I am not certain what result you want.
Try this:
MyTable.Properties.VariableNames = {{'Node Number'} {'X Location (m)'} {'Y Location (m)'} {'Z Location (m)'} {'Normal Stress (Pa)'}};
Outc = regexp([MyTable.Properties.VariableNames{:}], '\(\w*\)','match')
Out = [Outc{:}]
producing:
Out =
1×4 cell array
{'(m)'} {'(m)'} {'(m)'} {'(Pa)'}
EDIT — (31 Mar 2021 at 15:52)
Another option:
Out = extractBetween([MyTable.Properties.VariableNames{2:end}], '(',')')
producing:
Out =
1×4 cell array
{'m'} {'m'} {'m'} {'Pa'}
