Trainer Tip #21: Want greater fitness? Consider this vitamin.

Concentric muscle action: When a muscle is exerting greater force than the resistive force, resulting in shortening of the muscle. Eccentric muscle action: An a muscle develops tension while lengthening. Don’t understand the difference between concentric and eccentric? Think of a bicep curl: When you curl your arm up, that is the concentric motion. When…

Trainer Tip #10: Sitting for long periods of time? Make sure to stretch your hip flexors, which are a group of muscles that allow your leg to concentrically accelerate hip flexion and external rotation. (In layman’s terms: they allow you to do things like sit and walk. Kind of important.) Two ways to stretch these…

Line ten people up and ask them to show you a plank. More than likely, most of them know their toes or knees should be on the ground. But some will hold themselves up on their hands, and others on their elbows. What’s the difference? The difference lies in which muscles you want to activate…