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Hydration 2 of 4: Dehydration, Performance, Cramps and Sodium

Dr. Tim Noakes’ “Waterlogged, The Serious Problem of Overhydration in Endurance Sports” is a book that digs deep into hydration and endurance sports using a scientific language that is easy to understand and which contains all that you must know on the subject. Below is the second of a series of four tickets. If our first publication on this matter has failed to convince you to purchase this book, here are a few more dashing quotes

More sever level of weight loss or dehydration are not related to impaired performance

 

  • Athlete cannot ingest fluid at rates of 1.2l/h (like some scientific recommend), other than that they have no need: they are smaller and have smaller stomachs and intestines (less capacity to process fluid) AND the respiratory rate so high that they do not have time to ingest a large volume before they must take another breath. (p.224)
  • Studies show a linear relationship with a positive slope between percentage of body loss and total performance time… the more you perform, the more you lose weight (p.55)
  • Some world-class athletes can achieve exceptional performance even when they lose 7% to 10% of their body weight during competition (p.73)
  • A meta-analysis showed for the first time that drinking according to the dictates of thirst will maximize endurance performance (Goulet-2011)

 

If you are carbohydrate adapted, to optimize your performance during more prolonged competitive exercise; you will need to ingest some carbohydrate.The theory of sodium deficit and dehydration does not explain the development of Exercise-Associated Muscle Cramping (EAMC)

 

  • There is NO evidence or the available evidence DON’T support:
  1. Higher body temperature of subjects with EAMC is any higher than those of control subjects performing the same exercise.
  2. Blood electrolyte concentration, including sodium, are abnormal at the time subject develop EAMC
  3. Dehydration cause EAMC
  4. Athletes with EAMC are more dehydrated than control (no EAMC)
  5. Salty sweating cause EAMC  (p.118-119)
  • The EAMC typically affects only muscle groups that are involve in the repetitive contractions associated with that specific activity (p.119)
  • Neither EAMC or heat illnesses are caused by sodium deficiency (p.148)

 

Evidence simply does not exist that recreational or professional athlete competing in long duration event will inevitably develop a state of salt deficiency. (p.144)

 

  • Our evolution provided us with exquisite homeostatic controls to ensure that our daily urinary and sweat potassium losses exactly balance our daily dietary potassium intakes. The same applies for sodium. (p.111)
  • Sweat sodium losses are determined by the level of daily salt intake in the diet. (p.138)
  • Sodium losses match intakes, not the converse. (p.140)
  • There is no need to increase your habitual daily sodium intake above that dictates by your appetite (p.353)
  • There is no need to ingest additional sodium during exercise (p.353)

 

  Don’t miss our third ticket next week, “The Science of Hydration and its Consequences – Behind the Scenes.”