Acute effect of a ballistic and a static stretching exercise bout on flexibility and maximal strength.
Consequently, static stretching may not be recommended before athletic events or physical activities that require high levels of force. On the other hand, ballistic stretching could be more appropriate because it seems less likely to decrease maximal strength.
So don't do static stretching before your exercise......it makes you weaker. Ballistic stretching could be OK however.
Mike Nelson has been saying the same thing recently.