Hydration and Athletic Performance

Did you know…

  • Most of us (unknowingly) are experiencing chronic dehydration?
  • Up to 37% of the population mistake hunger for thirst? Some studies suggest the percentage is higher because foods contain water and many beverages contain energy thus creating weak associations between thirst and hunger.
  • When craving sweets, you may actually be thirsty!

Did you know the human body is nearly 75% water?
Relevant Facts. Water is –

  • 90% of our brain
  • 83% of blood
  • 75% of muscle tissue
  • 22% of bone

Water Benefits

  • Overall health including improved immune systems thus reducing the risk of colds, flu, allergy and general ill feelings.
  • Organ health: Evidence is reduction of wrinkles in the largest organ – the skin.
  • Body temperature regulation: Sweating and respiration
  • Nutrient and Oxygen transport: Blood viscosity
  • Cellular regeneration: linked to nutrient transport and waste removal
  • Mind: Improves clarity of thought
  • Waste removal: Urine
  • Ease of movement: lubricates joints
  • Reduction of Fatigue, Headaches. Muscles cramps
  • Weight loss and/or maintenance of optimal lean mass ratios. Partially due to increased metabolism but also when thirst is quenched by water and not food, a person consumes less kcal.
  • Improved athletic performance
  • Greater overall energy.

Compromise to athletic performance? YES

  • Exercise performance is impaired when an individual is dehydrated by as little as 2% of body weight (Armstrong LE, 1985, Aug 17 (4)),  Running performance was impaired more at the longer distances (by approximately 5% at 5,000 and 10,000 m) compared with the shortest distance (approximately 3% at 1,500 m).
  • Losses in excess of 5% of body weight can decrease the capacity for work by about 30% (Armstrong et al. 1985; Craig and Cummings 1966; Maughan 1991; Sawka and Pandolf 1990).

Why does dehydration have an adverse effect on athletic performance?
Here are a few of the reasons:

  • Reduction in overall blood volume thus reducing viscosity (making the blood more concentrated and reduces efficiency in flow through the body for nutrients in and waste out)
  • Decreased sweat rate which is critical to waste disposal and thermal regulation
    Increased core temperature related to decreased sweat rate, increased blood viscosity, plasma osmolarity (ie dissolved sodium concentration in the blood)
  • Increased rate of muscle glycogen use due to energy system inefficiencies.
  • Compromised mental acuity thus making decisions and reflex action more difficult.

How much do you need?

  • Begin with 64oz/day. Place a gallon jug on the counter and by the end of the day it needs to be consumed. Plan on a minimum of 8oz per 30min of exercise.  10-12oz if in hot, humid environments or intense exercise.
  • DO NOT drink the gallon all at once!!

Hydration doesn’t have to come from water alone.

Foods that hydrate- fruits and vegetables!  Top picks: cucumbers , iceberg lettuce, celery, tomatoes, watermelon, cantaloupe, grapefruit,

More information
Sports Nutrition – 2nd Edition. An Introduction to Energy Production and Performance (Jeukendrup & Gleeson, 2010)

Armstrong LE, C. D. (1985, Aug 17 (4)). Influence of diuretic-induced dehydration on competitive running performance. Med Sci Sports Exer , 456-61.


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