Staying Hydrated: Fluids and Electrolytes
Replacing fluids during and after exercise is very important for optimal recovery, and most people simply don’t rehydrate enough. The Australian Institute of Sport recommends replacing 125 — 150% of fluids lost during exercise.
One way to estimate this is to weigh yourself before and after exercise. The amount of weight you lost can be attributed to sweat. For every pound lost, replace with 2 cups of water and make a note for how much more you should drink during your next workout. Ideally, you should finish your workout at the same weight you started at.
Make sure you are well-hydrated before you start to work out. If your urine is clear, that is a quick way to determine if you are well-hydrated. If it is yellow to dark yellow, you are dehydrated and should drink some water.
Sweat contains electrolytes and water, so it is also important to replace electrolytes. Electrolytes are needed for fluid balance, muscle contraction and nerve activity. Common electrolytes include sodium, chloride, magnesium, calcium and potassium. Exercise lasting longer than 60-90 minutes may require electrolyte replacement, but rate of sweating and individual differences need to be accounted for.
When electrolytes are not replaced during exercise, blood volume will drop. Your blood likes to always contain the same amount of certain electrolytes, and will expand or contract to dilute or concentrate them. When you lose electrolytes, your blood volume contracts to accommodate, which means less oxygen and nutrient delivery as well.
Drinking beverages or eating foods with electrolytes can help replenish levels. Sports drinks, salty foods, fruits, and energy bars are some examples. There are many electrolyte supplements on the market that you can also take, but unless you are working out for many hours the only electrolyte you need to worry about is sodium. Check with a fitness professional if you have specific questions for your training and electrolyte replacements.