Exercise-induced Dehydration Research Articles

Assessment of Exercise-Induced Dehydration Status Based on Oral Mucosal Moisture in a Field Survey.

Background/Objective: Conventional techniques for evaluating hydration status include the analysis of blood, urine, and body weight. Recently, advancements in dentistry have introduced capacitance sensor-based oral epithelial moisture meters as promising avenues for assessment. This study aimed to examine the correlation between oral mucosal moisture content, as determined using a capacitance sensor, and exercise-induced dehydration. Methods: A total of 21 participants engaged in a 120 min slow distance exercise session. A series of measurements were taken before and after the exercise session, including body weight, sweat rate, secretory immunoglobulin A (s-IgA) concentration in saliva samples, saliva flow rate, and oral mucosal moisture content, which were assessed using a capacitance sensor. The relationship between physical dehydration and oral mucosal moisture content was investigated using statistical analysis. Receiver operating characteristic curves were constructed to ascertain whether variations in oral mucosal moisture content could discern body mass losses (BMLs) of 1.5% and 2%. Results: A significant correlation was observed between the sweat rate during exercise and the change in oral mucosal moisture content before and after exercise (Spearman's rank correlation coefficient: ρ = -0.58, p < 0.001). The salivary flow and s-IgA secretion rates were lower after the exercise period than before, whereas the s-IgA concentration was higher. Oral mucosal moisture decreased during the exercise period. Receiver operating characteristic curve analysis revealed that differences in oral mucosal moisture content exhibited discriminative capabilities, with area under the curve values of 0.79 at 1.5% BML and 0.72 at 2% BML. Conclusions: The measurement of oral mucosal moisture using capacitance sensors represents a promising noninvasive approach for the assessment of exercise-induced dehydration.

Phase angle is not influenced by hydration status after an aerobic session in recreational runners

Objective: Phase angle (PhA) has been proposed to be an indicator of muscle membrane integrity, which is useful for the evaluation of exercise-induced muscle soreness. PhA is derived from the bioimpedance analysis, which requires the participants to refrain from exercises prior to the evaluation. However, there are no studies in the literature regarding the effect of exercise-induced dehydration on the PhA analysis. This study aimed to compare the PhA after a running exercise session with and without hydration in recreational runners. Methods:14 male recreational runners (18-40 years old, VO2 max 51.08 ± 5.83 ml/min/kg) underwent a time-to-exhaustion running test in two conditions (with and without hydration). Mineral water was used in the hydration protocol. PhA and anthropometry were evaluated before and 1h after the time-to-exhaustion running tests. Results: There was no significant difference in body mass when comparing no hydration vs hydration protocols (1.4 ± 0.1 kg vs 0.7 ± 0.2 kg, respectively; p = 0.06). No significant difference between the procedures for the PhA of the right leg (7.89 ± 0.83 vs 7.82 ± 0+80; p = 0.15) and PhA of the left leg (7.86 ± 0.96 vs 8.07 ± 0.85 p = 1.00) were observed. Conclusion: The results indicated that the PhA is not influenced by exercise-induced dehydration when the water loss is approximately 2% of the body mass.

Mild Dehydration Triggered by Exercise Reduces Cognitive Performance in Children, But Does Not Affect Their Motor Skills

Objective Children face the risk of dehydration in varying amounts during the day due to reasons such as physical activity, sweating, eating salty foods and drinking carbonated beverages. It is assumed that dehydration can lead to impaired motor skills and cognitive performance since it affects brain function. However, inconsistencies in study results, test times and problems caused by heat stress make new research mandatory. In our research, we examined the effects of exercise-induced mild dehydration on motor skills and cognitive performance in active/sedentary boys who do/do not do regular physical activities in their daily lives. Methods The study included 112 boys who do regular physical activity (n:57; 12.40 ± 0.49age) and sedentary (n:55; 12.49 ± 0.50age). The children were given a 12-h hydration program. Mild dehydration was created by giving exercises after hydration measurements. In case of hydration and mild dehydration, Bruininks-Oseretsky Motor Proficiency and d2 attention test were applied to the children. For comparison, Repeated Measures ANOVA and Bonferroni post-hoc test was performed at the second level. Results According to the hydration and mild dehydration comparison results, there was no difference in total score of Fine Motor Skill Sensitivity, Fine Motor Skill Integration, Hand Dexterity and Bidirectional Coordination, Balance, Running Speed and Agility, Hand-Arm Coordination, Strength, and BOT-2 in children. There was a decrease in both groups in terms of Focused Attention, Processing Speed, Accuracy, Concentration Performance and Attention Span. Conclusion As a result, mild dehydration is associated with daily physical activity in children (physical education classes, etc.) or it can easily occur due to food/beverage preferences. It may affect children’s performance of school curriculum and extracurricular activities. It shows that maintaining optimal hydration is important.

