(1) Department of Human Nutrition, University of Otago, New Zealand
(2) Sport and Exercise Science, Swansea University, United Kingdom
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The reported incidence of exercise-associated hyponatraemia (plasma sodium concentration <135 mmol/L) in endurance sport has increased notably in recent decades. Sodium supplements have been suggested to attenuate the decline in plasma sodium concentration and hence, prevent the effects of exercise-associated hyponatraemia on performance. This article reviews intervention studies that have assessed the impact of sodium supplements on plasma sodium concentrations and/or performance during endurance exercise.
Despite significant results in some laboratory studies show benefits of sodium supplementation, more recent field studies suggest that sodium supplementation has little impact on plasma sodium concentration during a racing situation and no effect on performance. These discrepancies are likely because of design differences between the studies. However, a well-controlled crossover field trial in a hot environment is still required in order to develop practical recommendations.