This soleus muscle may get less glory than the gastrocnemius—but it’s actually way more powerful. Here’s how to strengthen it and rev up your running.

Fartleks are a well-known and popular running workout—or at least they’re something runners talk about all the time. The ...

Ever wonder why some people seem to pack on muscle effortlessly while others spend months in the gym with little show for it?

Former seven-time Mr. Olympia Arnold Schwarzenegger discussed why intentionally slow reps don't lead to more muscle growth.