A systematic review on oral rehydration beverages for treating exerciseassociated dehydrationPart II. The effectiveness of alternatives to carbohydrate-electrolyte drinks.

Dehydration associated with exertion is a commonly encountered condition in the first aid setting, particularly at outdoor sporting events. Part I of this back-to-back review demonstrated that commercial sports drinks can be suggested for effective restoration of fluid balance in dehydrated persons. This systematic review was undertaken to compare alternative liquids, such as milk, beer, and coconut water, with water for effective oral rehydration after prolonged exercise. Cochrane Library, PubMed, and Embase were searched for relevant literature in June 2022. Controlled experimental and observational studies involving adults and children were included when dehydration was induced by physical exercise and oral rehydration fluids were administered and compared with regular water. No additional food intake accompanied the rehydration drinks or water. Articles in all languages were included if an English abstract was available. The study design, study population, intervention, outcome measures, and study limitations were extracted from each included article. Out of 3485 records, 11 studies were included comparing skim or low-fat milk, coconut water, and beer (0-5% alcohol) with water. Four studies showed that drinking skim or low-fat milk, without additional food intake, led to a statistically significant improved volume/hydration status when compared with drinking water. In three trials, no significant differences were shown at multiple timepoints for outcomes related to volume and hydration status following rehydration with fresh coconut water compared with water. Lastly, there is insufficient evidence to recommend beer for rehydration (0-5% alcohol). Consuming skim or low-fat cow's milk without additional food as compared with water appears to improve volume/hydration status in persons with exercise-induced dehydration. However, evidence is of very low certainty and should be interpreted with caution.

COVID-19 symptoms are reduced by targeted hydration of the nose, larynx and trachea

Dehydration of the upper airways increases risks of respiratory diseases from COVID-19 to asthma and COPD. We find in human volunteer studies involving 464 human subjects in Germany, the US, and India that respiratory droplet generation increases by up to 4 orders of magnitude in dehydration-associated states of advanced age (n = 357), elevated BMI-age (n = 148), strenuous exercise (n = 20) and SARS-CoV-2 infection (n = 87), and falls with hydration of the nose, larynx and trachea by calcium-rich hypertonic salts. We also find in a protocol of exercise-induced airway dehydration that hydration of the airways by calcium-rich salts increases oxygenation relative to a non-treatment control (P < 0.05). In a random control study of COVID-19 positive subjects (n = 40), thrice-a-day delivery of the calcium-rich hypertonic salts (active) suppressed respiratory droplet generation by 51% ± 11% and increased oxygen saturation over three days of treatment by 48.08% ± 9.61% (P < 0.001), while no changes were observed in the nasal-saline control group. Self-reported symptoms significantly declined in the active group and did not decline in the control group. Hydration of the upper airways appears promising as a non-drug approach for reducing risks of respiratory diseases such as COVID-19.

