Drinking Behavior and Perception of Thirst in Untrained Women during 6 Weeks of Heat Acclimation and Outdoor Training

2003 ◽  
Vol 13 (1) ◽  
pp. 15-28 ◽  
Author(s):  
Jennifer K. Ormerod ◽  
Tabatha A. Elliott ◽  
Timothy P. Scheett ◽  
Jaci L. VanHeest ◽  
Lawrence E. Armstrong ◽  
...  
Keyword(s):  
Water Intake ◽  
Physiological Response ◽  
Response Pattern ◽  
Fluid Intake ◽  
Drinking Behavior ◽  
Heat Acclimation ◽  
Acclimation Period ◽  
Outdoor Training

The purposes of this study were to characterize measures of fluid intake and perception of thirst in women over a 6-week period of exercise-heat acclimation and outdoor training and examine if this lengthy acclimation period would result in changes in fluid intake that differ from those previously reported in men utilizing a shorter acclimation protocol of 8–10 days. Voluntary water intake (11–17 °C) and perception of thirst were measured in a group of 5 women (21–26 yr) undergoing exercise-heat acclimation for 90 min/day, 3 days/wk (36 °C, rh 50–70%) and outdoor training 3 days/wk for 6 weeks. Decreased drinking during acclimation was characterized by a decrease in the number of drinks (35 ± 10 to 17 ± 5; p < .05), greater time to first drink (9.9 ± 2.0 to 23.1 ± 4.7 min; p < .05), and a decrease in total volume ingested per week (3310 ± 810 to 1849 ± 446 ml; p < .05) through the 6-week study. Mean perceived thirst measurements remained low and showed only slight variance (3 ± 0.4 to 5 ± 0.4). These observations support a psycho-physiological response pattern different than that previously observed during 8–10 day acclimation protocols in men.

Cardiac-Autonomic and Hemodynamic Responses to a Hypertonic, Sugar-Sweetened Sports Beverage in Physically Active Men

2021 ◽  
Author(s):  
Mark Christiani ◽  
Gregory J Grosicki ◽  
Andrew A Flatt
Keyword(s):  
Water Intake ◽  
Fluid Intake ◽  
Cold Water ◽  
Random Order ◽  
Effect Sizes ◽  
Water Control ◽  
Hemodynamic Responses ◽  
Physically Active ◽  
Overnight Fasting ◽  
Sports Beverage

Hydration practices may confound heart rate variability (HRV) measurements when collected in the pre-training period. We aimed to determine the effects of ingesting a hypertonic, sugar-sweetened sports beverage on HRV and hemodynamic parameters in physically active young men. Fifteen subjects consumed 591 ml of Gatorade (6% carbohydrate, ~330 mOsmol/kg), 591 ml water, or 10 ml water (control) in random order on separate days following overnight fasting. HRV and hemodynamics were evaluated in 5-min windows immediately before (T1) and 5-10 min (T2), 25-30 min (T3), 40-45 min (T4), and 55-60 min (T5) post-drinking. Root-mean square of successive differences and the standard deviation of normal RR intervals increased post-water intake at all time-points relative to T1 (P <0.05). No increases were observed post-Gatorade intake, though small effect sizes (ES) were noted at T2 and T3 (P >0.05, ES = 0.27 - 0.32). Systemic vascular resistance increased at T2 post-Gatorade intake and at T2 and T3 post-water intake (P <0.05). No interactions were observed for blood pressure measures, stroke volume, or cardiac output. Gatorade does not evoke cardiovascular adjustments to the same magnitude as water. Practitioners should wait at least 45 min to record HRV post-Gatorade intake and >60 min post-water intake. Key Findings: ● Equal volumes of cold water and Gatorade produce inequivalent cardiac-autonomic and hemodynamic responses. ● HRV responses of greater amplitude and duration were observed following intake of water versus Gatorade. ● Failure to account for recent fluid intake may result in misinterpretation of autonomic status.

Substrate utilization in leg muscle of men after heat acclimation

1987 ◽  
Vol 63 (1) ◽  
pp. 31-35 ◽  
Author(s):  
J. P. Kirwan ◽  
D. L. Costill ◽  
H. Kuipers ◽  
M. J. Burrell ◽  
W. J. Fink ◽  
...  
Keyword(s):  
Blood Flow ◽  
Muscle Glycogen ◽  
Respiratory Exchange Ratio ◽  
Plasma Free Fatty Acid ◽  
Heat Acclimation ◽  
Substrate Utilization ◽  
Acclimation Period ◽  
Glycogen Utilization ◽  
Leg Muscle ◽  
Increased Blood Flow

