From core strength to full-body endurance, this winter sport works muscles you didn’t even know existed.

Hitting the pavement is, unsurprisingly, most runner’s go-to cardio workout, but introducing cross training into your weekly routine can be a game-changer in improving performance and reducing injury.

Jakob Roze, CSCS, is a health writer and high-end personal trainer. He is the founder and CEO of RozeFit, a high-end concierge personal training practice and online blog. Body-weight exercises are ...