Thanks again for your reply.Thanks for the wishes to Pakistan.
Quran does not describe design of hijab, what hijab in Arabic language means is probably just a cover (Arabs may correct and give in precise translation), and as i remember listening from a learned scholar, Quran only guides about covering one's sexual parts both men and women. Now whatever is a sexual part can be interpreted differently in different cultures, where as cultures in different regions are ever evolving, specially Islamic states has been going towards conservative direction ever since Iranian revolution, which as well triggered conservative behavior in countries where Iranian influence wasn't existing example middleast.
But technically speaking sexual parts are only reproductive organs, so no issues in wearing any sports gear as far Quranic guidance is concerned, I personally don't even see any issues with swim suit as well, but wearing a thong is another thing, which is designed to arouse sex appeal.
Sharia is a vogue term, but Quran does not restrict humans to make rules and laws of society as it suits them, expect few rules which are clearly stated in Quran, one example: with whom one is allowed to marry! but at the same time Quran does not restrict on number of marriages. but in different Islamic states the law about number of marriages is different.
In Turkey only one marriage is allowed by law, while in Saudi Arabia there's no limit on number of marriages, in Pakistan the number of marriages is fixed to max 4, but non violate any rules defined in Quran!
No forcing is allowed based on religious matters, however any law approved by society must be followed, unless it's conflicting with defined rules in Quran. example: if European law says girls are not allowed cover head or face, it must be followed even by Muslims, but if European law says all girls must remove cloths, here Muslims have right to fight any attempt of enforcing such law upon them.
Disclaimer, Others may correct me but use logic and reference from Quran.
"but wearing a thong...." I fully agree, but as in the case of these Malayan or Indonesian Muslim girls or Hindu girls swimming partially topless, I am convinced that this had nothing to do with arousing sex appeal, but simply being a part of their previous natural behavior.
The way I get to understand your reply is: Just before the Iranian Islamic revolution and especially upon the introduction or emphasis onto Sharia in Iran and Saudi Arabia - these "conservative/restrictive" issues start to get revived/introduced in Muslim communities throughout the world.
If so, then there must have been also quite a visible social change in Pakistan's society after 1991 (Enforcement of Shariat Act. Section 4 of the Constitution mandates) I have never been to Pakistan so I could imagine they went through the same process as e.g. Muslim Malaysians or Indonesians.