The Macrocosmic Orbit (or Great Heavenly Circulation (Da Zhou Tian (in Pinyin))) is basically an extension of the Microcosmic Orbit through the legs and arms. Practice this after you've been working with the Microcosmic Orbit for some time - as well as some of the moving Chi-gung forms. You will find that this meditation will make standing and moving Chi-gung forms all the more charged up and powerful.
As you direct your Chi flow beyond the Microcosmic Orbit and into the legs and arms you don't need to worry about the precise route - though over time you may tune into particular channels or choose to refine your route of circulation in one way or another. the primary distinction here will be on whether you're moving the Chi through either the inside (Yin) (Yang) or the outside sides of the arms and legs.
While the Macrocosmic Orbit will work well with standing and moving practices it is best to first practice it in a relaxed sitting position. And as with any meditation method sitting practice will always be useful for reaching deep levels of the Macro-Orbit practice.
* Assume the same posture as with the Microcosmic Orbit - back straight, feet on floor, hands clasped on lap, breathing through your nose - tongue on roof of your mouth - etc. )
* focus on the Tan-tien for some time - until you've connected with and activated the chi there.
* Perform a good cycle of the Microcosmic Orbit - bringing the Chi back to the lower Tan-tien.
* Now for the Macrocosmic Orbit proper: - bring the Chi out of the Tan-tien - to the sexual center and then down to the Hui-Yin (perineum point) - from here divide your focus as you direct the Chi on its journey through the legs.
Down the Legs
* Direct your focus and Chi down the inside of your thighs (again no need to follow a precise pathway here)
* Stop to focus for a while at the backs of the knees ( Wei Zhong or Bladder 40 point) a potent energy point where Chi can tend to be built up and somewhat stagnated in many people.
* Next continue along the inside of the lower legs - passing around the insides of the feet to ...
* ... the central sole point of the 'Bubbling Spring' or Yuan Chuan points - just behind the balls of the feet. (see picture below)
* Spend some time at the Yuan Chuan points - tuning in to your connection with the Earth's nourishing energy - before you bring your focus across your soles to the inside tip of your big toes (Da Dun - (LV-1) an important liver channel point)
* Then move your focus and Chi up the insteps of your feet to the outer front of your shins and begin the ascent of your Chi up the front and outer region of your lower legs.
* Stop to focus for a bit at the He Ding points at the top center edge of your kneecaps.
* Continue on up the front outer regions of your upper legs curling around to the backs of your thighs a little before reaching your buttocks and direct your Chi flow back to your Hui-Yin perineum point.
(some traditions of Chi-gung advise directing the chi flow down the outside of the legs and up the inside - while others just flow energy up and down all through the legs. Again I'd suggest experimenting a bit to find what works best for you - though in general my feeling is the more internally and the more of the whole leg area you can involve the better!)
* From the Hui Yin continue as usual up the spine - (Du Mai vessel) as in the Microcosmic Orbit - until you reach the C-7 (Ta Chui) point at the base of the neck.
(some Chi-gung /Nei-gung traditions teach to move the Chi flow into the arms from the C? point at the middle point between the shoulder-blades - I'd simply advise you to try both ways and see what works best in your experience. It may well be that both methods work through related chi-pathways - and a difference will only be noticed after significant Chi has been built up. )
Into the Arms
* From here again divide your Chi-flow focus in two - this time going down the insides of your arms.
* Follow your Chi flow all the way down your inner arms to the Lao gung points at the center of your palms and linger your attention there for a moment or two.
* Direct your focus back up the outside of your arms to reunite the arm Chi-streams again at the Ta Chui point at the base of your neck.
Complete the Orbit
* From this point continue the Orbit pathway as usual in the Microcosmic Orbit practice. - up to the Crown and Third-eye points and back down the front of the torso to collect the Chi in the lower Tan-tien - unless you feel like circulating more of course!
And there you have it - the essentials of the Macrocosmic Orbit practice!
This whole body Chi-flow will continue to grow with inner practices such as this as well as the Chi-focused practices of Internal martial arts such as Tai-Ji, Ba-Gua and Hsing-I, and healing methods.
Some practitioners enhance this foundational Macrocosmic Orbit method to include Chi-flow through all of the twelve organ meridians and other channels, but that takes a good deal of in-depth study and wouldn't necessarily be all that useful for most practitioners.