Original sentence: Although many of these substances are prescription medicines in many countries, in professional bodybuilding the use of substances such as anabolic steroids and precursor substances such as prohormones are sometimes essential to competing in world-class competitions.Some bodybuilders also use pharmaceuticals to gain an advantage over results due to natural hypertrophy, especially in professional competitions
Edited sentence: Although many of these substances are illegal in many countries, in professional bodybuilding the use of anabolic steroids and precursor substances such as prohormones are sometimes essential to competing in world-class competitions.Some bodybuilders may use drugs to gain an advantage over results due to natural hypertrophy, especially in professional competitions