We have all had it happen. You are out for a run, or maybe you were going up for a rebound, of perhaps you were simply stepping off the curb. You feel that “popping” feeling and you say to yourself “Oh crap! I just sprained my ankle.” The worst part is there wasn’t even a reason for it to happen. You didn’t land on someone else’s foot, or fall in a hole. You were doing exactly what you always do.
These kinds of injuries are frustrating because you feel like they never should have happened. It feels like maybe your body has failed you. The thing is you are right, these kind of injuries are preventable, so what’s the problem?
The problem is not that you have “weak ankles” or that your body “failed” you. The problem is in fact neurological. There are several parts of our brain which regulate the function of our joints 
(muscles, bones, ligaments, joint capsule, etc…). We have sensory input to one part, we have motor output from another, we have postural stability in another, we could go on and on. What happens is when our posture declines from optimal these areas of the brain actually function at a less than peak level. On the day to day this may cause us absolutely no harm. We might notice some tightness in our low back or hamstrings. Maybe we are a little more “sore” than we are used to, but no changes to our daily activities is necessary.
During all this time our brain is learning about its new “normal”. Less information is being received from the spine and the joints in the arms and legs. Thus making the brain less aware of it. Now you go to step off of a curb or grab that rebound and when you go to land your brain doesn’t know exactly where your foot is in relation to the ground and you land on the side of the foot instead of the bottom resulting in the sprained ankle.
This concept can be applied to most non-traumatic musculoskeletal injuries. These are not a case of “being old” or “having weak body part x” it is the byproduct of having a neurological system that is not functioning the way it should.
So, what’s the fix? The best way to treat a sprained ankle or a low back that has been “thrown out” is to simply prevent it from happening in the first place. This is done by first optimizing static posture (this is when you are simply standing still). Once we can hold ourselves appropriately at rest we can then move into a dynamic posture or what we more commonly call “form”. Using exercises and stretches we can activate the neurological systems which will provide us with the best chance to prevent non-traumatic musculoskeletal injuries.
Your body is a complex entity with a variety of systems all functioning together. By understanding and working within these systems are able to make amazing changes in the prevention and treatment of sports injuries.