For context, the difference in an average person's athletic performance in sports physiology tests varies by at least 5 percent from day to day, Foster said.
The average person with a 9-to-5 job may never reach Olympic heights, but they don't have to: 30 minutes of moderate activity most days of the week is enough to do wonders for the body, reducing the risk for cancer, heart disease, diabetes - "the big stuff that kills everyone now," Foster said.
"The big things happen early," he said. "That's the good news."
Adding time and intensity improves fitness, Foster said, but the curve has diminishing returns. Olympians train six or seven hours a day, because a gain of one-hundredth of a second could mean everything; for weekend warriors, that kind of fixation would be overkill.
But average people can learn something from their Olympic heroes. From curlers to bobsledders to figure skaters, all Olympians regularly hit the weight room. Strength training prevents injuries and underpins the other aspects of fitness, said Scott Caulfield, the head strength coach at the National Strength and Conditioning Association and for the Colorado College hockey team. That's especially true as people age, he said.