Tight end Rob Gronkowski's contract with the New England Patriots has language that allows the team to prevent him from "engaging in any activity other than football which may involve a significant risk of personal injury," according to a report by Ben Volin of the Boston Globe. That's about as specific as the clause gets.

The San Francisco 49ers are more specific in their contracts while defining the types of activities that aren't allowed. Volin reports that, according to copies of the new contracts signed by Jimmy Garoppolo and Richard Sherman, 49ers players are not permitted to engage in the following activities.

  • Skydiving
  • Hang gliding
  • Rock or mountain climbing
  • Racing of any kind including as a driver or a passenger
  • Motorcycling
  • Use of any off-road or all-terrain vehicle
  • Professional wrestling
  • Boxing
  • Firearms
  • Scuba diving
  • Jet skiing
  • Surfing
  • Bungee jumping
  • Diving
  • Snow or water skiing

That's a pretty extensive list. "Gronk is lucky he doesn't play for the 49ers," writes Volin.