Heat Exhaustion During 5 km Selection Run
At 06:30, 22 recruits begin a 5 km selection run. Temperature is 38°C, humidity 70%, and the flag system is at orange. Recruit A, aged 21, has BMI 31, ate no breakfast, and drank about 300 mL water since 20:00 the previous night. At 3.2 km he becomes dizzy, complains of headache, and slows to a walk. He is helped to the side: skin cool and clammy, pulse 128/min, respiration 24/min, temperature 38.9°C by ear thermometer, and he is confused about the date. Recruit B, aged 19, has finished and wants to run another 2 km to improve his time. The instructor has one 20 L water can, a shaded tent, ice packs, and a mobile phone with patchy network. The nearest ambulance is 12 minutes away by road.
1. Classify Recruit A's likely condition and list immediate first-aid actions in priority order. Explain why confusion changes the response.
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Recruit A has exertional heat illness with neurological signs. A temperature of 38.9°C by ear is not a reliable core reading, and confusion means heat stroke must be assumed until excluded. Do not wait for a rectal temperature if cooling can start. Priority actions:
- Stop the run, move him to shade, and remove excess clothing.
- Call the ambulance immediately; note the 12-minute road time.
- Cool rapidly: ice packs to neck, armpits, and groin; spray water; fan; do not cover him with blankets.
- Check airway, breathing, and circulation; monitor pulse, respiration, and consciousness.
- Give small sips of water only if he is fully alert and can swallow; confusion means no oral fluids.
- Record times and do not let him walk unaided. Confusion changes the response because it turns a suspected heat exhaustion case into a heat-stroke emergency.
2. Should Recruit B be allowed to run the extra 2 km? Give a decision and the physiological reasoning, including environmental and individual risk factors.
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No. B should not run the extra 2 km. At 38°C and 70% humidity, evaporation is impaired and core temperature rises even in fit recruits. B has just finished 5 km, so he is likely down on fluid and glycogen. Extra distance adds heat load with no selection benefit and increases the risk of collapse. The instructor should apply the flag system consistently: at orange, reduce or stop non-essential exertion. B can cool down in the tent, drink water, and be monitored. If he wants to improve his time, that should be done on a cooler day under a planned training session, not immediately after a selection run in heat. Allowing him to continue would also undermine the credibility of the safety rule.
3. Propose three changes to the run protocol to reduce recurrence, with a brief justification for each.
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Three changes:
- Move the start to 05:30 or postpone when the flag is orange/red. Justification: lower solar load and temperature reduce core-temperature rise.
- Add water stations at 1.5 km and 3 km and require pre-run hydration checks. Justification: A's 300 mL since the previous evening is inadequate; supervised drinking reduces dehydration.
- Screen and acclimatise: check sleep, breakfast, recent illness, and BMI; use a 10–14 day heat-acclimatisation programme and reduce distance for new recruits. Justification: A's BMI 31, empty stomach, and sudden heat exposure are modifiable risks. Also keep ice, shade, and a medical standby at the finish. These changes target the environment, the individual, and the protocol rather than blaming the recruit.