However, when used improperly or for the wrong reasons they can be very harmful. A steroid is a terpenoid lipid characterized by its sterane core and additional functional groups. The core is a carbon structure of four fused rings: three cyclohexane rings and one cyclopentane ring. The steroids vary by the functional groups attached to these rings and the oxidation state of the rings. If you over work the muscle or use too much of the muscle combined with steroid use, it could possibly explode the muscle.