This study sought to identify runner characteristics or symptoms that could distinguish those finishers developing exercise-associated hyponatremia (EAH) from those not developing EAH in a 161-km ultramarathon. Of 310 finishers, 207 (67%) underwent postrace blood studies. Twelve (6%) finishers had EAH (blood sodium range 131-134 mmol/L). Experience at 161-km ultramarathons was lower (p = 0.01) and blood creatine kinase (CK) concentration was higher (p = 0.04) among those with EAH than those not developing EAH. Blood sodium and CK concentration were negatively correlated (p = 0.0015, r = -0.22). There were no group differences in age, sex, regular running experience, weekly training distance, use of sodium supplements during training, immediately postrace sodium palatability and thirst ratings, body mass change, urination frequency, nonsteroidal anti-inflammatory drugs (NSAIDs) use, and various symptoms experienced during the race. These findings indicate that a clinical suspicion and measurement of blood sodium concentration remain the only viable means for determining when an ultramarathon runner has EAH.
[Show abstract][Hide abstract] ABSTRACT: Exercise-associated hyponatremia (EAH) typically occurs during or up to 24 hours after prolonged physical activity, and is defined by a serum or plasma sodium concentration below the normal reference range of 135 mEq/L. It is also reported to occur in individual physical activities or during organized endurance events conducted in austere environments in which medical care is limited or often not available, and patient evacuation to definitive care is often greatly delayed. Rapid recognition and appropriate treatment are essential in the severe form to ensure a positive outcome. Failure in this regard is a recognized cause of event-related fatality. In an effort to produce best practice guidelines for EAH in the austere environment, the Wilderness Medical Society convened an expert panel. The panel was charged with the development of evidence-based guidelines for management of EAH. Recommendations are made regarding the situations when sodium concentration can be assessed in the field and when these values are not known. These recommendations are graded based on the quality of supporting evidence and balance between the benefits and risks/burdens for each parameter according to the methodology stipulated by the American College of Chest Physicians.
Wilderness and Environmental Medicine 04/2013; 25(4). DOI:10.1016/j.wem.2013.01.011 · 1.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study aimed to assess the adequacy of energy, macronutrients, and water intake of ultra-endurance runners (UER) competing in a 24-hours ultra-marathon (distance range: 122-208km). Ad libitum food and fluid intakes of UER (n 25) were recorded throughout competition and analysed by dietary analysis software. Body mass (BM), urinary ketones, plasma osmolality and volume change were determined pre- and post-competition. Data were analysed using appropriate t-tests, with significance set at P<0•05. Total energy intake and expenditure of UER were 20(SD12)MJ and 55(SD11)MJ, respectively (control (n 17): 12(SD1)MJ and 14(SD5)MJ, respectively). Protein, carbohydrate, and fat intakes were 1•1(SD0•4)g/kgBM, 11•3(SD7•0)g/kgBM, and 1•5(SD0•7)g/kgBM for UER, respectively. Rate of carbohydrate intake during competition was (37(SD24)g/h). Total water ingestion of UER was 9•1(SD4•0)L (control: 2•1(SD1•0)L); while rate of water ingestion was 378(SD164)ml/h. Significant body mass loss occurred pre- to post-competition (P=0•001) in UER (1•6(SD2.0)%). No significant changes in plasma osmolality were observed pre- (285(SD11)mOsmol/kg) to post-competition (287(SD10)mOsmol/kg) in UER, and was lower than control (P<0•05). However, plasma volume increased post-competition in UER (10•2(SD9•7)%; P<0•001). Urinary ketones were evident in 90% of UER post-competition. Energy deficit was observed in all UER, with only one UER achieving benchmark recommendations for carbohydrate intake during endurance exercise. Despite relatively low water intakes by UER, hypohydration appears not to be an issue, considering increases in plasma volume observed in the majority (80%) of UER. Population specific dietary recommendations may be beneficial and warranted.
British Journal Of Nutrition 04/2014; In press. · 3.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present study aimed to assess the adequacy of energy, macronutrients and water intakes of ultra-endurance runners (UER) competing in a 24 h ultra-marathon (distance range: 122-208 km). The ad libitum food and fluid intakes of the UER (n 25) were recorded throughout the competition and analysed using dietary analysis software. Body mass (BM), urinary ketone presence, plasma osmolality (POsmol) and volume change were determined at pre- and post-competition time points. Data were analysed using appropriate t tests, with significance set at P <0·05. The total energy intake and expenditure of the UER were 20 (sd 12) and 55 (sd 11) MJ, respectively (control (CON) (n 17): 12 (sd 1) and 14 (sd 5) MJ, respectively). The protein, carbohydrate and fat intakes of the UER were 1·1 (sd 0·4), 11·3 (sd 7·0) and 1·5 (sd 0·7) g/kg BM, respectively. The rate of carbohydrate intake during the competition was 37 (sd 24) g/h. The total water intake of the UER was 9·1 (sd 4·0) litres (CON: 2·1 (sd 1·0) litres), while the rate of water intake was 378 (sd 164) ml/h. Significant BM loss occurred at pre- to post-competition time points (P =0·001) in the UER (1·6 (sd 2·0) %). No significant changes in POsmol values were observed at pre- (285 (sd 11) mOsmol/kg) to post-competition (287 (sd 10) mOsmol/kg) time points in the UER and were lower than those recorded in the CON group (P <0·05). However, plasma volume (PV) increased at post-competition time points in the UER (10·2 (sd 9·7) %; P <0·001). Urinary ketones were evident in the post-competition samples of 90 % of the UER. Energy deficit was observed in all the UER, with only one UER achieving the benchmark recommendations for carbohydrate intake during endurance exercise. Despite the relatively low water intake rates recorded in the UER, hypohydration does not appear to be an issue, considering increases in PV values observed in the majority (80 %) of the UER. Population-specific dietary recommendations may be beneficial and warranted.
The British journal of nutrition 05/2014; 112(03):1-10. DOI:10.1017/S0007114514000907 · 3.45 Impact Factor
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