Collapse After the 800 m in 41 Degree Heat

Working diagnosis: exercise-associated heat exhaustion with dehydration and sodium loss - not heat stroke.

• Fluid deficit: 54.2 minus 52.4 = 1.8 kg, which is 1.8 / 54.2 x 100 = about 3.3% of body mass in roughly an hour of running. Losses above about 2% of body mass already reduce performance; 3-5% produces the headache, nausea and dizziness he is showing.
• Cardiovascular response: plasma volume falls, so stroke volume falls; to keep blood pressure and muscle blood flow, heart rate must rise - hence 148 beats/min after ten minutes of rest. Skin blood flow is also competing with muscle for a reduced blood volume, so cooling becomes less efficient.
• Cramps: heavy sweating over a long hot day with only 300 mL of plain water and no food means loss of sodium as well as water; combined with neuromuscular fatigue this produces the calf cramps.
• Why not heat stroke: he is fully conscious and oriented with an oral temperature of 38.4 degrees C. Heat stroke means core temperature above about 40.5 degrees C plus central nervous system dysfunction - confusion, aggression, collapse, seizure. Note that sweating does not rule out heat stroke, so mental status matters more than dry skin. Oral temperature also underestimates core temperature, which is why you keep monitoring him.

Immediate management, in order:

1. Move him to shade or a ventilated room, loosen and remove unnecessary clothing, and lay him flat with legs slightly raised.
2. Cool actively: wet towels and fanning, ice packs to neck, axillae and groin, cool water sponging. Do not leave him in the sun as the teacher suggested.
3. If he is fully alert, give oral rehydration solution in small frequent sips (about 200 mL every 15-20 minutes); plain water alone is inadequate because sodium has been lost.
4. Refuse the painkiller for now. NSAIDs and paracetamol are not needed, can irritate the stomach in a nauseated athlete, add kidney load when dehydrated, and can mask a rising temperature.
5. No further race or training that day; he should not travel home alone.
6. Monitor pulse, breathing, mental status and temperature every 10-15 minutes and record them.

What would change the plan:

• Confusion, drowsiness, aggression, fainting, vomiting that prevents drinking, or temperature climbing above 40 degrees C - treat as heat stroke, call for emergency medical help, continue aggressive cooling and do not delay transport.
• No improvement within 30 minutes of cooling and fluids, or a rising pulse with falling blood pressure - refer to hospital for intravenous fluids.
• Cramps persisting after fluids and cooling - check electrolytes medically rather than giving salt tablets blindly.

1. Acclimatise, do not just turn up. Ten to fourteen days of progressive exposure (30-60 minutes of easy-to-moderate training in the heat) expands plasma volume, increases sweat rate and makes sweat more dilute, and lowers the heart rate for the same pace. Because he had trained only in cool mornings, his first hot race was always going to be his worst.

2. Replace what is lost. Weigh him before and after training: replace 1.25-1.5 L for every kilogram lost. In practice, 400-800 mL per hour of training in this heat, with sodium-containing fluid when sessions last over an hour. Race morning: about 400-600 mL in the two hours before the start, then small sips to the line - not 300 mL in four hours.

3. Use the weigh-in as a monitoring tool. A loss of more than 2% of body mass in a session is a warning; he lost 3.3% in one race.

4. Change the schedule and the environment. Request an early-morning slot, warm up in shade, use cold towels and iced drinks, and keep the call-room area shaded. If the organisers will not move the time, he must still complete acclimatisation.

5. Educate and rehearse. Teach him the early warning signs (headache, nausea, dizziness, cramps, unusual fatigue) and the rule that he reports them to a teacher immediately. Record the plan in his training diary so the next hot meet is predictable rather than a first exposure.