Repetitive strain injuries go back to the days of early scribes. Doing any one task for an extended period of time will cause stress and fatigue of the muscles.
Back in the days of the manual typewriter, there was variety, even in the days of the typist (now called a data entry clerk). Unlike today, where someone can type non-stop for hours on end, to type required putting in the paper, turning the cartridge, typing, hitting the carriage return, typing, hitting the carriage return, typing and so on. There were essentially micro breaks at the end of every line of type.
To reduce strain, look at ways to work those breaks into work tasks. If working with tool, having one employee complete various steps, using different tools, presents an opportunity for a micro break. With office work, reaching to answer the phone or pull a document off a printer provide opportunities for micro break.
A micro break does not have to mean stop working. It is simply a break from one task. What are ways you can work that into your daily tasks?