Football Training in the Heat
A 17-year-old footballer trains for 90 minutes at 2 p.m. in 33 °C heat and 78% relative humidity. He drinks 300 mL of water before training and nothing during. At 70 minutes he develops calf cramps, a throbbing headache, dizziness, and stops sweating. His skin is hot and dry, his pulse is 118 beats per minute, and he is confused. He has lost 1.8 kg since the start. The coach wants to give him two salt tablets and send him back on the field because 'cramps mean you need salt'. A first-aid kit contains water, oral rehydration salts, and a thermometer.
1. Explain how sweating normally helps to control body temperature, and why this player's signs suggest thermoregulation has failed.
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Sweating cools the body when sweat evaporates from the skin. Evaporation uses latent heat, removing heat from the body. In 78% relative humidity, the air already contains much water vapour, so evaporation is slow. The player is therefore losing fluid without getting the full cooling benefit.
A 1.8 kg loss is roughly equivalent to 1.8 litres of fluid, which is a large deficit for a 90-minute session. As dehydration develops, sweat rate falls and skin blood flow may be reduced. The player has now stopped sweating, his skin is hot and dry, his pulse is fast, and he is confused. These are warning signs of heat stroke, not simple heat cramps. Confusion and hot, dry skin indicate that the brain's temperature regulation is failing and that immediate cooling is needed.
The cramps and headache are earlier signs of heat strain and salt loss, but they do not justify returning him to play. The combination of high humidity, limited fluid intake, and prolonged exercise has overwhelmed his thermoregulatory capacity.
2. Judge the coach's plan to give salt tablets and return him to play. What should be done in the first 10 minutes, and why?
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The coach's plan is unsafe and should be rejected. Salt tablets do not treat heat stroke and can worsen dehydration by drawing water into the gut or increasing sodium load. Giving tablets and sending the player back on the field delays cooling, and heat stroke can progress rapidly to organ failure, seizures, or death.
In the first 10 minutes the priority is emergency cooling and medical help. The player should be moved to shade, his kit removed, and cool water applied to the skin with fanning. Cold packs can be placed at the neck, armpits, and groin. An ambulance should be called. He should not be given fluids by mouth while confused, because of the risk of choking. If he becomes fully alert, small sips of oral rehydration solution may be started, but cooling comes first. A thermometer should be used if available, but treatment should not wait for a temperature reading.
The reasoning is that the player's confused mental state and absence of sweating indicate heat stroke, a medical emergency. The correct judgement is to cool first and transfer to hospital, not to replace salt and resume exercise.