1. What is the need (amount and timing) of sodium during training?
Perspiration contains 20-80 mM salt (sodium chloride, like table salt). This
corresponds to 1-4 g of table salt per Quart or Liter of sweat, which, in turn,
corresponds 1/6 – 4/6 teaspoon of salt per Qt or L. The average sweat concentration
(~45 mM) corresponds to ~1/3 teaspoon / Qt or L. This is 1/3 the concentration of salt
in the blood. Therefore, as you perspire, the salt in your blood concentrates. If you
replace less than 2/3 of your perspiration losses during exercise you should drink pure
water to help your blood re-dilute its salts back to a normal concentration. If you
replace all of your perspiration losses you should include the same amount of salt in
your fluids that is in your sweat (1/3 teaspoon per quart or liter). You need pure
Replacing all of your perspiration losses without any electrolytes can lead to
hyponutramia (diluting your body salts with the potential of physical collapse) when
exercise exceeds a couple of hours since excess dilution is cumulative (kidney function
is decreased during exertion so the body has a tough time getting rid of large
quantities of excess water intake). Note that the concentration of salts in sweat goes
down with training (elite athletes should use less salt per Qt or L) but the amount of
sweat goes up (elite athletes need more water volume). The only way to know for sure
that you are replacing your perspiration losses is to occasionally weigh yourself before
and after training, keeping in mind that sweat rate changes by a factor of 2 or more
when training harder or in the heat. If you lose 1 kg in a training session then you are
deficient in water intake by 1 Qt or L over the entire training session. If your body
weight is the same after training as before, then your water consumption is on target. I
would not concern myself with what exact concentration of salt is in your sweat unless
you are pushing the limits to get into the Olympics. The main thing is that you replace
all your sweat losses and if your training is longer than 1 hour you include some
electrolytes (1/3 teaspoon / Qt or L) if >2/3 sweat losses are replaced).
2. What about potassium?
Perspiration contains 1/10 as much potassium as sodium. I recommend that
electrolyte concentrations reflect that i.e. that electrolytes in your training fluids have
1/10 the amount of potassium as sodium. For exercise less than an hour or so there
is little need to include any electrolytes in your fluids. The longer training is (greater
than an hour and longer) the more important electrolyte replacement becomes.
3. How much water do I likely lose during training?
Most likely ~1 L or Qt on cool days and double that on hot days. Two L or Qt is
approaching the absolute maximum amount that can be ingested during training, so
very hot humid days present an athlete with a potentially unsolvable dehydration
problem. Mechanical means of cooling, such as a hat or being splashed with tepid
water, may be options for assisting the internal cooling system of the body.
4. How much water do I need beyond what is required to replace perspiration
losses during training?
You need 1 L or Qt of water for each 1000 kcals that you eat for proper digestion
and absorption. This water should be ingested slowly throughout the day, not just with
meals, so that water is supplied as digestion proceeds. Drinking large amounts of
water at once results in the body sending the excess straight to the bladder. During
training, if you take in calories (which is recommended), it is particularly important to
replace all of your perspiration losses. Otherwise, you will be dehydrated both
because of perspiration losses as well as caloric intake. Dehydration can land you in
the emergency room.
5. What is the role of water in the conversion of food into energy?
Water is required to:
1) lower the concentration of food so that it can flow from the stomach to the intestine,
and to lower the concentration even more until it matches the concentration of
molecules in the blood so that the bloodstream can absorb the food. In sports and
training drinks, the calories are already dilute, and further dilution with water is not
required. But if the amount of sugar in your training drink exceeds 8%you may get
gastric distress.
2) break apart sugars and amino acids that enter the body as chains of sugars and
amino acids (This "breaking apart" entails water chemically reacting with the chains of
sugar and amino acids in a reaction called hydrolysis and results in permanent loss of
that water (I would work the parenthetical material into the text, and break it all up into
two sentences). The amount of water required for this break-down depends on how
broken down the sugar or protein is already. Simple sugars, for example, are nearly
completely broken down already.
