Stretching:

Often disregarded as an exercise of the weak, stretching is a key ingredient to mastery of any sport. Stretching decreases chances of injury, increases flexibility, and helps blood flow. Parkour demands flexibility and fluid movements, none of which can be performed satisfactorily without stretching. Stretches as simple as the one depicted here help dramatically. Whether it be hand stands or vaults, stretching gets it done.

Thanks to garryknight for the pic

Live Hardcore, Christoph