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Table 4 Hydration by sodium intake

From: Prospective Observational Study of Weight-based Assessment of Sodium Supplements on Ultramarathon Performance (WASSUP)

Variable Dehydration Mean (SD); Median (min/max) Euhydration Mean (SD); Median (min/max) Overhydration Mean (SD); Median (min–max) P value
Runner characteristics, n (%) 42 (29.1) 63 (43.8) 39 (27.1)  
Age, years 45 (7.4); 45 (28–63) 42 (8.8); 43 (23–65) 42 (9.5); 43 (26–57) 0.26
Sex
 Female, n (%) 16 (38) 16 (25) 12 (31) 0.38
 Male, n (%) 26 (62) 47 (75) 27 (69)
Height, cm 176 (7.7); 173 (164–193) 177 (8.4); 178 (158–189) 175 (9.2); 177 (157–195) 0.53
Weight (starting), kg 73 (13.2); 72 (52–103) 75 (10.9); 74 (55–105) 75 (11.3); 75 (57–107) 0.59
BMI, kg/m2 24 (2.9); 23 (18–31) 24 (2.7); 24 (20–33) 25 (3.3); 24 (19–34) 0.55
Pack weight (starting), kg 9 (2.1); 9 (6–15) 11 (2.8); 10 (7–17) 13 (3.4); 11 (8–16) < 0.01
 Body weight change, kg − 10 (7.6); − 10 (− 50–3) − 2 (0.8); − 2 (− 3–0) 1 (0.7); 1 (0–2) < 0.01
 Serum sodium, mEq 141 (4.3); 140 (133-153) 142 (6.8); 140 (124–160) 139 (5.4); 139 (126–156) 0.05
Sodium intake rate, mg/h 323 (198.6); 280 (74–860) 329 (264.3); 250 (40–1500) 279 (156.4); 240 (83–768) 0.52
Total sodium ingested, g 4 (2.4); 4 (1–9) 4 (3.5); 4 (1–18) 5 (3.1); 4 (1–14) 0.53
Sodium diagnoses     < 0.01
 Hyponatremia, n (%) 1 (2.4) 1 (1.9) 6 (18.8)  
 Hypernatremia, n (%) 8 (19.5) 14 (26.4) 4 (12.5)  
 Normonatremia, n (%) 32 (78.1) 38 (71.7) 22 (68.8)  
Temperature of races     0.31
 Hot races, n (%) 19 (45.2) 49 (77.8) 24 (60)  
 Cold races, n (%) 23 (54.8) 14 (22.2) 14 (40)  
Pace, min/km 9 (2.1); 9 (6–14) 11 (2.8); 10 (7–18) 13 (3.4); 13 (6–20) < 0.01
Total race time, h 12.4 (2.9); 12 (8–20) 14 (3.7); 13 (9–23) 17 (4.3); 18 (8–26) < 0.01
Finishing rank, n (%)     < 0.01
 Top 10% 8 (20) 9 (14.5) 4 (10)  
 11–25% 8 (20) 18 (29) 0  
 26–50% 14 (35) 17 (27.4) 6 (15)  
 51–75% 7 (17.5) 13 (21) 14 (35)  
 > 75% 3 (7.5) 5 (8.1) 16 (40)  
  1. Percentage of missing values from: pre-race weight = 26%, hydration = 33%, sodium = 32%, and rank = 11% (89% finished the races)
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