3) solvate sugar and protein molecules. By this, I mean more than just dilute the sugar
or protein like I discussed in (1) above. Sugar requires 5 to 6 times its weight in water
in order to dissolve. That water is not available to the body for any other purpose until
the sugar is broken down and used as fuel.
4) metabolize amino acids, sugars, and fat molecules. Metabolism is the production of
energy through chemical reactions.. Water is lost during metabolism because it is
involved in the chemical reactions and becomes chemically bound to the products of
metabolism.
Different foods require different amounts of water to be diluted, dissolved, hydrolyzed,
and metabolized. Also food will have an
average amount of fecal and urine material produced which will require an average
amount of water per kcal consumed for excretion of waste.
6. What do you think of Pedialyte and Electromix?
Both have problems associated with them. Pedialyte is designed for infants that
have diarrhea, vomiting, etc. It doesn't match perspiration losses. Its sodium and
chloride content are fine, but it is 4 times too high in potassium and has no other
minerals. A much cheaper way to go is to use a product called Electromix. This
product comes in a packet that is thrown into 1 gallon of water to give you potassium,
calcium, and magnesium in roughly the amounts contained in sweat. You can then
add some table salt (1 and 1/3 teaspoon for 1 gallon) for the sodium chloride. A box
of 5 packets (to make 5 gallons) costs $ 2.50, whereas five gallons of Pedialyte costs
over $ 100 if you buy it at Safeway. The other ingredients in Pedialyte are dextrin
(sugar) and citrate (one of the intermediates of sugar burning in the TCA cycle in
cellular mitochondria). There is no real advantage to either of these if you are using
maltodextrin, sugar, or any other carbohydrate source (Cliff Bars, etc). It is important
to note that one packet of Electromix contains the upper limits of manganese and
chromium picolinate that I recommend per day. Therefore, limit your use of Electromix
to 1 packet per day if you decide to use it, and avoid additional supplementation of
manganese and chromium picolinate (other chromium sources are OK). When and if I
find a better electrolyte replacement I will make sure everyone knows about it.
Perspiration contains 20-80 mM salt (sodium chloride, like table salt). This
corresponds to 1-4 g of table salt per Quart or Liter of sweat, which, in turn,
corresponds 1/6 – 4/6 teaspoon of salt per Qt or L. The average sweat concentration
(~45 mM) corresponds to ~1/3 teaspoon / Qt or L. This is 1/3 the concentration of salt
in the blood. Therefore, as you perspire, the salt in your blood concentrates. If you
replace less than 2/3 of your perspiration losses during exercise you should drink pure
water to help your blood re-dilute its salts back to a normal concentration. If you
replace all of your perspiration losses you should include the same amount of salt in
your fluids that is in your sweat (1/3 teaspoon per quart or liter). You need pure
Replacing all of your perspiration losses without any electrolytes can lead to
hyponutramia (diluting your body salts with the potential of physical collapse) when
exercise exceeds a couple of hours since excess dilution is cumulative (kidney function
is decreased during exertion so the body has a tough time getting rid of large
quantities of excess water intake). Note that the concentration of salts in sweat goes
down with training (elite athletes should use less salt per Qt or L) but the amount of
sweat goes up (elite athletes need more water volume). The only way to know for sure
that you are replacing your perspiration losses is to occasionally weigh yourself before
and after training, keeping in mind that sweat rate changes by a factor of 2 or more
when training harder or in the heat. If you lose 1 kg in a training session then you are
deficient in water intake by 1 Qt or L over the entire training session. If your body
weight is the same after training as before, then your water consumption is on target. I
would not concern myself with what exact concentration of salt is in your sweat unless
you are pushing the limits to get into the Olympics. The main thing is that you replace
all your sweat losses and if your training is longer than 1 hour you include some
electrolytes (1/3 teaspoon / Qt or L) if >2/3 sweat losses are replaced).
2. What about potassium?
Perspiration contains 1/10 as much potassium as sodium. I recommend that
electrolyte concentrations reflect that i.e. that electrolytes in your training fluids have
1/10 the amount of potassium as sodium. For exercise less than an hour or so there
is little need to include any electrolytes in your fluids. The longer training is (greater
than an hour and longer) the more important electrolyte replacement becomes.