Eight men were heat acclimated (39.6 degrees C and 29.2% rh) for 8 days to examine changes in substrate utilization. A heat exercise test (HET), (cycling for 60 min; 50% maximal O2 consumption) was performed before (UN-HET) and after (ACC-HET) the acclimation period. Muscle glycogen utilization (67.0 vs. 37.6 mmol/kg wet wt), respiratory exchange ratio (0.85 +/- 0.002 vs. 0.83 +/- 0.001), and calculated rate of carbohydrate oxidation (75.15 +/- 1.38 vs. 64.80 +/- 1.52 g/h) were significantly reduced (P less than 0.05) during the ACC-HET. Significantly lower (P less than 0.05) femoral venous glucose (15, 30, and 45 min) and lactate (15 min) levels were observed during the ACC-HET. No differences were observed in plasma free fatty acid (FFA) and glycerol concentrations or glucose, lactate and glycerol arteriovenous uptake/release between tests. A small but significant increase (P less than 0.05) above resting levels in FFA uptake was observed during the ACC-HET. Leg blood flow was slightly greater (P greater than 0.05) during the ACC-HET (4.64 +/- 0.13 vs. 4.80 +/- 0.13 l/min). These findings indicate a reduced use of muscle glycogen following heat acclimation. However, the decrease is not completely explained by a shift toward greater lipid oxidation or increased blood flow.

The Influence of Heat Acclimation and Hypohydration on Post-Weight-Loss Exercise Performance

2020 ◽  
Vol 15 (2) ◽  
pp. 213-221
Author(s):  
Oliver R. Barley ◽  
Dale W. Chapman ◽  
Georgios Mavropalias ◽  
Chris R. Abbiss
Keyword(s):  
Body Mass ◽  
Exercise Performance ◽  
Fluid Intake ◽  
Heat Acclimation ◽  
Hydration Status ◽  
Performance Variables ◽  
Pooled Data ◽  
Ad Libitum ◽  
Experimental Trials ◽  
Food And Fluid Intake

Purpose: To examine the influence of fluid intake on heat acclimation and the subsequent effects on exercise performance following acute hypohydration. Methods: Participants were randomly assigned to 1 of 2 groups, either able to consume water ad libitum (n = 10; age 23 [3] y, height 1.81 [0.09] m, body mass 87 [13] kg; HAW) or not allowed fluid (n = 10; age 26 [5] y, height 1.76 [0.05] m, body mass 79 [10] kg; HANW) throughout 12 × 1.5-h passive heat-acclimation sessions. Experimental trials were completed on 2 occasions before (2 baseline trials) and 1 following the heat-acclimation sessions. These sessions involved 3 h of passive heating (45°C, 38% relative humidity) to induce hypohydration followed by 3 h of ad libitum food and fluid intake after which participants performed a repeat sled-push test to assess physical performance. Urine and blood samples were collected before, immediately, and 3 h following hypohydration to assess hydration status. Mood was also assessed at the same time points. Results: No meaningful differences in physiological or performance variables were observed between HANW and HAW at any time point. Using pooled data, mean sprint speed was significantly (P < .001) faster following heat acclimation (4.6 [0.7] s compared with 5.1 [0.8] s). Furthermore, heat acclimation appeared to improve mood following hypohydration. Conclusions: Results suggest that passive heat-acclimation protocols may be effective at improving short-duration repeat-effort performance following acute hypohydration.

Polyuria and imparied ADH release following medial preoptic lesioning in the rat

1975 ◽  
Vol 228 (5) ◽  
pp. 1293-1297 ◽  
Author(s):  
M van Gemert ◽  
M Miller ◽  
RJ Carey ◽  
AM Moses
Keyword(s):  
Water Intake ◽  
Fluid Intake ◽  
Plasma Osmolality ◽  
Histological Evidence ◽  
Impaired Ability ◽  
Access To Water ◽  
The Central Nervous System ◽  
Ad Libitum ◽  
Urine Concentrating Ability ◽  
Supraoptic Nuclei

Studies were carried out in the rat to detemine if hypothalamic lesions which caused polydipsia and polyuria had their effect mediated through an alteration of the ability of the neurohypophyseal system to release ADH. Rats with medial preoptic lesions hadincreased water intake while on ad libitum access to water and slightly impaired ability to conserve water following dehydration, but with no impairment of urine-concentrating ability. These were associated with an increase in plasma osmolality both during ad libitum fluid intake and after dehydration. Urinary ADH excretion was at leastas great as in shamoperated controls during ad libitum water intake, but failed to increase during dehydration in spite of a marked increase in plasma osmolality. Pituitary ADH content did not differ from control animals either during ad libitum water intake of after dehydration. Animals with lesions in the lateral preoptic and septal areas did not differ from control animals during ad libitum fluid intake and after dehydration even though lateral preoptic lesions produced polydipsia. In all animals, lesions were remote from the supraoptic nuclei, which showed no histological evidence of damage. It is concluded thatareas of the central nervous system away from the supraoptic nuclei are involved in the regulation of both water intake and ADH release.

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.

