Sweaty Athletes More Likely to Need Electrolytes
by: Robbie Durand
For years, sports scientists have recommended that athletes stay adequately hydrated in hot, humid conditions especially in endurance athletes such as marathon running and long distance biking. During these types of endurance events, it is not uncommon for athletes to lose several liters of sweat during exercise. Most endurance athletes know they need carbohydrates during long distance events, but an essential aspect of distance training is maintaining electrolytes during exercise.
Most recovery and endurance drinks replace the fluid lost from sweating, but electrolytes also need to be maintained especially sodium. Severe sweating can cause hyponatraemia (a sodium concentration in the blood of less than 135 mmol/L which, in severe cases, can cause decreased consciousness, hallucinations or coma, brain herniation and even death). Hyponatraemia may be due to drinking too much water, for example during strenuous exercise, without adequate replacement of sodium. Maintaining the body’s sodium levels has become a key priority for the success of elite athletes and enthusiasts alike. Electrolyte concentration in sweat is an essential factor for predicting sodium requirements during sports activities-especially endurance activities such as marathons.
The importance of electrolyte replacement during exercise was recently demonstrated in the Scandinavian Journal of Medicine & Science in Sports, which found that serum electrolyte levels during the race prevented decreased performance as well as the associated health complications during intense aerobic exercise. Electrolytes are necessary for regulating the amount of fluid in your body, but they also help with managing acidity in your blood, muscle function, and regulating nerve function. When the body tries to cool itself by sweating, you lose these vital minerals.
Researchers had two patches specifically designed to collect sweat samples were placed on the skin of 51 marathon runners and were worn throughout the entire marathon. Immediately after completing the race, a blood sample was taken from each runner to analyse their electrolyte levels. The first analysis allowed the runners to be classified into three groups depending on their sodium concentrations:
-Runners with ‘low-salt’ sweat;
-Runners who were ‘typical’ sweaters with a normal amount of sodium in their sweat, and
-Runners who were ‘salty’ sweaters which are those runners who had an excessive amount of sodium in their sweat.
At the end of the study, the marathon runners who had very high concentrations of electrolytes in their sweat (the ‘salty’ sweaters) had lower electrolyte levels in their blood despite having properly rehydrated and having eaten the same amount of food with salt as the rest of the runners. These figures indicate that electrolyte levels in sweat can affect water and electrolyte homeostasis over the course of the marathon; in other words, sweat electrolyte levels can have an impact on the maintenance of stable and physiologically sound conditions that allow the body to carry out its functions. Sweat electrolyte concentration could influence post-race serum electrolyte concentration in the marathon.
Lara B, Salinero J, Areces F, Ruiz-Vicente D, Gallo-Salazar C, Abian-Vicen J, et al. Sweat sodium loss influences serum sodium concentration in a marathon. Scandinavian Journal of Medicine & Science in Sports. 2016.