Tightening up after a run is normal. A muscle that has no input from your nervous system is completely flaccid (this is what happens with paralysis). Running requires the body to become an efficient spring. To achieve this, the nervous system (brain) creates increased tension and set points in the muscles used for running. This set tension is very useful for running, but not so useful when it carries over to the rest of your life. This dynamic cool down routine will help reset your brain so you can leave that muscle tension at the end of your run instead of carrying it with you into the rest of your day. Doing it with deliberate attention and pace, is critical to success.
Use this as a base routine. It is designed to be quick, easy and comprehensive. Extend, repeat and add variations to each move as much as you would like based upon time available and what feels good to you as you go through the routine.