Um. no Steroids build muscle and reduce fat. Training and context does the rest. eg. if someone is hurt, they help him heal (by building and repairing muscle tears), if someone is training for endurance, they increase endurance (because they build slow twitch instead of fast-twitch bulky muscle fibers) etc. If someone is a bodybuilder and weight lifts, they increase muscle mass (big bulky fast twitch fibers;) and in combination with dehydrating agents and insulin reduce body fat and water content. Growth factors, like HGH, have a bit more broad effects and they can help in the healing of connective tissue, such as ligaments, organs, bones, etc... Reflexes is something they have no more than placebo power to improve, because it is an ingrained habitual reaction that happens by lots and lots and lots of repetition so it becomes "second nature". Steroids might improve the muscles involved in the reflex motion, but that's about it. Allegedly, stimulants (like "greenies" -amphetamines, a cousin of meth-amphetamine-, or the stuff that the Twins' manager snorted) "improve" reflexes, but there are no studies that suggest so.