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Table 4 Plasma (P Osmol ) and urine (U Osmol ) osmolality, and U Osmol /P Osmol ratio of UER along MSUM competition

From: Water and sodium intake habits and status of ultra-endurance runners during a multi-stage ultra-marathon conducted in a hot ambient environment: an observational field based study

  Stage 1 Stage 2 Stage 3 Stage 4 Stage 5
  Pre Post Pre Post Pre Post Pre Post Pre Post
Plasma Osmolality (mOsmol/kg)
UER 281 (16) 287 (14)* 283 (16) 297 (17)* 272 (13) 291 (16)** 271 (12) 298 (10)** 283 (15) 296 (10)**
CON 287 (13)     276 (14)     270 (9)  
SR 280 (18) 286 (17)* 282 (17) 294 (16)* 273 (15) 287 (16)** 270 (10) 298 (6)** 286 (13) 294 (10)*
FR 282 (12) 289 (9)* 285 (11) 302 (18)** 271 (9) 297 (14)** 273 (14) 299 (14)** 278 (17) 298 (11)**
Urine Osmolality (mOsmol/kg)
UER 535 (278) 811 (261)** 673 (311) 914 (367)** 792 (306)††b 997 (352)**† 750 (293)†† 898 (333)** 834 (343)†† 1050 (402)**††
CON 577 (197)     545 (78)     608 (349)  
SR 514 (295) 840 (226)** 702 (326) 969 (393)** 849 (294)†† 1075 (356)**†† 770 (301)†† 939 (323)** 846 (355)†† 1086 (400)**††
FR 562 (256) 775 (298)** 636 (293) 844 (324)** 722 (311) 899 (326)**c 724 (285) 847 (344)** 818 (334) 1004 (406)**
Urine to Plasma Osmolality ratio
UER 2.0 (0.6) 2.7 (0.9)** 2.6 (1.0) 3.3 (1.1)** 3.3 (1.0)††bb 3.9 (1.2)††** 3.1 (1.0)†† 3.3 (1.0)** 3.5 (1.1)††bb 4.2 (1.3)††**
CON 2.0 (0.3)     2.0 (1.0)     2.2 (1.2)  
SR 2.0 (0.7) 2.8 (0.9)** 2.8 (1.0) 3.7 (1.3)**cc 3.5 (0.9)†† 4.2 (1.1)††** 3.2 (1.0)†† 3.3 (1.0)** 3.6 (1.1)†† 4.4 (1.2)††**
FR 2.1 (0.6) 2.6 (0.9)** 2.1 (1.0) 2.8 (1.3)** 3.1 (1.0) 3.5 (1.1)** 3.1 (1.0) 3.3 (0.9)** 3.4 (1.3)†† 4.0 (1.5)††**
Individual UER response range (UOsmol/POsmol ratio)
  0.6 to 2.9 0.9 to 4.0 0.4 to 4.6 0.5 to 6.1 1.3 to 4.8 1.6 to 6.1 1.1 to 4.7 1.1 to 5.0 0.9 to 5.4 1.1 to 6.6
  1. Mean (SD): UER (UOsmo n = 72, POsmol n = 28); Control (CON, n = 12); slow runners (SR; MSUM mean speed <8 km/h, UOsmo n = 40, POsmol n = 17); fast runners (FR; MSUM mean speed ≥8 km/h, UOsmo n = 32, POsmol n = 11). †† p < 0.01 and † p < 0.01 vs. Stage 1; ** p < 0.01 and * p < 0.05 vs. pre-stage; bb p < 0.01 and b p < 0.05 vs. CON; cc p < 0.01 and c p < 0.05 vs. SR.