Ask someone in the gym to point to their trapezius muscles, and they’ll probably gesture toward the small mounds nestled between their neck and shoulders—but that’s really just the tip of the iceberg.

Fitness Pro Superhuman Troy shares a daily trap training routine that produces noticeable thickness and strength from the very first session.

“I like to tell my clients, ‘Where the arms go, the legs will follow,’” Dane Miklaus, C.S.C.S., founder of WORK Training Studio in Irvine, California, tells Runner’s World. It’s not just a verbal cue ...