Comparison of electrolyte levels, osmolality and immune function markers in blood and/or saliva, urine, and sweat, in resting and exercising males and females : Master of Health Science (Bioscience)
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Date
2021
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Massey University
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Abstract
Background: The gold standard method to measure physiological markers to monitor athletes’ training responses is to utilise blood samples. However, this method is invasive, requires a skilled technician and specific medical equipment for collection. Sports and exercise studies are based mostly on only male participants, and a few with males and females combined without acknowledging the sex differences. The aim of this study was to investigate differences in electrolyte and osmolality levels in blood, saliva, urine and sweat, and immunoglobulin A (IgA) levels in blood and saliva, between males and females. This study also aimed to study the changes in electrolyte and osmolality levels in blood, saliva, urine and sweat, and IgA levels in blood and saliva over time while exercising. A further aim was to explore relationships between electrolyte and osmolality levels in blood (gold standard) and saliva, urine and sweat, and IgA levels in blood and saliva, at rest and during exercise, as an alternative strategy to overcome the limitations of blood collection, particularly in a sports setting. Methods: Blood, saliva, urine and sweat were collected to measure electrolyte, osmolality and IgA levels from 20 healthy volunteers (12 males and 8 females), who participated in a cross-over design trial that involved a resting and exercising trials. The exercise protocol involved participants continuously cycling at 70% peak power for 90 min and body fluids were collected pre, during and/or post-exercise. Results: During exercise, significant differences (P<0.05) were found in serum Na+ and Cl-, salivary K+, urinary Na+ and sweat osmolality levels between males and females. Among males, there was a significant increase in serum Cl- levels at 30 min and 60 min (P<0.001) of the exercising trial, and among females, a significant decrease in serum Na+ level post-exercise (P=0.020) and increase in serum Cl- at 60 min (P<0.05), compared to pre-exercise levels. There were no sex differences for some analytes (serum K+ and osmolality, salivary Na+, Cl- and osmolality, urine K+, Cl- and osmolality, sweat Na+, Cl- and K+) and male and female data were combined for subsequent analysis. Serum K+ analysis (combined data) showed a significant increase serum K+ levels at 30 min (P<0.001) and 60 min (P<0.001) of the exercising trial. In urine, there was a significant increase in K+ levels (combined data) at 90 min and 120 min (P=0.024) compared to pre-exercise level. There was a strong positive correlation between serum and salivary K+ at 60 min (r=0.714, P=0.047) among exercising females, and a positive correlation between serum and salivary IgA (combined data) pre-exercise (r=0.445, P=0.49), 60 min (r=0.489, P=0.029), and post-exercise (r=0.513, P=0.016). Conclusion: These findings show that when studying changes in some biomarkers (i.e., serum Na+, Cl-, salivary K+, urine Na+ and sweat osmolality) during exercise, male and female participants’ results should not be pooled. The presence of positive correlations between serum and salivary IgA levels at multiple timepoints of the resting and exercising trials is promising. It opens the possibility of using saliva samples as indirect measures to predict serum IgA levels in athletes, thereby overcoming the requirement of a blood draw, which is technically demanding, invasive, stressful, and disruptive when exercising.
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Keywords
exercise, males, females, electrolytes, osmolality, IgA, body fluids