Does a woman’s hydration needs differ to a man’s?

Both genders benefit from taking in a reasonable amount of sodium and possibly a small amount of carbohydrate with drinks during activity lasting multiple hours.

This is especially true in hotter conditions, where sweat losses can be very high and the body needs to maintain high levels of blood plasma volume to allow the blood to transport heat to the skin and shuttle fuel and waste products to and from working muscles.

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However, due to differences in average body size and composition, as well as hormonal fluctuations in the menstrual cycle, women’s need can be different to men’s at key times.

Probably the most critical difference is that during the high hormone (luteal) phase of the cycle, women are significantly more likely to develop hyponatremia (low blood sodium levels, a condition that can be debilitating or fatal in extreme cases).

This is because the hormones released in this phase reduce the amount of sodium retained by the kidneys, resulting in a decrease in overall blood volume and blunted thirst signals to the brain.

So women are strongly advised to drink to the dictates of thirst during this phase and to experiment with higher amounts of sodium in drinks to aid the preservation of blood volume.

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Andy Blow Sports scientist

About

Andy Blow is a sports scientist with a degree in sports and exercise science from the University of Bath. An expert in sweat, dehydration and cramping, Andy previously worked as the team sports scientist for the Benetton and Renault Formula 1 teams, and remains an adviser to the Porsche Human Performance Centre. He specialises in electrolyte replenishment and founded the company he now runs, Precision Hydration. An elite-level triathlete in his younger days, Andy has finished in the top-10 of Ironman and Ironman 70.3 races, as well as winning an Xterra world title. Andy has also worked alongside Dr Raj Jutley, as well as other top sports scientists, to co-author a number of studies and books which have been published in BMJ Journals, the Journal of the International Society of Sports Nutrition and the Journal of the Endocrine Society.