Foot to foot contact is most used when treating the lower part of the body, from lower abdomen to feet.
Hand to hand contact is most used when treating the upper part of the body, from mid abdomen to head.
Of course you can use left foot to right hand, or vice versa, to make the current path cross over the zone to be treated, but remember that the human body has a high percentage of water, and thus, it is conductive, so, the current distributes over the entire body (at least over the conductive tissues). In fact, it is difficult to the electric current to reach the interior of the hollow organs, and the inside of the eye, due to its isolating layers.
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