A new wave of research is showing what the old gym myths about stretching got wrong—and what you really need to do to reap its benefits.

Proprioceptive neuromuscular facilitation (PNF) is a form of assisted stretching. It combines passive stretching with muscle contraction. First, your partner applies force to stretch your muscle ...

The subscapularis is a muscle in your shoulder that helps you internally rotate your arm. When your arm is internally rotated, it means that your palm is facing back, behind your body. The ...