The sign for "strong" has a couple of variations. A good general
version is to form fists and then pull them out away from your body a bit as
if flexing your biceps.
The sign STRONG is related to the concepts of: brave, courageous, heal,
healthy, robust, fit, and well.
The difference between all these concepts and the concept of
"strong" is that STRONG starts with "fist" handshapes
whereas the other concepts tend to start with "relaxed five" handshapes.
HEALTHY / BRAVE / ...
"Are most farmers strong?"