“Take having tight hamstrings as an example. If you have not trained your low back to hinge correctly, your core muscles are weak, or your hips are unstable, your nervous system will slam on the breaks when you try to touch your toes. It knows that if you extend all the way down to maximum hamstring muscle length, you’ll be open for all sorts of injuries. This is called protective tension. In this scenario, short hamstring muscles aren’t the problem. It’s lack of strength and stability through the midsection. For most people—especially nonathletes—this is often the case.”