If you've spent any time in a gym, yoga studio, or physical therapy clinic, you've probably heard the words mobility and flexibility used interchangeably. But they're not the same thing — and understanding the difference could be the key to moving better, avoiding injury, and unlocking the full potential of your body. In this post, we'll break down exactly what mobility and flexibility mean, how they differ, and how to train both for a healthier, more functional body. What Is Flexibility? Flexibility refers to the ability of a muscle or muscle group to lengthen passively through a range of motion. In simpler terms, it's how far a muscle can stretch when an external force — like gravity, a strap, or another person — is applied to it. Think about a classic seated hamstring stretch. When you reach toward your toes and feel a pull in the back of your thighs, that's your hamstring flexibility being tested. The muscle is being elongated, but you're relying...