Tournament Day in Heat and Humidity
A 16-year-old female footballer, 58 kg, plays in a one-day tournament in Malta in July. The temperature is 31°C and humidity about 70%. She plays two 30-minute matches, two hours apart. Before the first match she drinks 500 mL of water and eats nothing after an early breakfast of toast and jam at 07:00; the match starts at 09:00. During the first match she drinks nothing. Afterwards she weighs 57.1 kg, has a headache and passes dark urine. Between matches she plans to eat a chocolate bar and drink 750 mL of water in one go. She has no history of heat illness and is not taking medication. Her coach asks whether she should play the second match and what she should eat and drink.
1. Estimate her sweat rate from the first match and propose a fluid plan for the two hours between matches. State assumptions and show your calculation.
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Assumption: the 0.9 kg loss is sweat, with no drink and no urine during the match. 0.9 kg ≈ 900 mL over 30 min → about 1.8 L/h. This is high but plausible in 31°C and 70% humidity.
Between matches, aim to replace roughly 125–150% of the deficit: about 1.1–1.4 L over two hours. Start with 300–400 mL now, then 150–200 mL every 15–20 min, using a drink with sodium (roughly 300–500 mg/L) and some carbohydrate. Do not drink 750 mL in one go: a large bolus increases stomach fullness and nausea, and repeated large volumes of plain water without sodium can dilute plasma sodium. Recheck weight and urine colour before the second match.
2. Evaluate her pre-match breakfast and planned between-match snack. What would you change and why?
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A 07:00 breakfast for a 09:00 match gives about two hours, which is reasonable, and toast with jam provides carbohydrate. The bigger problems are no fluid during the match and the planned snack. A chocolate bar is high in fat and low in quickly available carbohydrate, so it empties from the stomach slowly and is a poor choice between matches in heat.
A better plan: after the first match, take a banana, a sandwich or a sports drink for carbohydrate and fluid, plus 400–600 mL of fluid in divided doses. She should also start drinking earlier before the first match, not only 500 mL two hours before. Headache and dark urine after only 30 minutes suggest she began dehydrated and lost more fluid than she replaced.
3. Should she play the second match? Justify your decision using risk factors.
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She should not play until she has been reassessed. Headache, dark urine and a 0.9 kg loss after 30 minutes indicate dehydration, and playing again in 31°C heat raises the risk of heat exhaustion and worse. Allow her to sit in shade, rehydrate and eat. She can play only if her headache resolves, she passes clearer urine, she can drink normally and she has no dizziness or confusion.
If she has confusion, vomiting, fainting or cannot drink, do not let her play and seek medical advice. The coach should not pressure her because the team is short. The reasoned judgement is to delay the decision for 30 minutes and withdraw her if she is not clearly improved.