How are joysticks 'powered' in gliders?

I note that some gliders are controlle with a joystick which
makes me curious as to how the control surfaces are powered.

Assuming these are useable by people who lack the forearms of
a truck driver, how are they powered?

Do these systems use electric servos with a battery recharged
on the ground? Do they use vaccumm assist from a venturi?

Just asking?

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FF