Psst: it's not another plank.

Flexion and extension refer to directions of motion that affect the angle of a joint. Flexion is when the joint is closed, while extension is when it is opened. Flexion and extension are the two ...

Whether you’re in your 20s building the foundation of your health and fitness or over 40 working to fight off muscle loss from age-related ailments, increasing muscle mass can be beneficial. Building ...

Skeletal muscle is the type of muscle that controls movement. Problems with these muscles can be minor, life-threatening, or ongoing problems that make it hard to perform basic daily activities.

The best moves, plus ideal reps, sets, and weight.