Measurement of Body Composition in the Dehydrated State

The purpose of the study is to examine the effect of exercise-induced dehydration on body composition using three indirect methods: bioelectrical impedance analysis (BIA), skinfold thickness (SF), and underwater weighing (UWW).Method: Thirty healthy, physically active subjects with normal weight (22 males) participated as study subjects. After baseline body composition measurements using the above three methods were obtained, the subjects began to dehydrate by exercise until an average of 1.5% body weight loss was accomplished. Within 10 minutes post-exercise, the subjects’ body composition measurements using the same measurement methods were repeated. Results: There was a significant (p&lt;0.05) difference between the three methods for determining fat free mass (FFM), fat mass (FM), and percent body fat (%BF). The %BF and FM measurements using the BIA method were significantly (p&lt;0.05) affected by exercise-induced dehydration, but not the UWW or the SF method. Compared to the UWW method before dehydration, the SF method significantly (p&lt;0.05) under-estimated FM, %BF, and over-estimated FFM, whereas the BIA method significantly (p&lt;0.05) over-estimated FM and % BF, and under-estimated FFM. These observations also occur after exercise-induced dehydration. Comparing genders, the BIA method produced higher %BF and FM values in the female subjects than in the male subjects both before and after dehydration. Conclusion: We concluded that exercise-induced dehydration of 1.5% weight loss significantly (p&lt;0.05) limits the usefulness of the BIA method for determining human body composition in physically active and normal weight adults, whereas dehydration induced an insignificant effect on the SF or UWW method.

Effect of Rehydration with Mineral Water on Cardiorespiratory Fitness Following Exercise-Induced Dehydration in Athletes

Background: The aim of the present study was to examine the effect of rehydration with mineral water on cardiorespiratory fitness in athletes. Methods: Twenty athletes (age 21.7 ± 3 years) underwent a random, crossover design experimental trial. Three visits were arranged, with the first for baseline measurement. The second visit included three phases (pre-dehydration, post-dehydration, and post-rehydration), with either Zamzam (mineral water) or bottled water (control water) used. The third visit was similar to the second visit, but with an exchange of the type of water used. Cardiorespiratory fitness and blood parameters were evaluated. Results were compared between Zamzam water and bottled water, and between the phases for each type of water. Results: No significant difference was found between Zamzam and bottled water for the cardiorespiratory fitness markers. However, Zamzam water maintained cardiorespiratory functions including VO2peak, VT1, VT2, and VEpeak, even with rehydration equivalent to 100% of the loss in body weight following exercise-induced dehydration (&gt;2% loss in body weight). Rehydration with bottled water was associated with a significant reduction in both the VO2peak and VEpeak. Conclusions: Rehydration with mineral water such as Zamzam is unlikely to impair cardiorespiratory fitness, even with an intake equal to 100% of the loss in body weight.

Effects of Acacia Honey Drink after Exercise-Induced Dehydration on Selected Physiological Parameters and Subsequent Running Performance

This study examined the effect of honey supplementation on exercise performance and biochemical markers in comparison to plain water and sports drink in the heat. Ten recreational athletes (Age: 22.2 ± 2.0 years, weight: 65.7 ± 5.3 kg; height: 170.4 ± 3.5 cm; VO2max: 51.5 ± 3.7 mL.kg−1.min−1) participated in this study. Participants ran at 70% of their VO2max for 1 h in a pre-load phase (Run-1), followed by a rehydration phase for 2 h and then a 20 min self-paced time trial (Run-2). After Run-1, participants drank either Acacia honey, sports drink or plain water with an amount equivalent to 150% of body weight loss. Subsequently, the participants performed the 20 min self-paced time trial. Acacia honey elicited an improved running time trial performance with a significantly (p&lt;0.05) longer distance ran compared to plain water trial, but it was not different from the sports drink trial. In addition, there was no significant difference in running performance between sports drink and plain water trials. Plasma glucose, insulin and free fatty acids were significantly (p&lt;0.05) higher in H and sports drink compared to the W trial during the rehydration phase. There were no significant differences in body weight changes, oxygen uptake, heart rate, rate of perceived exertion, tympanic temperature, plasma volume changes, plasma cortisol, urine osmolality, volume, and specific gravity among the three trials. Thus, Acacia honey can be recommended to be used as a rehydration drink for individuals who train and compete in the heat.

Sex differences in the physiological responses to exercise-induced dehydration: consequences and mechanisms.

