Is it permissible to go to weightlifting gyms?

Weightlifting is a permissible sport, and going to its gyms is permissible as long as there is no religious impediment. Sheikh Atiyyah Saqr issued a fatwa allowing it, stating that it has an ancient origin among Muslims, known as "ar-rab’," and that the Prophet, peace and blessings be upon him, passed by people who were lifting a stone (yarba’ūn ḥajaran) and said: "The workers of Allah are stronger than these."

It was narrated in the Marfu’ Hadith from Abdur-Rahman ibn Ajlan that he passed by people who were lifting a stone and asked, "What is this?" They replied, "This is the stone of the strong ones." He then said, "Shall I not tell you who among you is the strongest? He who controls himself when angry."