Pressure
This is the most common cause, and it’s important to be aware of how different amounts and duration of pressure can cause damage to skin. All of these conditions can be damaging:
Long periods of low pressure — it is estimated that between one and six hours of constant low pressure can cause some tissue damage. While sitting is relatively low pressure, forgetting to do pressure reliefs all day makes the pressure constant and can cause damage.
Recurrent pressure, such as frequently bumping your elbow against a table, desk, or arm rest many times each day.
Short periods of high pressure, such as accidently whacking yourself hard against a surface when doing a transfer.