A Comparison of Three Fluid Replacement Strategies for Maintaining Euhydration During Prolonged Exercise

1997 ◽  
Vol 22 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Jan M. Schroeder ◽  
Kris L. Heck ◽  
Jeffrey A. Potteiger
Keyword(s):  
Heart Rate ◽  
Plasma Volume ◽  
Prolonged Exercise ◽  
Fluid Intake ◽  
Fluid Replacement ◽  
Water Delivery ◽  
Total Water ◽  
Significant Difference ◽  
Ad Libitum ◽  
Total Water Intake

The effectiveness of a new water delivery system (the Water-Del) was examined for maintaining euhydration compared to other fluid replacement strategies. Subjects (N = 10) performed three 60-min cycling trials (@ 50% of VO2max) in an environmental chamber (27 °C; RH = 50%). Trials were randomly assigned from Water-Del (metered: 200 ml water every 15 min), ad libitum every 15 min (ad-lib-15), and ad libitum (ad-lib). Total water intake (TWI), changes in plasma volume (ΔPV), body Weight (ΔBW), thirst, skin temperature (Tsk), and heart rate (HR) were measured. A significant difference (p ≤.05) among trials was observed for TWI, with metered (1.200 ± 0.12 ml) being greater than ad-lib-15 (358 ± 48 ml) and ad-lib (522 ± 106 ml). No significant difference was found for ΔPV. A significant difference (p ≤.05) for ΔHW was observed with metered (0.28 ± 0.16 kg) being different than ad-lib-l5 (−0.63 ± 0.12 kg) and ad-lib (−0.34 ± 0.14 kg). No significant differences (p > .05) were found for thirst, Tsk, or HR. The Water-Del provides for greater fluid intake during exercise compared to other replacement strategies. Key words: hydration, dehydration, plasma volume

scholarly journals Hydration Status: Influence of Exercise and Diet Quality

2017 ◽  
Vol 13 (4) ◽  
pp. 414-423
Author(s):  
Ismael San Mauro Martín ◽  
Elena Garicano Vilar ◽  
Denisse Aracely Romo Orozco ◽  
Paula Mendive Dubourdieu ◽  
Victor Paredes Barato ◽  
...  
Keyword(s):  
Physical Exercise ◽  
Water Intake ◽  
Diet Quality ◽  
Fluid Intake ◽  
Healthy Eating Index ◽  
Hydration Status ◽  
Total Water ◽  
Essential Components ◽  
Significant Difference ◽  
Total Water Intake

Physical activity, adherence to a healthy diet, and healthy beverage pattern are considered essential components of a healthy lifestyle. We aimed to evaluate the associations between physical exercise, diet quality, and total fluid intake, along with fluid recommendations compliance in a sample of adults. Data on fluid intake from different types of beverages were collected in a cross-sectional study, in 1161 men and women between 18 and 65 years of age, using a fluid-specific diary. Exercise was evaluated with a self-reported questionnaire, and quality of diet was assessed using the Healthy Eating Index-2010 (HEI). Mean volume of water consumed was 1497.5 mL for men, 1309.5 mL for women. A total of 37.4% did not follow the recommendations of the European Food Safety Agency for total water intake. There was a statistically significant difference ( P = .002) between total water intake and follow-up of recommendations, as well as for sex ( P < .001). Mean HEI-2010 score was 65.21. There were no statistically significant differences ( P = .301) in HEI index among better or worse hydration. Sport variables had influence on milliliters of water consumed ( P < .001). Participants who engaged in more physical exercise exhibit a healthier pattern of fluid intake. Healthy individuals with the highest scores for HEI-2010 did not present the healthiest beverage patterns.

Immersion diuresis without expected suppression of vasopressin

1984 ◽  
Vol 57 (1) ◽  
pp. 123-128 ◽  
Author(s):  
S. E. Kravik ◽  
L. C. Keil ◽  
J. E. Silver ◽  
N. Wong ◽  
W. A. Spaul ◽  
...  
Keyword(s):  
Water Balance ◽  
Plasma Volume ◽  
Fluid Intake ◽  
Serum Osmolality ◽  
Renin Activity ◽  
Fluid Restriction ◽  
Angiotensin I ◽  
Plasma Vasopressin ◽  
Immersion Diuresis ◽  
Ad Libitum

