Don’t Always Pass On the Salt
-Eve Pearce
The mantra to use less salt has
become ingrained in the health conscious, with many throwing away their salt
shaker and scrutinizing food labels to choose those with the lowest salt
content. Whilst reducing our salt intake holds benefits to many
people – high intakes are linked to hypertension, osteoporosis and stomach
cancer – there are a number of instances where additional salt is vital. Certain
medical conditions and medications can deplete the body of sodium – one of the
main components of salt - and during an episode of vomiting and diarrhoea you
are at risk of low sodium levels. However, participating
in vigorous activity can also increase your chances of sodium depletion, so
during and after an intense training session or game it’s essential for
basketball players to ensure that they appropriately rehydrate to preserve
their sodium levels. Here we take a look at the role of sodium in the
body, why depletion occurs during activity, its consequences and how athletes
can maintain their levels. However, if you have previously been told you
have high sodium levels, discuss this with your
physician before implementing any of the advice below, as they may wish to run
another blood test.
The importance of sodium
Sodium is present in body fluids,
including the blood, inside the cells of the body and the fluid in which they
are bathed. It plays an important role in controlling
fluid balance and blood pressure, but is also essential for correct nerve and
muscle function. The body aims to match its fluid intake and output by
controlling fluid losses via the kidneys, in which sodium plays a role.
Specialist cells in the nephrons of the kidneys – the part which filters the
blood - are able to sense changes in blood pressure, which occurs when there is
a change in fluid volume. When they sense a fall in blood pressure, the kidney
secretes a hormone called aldosterone, which increases the reabsorption of
sodium and in turn this draws water into the blood helping to restore the
circulating fluid levels. Meanwhile the nervous system is able to control organ
function and movement through the transfer of electrical impulses via nerve
cells throughout the body. The movement of sodium and potassium ions across the
nerve cell membranes allows these impulses to be generated and travel along the
nerves to stimulate the target cells, which commonly might be glandular tissue
to secrete a hormone or muscle fibres to initiate movement.
Sodium losses during activity
During exercise sodium is lost during sweating, so the body loses both
salt and water. Dehydration itself can lead to a varying degree of problems
such as headaches, confusion, muscle cramps, impaired cardiac output and heat
exhaustion,
where the body begins to overheat; if not treated it can lead to more serious
heatstroke, which can hinder breathing and mental function and at its most
severe cause organ failure. The reduction of sodium within the body drives
water into the cells to balance the sodium concentration inside and outside of
the cells. This causes a fall in blood volume, which is compounded by the water
lost in sweat. As a result blood pressure decreases – this tends to already be
lower in those who take regular exercise - which can lead to feelings of
tiredness, nausea and dizziness, as well as a rapid or irregular pulse, blurred
vision and even fainting. While some of these will impair performance, others
will put an athlete’s safety at risk. Not only this, but the entry of
water into the cells causes them to swell, which can be particularly dangerous
if this occurs in the brain. If allowed to progress low sodium levels can
develop into a condition called hyponatremia, which can lead to muscle
weakness, loss of consciousness, seizures and in the worst cases can be fatal.
Appropriate hydration for athletes
Although water is commonly taken to replace fluid losses during
activity, this is a hypotonic solution, meaning that it has a low concentration
of salts in it including sodium. While this might be adequate for gentle
exercise or short bursts of activity, if taken during or after vigorous
exercise rehydration will be incomplete, as salt levels will not be adequately
replenished.
In fact if you take too much water on board, you will dilute your sodium levels
further and the risk of hyponatremia is increased. Not only is it important to
consider the type of fluids consumed during and after exercise, but players
need to ensure that they are adequately hydrated prior to training or a game.
The American College of Sports
Medicine have produced guidelines on
hydration before, during and after exercise. Two hours prior to exercise it is recommended that players drink 17
fluid ounces, which will ensure they take sufficient fluid on board and
that their body has time to excrete any excess prior to the game. Ideally players should drink at regular
intervals to top up their fluids and that this should be cooler than
their surroundings to prevent overheating and flavoured to aid consumption. If
exercising for more than an hour the fluid needs to contain added carbohydrate
and salts; it is suggested that 30-60g of carbohydrate is taken in 20 to 40
fluid ounces every hour and that the sodium content is 0.5-0.7g per litre.
Gatorade, Powerade and Accelerade would all be appropriate choices, though it
is possible to make up your own sports drink. To determine how much sports drink you need to take after a game,
ideally weigh yourself before and after; for each pound in weight lost as a
consequence of fluid losses you will need to drink 24 fluid ounces to rehydrate
