if you are a boy and try to lift something heavy or strain too much.
there could be herniation of the testicles etc.
one of a few things I heard that not to train too hard for kung fu when you are young.
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also you may not grow too tall etc. wonder why Jackie Chan (Kung Fu opera) and Jet Li (wushu champ at 13) are not tall
people lifting heavy stuff in the olympics are kind of short athletes, too.
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