Hi canadiankyosa , think largely it depends greatly on how you train them . Heavy bag i still do regularly but with the amkiwara i generally cycle training to harder single impact strikes and softer fast striking there is a good sectio0n in general choi taekwon-do encylopedia on the subject . Pretty much my arms and legs are still good though i also know people who went at it full bore who are fubar now so i guess its a multi question as genetics can also play apart.
