Why not use an ab wheel to work muscles harder during planks? It's a good way to change things up and the variation challenges balance and stability, activating muscle groups all over the body.

Which ab wheels are best? Often considered a difficult part of the body to exercise and define, abdominal work can be tedious. Yet, the results are rewarding. If you want to strengthen your muscles ...

"Hearst Magazines and Yahoo may earn commission or revenue on some items through these links." Reviewers rave about the product, too. One shopper called it a “game changer for core workouts,” and ...