3. How much water do I likely lose during training?
Most likely ~1 L or Qt on cool days and double that on hot days. Two L or Qt is
approaching the absolute maximum amount that can be ingested during training, so
very hot humid days present an athlete with a potentially unsolvable dehydration
problem. Mechanical means of cooling, such as a hat or being splashed with tepid
water, may be options for assisting the internal cooling system of the body.
4. How much water do I need beyond what is required to replace perspiration
losses during training?
You need 1 L or Qt of water for each 1000 kcals that you eat for proper digestion
and absorption. This water should be ingested slowly throughout the day, not just with
meals, so that water is supplied as digestion proceeds. Drinking large amounts of
water at once results in the body sending the excess straight to the bladder. During
training, if you take in calories (which is recommended), it is particularly important to
replace all of your perspiration losses. Otherwise, you will be dehydrated both
because of perspiration losses as well as caloric intake. Dehydration can land you in
the emergency room.
5. What is the role of water in the conversion of food into energy?
Water is required to:
1) lower the concentration of food so that it can flow from the stomach to the intestine,
and to lower the concentration even more until it matches the concentration of
molecules in the blood so that the bloodstream can absorb the food. In sports and
training drinks, the calories are already dilute, and further dilution with water is not
required. But if the amount of sugar in your training drink exceeds 8%you may get
gastric distress.
2) break apart sugars and amino acids that enter the body as chains of sugars and
amino acids (This "breaking apart" entails water chemically reacting with the chains of
sugar and amino acids in a reaction called hydrolysis and results in permanent loss of
that water (I would work the parenthetical material into the text, and break it all up into
two sentences). The amount of water required for this break-down depends on how
broken down the sugar or protein is already. Simple sugars, for example, are nearly
completely broken down already.
3) solvate sugar and protein molecules. By this, I mean more than just dilute the sugar
or protein like I discussed in (1) above. Sugar requires 5 to 6 times its weight in water
in order to dissolve. That water is not available to the body for any other purpose until
the sugar is broken down and used as fuel.
4) metabolize amino acids, sugars, and fat molecules. Metabolism is the production of
energy through chemical reactions.. Water is lost during metabolism because it is
involved in the chemical reactions and becomes chemically bound to the products of
metabolism.
Different foods require different amounts of water to be diluted, dissolved, hydrolyzed,
and metabolized. Also food will have an
average amount of fecal and urine material produced which will require an average
amount of water per kcal consumed for excretion of waste.
6. What do you think of Pedialyte and Electromix?
Both have problems associated with them. Pedialyte is designed for infants that
have diarrhea, vomiting, etc. It doesn't match perspiration losses. Its sodium and
chloride content are fine, but it is 4 times too high in potassium and has no other
minerals. A much cheaper way to go is to use a product called Electromix. This
product comes in a packet that is thrown into 1 gallon of water to give you potassium,
calcium, and magnesium in roughly the amounts contained in sweat. You can then
add some table salt (1 and 1/3 teaspoon for 1 gallon) for the sodium chloride. A box
of 5 packets (to make 5 gallons) costs $ 2.50, whereas five gallons of Pedialyte costs
over $ 100 if you buy it at Safeway. The other ingredients in Pedialyte are dextrin
(sugar) and citrate (one of the intermediates of sugar burning in the TCA cycle in
cellular mitochondria). There is no real advantage to either of these if you are using
maltodextrin, sugar, or any other carbohydrate source (Cliff Bars, etc). It is important
to note that one packet of Electromix contains the upper limits of manganese and
chromium picolinate that I recommend per day. Therefore, limit your use of Electromix
to 1 packet per day if you decide to use it, and avoid additional supplementation of
manganese and chromium picolinate (other chromium sources are OK). When and if I
find a better electrolyte replacement I will make sure everyone knows about it.
© Clyde F. Wilson
Electrolytes and Water
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