There's no denying that the 162-game MLB regular season takes a physical toll on the body. For more than six months, big leaguers are tasked with playing nearly every day with just a handful of off days sprinkled throughout. That toll is worsened for players who occupy the most physically demanding position on the diamond: catcher.
Most big league backstops have a counterpart who generally covers roughly a fifth of the team's games. Occasionally, the backup catcher will match up with one of the five starting pitchers and catch their start every five games. Other times, the backup is reserved for day games after night games, or used to give the primary catcher a game as the designated hitter.