Three reasons to do ... single leg arm curl

The move: Single leg arm curl

Three reasons to do it now:

• You'll hone your balance: "Adding an unstable element to the traditional bicep curl makes this a more sport-specific exercise because nearly every sport requires a single-leg stance at some point," said Tom Holland, author of "Beat the Gym."

• It builds coordination: Doing two completely different actions with your upper and lower body is trickier than you may realize. But it'll payoff: Balance and coordination are essential in sports that call for sudden starts and stops like soccer, basketball and lacrosse.

• It'll help you break out of a rut: How many bicep curls have you done in your lifetime? That's what we thought -- lots! Over time, exercises become less effective because your body adapts. Finding new ways to challenge your muscles (like lifting one leg here) jump starts your body's response.