Dehydration occurs when amount of water leaving the body is greater than the amount being taken in. Sweating leads to decrease in circulating blood volume leading to thickening of blood, strain on cardio vascular system with rise in heat rate which hinders performance.
If you are dehydrated by as little as 2% your performance will be impaired. If dehydration is 5% aerobic capacity is reduced by 30%. A water loss of 9-12% of an individuals total body weight can result in death.
Symptoms of dehydration usually start with thirst and progress, if you already feel thirsty then you are already dehydrated;
mild dehydration (around 2% of fluid loss)
thirst
loss of appetite
dry skin
skin flushing
dark coloured urine
dry mouth and lips
fatigue and weakness
dizziness
5% fluid loss;
increased heart rate
increased respiration
decreased sweating
decreased urination
increased body temperature
extreme fatigue
muscle cramps
headaches
nausea
tingling of the limbs
Tips to stay hydrated;
Drink little and often
Don’t wait until you are thirsty
Aim to meet 1ml of fluid per kcal burnt
Aim for straw coloured urine
Drink 5-6ml/kg body weight at least 4 hours prior to exercise
Calculate fluid loss during training by weighing yourself before and after the session, then divide fluid loss into 10-15 minutes segments and aim to drink that much in next session
Replace 150% of fluid loss after exercise
For training over an hour some sports drink or energy is recommended. Under an hour and it’s not.
Sports drinks contain fluids, carbs and electrolyte. There are three types;
Isotonic; provide carbs and maintain hydration
same osmolality as bodies fluids.
4-8g/100ml carbs
ideal for sports where both hydration and carbs limit performance
Hypotonic; maintain hydration
less than 4g carbs per 100ml
provide better hydration
for enough fuel for long workouts
Hypertonic; provide carbs
Higher osmolality than the body
slower to absorb
higher than 8g per 100ml
useful after exercise
need to be used with hypotonic drinks during exercise
Homemade sports drink, fruit juice and water;
isotonic; 50:50 juice and water plus pinch of salt
hypotonic; 750 water to 240 juice plus pinch of salt
The ideal drink should; taste good, not cause stomach discomfort, provide some carbs and electrolytes.
Look at lots of sports drinks and compare by;
carb concentration
type of carb used
other ingredients like electrolytes, sweeteners, vitamins
claims made on label
Electrolytes have a number of roles; muscles contraction, fluid balance, maintaining PH balance. The most common electrolytes are;
sodium
potassium
magnesium
chloride
calcium
Maintaining an electrolyte balance is important for blood acidity, muscle contraction and other important processes so including them in sports drinks helps keep things in balance, avoid cramp, maintain performance and gives you thirst to drink more.
