Is your workout routine getting stale? Pep it up with one of these incredible fitness stories in the new book from Ripley's Believe It or Not! called Enter If You Dare! The book is an annual collection of unusual, unbelievable and amazing stories from around the world. Here are a couple of the book's unusual fitness stories:

Knuckle Buster: Mick Gooch must have the strongest finger in the world. The martial arts expert from Kent, England, is capable of 17 one-armed, single-fingered push-ups on the head of a nail.

Human Weights: In January 2009, a gym in London set up weight-lifting machines using people as weights. The five people - ranging from a 66-pound man to one weighing 340 pounds - not only helped gym goers visualize the weight they were lifting, but also shouted words of encouragement.

Mountain Bike: Extreme yoga artist Khiv Raj Gurjar from Jodhpur in Rajasthan, India, balances in extraordinary positions on his bicycle just inches from the edge of rocky outcrops 300 feet high.

Stiletto Sprint: At a race in Nanning, Guangxi Province, China, all the runners wear high heels - both men and women! Male runners must wear shoes with heels at least 3-in high, while women have to run in 4-in (10-cm) stilettos because they are more used to wearing high heels.

Plane Crazy: In perhaps the greatest feat of strength ever, Rev. Kevin Fast from Cobourg, Ont., pulled a giant Globemaster airplane weighing 416,000 pounds - the weight of more than 50 African elephants - for 29 feet across the runway at an airbase in Trenton in 2009.