I have created a tutorial on this subject, it is simply the oscillation of the bellows in rhythm.personally I do not practice it or badly.I will be very interested in your opinions....the discussion is open. Here is a good example by our champion Eric Bouvelle.
Thank you for this method I will test I think it can help in the handling of the bellows. All my wishes for the new year and thank you for your investment and the time you spend to make the site live. kouros