Due to the nature of the physical measures necessary, such as barrier restraints.
People go on courses to write sentences like that.
'Barrier restraints' is a tautology so we can take one of them out.
'the nature of the physical measures necessary' Well, we're not interested in the emotional nature of unnecessary measures so that can go in its entirety.
We're left with 'Due to barriers', which can be further parsed to its final form; 'Because.'