Typical normal-service engine valve-train components may be too lightweight for operating at high revolutions per minute (RPM), leading to valve float.  This occurs when the action of the valve no longer completely opens or closes, such as when the valve spring force is insufficient to close the valve (it does not fully rest on its seat even though the cam would allow the valve to close) causing a loss of control of the valvetrain, as well as a drop in power output.  Valve float will damage the valvetrain over time, and could cause the valve to be damaged as it is still partially open while the piston comes to the top of its stroke.  Upgrading to high pressure valve springs could allow higher valvetrain speeds, but this would also overload the valvetrain components and cause excessive and costly wear. 
As for individual use of a personal nature, outside therapeutic treatment, this is where we will find the vast majority of anabolic steroids. It is here we will also find the biggest problems, not in terms of ill-effects of a physical or mental nature but of those surrounding legality. In places like the . anabolic steroids are controlled substances, and here we will find the strictest of laws. This has created a new class of criminal; most commonly an adult man with a family who is simply living an every day life like everyone else. These are issues that need to be discussed and you will find very few are willing to touch them unlike .