Which participant at a marathon race is at the greatest risk for developing heatstroke?

The individual who is 72 years old and takes furosemide and atenolol daily is at the greatest risk for developing heatstroke during a marathon race. Furosemide is a diuretic that can lead to increased fluid loss and dehydration, making the body more susceptible to overheating. As dehydration progresses, the body's ability to regulate temperature diminishes, which significantly raises the risk of heat-related illnesses like heatstroke. Furthermore, the physiological changes associated with aging can also impair thermoregulation, thereby compounding the vulnerability of older adults in high-temperature environments.

Atenolol, a beta-blocker, may also affect cardiovascular response during physical exertion, potentially limiting the heart's ability to respond to increased demands during exercise. This combination of medications along with advanced age creates an unfavorable situation in a marathon setting where heat and exertion can lead to serious health risks.

The other individuals listed may have conditions that could also present risks, but they do not have the same level of factors contributing to dehydration and impaired thermoregulation as seen in the participant on furosemide. For example, the 46-year-old with a family history of stroke does not have any direct medication-related risks affecting hydration, while the individual with high fasting