Physiological strain during exercise is increased by mild dehydration (∼1%-3% body mass loss). This response may be sex-dependent, but there are no direct comparative data in this regard. This review aimed to develop a framework for future research by exploring the potential impact of sex on thermoregulatory and cardiac strain associated with exercise-induced dehydration. Sex-based comparisons were achieved by comparing trends from studies that implemented similar experimental protocols but recruited males and females separately. This revealed a higher core temperature (Tc) in response to exercise-induced dehydration in both sexes; however, it seemingly occurred at a lower percent body mass loss in females. Although less clear, similar trends existed for cardiac strain. The average female may have a lower body water volume per body mass compared with males, and therefore the same percent body mass loss between the sexes may represent a larger portion of total body water in females potentially posing a greater physiological strain. In addition, the rate at which Tc increases at exercise onset might be faster in females and induce a greater thermoregulatory challenge earlier into exercise. The Tc response at exercise onset is associated with lower sweating rates in females, which is commonly attributed to sex differences in metabolic heat production. However, a reduced sweat gland sensitivity to stimuli, lower fluid output per sweat gland, and sex hormones promoting fluid retention in females may also contribute. In conclusion, the limited evidence suggests that sex-based differences exist in thermoregulatory and cardiac strain associated with exercise-induced dehydration, and this warrants future investigations.

Effects of coconut sport gel on hydration measures, cognitive performance and anaerobic capacity in soccer players

Purpose: This study examined the effects of coconut sports gel (CSG) on hydration measures, cognitive performance and anaerobic capacity in soccer players. Materials and Methods: Seven soccer players (age: 21 ± 1.6 years; body weight (BW): 63.2 ± 6.6 kg; height: 172.3 ± 6.0 cm; VO2 max: 52.8 ± 1.4 ml. kg. min−1) participated in this study. Participants underwent one preliminary testing and two experimental trials: CSG and placebo (PLA) separated at least 7 days apart. Each trial consisted of hydration measurements and two cognitive (concentration and reaction time [RT]) and anaerobic capacity (vertical jump [VJ] and repeated sprint ability [RSA]) tests at (i) baseline, (ii) dehydration and (iii) rehydration. A 90-min exercise-induced dehydration protocol was used to induce ~ 2.0% of BW loss after baseline testing. Participants were required to ingest either CSG (CHO: 26 g, K+: 381 mg) or PLA (CHO: 26 g, K+: 0 mg) at 1.2 g. kg−1 BW of CHO within 30 min in a randomised order and replenished plain water (100% BW loss) during the 120 min of recovery period. Results: The results showed that participants were rehydrated after 2 h of recovery. Participants regained their BW from dehydration to rehydration: 61.3 ± 6.5 kg to 62.7 ± 6.6 kg (CSG trial) (p &lt; 0.001) and 61.4 ± 6.3 kg to 62.6 ± 6.4 kg (PLA trial) (p = 0.001). Urine-specific gravity reduced from dehydration to rehydration: 1.0168 ± 0.0073–1.0082 ± 0.0068 (p = 0.019) and 1.0148 ± 0.0061–1.0108 ± 0.0054 (p = 0.286) in CSG and PLA trials, respectively. VJ and RSA performance were similar between trials and among time points (p &gt; 0.05). The concentration scores, simple and choice RT tests showed no statistically significant difference in all time points between trials (p &gt; 0.05). Conclusion: Cognitive performance and anaerobic capacity in soccer players were well maintained after rehydration. Therefore, CSG could be an alternative option for athletes for rehydration purposes.

Chronic Ingestion of Bicarbonate-Rich Water Improves Anaerobic Performance in Hypohydrated Elite Judo Athletes: A Pilot Study.

In combat sports, anaerobic power and anaerobic capacity determine sport performance and the dominant metabolic pathways. The decline in performance during exercise that is attributed to the cumulative effects of fatigue, including excessive accumulation of metabolites, depletion of energy substrates, and water and electrolyte disturbances, seems to be of greatest significance. In our experiment, we evaluated the effectiveness of three weeks of bicarbonate-rich water ingestion on anaerobic performance in a state of hydration and dehydration in elite judo athletes. Eight male, elite judo athletes participated in two single-blind, repeated-measures trials. They were assigned to two hydration protocols, ingesting low mineralized table water and bicarbonate-rich water. Anaerobic performance was evaluated by two 30 s Wingate tests for lower and upper limbs, respectively, under conditions of hydration as well as exercise-induced dehydration. Resting, post-ingestion, and post-exercise concentrations of bicarbonate (HCO3), urine osmolality (UOSM), urine specific gravity (UGRAV), and lactate (La) were measured. The current investigation assessed two related factors that impair anaerobic performance—hypohydration and buffering capacity. High-bicarbonate water ingestion improved buffering capacity, and we demonstrated the potential role of this mechanism and its phenomenon in masking the adverse effects of dehydration in the context of repeated high-intensity anaerobic exercise (HIAE).

