Final answer:
The regulation that protects athletes' health information in Sophia's scenario is the Health Insurance Portability and Accountability Act (HIPAA), which maintains strict confidentiality of patient records.
Step-by-step explanation:
The regulation that guards the privacy of athletes and prohibits Sophia from providing details about their health status to her friends is the Health Insurance Portability and Accountability Act (HIPAA). Enacted in 1996, HIPAA protects the confidentiality of patient records and personal health information. Healthcare providers and other entities dealing with personal health information must adhere to strict privacy rules set forth by HIPAA, ensuring that sensitive health information is not disclosed without the patient's consent.