To investigate fluid, electrolyte, and plasma vasopressin (PVP) and renin activity (PRA) responses, six men (20–35 yr) were immersed to the neck (NI) in water at 34.5 degrees C for six h after overnight food and fluid restriction. Diuresis was 1,061 +/- 160 (SE) ml/6 h during immersion and water balance was -1,285 +/- 104 ml/6 h. Preimmersion PVP was 0.7 +/- 0.2 pg/ml and increased to 3.0 +/- 0.6 pg/ml (P less than 0.05) at 6 h. PVP was unchanged at 1.2 +/- 0.1 pg/ml in the 6-h seated nonimmersionexperiment at 25 degrees C. Plasma volume increased by 7.8 +/- 1.6% (P less than 0.05) at 60 min of NI and decreased thereafter. Serum osmolality was constant (292 +/- 1 mosmol/kg) throughout NI, whereas PRA decreased progressively from 1.9 to 0.5 ng angiotensin I X ml-1 X h-1 (P less than 0.05) at theend of immersion. In spite of moderate thirst just before NI, thirst sensations were attenuated and no water was consumed ad libitum during immersion. These data indicate that PVP is not suppressed whenthere is no fluid intake during immersion and suggest that the action of factors other than PVP suppression are necessary to explain the mechanism of immersion diuresis.

scholarly journals Drinking to Thirst Versus Drinking Ad Libitum During Road Cycling

2014 ◽  
Vol 49 (5) ◽  
pp. 624-631 ◽  
Author(s):  
Lawrence E. Armstrong ◽  
Evan C. Johnson ◽  
Laura J. Kunces ◽  
Matthew S. Ganio ◽  
Daniel A. Judelson ◽  
...  
Keyword(s):  
Body Mass ◽  
Perceived Exertion ◽  
Fluid Intake ◽  
Thermal Sensation ◽  
Drinking Behavior ◽  
Total Fluid Intake ◽  
Finish Line ◽  
Road Cycling ◽  
Significant Difference ◽  
Ad Libitum

Context: The sensation of thirst is different from the complex behavior of drinking ad libitum. Rehydration recommendations to athletes differ, depending on the source, yet no previous researchers have systematically compared drinking to thirst (DTT) versus ad libitum drinking behavior (DAL). Objective: To compare 2 groups of trained cyclists (DTT and DAL) who had similar physical characteristics and training programs (P &gt; .05). The DTT group (n = 12, age = 47 ± 7 years) drank only when thirsty, whereas the DAL group (n = 12, age = 44 ± 7 years) consumed fluid ad libitum (ie, whenever and in whatever volume desired). Design: Cohort study. Setting: Road cycling (164 km) in the heat (36.1°C ± 6.5°C). Patients or Other Participants: Ultraendurance cyclists (4 women, 20 men). Intervention(s): We recorded measurements 1 day before the event, on event day before the start, at 3 roadside aid stations, at the finish line, and 1 day after the event. Main Outcome Measure(s): Body mass, urinary hydration indices, and food and fluids consumed. Results: No between-groups differences were seen on event day for total exercise time (DTT = 6.69 ± 0.89 hours, DAL = 6.66 ± 0.77 hours), urinary indices (specific gravity, color), body mass change (DTT = −2.22% ± 1.73%, DAL = −2.29% ± 1.62%), fluid intake (DTT = 5.63 ± 2.59 L/6.7 h, DAL = 6.04 ± 2.37 L/6.7 h), dietary energy intake, macronutrient intake, ratings of thirst (DTT start = 2 ± 1, DTT finish = 6 ± 1, DAL start = 2 ± 1, DAL finish = 6 ± 1), pain, perceived exertion, or thermal sensation. Total fluid intake on recovery day +1 was the primary significant difference (DAL = 5.13 ± 1.87 L/24 h, DTT = 3.13 ± 1.53 L/24 h, t18 = 2.59, P = .02). Conclusions: Observations on event day indicated that drinking to thirst and drinking ad libitum resulted in similar physiologic and perceptual outcomes. This suggests that specific instructions to “drink to thirst” were unnecessary. Indeed, if athletes drink ad libitum, they can focus on training and competition rather than being distracted by ongoing evaluation of thirst sensations.

scholarly journals Sodium Replacement and Plasma Sodium Drop During Exercise in the Heat When Fluid Intake Matches Fluid Loss

2009 ◽  
Vol 44 (2) ◽  
pp. 117-123 ◽  
Author(s):  
Costas A. Anastasiou ◽  
Stavros A. Kavouras ◽  
Giannis Arnaoutis ◽  
Aristea Gioxari ◽  
Maria Kollia ◽  
...  
Keyword(s):  
Plasma Volume ◽  
Serum Sodium ◽  
Prolonged Exercise ◽  
Fluid Intake ◽  
Sodium Intake ◽  
Plasma Osmolality ◽  
Plasma Sodium ◽  
Fluid Loss ◽  
Electrolyte Balance ◽  
Sodium Replacement