The Effect Of Mild Exercise Induced Dehydration On Sport Concussion Assessment Tool 3 (SCAT3) Scores: A within-subjects design.

BackgroundSports-related concussions are prevalent in the United States. Various diagnostic tools are utilized in order to monitor deviations from baseline in memory, reaction time, symptoms, and balance. Evidence indicates that dehydration may also alter the results of diagnostic tests.PurposeThe purpose was to determine the effect of exercise-induced dehydration on performance related to concussion examination tools.Study DesignRepeated measures design.MethodsSeventeen recreationally competitive, non-concussed participants (age: 23.1±3.1 years, height:168.93±10.71 cm, mass: 66.16 ± 6.91 kg) performed three thermoneutral, counterbalanced sessions (rested control, euhydrated, dehydrated). Participants were either restricted (0.0 L/hr) or provided fluids (1.0 L/hr) while treadmill running for 60 min at an intensity equal to 65-70% age-predicted maximum heart rate (APMHR). The Sport Concussion Assessment Tool 3 (SCAT3) was utilized to assess symptoms, memory, balance, and coordination.ResultsStatistically significant differences were seen among sessions for symptom severity and symptom total. The rested control session had significantly lower values when compared to the dehydrated session. Additionally, the symptom total in the rested control was significantly lower than the euhydrated condition as well. No statistically significant differences were seen for the BESS or memory scores.ConclusionsMild exercise-induced dehydration results in increased self-reported symptoms associated with concussions. Clinicians tasked with monitoring and accurately diagnosing head trauma should take factors such as hydration status into account when assessing patients for concussion with the SCAT3. Clinicians should proceed with caution and not assume concussion as primary cause for symptom change.Level of evidenceLevel 3

Movement Technique and Standing Balance After Graded Exercise-Induced Dehydration.

Hypohydration has been shown to alter neuromuscular function. However, the longevity of these impairments remains unclear. To examine the effects of graded exercise-induced dehydration on neuromuscular control 24 hours after exercise-induced hypohydration. Crossover study. Laboratory. A total of 23 men (age = 21 ± 2 years, height = 179.8 ± 6.4 cm, mass = 75.24 ± 7.93 kg, maximal oxygen uptake [VO2max] = 51.7 ± 5.5 mL·kg-1·min-1, body fat = 14.2% ± 4.6%). Participants completed 3 randomized exercise trials: euhydrated arrival plus fluid replacement (EUR), euhydrated arrival plus no fluid (EUD), and hypohydrated arrival plus no fluid (HYD) in hot conditions (ambient temperature = 35.2°C ± 0.6°C, relative humidity = 31.3% ± 2.5%). Each trial consisted of 180 minutes of exercise (six 30-minute cycles: 8 minutes at 40% VO2max; 8 minutes, 60% VO2max; 8 minutes, 40% VO2max; 6 minutes, passive rest) followed by 60 minutes of passive recovery. We used the Landing Error Scoring System and Balance Error Scoring System (BESS) to measure movement technique and postural control at pre-exercise, postexercise and passive rest (POSTEX), and 24 hours postexercise (POST24). Differences were assessed using separate mixed-design (trial × time) repeated-measures analyses of variance. The magnitude of hypohydration at POSTEX was different among EUR, EUD, and HYD trials (0.2% ± 1%, 3.5% ± 1%, and 5% ± 0.9%, respectively; P < .05). We observed no differences in Landing Error Scoring System scores at pre-exercise (2.9 ± 1.6, 3.0 ± 2.1, 3.0 ± 2.0), POSTEX (3.3 ± 1.5, 3.0 ± 2.0, 3.1 ± 1.9), or POST24 (3.3 ± 1.9, 3.2 ± 1.4, 3.3 ± 1.6) among the EUD, EUR, and HYD trials, respectively (P = .90). Hydration status did not affect BESS scores (P = .11), but BESS scores at POSTEX (10.4 ± 1.1) were greater than at POST24 (7.7 ± 0.9; P = .03). Whereas exercise-induced dehydration up to 5% body mass did not impair movement technique or postural control 24 hours after a prolonged bout of exercise in a hot environment, postural control was impaired at 60 minutes after prolonged exercise in the heat. Consideration of the length of recovery time between bouts of exercise in hot environments is warranted.

