This is the formula for your happiest workout yet

A professor from Fukuoka University in Japanrun wants you to calculate your run pace using the "smile" formula. Here's how to find your ideal speed now.

alt
Photo: Getty Images/Blends Images and Erik Isakson

The Surprising Way to Strengthen Your Hip Joint, According to Experts

Hint: Giving that ball and socket some love doesn't always mean more stretching.