Deep, Superficial Fascial Release
Performing an Active Isolated Stretch of no longer than two seconds allows the target muscles to optimally lengthen without triggering the protective stretch reflex and subsequent reciprocal antagonistic muscle contraction as the isolated muscle achieves a state of relaxation. These stretches provide maximum benefit and can be accomplished without opposing tension or resulting trauma.
LING: http://www.stretchingusa.com/active-isolated-stretching