Alexander technique, yoga, muscular relaxation programs, frequent breaks and so on may all be included to organize "healthy" work methods.All of that should always be considered/investigated whatever *work* you are up to.
Along with that there better be a continuous struggle in order to improve the tool or instrument whatever which is used and this may be a tricky part since habits and conservatism always counteract such actions.
With concertinas there are always two issues in conflict with each other which - often unconsciously - cause confusion for the players:
a) to work the bellows efficiently and to articulate the tone you want as much stability as possible of the connection between player and instrument
b) to reach all buttons of a wide keyboard you want as much flexibility as possible ( or a flying hand as with the piano which you never get)
These needs of course can never be fully satisfied simultaneously.
The Anglo/Duet kind of handle and the English variant both suffer from the same problem: if set tight for good stability the fingering of buttons suffers, if set looser the meansfor tonal control and rhytmical expression are lost.

I have reformed the handles for all systems in order to improve the options combining stabiliy and flexibility based on very simple
rulesfor ergonomic