Question

Anatomy and Physiology RCT 1

Phenomenon: Marathon Runner Ends up in a Coma

A marathon is a 26.2-mile race. People often train for months leading up to the race in order to successfully complete this type of long-distance running challenge. Sometimes, runners aren’t able to finish the race or runners' collapse. Your challenge is to use your findings from research articles and data sets in order to determine and explain what is causing some marathon runners to collapse.


These days, many amateur athletes participate in marathons. One such amateur athlete -- a 40-year-old woman running a marathon for the first time, runner #0358 -- got very sick and disoriented during the second half of a New York City marathon. She kept running the race, and she even took pictures with her family along the racecourse, but she later had no memory of running the second half of the race! Runner #0358 went home, then became very ill and disoriented, eventually ending up in a coma. While the runner did recover after a while, this event concerned the race organizers. The marathon was held on an unusually hot, humid, and sunny day. The race started at 10:00 AM, but some runners were on the course for 4 or 5 hours. During that time, the temperature got as high as 28◦ C (about 82◦ F), and the sun was out all day. Many runners ended up seeking medical care either at a stop along the racecourse, or at the end of the race.


What could have happened to her to make her so sick? Below is additional information about challenges that athletes may face with strenuous exercise in extreme conditions.


Athletes need more sodium because it is lost while sweating. The amount of sodium excreted in sweat is large and depends on many factors, such as body mass, training level, temperature, clothing, gender, and heat/humidity acclimatization. The level of sodium in your body can become too low or too high based on the amount of water in your body. If the amount of water you consume isn’t equal to the amount you lose, you can become dehydrated (too little water).


Hyponatremia occurs when sweating causes disproportionate sodium loss or an excessive intake of plain water, which dilutes the level of sodium in the blood. This is why it’s imperative to drink sports drinks containing electrolytes and not plain water for any physical activity over an hour.


If your blood sugar drops to a low enough level and you don't elevate it with some sort of fast-acting carbohydrate such as fruit juice or a sports drink, you may begin to experience symptoms of hypoglycemia. Hypoglycemia can cause symptoms such as headache, shakiness or trembling, excessive sweating, mental confusion and heart palpitations.


Exercise is one of the strong factors disturbing the maintenance of body temperature. Some conditions, such as heavy exercise in thermal extremes, could rapidly lead to dangerous internal temperatures. The thermal load posed by the environment or by heavy exercise may be too great for the capacity of the regulators. Or the regulator could be deranged due to extreme temperatures.




Table 1. Marathon Runner. The medical data in the table are from the assessment of four participants, including runner #0358 who had the most negative outcomes.


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*Normal values for Blood Glucose: 135-140 mg/dL

*Normal values for Plasma Sodium: 135-145 mEq/L, <125mEq/L = high mortality

*Normal body temperature: 37◦C= 98.6◦F

* Normal Oxygen Saturation: 95%-100%

this is the text this is the question


Reasoning:

Using the evidence gathered from the text and medical data in the table, write an explanation as to why marathon runner #0358 ended up in a coma?

Runner #0358 most likely developed severe hyponatremia because of her exercising and running on a hot and humid day. As a result she had felt sick due to her prolonged sweating and drinking plain water. The text says " hyponatremia occurs when sweating causes disproportionate sodium loss or an excessive intake of plain water, which dilutes the level of sodium in the blood" and that plasma sodium "<125 mEq/L = high mortality.

lastly here is my teachers feedback please respond

Tarina Wallace: Did not explain her sodium levels. Also always provide at least 2 pieces of evidence.

Answer 1

Revised explanation (addresses Tarina Wallace’s feedback):

Conclusion — what happened:
Runner #0358 most likely developed severe exercise‑associated hyponatremia (very low plasma sodium), which caused cerebral edema and resulted in the confusion, memory loss and eventual coma.

Why (mechanism, explained):
- During prolonged heavy sweating the body loses sodium along with water. If a runner replaces fluid losses mainly with plain water (no or few electrolytes), the plasma sodium concentration falls and plasma osmolality decreases. Because of this osmotic gradient, water moves into brain cells, causing cerebral swelling (edema). Cerebral edema raises intracranial pressure and disrupts neuronal function, producing headache, confusion, seizures and, in severe cases, coma.
- In short: sweat → net Na+ loss + excess plain water intake → low plasma [Na+] (hyponatremia) → water into brain cells → cerebral edema → altered mental status/coma.

Evidence (at least two pieces):
1. Environmental/behavioral evidence from the passage: the marathon was unusually hot and humid, runners were on course 4–5 hours while the temperature reached ~28°C, and the text explicitly warns that hyponatremia can result from “sweating [that] causes disproportionate sodium loss or an excessive intake of plain water.” These facts make heavy sodium loss plus excess plain-water replacement very likely.
2. Medical data in Table 1: runner #0358 is listed with a plasma sodium well below the normal range (below 125 mEq/L, the threshold noted in the table as associated with high mortality), and she presented with severe neurological symptoms (disorientation, memory loss and coma). The combination of markedly low plasma [Na+] and the neurologic presentation matches severe hyponatremia with cerebral edema.

Other possible contributors (brief):
- Heat strain / hyperthermia from the hot conditions could have worsened her condition, and hypoglycemia can also cause confusion; however the hallmark finding linking the clinical course to the coma is the severely low plasma sodium and the known mechanism of brain swelling.

One‑sentence summary:
Runner #0358’s prolonged sweating in hot, humid conditions plus replacement with plain water caused severe hyponatremia; the resulting cerebral edema produced the confusion, memory loss and coma seen in her case.