean the former marathon world record holder is finished with the sport.
Your lungs and legs may be just as efficient as they once were.
She hadn't run her first marathon until she was 86.
As marathoners reach their 80s and 90s, the 26.2-mile distance becomes increasingly difficult.