Did you know that static stretching (a stretch where you hold a position for a set time) can actually inhibit your workout performance and make you more susceptible to injury if done pre workout? It is something that people have done for years, especially in team sports and gym class settings.
Our muscles contain protein filaments called actin and myosin. These filaments form cross bridges and pull on each other during muscular contractions. This brings us to what is called the length tension relationship.
Basically, there is an ideal level of overlap between the actin and myosin filaments that is best suited for optimal movement. With a static stretch, the muscle is lengthened past this ideal level of the length tension relationship and can actually inhibit optimal muscle function. That being said, most static stretching is better to perform post workout in order to maintain, improve, and/ or restore flexibility at certain joints. However, under certain circumstances, there may be a very stiff or short joint that needs to be stretched pre workout to get it moving better. For example, there are many people who have very stiff hip flexors and performing a stretch for them pre workout can help. Everybody is different.
Moving on, dynamic stretching means moving muscles through an active range of motion. This gets blood flowing, warms joints up, loosens up stiff areas, and gets the body moving much more efficiently. Mobility exercises for the hips, thoracic spine, shoulders, and whatever is needed are performed and prime the body not only for the workout ahead, but for everyday activities.
There has been tons of research done that support the practice of dynamic stretching pre activity over static stretching. In a study done (there are lots of them) in the Journal of Strength and Conditioning Research in Sep 2008, Acute Effects of Static and Ballistic Stretching on Measures of Strength and Power Subjects by Samuel, Holcomb, and others, subjects demonstrated less lower extremity power following static stretching and performed better following dynamic stretching.
In conclusion, perform dynamic stretches before your workout and perform static stretches for areas that need it after your workout or at another time (there are certain exceptions as I mentioned before.)