Boston investment manager Jim Pallotta is making a multimillion-dollar bet on sweat, mud, and adventure.

Pallotta’s firm, Raptor Capital Management, is investing in Spartan Race Inc., which runs a new breed of obstacle-race events that involve climbing walls, slogging through mud, and crawling under barbed wire. Raptor is looking to capitalize on a craze that’s attracting about two million participants yearly to events around the world.