Is it possible to have too much of a good thing? Dr. Sanjay Gupta breaks down what research says about long-distance training and neurodegenerative diseases. Plus, he reports on which type of field is safer for young athletes to play on: turf or grass. This episode was produced by Jesse Remedios. Showrunner: Amanda Sealy Medical Writer: Andrea Kane Senior Producer: Dan Bloom Technical Director: Dan Dzula Learn more about your ad choices. Visit podcastchoices.com/adchoices