A number of nandrolone cases in athletics occurred in 1999, which included high-profile athletes such as Merlene Ottey , Dieter Baumann and Linford Christie .  However, the following year the detection method for nandrolone at the time was proved to be faulty. Mark Richardson , a British Olympic relay runner who tested positive for the substance, gave a significant amount of urine samples in a controlled environment and delivered a positive test for the drug, demonstrating that false positives could occur, which led to an overhaul of his competitive ban. 
Testosterone can be administered parenterally , but it has more irregular prolonged absorption time and greater activity in muscle in enanthate , undecanoate , or cypionate ester form. These derivatives are hydrolyzed to release free testosterone at the site of injection; absorption rate (and thus injection schedule) varies among different esters, but medical injections are normally done anywhere between semi-weekly to once every 12 weeks. A more frequent schedule may be desirable in order to maintain a more constant level of hormone in the system.  Injectable steroids are typically administered into the muscle, not into the vein, to avoid sudden changes in the amount of the drug in the bloodstream. In addition, because estered testosterone is dissolved in oil, intravenous injection has the potential to cause a dangerous embolism (clot) in the bloodstream.