In order to lay the ground work for the question in the post title, we first must explain the concept of Altered Neurodynamics. 

When we think about movement, we think about how our muscles contract and relax to allow movement to happen.  But what about all the other connective tissue in the body? Do they stay in place?  Consider nerves, they too glide within there nerve beds as we move which prevents us from having sciatica symptoms every time we bend to pick something up.  

But just as muscles can become tight or have increased tone, nerve tissue can become “trapped” within there nerve beds.  When this happens it is called adverse neural tension. The nerve itself no longer slides and glides properly and causes pain within the distribution of said nerve.  

Outside of structural damage like a herniated disc or inflammation to an area, adverse neural tension can be caused by excessively stretching neural tissue.  Yes you read that correctly, if you excessively place tension through the nervous system (especially continuously) you can cause pain. 

In order to maximally stress our nervous tissue, we must stretch the nerve from both sides.  For example, flexion of the neck and spine as well as extension of the knees and DF of the ankles will place the greatest strain on your sciatic nerve. 

This looks very similar to something called a seated hamstring stretch or the sit and reach test. And as badly as you want to touch those toes, that awful feeling in the back of our knees or calves is not a muscle being stretched but rather our sciatic nerve being pulled on.  

So back to the question, are you really stretching your hamstrings?  The question is, where do you feel your stretch?  If it is in the back of the knee or calf and not the hamstring itself, then no, you are not stretching your hamstring but rather your sciatic nerve.  If you feel it in your hamstring and no where else, then you are effectively stretching your hamstring, congratulations. 

We would caution you to continue to stress the nerve tissues when stretching your hamstrings. This is because just like with all things, if you do it too much you can overload the tissue and cause dysfunction and pain.

So how do we effectively stretch the hamstrings if you are feeling tension in the calf?  Just simply add a slight knee bend.  This will take the pressure off the nerve and place it back on the muscle where we want it.  

– Happy Rehabbing!