Fluid and electrolyte status have a significant impact on physiological homeostasis and may impact physical performance [1
], cognitive performance [3
] and overall health [4
]. Physical performance decrements have been observed with less than 2% loss of body mass. Fluid loss during exercise or sport competitions can be as high as 5 L per hour [6
], with heterogeneous sodium (Na+
) and potassium (K+
) losses in sweat that can affect plasma osmolality, health and performance [7
In spite of current recommendations for improving fluid and electrolyte status in sports, hydration strategies of athletes are far from optimal [8
] with hypohydration and dehydration being common. Recent research has demonstrated a high proportion of soccer players become hypohydrated during practice and competition [10
], where hydration status is particularly important. Small changes in hydration status in these athletes have been shown to increase the perception of fatigue [13
], reduce performance in sport-specific tasks and alter cognitive performance [14
]. In addition, soccer matches may last up to 120 min, under conditions of high temperature and humidity in certain geographical regions [15
] increasing the probabilities of reaching a dehydration state. Although hydration strategies during and after exercise are fundamental, hydration before the onset of exercise or sport could be an equally important strategy for maintaining optimal performance and physiologic function during exercise and competition [16
]. Specifically, pre-exercise recommendations cite the possibility of consuming foods and beverages with high amounts of sodium to reduce the amount of fluid loss and improve fluid balance [6
]. In this sense, sport drinks are a common option due to their considerable sodium content (e.g., 300–400 mg/L). However, another beverage that has considerable sodium content (80–100 mg/L), though less than sports drinks, but with higher preference among athletes [18
] and relatively reduced economic cost, is beer. Previously, light beer (2.3% alcohol) was shown to improve hydration status after exercise [19
]. Nowadays, there is a commercial explosion in non-alcoholic beers, which claim to have a similar nutrient composition without the negative effects of alcohol consumption. These negative effects are associated with a delay of muscle recovery, given the diuretic effect that leads to a known and well-recognized electrolyte imbalance making non-alcoholic beer a potentially attractive rehydration drink [20
The aim of this study was to compare the acute effects of consuming 0.7 L of beer (4.6% alcohol), non-alcoholic beer (0% alcohol) or water, 45 min prior to exercise at 65% of the maximal heart rate (HRmax) on urine volume, sweat rate, evaporative water loss, plasma electrolytes (Na+ and K+), and USG in young athletes. We hypothesized that, compared to alcoholic beer or water, non-alcoholic beer would be more effective at maintaining fluid homeostasis.
Baseline body mass (mean of all trials) was 68.8 ± 6.2 kg, without significant differences between trials (p
= 0.97 to 0.99). After exercise, all trials showed a significant (p
< 0.01) body mass reduction, although no significant differences were observed between trials regarding relative changes (%) or after-exercise absolute values (Table 3
Baseline USG (mean of all trials) was 1.025 ± 6.1 g/mL, without significant differences between trials (p
= 0.21 to 0.95). During trials only two participants showed a basal USG <1.020 g/mL. A significant (p
< 0.05) time effect was noted for USG, with W and NAB showing a reduction after exercise, although no time group × time interaction was observed. No significant differences were observed between trials regarding relative changes (%) or after-exercise absolute values (Table 3
). Baseline plasma Na+
(mean of all trials) were 143 ± 2.9 mmol/L and 4.3 ± 0.5 mmol/L, respectively, without significant (Na+
= 0.3 to 0.93; K+
= 0.5 to 0.97) differences between trials. W and AB trials showed a significant decrease in plasma Na+
< 0.01) in the last minute (i.e.
, 45-min) of exercise (Table 3
), although no group × time interaction was noted. Plasma K+
showed a significant (p
< 0.05) increase in the last minute of exercise only with the AB trial, with no group × time interaction (Table 3
). In the last minute of exercise, no significant differences were observed between trials for plasma Na+
regarding relative changes (%) or absolute values (Table 3
No significant differences were observed between trials regarding the excretion of urine (p
= 0.35), sweat rate (p
= 0.2), or total evaporative water loss (p
= 0.36) (Table 4
Results showed no significant change of plasma Na+
with NAB or of plasma K+
with NAB and W. Regarding USG, a significant reduction was observed after NAB and W. Although previous studies suggested the favorable effect of post-exercise non-alcoholic and low-alcoholic beer on hydration status [19
], to our knowledge, this is the first study to compare the effect of beer, non-alcoholic beer, and water consumption before exercise on fluid homeostasis.
Body mass significantly decreased after exercise in all trials, and urine losses, sweat rates and evaporative water losses were not significantly different among trials. However, USG was significantly reduced after exercise in the W and NAB trials. These results suggest that kidney function is altered with non-alcoholic beer, similarly to water consumption, and that consumption of non-alcoholic beer before exercise might aid in hydration status regulation during exercise in the same way as water, although the former might be preferred due to its flavor. More studies with better and more reliable hydration markers are needed to confirm the previous statement.
regulation is essential for athletic performance and the health of the athletes [24
]. Our results showed that plasma Na+
decreased significantly in the W and AB trials, and remained unchanged in the NAB trial (Table 3
). However, plasma Na+
values remained within normal physiological limits, reflecting eunatremic status after all trials. In our study, fluid intake was not allowed during exercise since the main objective was to evaluate the effects of three beverages as a pre-exercise hydration strategy. Future research could focus on the effect of non-alcoholic beer ingestion before exercise on fluid ingested during and after exercise, through its effects on thirst [25
increases during exercise [26
], which may be associated with muscle fatigue [27
] and reduced muscular strength [28
]. Our results showed that plasma K+
was higher in the last minutes of exercise (p
< 0.05) in the alcoholic beer trial only, while no significant alterations in plasma K+
were observed after the non-alcoholic beer and water trials. Therefore, water and non-alcoholic beer consumed before exercise helped to maintain plasma K+
homeostasis. Future studies should focus on the effects of non-alcoholic beer consumed before exercise on muscle performance during prolonged exercise.
One of the limitations of this study is that continuous steady-state exercise was used as a model to assess the effects of pre-exercise hydration beverages; however, the evaluated athletes usually perform intermittent, high-intensity bouts of activity. Future studies may incorporate exercise models with better ecological validity (e.g., Loughborough Intermittent Shuttle Test). In the same line, future studies may incorporate exercise models with a longer duration (e.g., >60 min) and greater environmental thermal stress (e.g., >27 °C and >80% of relative humidity), as soccer matches may last up to 120 min under conditions of high temperature and humidity in certain geographical regions where this sport is very popular (e.g., Brazil), although strict ethical and safety considerations should be taken. Another potential limitation of this study is the low number of participants. Although not a main objective of study, our results suggested that athletes (i.e.
, soccer players) showed a relatively high prevalence of hypohydration before exercise trials (i.e.
, mean USG = 1.024 g/mL), which appears to be common among soccer players. For instance, among elite Brazilian young male soccer players, a mean USG value of 1.021 g/mL was found before competitive games [11
]. Most recently a mean USG value of 1.026 g/mL was reported in Chilean soccer players before training practice [12
]. Within these considerations, it is our hope that the study’s findings provide the impetus for further investigation regarding the use of non-alcoholic beer in intermittent sports athletes and that these findings now need to be replicated in larger clinical trials, considering the limitations previously raised.
Similarly, replication studies might consider hydration assessment recommendations with more consensus [29
] and the comparison of NAB with well-established hydration beverages (e.g., sports drinks). Also, although subjects reported no gastrointestinal-related symptoms after NAB (or AB) consumption, further investigations should consider the possible effects of gas contained in beer on stomach disturbances and fluid emptying [30