Five reasons to take recovery seriously

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I'm just recovering from over training syndrome. I had it at the start of the year and even now I'm struggling to get my speed back. Struggling in cross country races, really hard when you are being over taken by the people you used to beat.

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As regards hydration, the advice in this article to "Drink to your thirst" is excellent and has shown to be the correct way in recent research.  The idea that the human body, following millions of years of evolution, does not know how to control the amount of water it needs, is spurious to say the least. More deaths have been caused by over hydration in marathons than by dehydration, due to too little salt in the system compared with water, known as hyponatremia.  If severe, this can cause a swelling of the brain and lead to death.  People are so scared by the media hype surrounding dehydration that they are drinking more water than they need both before and during a race.  In a recent study on ultra marathon runners running in hot desert conditions. the majority of the runners had mild though symptomless hyponatremia during and after the race caused by overhydration, some even before the race.  

The body has well rehearsed mechanisms for keeping the concentration of sodium in the plasma within narrow limits and maintaining plasma volume.  When water is being lost due to evaporation through the skin, from the breath and in sweating, the concentration of sodium increases in the plasma and this stimulates the thirst receptors to encourage drinking.  Great......drink some fluid!  At the same time the body also inhibits the amount of water lost in the kidneys to conserve water.  Loss of some sodium in the sweat will also be an advantage when plasma levels are higher than normal.  If excessive water is consumed, then the body will try to conserve sodium in the kidneys and excrete less in the sweat to keep the concentration of sodium constant in the plasma, as well as excrete more water in the urine of course.   However, under water overload conditions, the body may not be able to maintain enough sodium to compensate for the excessive water intake, leading to hyponatremia, unless some sodium is consumed in tablets or in energy drinks.

I do not agree with the comment in the article that the colour of urine is a useful guide to dehydration.  Yes, maybe under rest conditions but not under race conditions.  The urine will be automatically concentrated during a race in hot conditions, in order to conserve water and maintain the sodium concentration in the plasma at optimal levels.  Therefore it is the plasma concentration , not the urine concentration that indicates dehydration. If the body is doing its job right, the urine should be concentrated under these conditions.  By concentrating the urine, water is being conserved for the body.  Drinking too much water merely messes up the body's tried and trusted means of hydration control. See reference:

Water and sodium intake habits and status of ultra-endurance runners during a multi-stage ultra-marathon conducted in a hot ambient environment: an observational field based study

Nutrition Journal 2013, 12:13 doi:10.1186/1475-2891-12-13

Published: 15 January 2013

Ricardo JS Costa, Ana Teixeira, Luis Rama, Abigail JM Swancott, Lisa D Hardy, Benjamin Lee, Vera Camões-Costa, Samantha Gill, Jessica P Waterman, Emily C Freeth, Edel Barrett, Joanne Hankey, Slawomir Marczak, Encarna Valero-Burgos, Volker Scheer, Andrew Murray and Charles D Thake

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