Influence of taste
Many nutritional companies across the world have responded to research on the benefits of isotonic drinks by producing a wide range of products specifically developed to optimise the rate of fluid and fuel absorption. But whilst the ingredients of such a drink may be optimised for technical performance, it has also been shown that the more fundamental variable of taste, has an impact on the desire to drink, and hence the quantity of fluid that is ingested (10,11). Voluntary consumption of a flavoured drink was shown to be greater than that of unflavoured water during cycling exercise at 50% of maximum oxygen uptake suggesting that a palatable flavour can increase consumption of a drink (4). This is particularly an issue when a sports drink contains the electrolyte sodium, which is required to enhance the absorption of fluid from the gut and to replace sodium that is lost from sweating, particularly in hot and humid environments (4). The ‘salty’ taste that results from the inclusion of sodium in a drink can be off-putting for users, and restrict the volumes that are consumed. One option is to mask this taste with additional carbohydrate to provide a sweeter taste. However this will increase the calorific content of the drink and can quite easily increase the drink’s osmolality to a level that changes its scientific properties, such that drinks designed to be either hypotonic or isotonic no longer fit into these categories