Running Dry

Aircrew dehydration and its effect on health and performance.

Fluid loss during normal activity in a desert environment is linked to the need to maintain body temperature within narrow limits and unless fluid intake keeps pace with sweat loss, dehydration can result, leading to adverse health consequences, fatigue and poor performance.

It is important that aircrew monitor their hydration status. You should be aware of the symptoms of dehydration, of how to use urine volume and colour as an indicator of hydration status. Thirst is a poor indicator of the need to drink. If you are thirsty you have already lost 1.5-2.0 litres of fluid (2%).

Signs and symptoms of dehydration include thirst, irritability, and general discomfort, followed by headache, weakness, dizziness, cramps, chills, vomiting, nausea and decreased performance.

Cognitive performance in complex tasks like flying starts to become impaired at 2% dehydration and gets progressively worse. Long term, aircrew who ’run dry’ will increase their chance of conditions such as kidney stones, an extremely painful and possibly career-limiting problem.

‘But I don’t want to need to pee in flight’
Almost all aircrew are reluctant to use the provided relief bags, but what would you rather lose: your dignity or your safety?

So what should I be drinking?
Water is generally the best, but pretty much any fluid will help. Try not to drink liquids containing too much caffeine as this will limit the benefit and may induce a diuresis (make you pee more) negating the effects of the extra fluid. Energy drinks have their place but as no more than 10% of your intake, and needless to say alcohol is a bad idea, and very dehydrating.

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