Nitrate-rich beetroot juice offsets salivary acidity following carbohydrate ingestion before and after endurance exercise in healthy male runners.

There have been recent calls for strategies to improve oral health in athletes. High carbohydrate diets, exercise induced dehydration and transient perturbations to immune function combine to increase oral disease risk in this group. We tested whether a single dose of nitrate (NO3-) would offset the reduction in salivary pH following carbohydrate ingestion before and after an exercise bout designed to cause mild dehydration. Eleven trained male runners ( 53 ± 9 ml∙kg-1∙min-1, age 30 ± 7 years) completed a randomised placebo-controlled study comprising four experimental trials. Participants ingested the following fluids one hour before each trial: (a) 140 ml of water (negative-control), (b) 140 ml of water (positive-control), (c) 140 ml of NO3- rich beetroot juice (~12.4 mmol NO3-) (NO3- trial) or (d) 140 ml NO3- depleted beetroot juice (placebo-trial). During the negative-control trial, participants ingested 795 ml of water in three equal aliquots: before, during, and after 90 min of submaximal running. In the other trials they received 795 ml of carbohydrate supplements in the same fashion. Venous blood was collected before and after the exercise bout and saliva was sampled before and repeatedly over the 20 min following carbohydrate or water ingestion. As expected, nitrite (NO2-) and NO3- were higher in plasma and saliva during the NO3- trial than all other trials (all P<0.001). Compared to the negative-control, salivary-pH was significantly reduced following the ingestion of carbohydrate in the positive-control and placebo trials (both P <0.05). Salivary-pH was similar between the negative-control and NO3- trials before and after exercise despite ingestion of carbohydrate in the NO3- trial (both P≥0.221). Ingesting NO3- attenuates the expected reduction in salivary-pH following carbohydrate supplements and exercise-induced dehydration. NO3- should be considered by athletes as a novel nutritional strategy to reduce the risk of developing acidity related oral health conditions.

The Effect of Caffeine Intake on Body Fluids Replacement After Exercise-Induced Dehydration

We studied the effect of a plain espresso coffee (171 ± 8.9 mg caffeine) which is roughly the amount in a cup of regular coffee or caffeine soda drink on fluid replacement in mildly dehydrated healthy subjects following moderate exercise, which induced dehydration to approximately 1.2% of their body weight. Subjects then rehydrated by drinking either water alone as control or caffeinated beverage plus up to 150% of the body weight they had lost. All subjects underwent both conditions. There were differences between the control and caffeine in urine specific gravity (control: 1.018 ± 0.00 vs caffeine: 1.024 ± 0.00, P = .001), urine volume (control: 200 ± 71 mL vs caffeine: 302 ± 151 mL, P = .05), and urine color (control: 2 ± 0.9 and caffeine: 4 ± 1.66, P = .00). We conclude that intake of an espresso coffee possibly impedes replacement of body fluids.

Low-Osmolality Carbohydrate-Electrolyte Solution Ingestion Avoid Fluid Loss and Oxidative Stress After Exhaustive Endurance Exercise.

