It may be that some of those pests "settled" in those joints, so that is where they are being killed. As David Bourke said recently, the body's immune system is largely blood-based, so the joints are often used by pathogens as a hiding place.
The Remote signal penetrates into the joint area well, so these pathogens may be attacking with vigor as they perish - then the body has to work hard to clean out the waste... Some additional exercise of these joints may help the blood flow into these joints to carry the waste products away faster.
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