Incidence of exercise-associated hyponatremia during a high-altitude 161-km ultramarathon

Abstract

[Purpose] Exercise-associated hyponatremia (EAH) is a well-known condition among endurance athletes at low altitudes. The incidence of EAH during ultramarathons at high altitudes warrants further investigation. This prospective observational study was conducted on the participants of the Leadville Trail 100 run, a 161- km race held at a high altitude (2,800 m-3,840 m).[Methods] Venous blood samples were collected before and immediately after the race. The participants completed an electronic survey after the race. Our main outcome measure was the post-race serum sodium ([Na+]) level.[Results] Of the 672 athletes who started the race, 351 (52%) successfully completed the event within the 30- hour cut-off. Post-race blood samples were collected from 84 runners (66 finishers). Both pre- and post-race blood samples were collected from 37 participants. Twenty percent of the post-race participants had EAH. Only one post-race participant had a [Na+] level of <130 mmol/L. All participants with EAH were asymptomatic. One participant had an abnormal pre-race [Na+] level (134 mmol/L). Female participants had a significantly higher rate of EAH than male participants (40% vs. 16%; p=0.039). Age, body mass index, weight changes, race completion status, nonsteroidal anti-inflammatory drug use, and urine specific gravity were not associated with the development of EAH. Lower postrace [Na+] levels were associated with higher serum creatine kinase values (R2=0.1, p<0.005).[Conclusion] High altitude (3,840 m peak) does not appear to enhance the incidence of EAH after an ultramarathon footrace. This suggests that ambient temperature (low temperatures reduce risk), sex (female predilection), endurance running, and overhydration are more prominent risk factors for EAH than high altitude.

Is There Evidence for the Development of Sex-Specific Guidelines for Ultramarathon Coaches and Athletes? A Systematic Review

“…Significant decrease in Hct in females (-1.2%, p > 0.05) but not in males (-1.1%, p < 0.05). No sex differences in electrolyte changes Hoffman et al[ 62 ] 47 athletes (Sex split not reported) who completed a 161 km ultramarathon Serum sodium Cohort study Low Overall EAH incidence was 30% Females made up 28.6% of hyponatraemic group and 18.2% of normonatraemic group (significant > 0.05) Chlibkova et al[ 60 ] 113 athletes (25 females and 88 males) who completed an ultramarathon Serum sodium Cohort study Low No sex differences in the incidence of hyponatraemia Costa et al[ 61 ] 74 athletes (28 females and 46 males) who completed a 225 km multi-stage ultramarathon Mean age 41 years Fluid and sodium intake, serum sodium and osmolality, plasma volume, urine osmolality Cohort study Low Females had a higher water intake (daily and during running) when corrected for body mass ( p < 0.001). No significant sex differences in sodium intake, serum sodium, plasma volume, serum osmolality Khodaee et al[ 63 ] 84 athletes (15 females and 69 males) who competed in a 100 mile high altitude ultramarathon in Colorado Serum sodium, post-race survey Cohort study Low 15.9% of males had EAH, compared with 40% of females ( p = 0.66) Schwellnus et al[ 56 ] 49 athletes who completed a 56 km ultramarathon Incidence of EAMC Cohort study Low No sex differences of EAMC incidence during, or within 6 h of an ultramarathon Bouscaren et al[ 55 ] 3126 athletes (525 females and 2601 males) who competed in a trail ultra...…”

Acute Kidney Injury and Hyponatremia in Ultra-Trail Racing: A Systematic Review

“…These selected articles were fully reviewed and evaluated to verify whether they met the inclusion criteria. A total of 28 articles were accepted for final review, 13 of which focused on AKI ( Table 1 ) [ 28 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ] and the remaining 15 on EAH ( Table 2 ) [ 24 , 27 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 ]. Nine of the studies reported combined results of AKI and EAH [ 24 , 27 , 28 , 44 , 45 , 49 , 51 , 52 , 58 ].…”

“…The one-stage category included races ranging from 45 to 217 km. Single-stage races were classified into three different groups according to length [ 5 ]: 14 extra-long races (≥100 km) [ 24 , 44 , 47 , 50 , 51 , 52 , 53 , 54 , 57 , 58 , 59 , 62 , 64 , 66 , 67 ], 3 long ones (70–99 km) [ 27 , 28 , 45 ] and 8 medium ones (>42.195–69 km) [ 44 , 47 , 49 , 54 , 55 , 60 , 64 , 65 ]. The cumulative elevation gains and losses ranged between 645 m [ 59 ] and 12,000 m [ 51 ].…”

“…This case occurred in a 95-mile ultra-trail [ 24 ]. Five of the reviewed studies evaluating AKI found no cases [ 27 , 47 , 52 , 58 , 67 ].…”

“…Of the total ultra-trail runners included in this review, EAH and AKI were studied ( n = 228). Of the 11 studies whose main objective was AKI, 6 studies also evaluated EAH episodes [ 28 , 44 , 45 , 49 , 52 , 67 ]. A total of 18 cases of AKI+EAH (13.63%) were found in extra-long races ( n = 132) [ 24 , 49 , 51 , 52 ], 4 subjects suffered both AKI and EAH (5.79%) in long ones ( n = 69) [ 28 ] and 5 (18.51%) cases were reported in medium races ( n = 27) [ 45 , 50 ].…”