 Track and field athletes are banned from <unk> or using certain substances by governing bodies for the sport , from the national to the international level . The IAAF 's constitution incorporates the World Anti @-@ Doping Code among other anti @-@ doping measures . <unk> such as blood doping and the use of anabolic steroids , peptide hormones , <unk> , or <unk> can give athletes a physical competitive advantage in track and field . The use of such substances in track and field is opposed on both ethical and medical grounds . Given that the sport functions by measuring and comparing athletes ' performances , performance @-@ enhancing substances create an uneven playing field — athletes who do not use doping substances have a disadvantage over rivals who do . <unk> , the use of banned substances may have an adverse effect upon athletes ' health . However , some exemptions are made for athletes who take banned substances for therapeutic use , and athletes are not sanctioned for usage in these cases , such as Kim Collins ' failed drug test due to asthma medication . 
