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Table 2 Post-race analysis by weight-based sodium intake

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

Variable Low sodium intake Mean (SD); Median (min–max) Medium sodium intake Mean (SD); Median (min–max) High sodium intake Mean (SD); Median (min–max) P value
Runner characteristics, n (%) 53 (32.9) 53 (32.9) 55 (34.2)
Body weight change, kg − 4 (7.9); − 2 (− 50–2) − 2 (4.4); − 2 (− 14–3) − 4 (5.5); − 2 (− 17–2) 0.24
Hydration     0.31
 Dehydration, n (%) 15 (31.9) 10 (20) 17 (35.4)  
 Euhydration, n (%) 18 (38.3) 23 (46) 22 (45.8)  
 Overhydration, n (%) 14 (29.8) 17 (34) 9 (18.8)  
Serum sodium, mEq 141 (5.8); 140 (126–158) 140 (6.3); 140 (126–158) 142 (5.8); 140 (133–160) 0.38
Creatinine, mg/dL 1 (0.3); 1 (0.5–1.8) 1 (0.5); 1 (0.5–3.7) 1 (0.3); 1 (0.1–1.8) 0.62
Sodium intake rate, mg/h/kg 132 (55.5); 122 (25–235) 269 (66); 250 (175–450) 533 (260.7); 450 (267–1500) < 0.01
Total sodium ingested, g 2 (1.2); 2 (0–6) 4 (1.6); 4 (1–9) 7 (3.6); 7 (3–18) < 0.01
Sodium diagnoses     0.64
 Hyponatremia, n (%) 3 (7.1) 4 (9.8) 1 (2.2)  
 Hypernatremia, n (%) 10 (23.8) 8 (19.5) 9 (20)  
 Normonatremia, n (%) 29 (69.1) 29 (70.7) 35 (77.8)  
Temperature of races     0.81
 Hot races, n (%) 33 (62.3) 35 (66) 33 (60)  
 Cold races, n (%) 20 (37.7) 18 (34) 22 (40)  
Pace, min/km 11 (3); 11 (6–18) 11 (3.2); 10 (6–20) 10 (3); 9 (7–18) 0.31
Total race time, h 15 (3.9); 15 (8–23) 14 (4.2); 14 (8–26) 13 (3.8); 12 (9–23) 0.28
Finishing rank, n (%)     0.35
 Top 10% 7 (14.3) 8 (15.4) 7 (14.3)  
 11–25% 8 (16.4) 8 (15.4) 12 (24.5)  
 26–50% 9 (18.4) 13 (25) 17 (34.7)  
 51–75% 16 (32.7) 15 (28.9) 6 (12.2)  
 > 75% 9 (18.4) 8 (15.4) 7 (14.3)  
  1. Percentage of missing values from pre-race weight = 26%, hydration = 33%, sodium and creatinine = 32%, and rank = 11% (89% finished the races)