Can running become its own addiction? One gruesome study showed that rats love running so much, they can actually run themselves to death. When offered food for only one 90-minute period per day, the rats in the control group (without an exercise wheel) soon learned to adapt, taking in all the calories they needed during that meal. Rats with running wheels, however, ran more and more every day while eating less and less. They eventually starved to death. Some of ultrarunning’s
