Fluid and Electrolyte Balance During Two Different Preseason Training Sessions in Elite Rugby Union Players

Abstract

The purpose of this study was to compare fluid balance between a resistance and an aerobic training sessions, in elite rugby players. It is hypothesized that resistance exercise will result in a higher prevalence of overdrinking, whereas during the aerobic session, underdrinking will be more prevalent. As with previous fluid balance studies, this was an observational study. Twenty-six players completed the resistance training session, and 20 players completed the aerobic training session. All players were members of an elite rugby union squad competing in the southern hemisphere's premier competition. For both sessions, players provided a preexercise urine sample to determine hydration status, pre- and postexercise measures of body mass, and blood sodium concentration were taken, and the weight of drink bottles were recorded to calculate sweat rates and fluid intake rates. Sweat patches were positioned on the shoulder of the players, and these remained in place throughout each training session and were later analyzed for sodium concentration. The percentage of sweat loss replaced was higher in the resistance (196 ± 130%) than the aerobic training session (56 ± 17%; p = 0.002). Despite this, no cases of hyponatremia were detected. The results also indicated that more than 80% of players started training in a hypohydrated state. Fluid intake seems to differ depending on the nature of the exercise session. In this group of athletes, players did not match their fluid intakes with their sweat loss, resulting in overdrinking during resistance training and underdrinking in aerobic training. Therefore, hydration strategies and education need to be tailored to the exercise session. Furthermore, given the large number of players arriving at training hypohydrated, improved hydration strategies away from the training venue are required.

Relationship between fluid loss variation and physical activity during official games in elite soccer players. [Relaciones entre la variación de pérdida de líquidos y la actividad física durante partidos oficiales en jugadores de fútbol de élite].

“…In this context, Duffield et al (2012) have recently shown that professional Australian football players lost more water when practising high-vs. low-intensity training sessions. In rugby and US football, it was observed that players lost more water while training in high intensity aerobic sessions than in resistance training sessions (Stofan, Osterberg, Horswill, Lacamba, Eichner, Anderson et al, 2007;Cosgrove, Love, Brown, Baker, Howe & Black, 2014). All together, these results confirmed that water loss could depend on duration and nature of the physical activity.…”

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

“…Average post-exercise POsm was within the euhydrated threshold (291.50 ± 4.14 mOsmol.kg -1 ) (Kratz et al 2004) Observations demonstrating participants who arrived more hydrated, drank more, and were at a greater risk of diluting their S[Na + ] is consistent with the findings by Jones et al (2015) and Cosgrove et al (2014), who observed rugby union players during training and match play. In the population observed by Jones et al (2015), 94% of players arrived euhydrated and on 36% of the time, players experienced EAH.…”

“…In the population observed by Jones et al (2015), 94% of players arrived euhydrated and on 36% of the time, players experienced EAH. In contrast, for the population observed in Cosgrove et al (2014), 89% of players arrived hypohydrated, and there were no observations of EAH. Interestingly, within the current study, those that commenced exercise in a hypohydrated state were more capable of regulating S[Na + ] as no changes from pre to post were observed within these individuals.…”

“…To reduce performer bias, the specific purpose of the study was partially disclosed to participants, as the aim to investigate thermoregulatory responses during SSG (Cosgrove et al 2014). All participants were fully informed of the true purposes after completion of the study.…”

“…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.…”