Low-osmolality carbohydrate–electrolyte solution (LCS) ingestion can replace losses from exercise-induced dehydration, but the benefits of LCS ingestion strategy after exhaustive endurance exercise (EEE) remain unknown. The present study evaluated the effects of LCS ingestion on dehydration, oxidative stress, renal function, and aerobic capacity after EEE. In our study with its double-blind, crossover, counterbalanced design, 12 healthy male participants were asked to consume LCS (150 mL four times per hour) or placebo (water) 1 h before and 1 h after EEE. All participants completed a graded exercise test to exhaustion on a treadmill for the determination of maximal oxygen consumption (), applied to further intensity calibration, and then completed the EEE test. The average heart rate, maximal heart rate, running time to exhaustion, and peak oxygen uptake (VO2peak) were recorded during the exercise period. The participants’ body weight was recorded at different time points before and after the EEE to calculate the dehydration rate. Blood samples were drawn at baseline and before, immediately after, 1 h after, and 2 h after EEE to determine indicators of oxidative stress and renal function. The results indicated that the dehydration rates in participants with LCS ingestion at 15 min, 30 min, and 45 min after EEE were significantly lower than in participants with placebo ingestion (−1.86 ± 0.47% vs. −2.24 ± 0.72%; −1.78 ± 0.50% vs. −2.13 ± 0.74%; −1.54 ± 0.51% vs. −1.94 ± 0.72%, respectively; p < 0.05). In addition, the concentration of catalase in participants with LCS ingestion immediately after EEE was significantly higher than in participants with placebo ingestion (2046.21 ± 381.98 nmol/min/mL vs. 1820.37 ± 417.35 nmol/min/mL; p < 0.05). Moreover, the concentration of protein carbonyl in participants with LCS ingestion immediately after EEE was slightly lower than in participants with placebo ingestion (2.72 ± 0.31 nmol carbonyl/mg protein vs. 2.89 ± 0.43 nmol carbonyl/mg protein; p = 0.06). No differences were noted for other variables. Our findings conclude that LCS ingestion can effectively avoid fluid loss and oxidative stress after EEE. However, LCS ingestion had no benefits for renal function or aerobic capacity.

Diagnostic accuracy of urinary indices to detect mild dehydration in young men following acute riboflavin, Vitamin C or beetroot supplementation

Individuals of all ages are encouraged to monitor their hydration status daily to prevent clinically severe fluid imbalances such as hyponatremia or dehydration. However, acute oral nutritional supplementation may alter urinary hydration assessments and potentially increase the likelihood of inappropriate clinical decisions or diagnosis. This investigation sought to examine the influence of three common over-the-counter nutritional supplements (beetroot, riboflavin, and Vitamin C) on urinary hydration assessments in physically active young men after a 2% exercise-induced dehydration. Eight males (Mean±SD; age: 22±3yr; body mass index: 27±5.0) consumed either a standard meal with supplementation (intervention) or a standard meal without supplementation (control). Participants performed a variety of aerobic or resistance exercises until reaching ≥2% body mass loss in a counter-balanced, double-blinded design. Following exercise participation, urine samples were collected for an 8h observational period during which food consumption was replicated. Urine samples were analyzed for urine color, specific gravity, volume, and osmolality. Maintenance of ~2% body mass loss (2.6±0.5%; range: 1.7-4.0%) was confirmed following the 8h observational period. Statistically significant (p<0.05) changes were noted in urine color following Vitamin C supplementation compared to control; however, the difference was not clinically meaningful. These findings indicate that urine color, specific gravity, and osmolality maintain clinical utility to detect moderate levels of dehydration in physically active men consuming commercially available doses of beetroot, riboflavin, or Vitamin C.

Comment on: "The Utility of Thirst as a Measure of Hydration Status Following Exercise-Induced Dehydration".

In their study, Adams et al. [1] attempted to determine whether thirst perception could serve as a reliable marker of hydration status during 3 h of exercise where participants either dehydrated by 3% of their body mass or maintained euhydration through water intake, and following exercise where they either could not drink or were allowed to consume water ad libitum during the first 10 min of a 60 min long recovery period [...].

Effect of Drinking Rate on the Retention of Water or Milk Following Exercise-Induced Dehydration.

