Don't Always Pass on the Salt

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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