Abstract Context: Sodium replacement during prolonged exercise in the heat may be critically important to maintaining fluid and electrolyte balance and muscle contractility. Objective: To examine the effectiveness of sodium-containing sports drinks in preventing hyponatremia and muscle cramping during prolonged exercise in the heat. Design: Randomized crossover study. Patients or Other Participants: Thirteen active men. Intervention(s): Participants completed 4 trials of an exercise protocol in the heat (30°C) consisting of 3 hours of exercise (alternating 30 minutes of walking and cycling at a heart rate of 130 and 140 beats per minute, respectively); a set of standing calf raises (8 sets of 30 repetitions); and 45 minutes of steep, brisk walking (5.5 kmṡh−1 on a 12% grade). During exercise, participants consumed fluids to match body mass loss. A different drink was consumed for each trial: carbohydrate-electrolyte drink containing 36.2 mmol/L sodium (HNa), carbohydrate-electrolyte drink containing 19.9 mmol/L sodium (LNa), mineral water (W), and colored and flavored distilled water (PL). Main Outcome Measure(s): Serum sodium, plasma osmolality, plasma volume changes, and muscle cramping frequency. Results: During both HNa and LNa trials, serum sodium remained relatively constant (serum sodium concentration at the end of the protocol was 137.3 mmol/L and 136.7 mmol/L, respectively). However, a clear decrease was observed in W (134.5 ± 0.8 mmol/L) and PL (134.4 ± 0.8 mmol/L) trials compared with HNa and LNa trials (P &lt; .05). The same trends were observed for plasma osmolality (P &lt; .05). Albeit not significant, plasma volume was preserved during the HNa and LNa trials, but a reduction of 2.5% was observed in the W and PL trials. None of the volunteers experienced cramping. Conclusions: The data suggest that sodium intake during prolonged exercise in the heat plays a significant role in preventing sodium losses that may lead to hyponatremia when fluid intake matches sweat losses.

scholarly journals Fluid Balance and Sodium Losses During Indoor Tennis Match Play

2011 ◽  
Vol 21 (6) ◽  
pp. 492-500 ◽  
Author(s):  
Matthew J.E. Lott ◽  
Stuart D.R. Galloway
Keyword(s):  
Heart Rate ◽  
Body Mass ◽  
Fluid Balance ◽  
Fluid Intake ◽  
Sweat Rate ◽  
Fluid Replacement ◽  
Whole Body ◽  
Electrolyte Balance ◽  
Match Play ◽  
Tennis Match

This study assessed fluid balance, sodium losses, and effort intensity during indoor tennis match play (17 ± 2 °C, 42% ± 9% relative humidity) over a mean match duration of 68.1 ± 12.8 min in 16 male tennis players. Ad libitum fluid intake was recorded throughout the match. Sweat loss from change in nude body mass; sweat electrolyte content from patches applied to the forearm, calf, and thigh, and back of each player; and electrolyte balance derived from sweat, urine, and daily food-intake analysis were measured. Effort intensity was assessed from on-court heart rate compared with data obtained during a maximal treadmill test. Sweat rate (M ± SD) was 1.1 ± 0.4 L/hr, and fluid-ingestion rate was 1.0 ± 0.6 L/hr (replacing 93% ± 47% of fluid lost), resulting in only a small mean loss in body mass of 0.15% ± 0.74%. Large interindividual variabilities in sweat rate (range 0.3–2.0 L/hr) and fluid intake (range 0.31–2.52 L/hr) were noted. Whole-body sweat sodium concentration was 38 ± 12 mmol/L, and total sodium losses during match play were 1.1 ± 0.4 g (range 0.5–1.8 g). Daily sodium intake was 2.8 ± 1.1 g. Indoor match play largely consisted of low-intensity exercise below ventilatory threshold (mean match heart rate was 138 ± 24 beats/min). This study shows that in moderate indoor temperature conditions players ingest sufficient fluid to replace sweat losses. However, the wide range in data obtained highlights the need for individualized fluid-replacement guidance.

