SO marathon runners are actually at risk at the carefully placed water stations?
Exercised-Associated Hyponatremia affects marathon runners, particularly those finishing in over 4 hours.
What about the fittest of our runners-the Ultrarunners?
Increased fluid intake can also lead to foot swelling, as demonstrated in the paper by Cejka et al in the Journal of International Society of Sports Nutrition (see JSSN 2012 paper ). This was shown in ultra runners, and the measurement of swelling was determined by plethysmography-the use of Plexiglas® vessel with the internal dimensions of 386 mm length and 234 mm width with markings in millimetres on the external surface. These dimensions were chosen so that any foot size of a male runner would fit in the vessel.
Other markers such as haematocrit, urine specific gravity, urine and body mass. The numbers tested were a respectable seventy-six, and all were 100km plus ultra marathon runners.
After one such race, the ‘100 km Lauf Biel’ (www.100km.ch) in Biel, Switzerland, foot swelling was demonstrated, and the authors concluded that this was as a direct result of increased fluid intake during the race.
In case of fluid overload leading to an increase in the feet volume, the authors had hypothesized that there would be an association between changes in plasma [Na+] and the feet volume and a higher prevalence of exercise-associated hyponatraemia or EAH: in accordance with our hypothesis, fluid intake was related to the change in feet volume, and we found an association between the change in plasma [Na+] and the change in the feet volume.
In addition, four subjects (5.3%) developed asymptomatic exercise-associated hyponatremia (EAH) with plasma [Na+] between 132 and 134 mmol/L.
The most important finding in this study was that fluid intake was significantly and positively related to the change in the foot volume, where an increased fluid intake was leading to an increased volume of the foot. Both the change in the foot volume and fluid intake were significantly and negatively related to running speed. Faster runners were drinking less during the race, and their foot volume tended to decrease.
The conclusions therefore are stark for the slower runners in the field: slower running speed was associated with an increase in the foot volume and the change in foot volume was negatively correlated to the change in plasma [Na+].
Therefore, fluid overload occurred in slower runners and was responsible for the development of oedemas in the foot. In addition, post-race plasma [Na+] decreased in those runners.
The data supports the finding that fluid overload is the main risk factor for developing EAH, albeit in this one race all were without symptoms. The outcome is not the same in all cases.
Exercised-Associated Hyponatremia affects marathon runners, particularly those finishing in over 4 hours.
What about the fittest of our runners-the Ultrarunners?
Other markers such as haematocrit, urine specific gravity, urine and body mass. The numbers tested were a respectable seventy-six, and all were 100km plus ultra marathon runners.
After one such race, the ‘100 km Lauf Biel’ (www.100km.ch) in Biel, Switzerland, foot swelling was demonstrated, and the authors concluded that this was as a direct result of increased fluid intake during the race.
In case of fluid overload leading to an increase in the feet volume, the authors had hypothesized that there would be an association between changes in plasma [Na+] and the feet volume and a higher prevalence of exercise-associated hyponatraemia or EAH: in accordance with our hypothesis, fluid intake was related to the change in feet volume, and we found an association between the change in plasma [Na+] and the change in the feet volume.
In addition, four subjects (5.3%) developed asymptomatic exercise-associated hyponatremia (EAH) with plasma [Na+] between 132 and 134 mmol/L.
The most important finding in this study was that fluid intake was significantly and positively related to the change in the foot volume, where an increased fluid intake was leading to an increased volume of the foot. Both the change in the foot volume and fluid intake were significantly and negatively related to running speed. Faster runners were drinking less during the race, and their foot volume tended to decrease.
The conclusions therefore are stark for the slower runners in the field: slower running speed was associated with an increase in the foot volume and the change in foot volume was negatively correlated to the change in plasma [Na+].
Therefore, fluid overload occurred in slower runners and was responsible for the development of oedemas in the foot. In addition, post-race plasma [Na+] decreased in those runners.
The data supports the finding that fluid overload is the main risk factor for developing EAH, albeit in this one race all were without symptoms. The outcome is not the same in all cases.
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