This study investigated the effect of drinking rate on fluid retention of milk and water following exercise-induced dehydration. In Part A, 12 male participants lost 1.9% ± 0.3% body mass through cycle exercise on four occasions. Following exercise, plain water or low-fat milk equal to the volume of sweat lost during exercise was provided. Beverages were ingested over 30 or 90min, resulting in four beverage treatments: water 30min, water 90min, milk 30min, and milk 90min. In Part B, 12 participants (nine males and three females) lost 2.0% ± 0.3% body mass through cycle exercise on four occasions. Following exercise, plain water equal to the volume of sweat lost during exercise was provided. Water was ingested over 15min (DR15), 45min (DR45), or 90min (DR90), with either DR15 or DR45 repeated. In both trials, nude body mass, urine volume, urine specific gravity and osmolality, plasma osmolality, and subjective ratings of gastrointestinal symptoms were obtained preexercise and every hour for 3hr after the onset of drinking. In Part A, no effect of drinking rate was observed on the proportion of fluid retained, but milk retention was greater (p < .01) than water (water 30min: 57% ± 16%, water 90min: 60% ± 20%, milk 30min: 83% ± 6%, and milk 90min: 85% ± 7%). In Part B, fluid retention was greater in DR90 (57% ± 13%) than DR15 (50% ± 11%, p < .05), but this was within test-retest variation determined from the repeated trials (coefficient of variation: 17%). Within the range of drinking rates investigated the nutrient composition of a beverage has a more pronounced impact on fluid retention than the ingestion rate.

Impact of Pre-exercise Hypohydration on Aerobic Exercise Performance, Peak Oxygen Consumption and Oxygen Consumption at Lactate Threshold: A Systematic Review with Meta-analysis.

Progressive exercise-induced dehydration may impair aerobic exercise performance (AEP). However, no systematic approach has yet been used to determine how pre-exercise hypohydration, which imposes physiological challenges differing from those of a well-hydrated pre-exercise state, affects AEP and related components such as peak oxygen consumption [Formula: see text] and [Formula: see text] at lactate threshold [Formula: see text]. To determine, using a systematic approach with meta-analysis, the magnitude of the effect of pre-exercise hypohydration on AEP, [Formula: see text] and [Formula: see text]. This was a systematic review with meta-analysis of well-controlled studies. MEDLINE, SPORTDiscus and CINAHL databases and cross-referencing. INCLUSION CRITERIA FOR SELECTING STUDIES: (1) well-controlled human (≥ 18years) studies; (2) pre-exercise hypohydration induced at least 1h prior to exercise onset; (3) pre-exercise body mass loss in the hypohydrated, experimental condition was ≥ 1% and ≥ 0.5% than the well-hydrated, control condition; (4) following the dehydrating protocol body mass change in the control condition was within - 1% to + 0.5% of the well-hydrated body mass. A total of 15 manuscripts were included, among which 14, 6 and 6 met the inclusion criteria for AEP, [Formula: see text]and [Formula: see text], respectively, providing 21, 10 and 9 effect estimates, representing 186 subjects. Mean body mass decrease was 3.6 ± 1.0% (range 1.7-5.6%). Mean AEP test time among studies was 22.3 ± 13.5min (range 4.5-54.4 min). Pre-exercise hypohydration impaired AEP by 2.4 ± 0.8% (95% CI 0.8-4.0%), relative to the control condition. Peak oxygen consumption and [Formula: see text], respectively, decreased by 2.4 ± 0.8% (95% CI 0.7-4.0%) and 4.4 ± 1.4% (95% CI 1.7-7.1%), relative to the control condition. Compared with starting an exercise hypohydrated, it is respectively likely, possible and likely that AEP, [Formula: see text] and [Formula: see text] benefit from a euhydrated state prior to exercise. Meta-regression analyses did not establish any significant relationship between differences in body mass loss and differences in the percent change in AEP or [Formula: see text]. However, [Formula: see text] was found to decrease by 2.6 ± 0.8 % (95% CI 0.7-4.5%) for each percent loss in body mass above a body mass loss threshold of 2.8%. Pre-exercise hypohydration likely impairs AEP and likely reduces [Formula: see text] (i.e., the aerobic contribution to exercise was lower) during running and cycling exercises ≤ 1h across different environmental conditions (i.e., from 19 to 40°C). Moreover, pre-exercise hypohydration possibly impedes [Formula: see text] during such exercises.