warrwych wrote:
> Martin Wrote:
>
>> OzCableguy wrote:
>>
>>> Can anyone recommend a good electrolyte drink powder that I can
>>> mix
>>
>> up into
>>
>>> a biddon, is easy to get hold of, works, tastes ok and doesn't
>>> cost
>>
>> the
>>
>>> earth?
>>
>> Almost all the studies and guidelines I have read on this topic
>> agree that the only mineral in sweat that might be important to
>> replace is sodium. Recent evidence, however, suggests that we don't
>> need to replace electrolytes during exercise. See
>>
>> http://tinyurl.com/2gsvym
>>
>> This paper suggests that we need only about 65 mmol of sodium (1.5
>> grams of sodium, equivalent to about 4 grams of salt) of sodium per
>> day.
>>
>> See also www.saltmatters.org for very strong evidence supporting 50
>> mmol/day (about 1 gram of sodium or 3 grams of salt) as an upper
>> limit for sodium intake from all sources. Trevor Beard and others
>> suggest that most of us eat way too much salt, even if we don't
>> cook with salt or put salt on our food. We get much more salt than
>> we need from processed foods like bread. Too much salt causes
>> health problems, mainly high blood pressure, even in people who
>> exercise a lot. See also http://tinyurl.com/36cn5j.
>>
>> www.saltmatters.org (see 'Safety issues') suggests that we loose a
>> lot less (about 70 - 85% less) sodium in sweat if we eat a low salt
>> diet.
>>
>> My limited experience: Fow a few years I got headaches a few hours
>> after a moderate ride (30 - 60 km solo or in a group at about 27 -
>> 30 km/hr ). Headache is one of the symptoms of hyponatraemia (low
>> blood sodium). I started putting salt in my water bottle and the
>> headaches seemed to stop. I have been on a low salt diet for about
>> 6 weeks now - no additional salt in my water bottle and no
>> post-ride headaches (so far).
>>
>> I am interested to hear other cyclists' experience with post-ride
>> headaches.
>>
>> Martin
>>
>> -- Removed z before replying by email.
>
>
> you are saying that all electrolytes = sodium. The study you site
> ONLY refers to sodium. it does not discuss calcium, potassium,
> magnesium etc.
>
> I'd like to see some of this research you allude to regarding "the
> only mineral in sweat that might be important to replace is sodium."
>
> The conversation was about cramping, and using electrolytes (in
> general) to help with this issue.
I did not say that all electrolytes = sodium. Body stores of sodium are
relatively small and sodium is the electrolyte that is secreted at
highest concentration in sweat. The body stores of potassium are
relativley large and potassium is secreted at lowew concentration in
sweat. So, if you are going to take any electrolyte replacement, sodium
is probably more important than potassium. I don't know about readily
available body stores of magnesium and calcium, but they are also
secreted at low concentrations in sweat.
Some recent evidence:
'Compared with sodium and chloride, the concentration
of other electrolytes in sweat is low. For example, the
average concentrations are: potassium, 5 mmol/L
(range 3-15 mmol/L); calcium, 1 mmol/L (range
0.3-2.0 mmol/L); and magnesium, 0.8 mmol/L
(range 0.2-1.5 mmol/L). Presently, there are no data
that make a compelling case for including these
electrolytes in fluids consumed during exercise
From the full text of:
Coyle (2004) Fluid and fuel intake during exercise
http://tinyurl.com/2utrln
'Sodium is the most important electrolyte in terms of
recovery after exercise. Without its replacement, water
retention is hampered. Potassium is also included in
sports drinks in concentrations similar to those in sweat.
Although there is strong evidence for the inclusion of
sodium, this is not the case with potassium. There is no
evidence for the inclusion of any other electrolytes.'
From the full text of:
SHIRREFFS et al 2004. Fluid and electrolyte needs for preparation and
recovery from training and competition
http://tinyurl.com/2msvhx
On cramp:
'exercise-associated muscle cramping in ironman triathletes is not
associated with a greater percent body mass loss or clinically
significant differences in serum electrolyte concentrations.'
From:
Sulzer et al 2005: Serum electrolytes in Ironman triathletes with
exercise- associated muscle cramping.
http://tinyurl.com/3643e6
There are many more studies of both electrolyte replacement and cramp,
although I don't think any have been done in people on low-salt diets. I
don't think the causes of cramp are properly understood. In any event,
Pubmed is a better source of reliable information than the advertising
of sports drink manufacturers. When you see an article that concludes
that sports drinks aid rehydration look to see if the authors were
funded by Gatorade etc. I suspect the sports drink manufacturers are
pulling the wool over our eyes and (very successfully) lightening our
wallets.
Martin
--
Removed z before replying by email.
