Stretches before exercise and warming up prior to any type of full body workout routine is is essential to avoid injuries dynamic stretches and flexibility stretches can dramatically help reduce the risk injury.

Notice, the rapid pull apart of the elastic band
results in an immediate snap. However, the elastic band constantly
being stretched continues to increase its max breaking
point.
This
is much like the muscles and ligaments of our bodies. Heat flows via
the blood being past through our body and as a result warming up all
the parts used for exercise which helps bring relaxation to muscles and
joints.
This also reduces the possibilities of pulling or aggravating a muscle or joint as they tend to become more elastic during the warm-up phase of your workout.
While the physical benefits of dynamic stretches and flexibility stretches are obvious, there are also mental benefits to your pre-workout warm-up. The warm-up routine helps to focus the mind on the task that lies ahead and leave other distractions from work, school, sports etc. behind you.
Post warm-up, the body and mind should be fully
prepared to take on the goal at hand whether it be complete every rep
with perfect form or to endure every last minute of your work-out.
Your warm-up and cool-down stretch before and after your workout respectively should follow a head-to-toe procedure. Starting with neck and continuing down through to the ankles.