Exercise-Associated Hyponatremia, Hypernatremia, and Hydration Status in Multistage Ultramarathons

Abstract

The incidence of EAH in multistage ultramarathons was similar to marathons and single-stage ultramarathons, but the cumulative incidence of hypernatremia was 3 times greater than that of EAH. EAH was associated with increased weight gain (overhydration) in early stage nonfinishers and postrace finishers.

Fluid Metabolism in Athletes Running Seven Marathons in Seven Consecutive Days

“…The highest number of dehydrated athletes based on their body mass changes (Noakes et al, 2005 ) was found at A 7 . A similar number of athletes were probably dehydrated after a multi-stage ultramarathon in the study of Krabak et al ( 2017 ). Nevertheless, the present runners had a significantly higher percentage change in plasma volume than after A 1 and no relationship between the change in plasma volume and plasma osmolality or fluid intake was found.…”

“…Altered hydration status has not been well studied in multi-stage races (Krabak et al, 2017 ). In a multi-stage ultramarathon, athletes often compete for several days (Knechtle et al, 2012a ), run at a slow pace (Costa et al, 2013 ), and are at an increased risk of fluid overload (Rüst et al, 2012 ).…”

“…In case of excess fluid consumption, an increase in body mass, total body water and a decrease in plasma sodium [Na + ] (Hew-Butler et al, 2015 ) can be expected. Exercise-associated hyponatremia (EAH) is a common occurrence among endurance athletes (Hew-Butler et al, 2015 ) and the incidence of EAH in multi-stage marathons is similar to its incidence in marathons and single-stage ultramarathons (Krabak et al, 2017 ). EAH occurred during multi-stage races with both increased and stable levels of total body water (Knechtle et al, 2011 , 2012a ; Rüst et al, 2012 ; Costa et al, 2013 ).…”

“…By contrast, anecdotal evidence suggests that multi-stage ultra-runners do not consume sufficient fluid to maintain euhydration, especially in hot ambient conditions (Costa et al, 2013 ). During multi-stage races, body mass often decreases (Knechtle et al, 2008a , b , 2010a , b , 2011 , 2012b , 2015 ; Zouhal et al, 2009 ; Rüst et al, 2012 ; Costa et al, 2013 ; Hue et al, 2014 ; Krabak et al, 2017 ) or remains unchanged (Knechtle and Kohler, 2007 ; Knechtle et al, 2008c , 2010b ). The decrease in body mass and the increase in urine specific gravity can indicate dehydration (Kavouras, 2002 ).…”

“…It is worth mentioning that that the appropriate body mass loss depends on the exercise duration. Multistage ultramarathon runners were most likely dehydrated after the last and longest stage of the race in a prospective observational cohort study (Krabak et al, 2017 ) though with the highest EAH prevalence. Contributing factors to body mass losses can be excessive distances, limited access to fluids and gastrointestinal problems (Hew-Butler et al, 2015 ).…”