Final answer:
The principle known as informed consent requires athletes to be fully informed about the risks, benefits, and alternatives of a treatment before proceeding.
Step-by-step explanation:
The principle that requires an athlete to receive a full disclosure of the risks, benefits, and possible alternatives for treatment is the principle of informed consent. Informed consent ensures that an individual is fully educated about the important aspects of a potential treatment, including any associated risks, advantages, and other viable options before they agree to proceed. This principle aligns with both ethical standards in clinical practices and the principle of autonomy, which signifies a person's right to make informed decisions about their own health care.