Complex sentence: For that reason foot whipping is regarded as one of the most intimidatory and effectual methods of corporal punishment and is therefore frequently employed in penal institutions of several countries in the present and past (see above).
Split into simpler sentences: For that reason foot whipping is widely regarded as one of the most intimidatory and effectual methods of corporal punishment. Therefore it is still frequently employed in penal institutions of several countries to the present (see above).