Electrolytes and
their importance to the athlete.
During intensive exercise the body needs to convert oxygen
into energy (oxidative metabolism) yet only one quarter of the energy produced
enables you to move, the rest is released from the body as heat. This is where
sweat comes in; when working in a warm environment the heat produced must be
eliminated from the muscles being used, to the blood. Without this effectively
occurring in the body there is risk of a noticeable decrease in capacity to
perform, possible hyperthermia and further health risks. Rehydration,
particularly in the hot weather is crucial for replacing lost fluids and
maximising performance.
In April of last year Olympic medallist and extreme
sportsman, James Cracknell endured the 156 mile, gruelling Marathon des Sabres
in the scorching Moroccan heat. During this marathon he had his urine tested
twice a day in order to detect any signs of dehydration, trauma or malfunction.
The tests where essential in enabling him to not only perform at his best but
survive the experience under those conditions.
If there is no one at hand to test urine and check for
dehydration there is a simple test that can be done.
The nail blanch test/capillary nail refill test; Hold your
hand above you heart line and press down on the nail bed until it turns white
but not so that it hurts, then let go. If the nail bed returns to the normal pink
colour within 2 seconds, your circulation is good. If it takes longer than 2
seconds the result may be a sign of dehydration.
It isn’t just water you need for adequate hydration over
long periods of exercise. The body can only absorb a safe and proportionate
amount of fluid (plain water) this is approximately one litre of water per hour.
A 2% decrease in hydration results in a 20-35% drop in performance whether that
be mental or physical or both. In order for the produced heat to be transferred
from the muscles being used to the blood where it can then reach the
extremities of the body and/or be released as sweat, other components need to
be added to water.
Electrolytes are minerals such as sodium, chloride,
potassium, bicarbonate, calcium, phosphate and magnesium. These electrolytes
are found in the fluid within the body and are obtained by the food and drinks
we consume in our diets. They are fundamental in regulating nerve and muscle
function, blood pressure and pH, hydration and the repair of damaged tissue. When
there is an imbalance of fluid within the body, mineral levels change and can
be lost. This loss can alter blood chemistry; affect muscle action and other
mechanisms of the body. Not only inadequate intake of fluids can cause an
imbalance of electrolytes but also some medication, vomiting, diarrhoea and
sweating.
Blood contains more minerals than sweat and therefore at
times when there is inadequate water taken in to counteract the water lost
during exercise, the concentration of these minerals (electrolytes) in the
blood increases. When the amount of water lost through sweating is equal to the
amount consumed, the major electrolytes (sodium and chloride) decrease. This
however is more apparent in ultra-endurance athletes where exercise lasts
longer than 3 to 4 hours. For training of up to several hours at a time, it is
important that fluid along with glucose, are taken in to prevent dehydration,
exhaustion and heat stroke. The combination of sodium and carbohydrates can
help stimulate the absorption of water in the body and this is especially
important during periods of recovery where rehydration of both fluid and
electrolytes are essential. It is thought that the most effective post training
rehydration drink should have around 1100mg of sodium per litre1. Vita-coco is natural coconut water that
contains naturally occurring minerals, though relatively expensive it is one of
the best hydration drinks available.
Stroud Sports Clinic Ltd.
