Praise be to Allah.
We hope that you are playing this sport according to the conditions set out in sharee’ah, because these games are based on showing the ‘awrah in front of spectators, let alone taking harmful things to strengthen the body as they claim.
Vitamins and hormones, and food and drink in general, should be consumed during the night. If the effects last all day whilst fasting, that is something that is permissible. What is forbidden is to do that during the day from dawn until sunset. Allaah says (interpretation of the meaning):
“and eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night), then complete your Sawm (fast) till the nightfall”
Islam encourages us to eat sahoor, which is to be delayed until the end of the night, because that helps the fasting person to fast.
It was narrated that Anas ibn Maalik (may Allaah have mercy on him) said: The Prophet (peace and blessings of Allaah be upon him) said: “Eat sahoor for in sahoor there is blessing.” Narrated by al-Bukhaari, 1823; Muslim, 1095.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was asked:
What is meant by the blessings of sahoor that is mentioned in the hadeeth?
What is meant by the blessing of sahoor is spiritual blessing and physical blessing. The spiritual blessing includes following the command and example of the Messenger (peace and blessings of Allaah be upon him). The physical blessing includes nourishing the body and strengthening it for the fast.
Majmoo’ Fataawa al-Shaykh Ibn ‘Uthyameen, 19 Shawwaal, no. 339.
For more information please see the answer to question no. 26111.
It remains for us to mention another matter that has to do with the hormones that are taken for these sports, which is to enquire whether any harm is caused by them. If it is proven that they are harmful, then it is not permissible to take them.
It was narrated from ‘Ubaadah ibn al-Saamit that the Messenger of Allaah (peace and blessings of Allaah be upon him) ruled that there should be neither harming nor reciprocating harm. Narrated by Ibn Maajah, 2340.
Al-Nawawi said: It is a hasan hadeeth with several isnaads that strengthen one another.
It was classed as saheeh by Shaykh al-Albaani in Irwa’ al-Ghaleel, 896.
And Allaah knows best.