Static means no movement, still, fixed in the same position. This sort of position can take place while standing or sitting for extended periods of time in the same position with no movement causing restriction of blood flow around the body and can damage your muscles either through too much pressure being placed on certain parts of the body or no movement at all.
By ensuring that the equipment is regularly cleaned and disinfected, it majorly decreases the chance of transmitting any germs/cells from one person to plenty others.