Races: RacingThePlanet: Patagonia 2017, Atacama Crossing (Chile) 2017, Sahara Race (Namibia) 2018, Gobi March (Mongolia) 2018, Atacama Crossing (Chile) 2018.
Researchers: Grant S. LIPMAN, MD; Patrick BURNS, MD; Caleb PHILLIPS, PhD; Jacob JENSEN, DO; Colin LITTLE, MD; Carrie JURKIEWICZ, MD; Bryan JARRETT, MD; Anne WALKER, MD; Nicky MANSFIELD, MD; and Brian J. KRABAK, MD
Publication: Clinical Journal of Sport Medicine. February 2020.
Abstract:
Objective:
Analyze the effect of sodium supplementation, hydration, and climate on dysnatremia in ultramarathon runners.
Design:
Prospective observational study.
Setting:
The 2017 80 km (50 mile) stage of the 250 km (150 mile) 6-stage RacingThePlanet ultramarathon in 2017 Chilean, Patagonian, and 2018 Namibian, Mongolian, and Chilean deserts.
Participants:
All race entrants who could understand English were invited to participate, with 266 runners enrolled, mean age of 43 years (±9), 61 (36%) females, average weight 74 kg (±12.5), and average race time 14.5 (±4.1) hours. Post-race sodium collected on 174 (74%) and 164 (62%) participants with both the blood sample and post-race questionnaire.
Intervention:
Weight change and finish line serum sodium levels were gathered.
Main outcome measures:
Incidence of exercise associated hyponatremia and hypernatremia by sodium ingestion and climate.
Results:
Eleven (6.3%) runners developed EAH, and 30 (17.2%) developed hypernatremia. Those with EAH were 14 kg heavier at baseline, had significantly less training distances, and averaged 5 to 6 hours longer to cover 50 miles (80 km) than the other participants. Neither rate nor total ingested supplemental sodium was correlated with dysnatremia, without significant differences in drinking behaviors or type of supplement compared with normonatremic runners. Hypernatremic runners were more often dehydrated [8 (28%), -4.7 kg (± 9.8)] than EAH [4 (14%), -1.1 kg (± 3.8)] (P < 0.01), and EAH runners were more frequently overhydrated (6, 67%) than hypernatremia (1, 11%) (P < 0.01). In the 98 (56%) runners from hot races, there was EAH OR = 3.5 [95% confidence interval (CI), 0.9-25.9] and hypernatremia OR = 8.8 (95% CI, 2.9-39.5) compared with cold races.
Conclusions:
This was the first study to show that hot race climates are an independent risk factor for EAH and hypernatremia. Sodium supplementation did not prevent EAH nor cause hypernatremia. Longer training distances, lower body mass, and avoidance of overhydration were shown to be the most important factors to prevent EAH and avoidance of dehydration to prevent hypernatremia.
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Prospective Observational Study of Weightbased Assessment of Sodium Supplements on Ultramarathon Performance (WASSUP)
Races: RacingThePlanet: Patagonia 2017, Atacama Crossing (Chile) 2017, Sahara Race (Namibia) 2018, Gobi March (Mongolia) 2018, Atacama Crossing (Chile) 2018.
Researchers: Grant S. LIPMAN; Tamara HEW-BUTLER; Caleb PHILLIPS; Brian J. KRABAK; and Patrick BURNS, MD
Publication: Sports Medicine - Open. February 2021.
Abstract:
Background:
Sodium supplements are ubiquitous in endurance running, but their impact on performance has been subjected to much debate. The objective of the study was to assess the effect of sodium supplementation as a weight-based predictor of race performance in ultramarathon runners.
Methods:
Prospective observational study during an 80 km (50 mi) stage of a 6-stage 250 km (155 mi) ultramarathon in Chile, Patagonia, Namibia, and Mongolia. Finish line hydration status as measured by weight change, point-of-care serum sodium, and questionnaire provided sodium ingestion categories at 33rd percentile and 66th percentile both for weight-adjusted rate and total sodium consumption, then analyzed for significant relationships to race performance, dysnatremia, and hydration.
Results:
Two hundred sixty-six participants were enrolled, with 217 (82%) with complete sodium supplement rate data, 174 (80%) with finish line sodium, and 161 (74%) with both pre-race weights and total sodium ingestion allowing weight-based analysis. Sodium intake ranged from 131–533 mg/h/kg (2–7.2 gm), with no statistically significant impact on pace, race time, or quintile rank. These outcomes did not change when sodium intake was analyzed as a continuous variable or by sub-group analysis of the 109 (68%) normonatremic runners. When controlled for weight-adjusted sodium intake, performance was poorly correlated with hydration (r = − 0.152, 95% CI − 0.348–0.057). Dehydrated runners outperformed those overhydrated, with 11% of top 25th percentile finishers dehydrated (versus 2.8% overhydrated), with 3.6 min/km faster pace and time 4.6 h faster finishing time.
Conclusions:
No association was found between sodium supplement intake and ultramarathon performance. Dehydrated runners were found to have the best performance. This reinforces the message to avoid overhydration.
Keywords:
Electrolytes, Supplements, Performance, Ultramarathon, Running, Endurance, Dehydration, Overhydration, Exercise-associated hyponatremia.
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