Starting from around 16 years of age with a ruck sack of around 15Ibs - 20Ibs - a practitioner should start running over various types of terrain, and for different distances at various times of the year. The point is to 'sweat' and a number of clothing layers should be worn. This practice is a combination of weight-lifting and running. As the body (and mind) strengthens, the weight should be slowly increased. As a grown man, the weight should reach 56Ibs (perhaps 40Ibs for a woman) - but temporary increases up to 76Ibs can be used for short periods. Distances should vary from 1.5 miles to 5 miles on paved roads, but it is also good to run on grass and occasionally on sand. Much longer distances can be used if running is replaced with hiking. If a practitioner is only just beginning to get fit, or is recovering from injury or illness, always start by walking over a certain distance. It is a good idea to lift free weights for a time prior to ruck sack running so as to build the bones, muscles and joints, and to practice ordinary running (and periodic sprinting) to condition the cardiovascular system. For many, just 'wearing' the iron vest for any extended period of time is very difficult to do, and creates substantial muscular pain in the neck, shoulders and back, as well as in the knees, ankles and various parts of the feet. This is normal and will pass. Just as the iron vest compresses the body - the structures of the body 'resist' and generate an outward counter-pressure - which generates a substantial repelling force. This is how the body withstands and rejects any incoming power. Furthermore, carrying this weight forward generates tremendous 'forward' momentum which is very difficult for an opponent to 'stop', and which has the effect of 'uprooting'. All the blood vessels are opened and strengthened through a stimulated circulation, the bones are hardened and the both strengthened and relaxed in a coordinated and dynamic manner. The mind becomes calm and all expansive as the qi (vital force), jing (essential nature) and shen (all embracing empty mind) are thoroughly cultivated.
Shifu Adrian Chan-Wyles (b. 1967) - Lineage (Generational) Inheritor of the Ch'an Dao Hakka Gongfu System.