Fluid and Sodium Balance of Elite Wheelchair Rugby Players

Abstract

Blood sodium concentration of tetraplegics during exercise has not been investigated. This study aimed to measure blood sodium changes in relation to fluid intakes and thermal comfort in tetraplegics during wheelchair rugby training. Twelve international male wheelchair rugby players volunteered, and measures were taken during 2 training sessions. Body mass, blood sodium concentration, and subjective thermal comfort using a 10-point scale were recorded before and after both training sessions. Fluid intake and the distance covered were measured during both sessions. The mean (SD) percentage changes in body mass during the morning and afternoon training sessions were +0.4%1 (0.65%) and +0.69% (1.24%), respectively. There was a tendency for fluid intake rate to be correlated with the percentage change in blood sodium concentration (p = .072, r2 = .642) during the morning training session; this correlation reached significance during the afternoon session (p = .004, r2 = .717). Fluid intake was significantly correlated to change in thermal comfort in the morning session (p = .018, r2 = .533), with this correlation showing a tendency in the afternoon session (p = .066, r2 = .151). This is the first study to investigate blood sodium concentrations in a group of tetraplegics. Over the day, blood sodium concentrations significantly declined; 2 players recorded blood sodium concentrations of 135 mmol/L, and 5 recorded blood sodium concentrations of 136 mmol/L. Excessive fluid intake as a means of attenuating thermal discomfort seems to be the primary cause of low blood sodium concentrations in tetraplegic athletes. Findings from this study could aid in the design of fluid-intake strategies for tetraplegics.

Why do team-sport athletes drink fluid in excess when exercising in cool conditions?

“…Consequently, these data do not support the proposed theory that fluid intake occurs to attenuate rises in thermal discomfort/strain (Price and Campbell 2003;Black et al 2013;Jones et al 2015). The lack of correlation between thermal comfort and thirst ( Table 2) also suggests that no physiological mechanism existed in stimulating water retention/acquisition mechanisms (i.e.…”

“…Over-drinking in high-intensity intermittent sporting activities may be caused by the drive to consume fluid to attenuate thermal discomfort (Price and Campbell 2003;Black et al 2013;Jones et al 2015) similar to observations in some wheelchair athletes who are unable to produce sweat and thus less able to dissipate heat (Goosey-Tolfrey et al 2008;Black et al 2013). Although the mechanisms behind this were previously not suggested, this could be 5 plausible due to the associations between increases in body temperature and water retention mechanisms (Takamata et al 1995).…”

“…In contrast to the plethora of studies reporting fluid losses sufficient to cause a decrease in BM (reported as 'dehydration') (See review: Garth and Burke (2013)) other studies have reported potential cases of over-drinking in team sports (Horswill et al 2009;MacLeod and Sunderland 2009;Black et al 2013;Cosgrove et al 2014;Jones et al 2015). Over-drinking appears to be reported when athletes consume fluid in the absence of body fluid deficits to magnitudes which would stimulate the physiologically driven responses for compensatory water acquisition (≥2% change in plasma osmolality (POsm) and / or ≥10% change in blood volume) (Cheuvront et al 2013;Cheuvront and Kenefick 2014) and thus in excess of homeostatic needs.…”

Effects of cooling before and during simulated match play on thermoregulatory responses of athletes with tetraplegia

“…In NC the greater amount of fluid consumed, coupled with an absence or minimal sweating, resulted in a greater gain in body mass, akin to previous research. 31 Although significant differences in fluid consumption occurred between NC and PW, due to the individual's sweating dysfunction a significant difference between conditions in total mass loss was not apparent. Thus, the use of cooling strategies in this population group in the ambient conditions studied does not seem to have a detrimental effect on fluid ingestion, in contrast to previous research in the heat 13 .…”

Evaluation of Dietary Supplement Use in Wheelchair Rugby Athletes

“…The sport is comprised of intense physicality, aggression, and full body contact [1,3] while requiring efficient wheelchair manoeuvrability skills [4]. Wheelchair rugby differs from other wheelchair sports in that players must be tetraplegic also known as quadriplegic [5]. Furthermore, participants are classified based on impairment level, ranging from 0.5 (most impaired) to 3.5 (least impaired) [6] and the classification points of a team on the court cannot exceed eight points [2].…”