Fluid replacement and glucose infusion during exercise prevent cardiovascular drift

1991 ◽  
Vol 71 (3) ◽  
pp. 871-877 ◽  
Author(s):  
M. T. Hamilton ◽  
J. Gonzalez-Alonso ◽  
S. J. Montain ◽  
E. F. Coyle
Keyword(s):  
Heart Rate ◽  
Body Weight ◽  
Cardiac Output ◽  
Rectal Temperature ◽  
Prolonged Exercise ◽  
Blood Glucose Concentration ◽  
Fluid Replacement ◽  
O2 Uptake ◽  
Trained Subjects ◽  
Cardiovascular Drift

This study examined the influence of both hydration and blood glucose concentration on cardiovascular drift during exercise. We first determined if the prevention of dehydration during exercise by full fluid replacement prevents the decline in stroke volume (SV) and cardiac output (CO) during prolonged exercise. On two occasions, 10 endurance-trained subjects cycled an ergometer in a 22 degrees C room for 2 h, beginning at 70 +/- 1% maximal O2 uptake (VO2max) and in a euhydrated state. During one trial, no fluid (NF) replacement was provided and the subject's body weight declined 2.09 +/- 0.19 kg or 2.9%. During the fluid replacement trial (FR), water was ingested at a rate that prevented body weight from declining after 2 h of exercise (i.e., 2.34 +/- 0.17 1/2 h). SV declined 15% and CO declined 7% during the 20- to 120-min period of the NF trial while heart rate (HR) increased 10% and O2 uptake (VO2) increased 6% (all P less than 0.05). In contrast, SV was maintained during the 20- to 120-min period of FR while HR increased 5% and thus CO actually increased 7% (all P less than 0.05). Rectal temperature, SV, and HR were similar during the 1st h of exercise during NF and FR. However, after 2 h of exercise, rectal temperature was 0.6 degree C higher (P less than 0.05) and SV and CO were 11–16% lower (P less than 0.05) during NF compared with FR.(ABSTRACT TRUNCATED AT 250 WORDS)

Responses to Moderate and Low Sodium Diets during Exercise-Heat Acclimation

1993 ◽  
Vol 3 (2) ◽  
pp. 207-221 ◽  
Author(s):  
Lawrence E. Armstrong ◽  
Roger W. Hubbard ◽  
E. Wayne Askew ◽  
Jane P. De Luca ◽  
Catherine O'Brien ◽  
...  
Keyword(s):  
Heart Rate ◽  
Plasma Volume ◽  
Rectal Temperature ◽  
Prolonged Exercise ◽  
Heat Acclimation ◽  
Treadmill Walking ◽  
Heat Illness ◽  
Low Sodium ◽  
Physiologic Function ◽  
Physiologic Responses

This investigation examined whether low sodium (Na+) (LNA; 68 mEq Na+·d-1) or moderate Na+(MNA; 137 mEq Na+.d-1) intake allowed humans to maintain health, exercise, and physiologic function during 10 days of prolonged exercise-heat acclimation (HA). Seventeen volunteers, ages 19 to 21, consumed either LNA (n=8) or MNA (n=9) during HA (41°C, 21% RH; treadmill walking for 30 min.h-1, 8 h·d-1at 5.6 kmh-l, 5% grade), which resulted in significantly reduced heart rate, rectal temperature, and urine Na+for both groups. There were few between-diet differences in any variables measured. Mean plasma volume in LNA expanded significantly less than in MNA by Days 11 and 15, but reached the MNA level on Day 17 (+12.3 vs. +12.4%). The absence of heat illness, the presence of normal physiologic responses, and the total distance walked indicated successful and similar HA with both levels of dietary Na+.

scholarly journals The Utility of Thirst as a Measure of Hydration Status Following Exercise-Induced Dehydration

Nutrients ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2689 ◽  
Author(s):  
William M. Adams ◽  
Lesley W. Vandermark ◽  
Luke N. Belval ◽  
Douglas J. Casa
Keyword(s):  
Body Mass ◽  
Prolonged Exercise ◽  
Recovery Period ◽  
Fluid Replacement ◽  
Hydration Status ◽  
Post Exercise ◽  
Visual Analog Scales ◽  
Hot Environment ◽  
Ad Libitum ◽  
Exercise Induced

