Cross‐validation of equations to predict whole‐body sweat sodium concentration from regional measures during exercise

Context:There is interest in including recommendations for the replacement of the sodium lost in sweat in individualized hydration plans for athletes.Purpose:Although the regional absorbent-patch method provides a practical approach to measuring sweat sodium losses in field conditions, there is a need to understand the variability of estimates associated with this technique.Methods:Sweat samples were collected from the forearms, chest, scapula, and thigh of 12 cyclists during 2 standardized cycling time trials in the heat and 2 in temperate conditions. Single measure analysis of sodium concentration was conducted immediately by ion-selective electrodes (ISE). A subset of 30 samples was frozen for reanalysis of sodium concentration using ISE, flame photometry (FP), and conductivity (SC).Results:Sweat samples collected in hot conditions produced higher sweat sodium concentrations than those from the temperate environment (P= .0032). A significant difference (P= .0048) in estimates of sweat sodium concentration was evident when calculated from the forearm average (mean ± 95% CL; 64 ± 12 mmol/L) compared with using a 4-site equation (70 ± 12 mmol/L). There was a high correlation between the values produced using different analytical techniques (r2= .95), but mean values were different between treatments (frozen FP, frozen SC > immediate ISE > frozen ISE;P< .0001).Conclusion:Whole-body sweat sodium concentration estimates differed depending on the number of sites included in the calculation. Environmental testing conditions should be considered in the interpretation of results. The impact of sample freezing and subsequent analytical technique was small but statistically significant. Nevertheless, when undertaken using a standardized protocol, the regional absorbent-patch method appears to be a relatively robust field test.

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No Relation Between Short-term Sodium Intake And Whole Body Sweat Sodium Concentration During Exercise-heat Stress

Medicine & Science in Sports & Exercise ◽

10.1249/01.mss.0000686072.95026.84 ◽

2020 ◽

Vol 52 (7S) ◽

pp. 967-967

Author(s):

Ryan P. Nuccio ◽

Meagan O'Connor ◽

Corey T. Ungaro ◽

Kelly A. Barnes ◽

Adam J. Reimel ◽

...

Keyword(s):

Heat Stress ◽

Sodium Intake ◽

Sodium Concentration ◽

Whole Body ◽

Short Term ◽

Sweat Sodium Concentration ◽

Sweat Sodium

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Relation between Regional and Whole Body Sweat Sodium Concentration and the Effect of Exercise Intensity

Medicine & Science in Sports & Exercise ◽

10.1249/01.mss.0000537132.67188.d9 ◽

2018 ◽

Vol 50 (5S) ◽

pp. 620

Author(s):

Lindsay B. Baker ◽

Corey T. Ungaro ◽

Bridget C. Sopeña ◽

Ryan P. Nuccio ◽

Adam J. Reimel ◽

...

Keyword(s):

Exercise Intensity ◽

Sodium Concentration ◽

Whole Body ◽

Sweat Sodium Concentration ◽

Sweat Sodium

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Hydration Status, Fluid Intake, Sweat Rate, and Sweat Sodium Concentration in Recreational Tropical Native Runners

Nutrients ◽

10.3390/nu13041374 ◽

2021 ◽

Vol 13 (4) ◽

pp. 1374

Author(s):

Juthamard Surapongchai ◽

Vitoon Saengsirisuwan ◽

Ian Rollo ◽

Rebecca K. Randell ◽

Kanpiraya Nithitsuttibuta ◽

...

Keyword(s):

Fluid Intake ◽

Sweat Rate ◽

Statistical Significance ◽

Sodium Concentration ◽

Fluid Replacement ◽

Whole Body ◽

Hydration Status ◽

P Value ◽

Sweat Sodium Concentration ◽

Sweat Sodium

Aim: The purpose of this study was to evaluate hydration status, fluid intake, sweat rate, and sweat sodium concentration in recreational tropical native runners. Methods: A total of 102 males and 64 females participated in this study. Participants ran at their self-selected pace for 30–100 min. Age, environmental conditions, running profiles, sweat rates, and sweat sodium data were recorded. Differences in age, running duration, distance and pace, and physiological changes between sexes were analysed. A p-value cut-off of 0.05 depicted statistical significance. Results: Males had lower relative fluid intake (6 ± 6 vs. 8 ± 7 mL·kg−1·h−1, p < 0.05) and greater relative fluid balance deficit (−13 ± 8 mL·kg−1·h−1 vs. −8 ± 7 mL·kg−1·h−1, p < 0.05) than females. Males had higher whole-body sweat rates (1.3 ± 0.5 L·h−1 vs. 0.9 ± 0.3 L·h−1, p < 0.05) than females. Mean rates of sweat sodium loss (54 ± 27 vs. 39 ± 22 mmol·h−1) were higher in males than females (p < 0.05). Conclusions: The sweat profile and composition in tropical native runners are similar to reported values in the literature. The current fluid replacement guidelines pertaining to volume and electrolyte replacement are applicable to tropical native runners.

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