The purpose of this study was to examine the perception of thirst as a marker of hydration status following prolonged exercise in the heat. Twelve men (mean ± SD; age, 23 ± 4 y; body mass, 81.4 ± 9.9 kg; height, 182 ± 9 cm; body fat, 14.3% ± 4.7%) completed two 180 min bouts of exercise on a motorized treadmill in a hot environment (35.2 ± 0.6 °C; RH, 30.0 ± 5.4%), followed by a 60 min recovery period. Participants completed a euhydrated (EUH) and hypohydrated (HYPO) trial. During recovery, participants were randomly assigned to either fluid replacement (EUHFL and HYPOFL; 10 min ad libitum consumption) or no fluid replacement (EUHNF and HYPONF). Thirst was measured using both a nine-point scale and separate visual analog scales. The percent of body mass loss (%BML) was significantly greater immediately post exercise in HYPO (HYPOFL, 3.0% ± 1.2%; HYPONF, 2.6% ± 0.6%) compared to EUH (EUHFL, 0.2% ± 0.7%; EUHNF, 0.6% ± 0.5%) trials (p < 0.001). Following recovery, there were no differences in %BML between HYPOFL and HYPONF (p > 0.05) or between EUHFL and EUHNF (p > 0.05). Beginning at minute 5 during the recovery period, thirst perception was significantly greater in HYPONF than EUHFL, EUHNF, and HYPOFL (p < 0.05). A 10 min, ad libitum consumption of fluid post exercise when hypohydrated (%BML > 2%), negated differences in perception of thirst between euhydrated and hypohydrated trials. These results represent a limitation in the utility of thirst in guiding hydration practices.

Fluid Retention and Utility of Practical Hydration Markers to Detect Three Levels of Recovery Fluid Intake in Male Runners

2017 ◽  
Vol 27 (2) ◽  
pp. 178-185 ◽  
Author(s):  
Mary Caitlin Stevenson Wilcoxson ◽  
Samantha Louise Johnson ◽  
Veronika Pribyslavska ◽  
James Mathew Green ◽  
Eric Kyle O’Neal
Keyword(s):  
Specific Gravity ◽  
Urine Output ◽  
Fluid Intake ◽  
Fluid Retention ◽  
Fluid Replacement ◽  
Urine Specific Gravity ◽  
Retention Data ◽  
Sweat Loss ◽  
Ad Libitum ◽  
Low Levels

Runners are unlikely to consume fluid during training bouts increasing the importance of recovery rehydration efforts. This study assessed urine specific gravity (USG) responses following runs in the heat with different recovery fluid intake volumes. Thirteen male runners completed 3 evening running sessions resulting in approximately 2,200 ± 300 ml of sweat loss (3.1 ± 0.4% body mass) followed by a standardized dinner and breakfast. Beverage fluid intake (pre/postbreakfast) equaled 1,565/2,093 ml (low; L), 2,065/2,593 ml (moderate; M) and 2,565/3,356 mL (high; H). Voids were collected in separate containers. Increased urine output resulted in no differences (p > .05) in absolute mean fluid retention for waking or first postbreakfast voids. Night void averages excluding the first void postrun (1.025 ± 0.008; 1.013 ± 0.008; 1.006 ± 0.003), first morning (1.024 ± 0.004; 1.015 ± 0.005; 1.014 ± 0.005), and postbreakfast (1.022 ± 0.007; 1.014 ± 0.007; 1.008 ± 0.003) USG were higher (p < .05) for L versus M and H respectively and more clearly differentiated fluid intake volume between L and M than color or thirst sensation. Waking (r = -0.66) and postbreakfast (r = -0.71) USG were both significantly correlated (p < .001) with fluid replacement percentage, but not absolute fluid retention. Fluid intake M was reported as most similar to normal consumption (5.6 ± 1.0 on 0–10 scale) after breakfast and equaled 122 ± 16% of sweat losses. Retention data suggests consumption above this level is not warranted or actually practiced by most runners drinking ad libitum, but that periodic prerun USG assessment may be useful for coaches to detect runners that habitually consume low levels of fluids between training bouts in warm seasons.

The intake and excretion of sodium by sheep fed on species of Atriplex (Saltbush) and Kochia (Bluebush)

1966 ◽  
Vol 17 (2) ◽  
pp. 155 ◽  
Author(s):  
AD Wilson
Keyword(s):  
Drinking Water ◽  
Sodium Chloride ◽  
Food Intake ◽  
Sodium Intake ◽  
Dry Weight ◽  
Sodium Content ◽  
Total Water ◽  
Ad Libitum ◽  
Sodium Chloride Intake ◽  
Total Water Intake

Penned sheep were fed ad libitum on the fresh leaves of various species of Atriplex and Kochia,and records were made of the intake and excretion of sodium by these sheep. The sodium content of the diets varied from 3.2 to 8.2% of the dry weight, the higher values being recorded in summer and the lower values in winter. The sodium intakes of the sheep varied from 25 to 97 g/day. Most of this sodium was excreted in the urine at concentrations up to 500 m-equiv./l. The voluntary water consumption of these sheep was related to the sodium intake, such that the ratio of sodium chloride intake to total water intake was within the range 1.82 to 2.17%. Voluntary water intakes varied up to 11.3 l./day. The food intake of A. nummularia decreased to less than half when the drinking water was replaced by water containing 0.9 or 1.2% sodium chloride.

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