Energy Balance, Macronutrient Intake, and Hydration Status During a 1,230 km Ultra-Endurance Bike Marathon

2014 ◽  
Vol 24 (5) ◽  
pp. 497-506 ◽  
Author(s):  
Bjoern Geesmann ◽  
Joachim Mester ◽  
Karsten Koehler
Keyword(s):  
Energy Balance ◽  
Fluid Intake ◽  
Drinking Behavior ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Macronutrient Intake ◽  
Gastrointestinal Discomfort ◽  
Individual Strategies ◽  
Ultra Endurance ◽  
Food And Fluid Intake

Athletes competing in ultra-endurance events are advised to meet energy requirements, to supply appropriate amounts of carbohydrates (CHO), and to be adequately hydrated before and during exercise. In practice, these recommendations may not be followed because of satiety, gastrointestinal discomfort, and fatigue. The purpose of the study was to assess energy balance, macronutrient intake and hydration status before and during a 1,230-km bike marathon. A group of 14 well-trained participants (VO2max: 63.2 ± 3.3 ml/kg/min) completed the marathon after 42:47 hr. Ad libitum food and fluid intake were monitored throughout the event. Energy expenditure (EE) was derived from power output and urine and blood markers were collected before the start, after 310, 618, and 921 km, after the finish, and 12 hr after the finish. Energy intake (EI; 19,749 ± 4,502 kcal) was lower than EE (25,303 ± 2,436 kcal) in 12 of 14 athletes. EI and CHO intake (average: 57.1 ± 17.7 g/hr) decreased significantly after km 618 (p < .05). Participants ingested on average 392 ± 85 ml/hr of fluid, but fluid intake decreased after km 618 (p < .05). Hydration appeared suboptimal before the start (urine specific gravity: 1.022 ± 0.010 g/ml) but did not change significantly throughout the event. The results show that participants failed to maintain in energy balance and that CHO and fluid intake dropped below recommended values during the second half of the bike marathon. Individual strategies to overcome satiety and fatigue may be necessary to improve eating and drinking behavior during prolonged ultra-endurance exercise.

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.

scholarly journals mTORC1 Signaling Contributes to Drinking But Not Blood Pressure Responses to Brain Angiotensin II

Endocrinology ◽  
2016 ◽  
Vol 157 (8) ◽  
pp. 3140-3148 ◽  
Author(s):  
Kenjiro Muta ◽  
Donald A. Morgan ◽  
Justin L. Grobe ◽  
Curt D. Sigmund ◽  
Kamal Rahmouni
Keyword(s):  
Angiotensin Ii ◽  
Water Intake ◽  
Drinking Behavior ◽  
Subfornical Organ ◽  
Dependent Manner ◽  
Ang Ii ◽  
Mtorc1 Signaling ◽  
Wide Range ◽  
The Brain

Mechanistic target of rapamycin complex 1 (mTORC1) is a molecular node that couples extracellular cues to a wide range of cellular events controlling various physiological processes. Here, we identified mTORC1 signaling as a critical mediator of angiotensin II (Ang II) action in the brain. In neuronal GT1–7 cells, we show that Ang II stimulates neuronal mTORC1 signaling in an Ang II type 1 receptor-dependent manner. In mice, a single intracerebroventricular (ICV) injection or chronic sc infusion of Ang II activated mTORC1 signaling in the subfornical organ, a critical brain region in cardiovascular control and fluid balance. Moreover, transgenic sRA mice with brain-specific overproduction of Ang II displayed increased mTORC1 signaling in the subfornical organ. To test the functional role of brain mTORC1 in mediating the action of Ang II, we examined the consequence of mTORC1 inhibition with rapamycin on Ang II-induced increase in water intake and arterial pressure. ICV pretreatment with rapamycin blocked ICV Ang II-mediated increases in the frequency, duration, and amount of water intake but did not interfere with the pressor response evoked by Ang II. In addition, ICV delivery of rapamycin significantly reduced polydipsia, but not hypertension, of sRA mice. These results demonstrate that mTORC1 is a novel downstream pathway of Ang II type 1 receptor signaling in the brain and selectively mediates the effect of Ang II on drinking behavior.

scholarly journals Awareness of dehydration state and fluid intake practice among adults population in the Jazan Region of Saudi Arabia, 2019

2021 ◽  
Vol 10 ◽  
Author(s):  
Osama B. Albasheer ◽  
Abdullah Hakami ◽  
Abdullah A. Al Faqih ◽  
Ibrahim Akkam ◽  
Safwan K. Soraihy ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Water Intake ◽  
Fluid Intake ◽  
Healthcare Providers ◽  
Active Role ◽  
Cross Sectional Study ◽  
Good Knowledge ◽  
Cross Sectional ◽  
Hot Climate ◽  
Daily Water Intake

Abstract Despite the hot climate and high humidity in the Jazan Region of Saudi Arabia, which increases risk for dehydration, no previous studies have assessed awareness of dehydration and fluid intake practice among adults in this region. Therefore, the aim of this cross-sectional study was to determine awareness of the dehydration state and fluid intake practices among 440 adults in the Jazan Region of Saudi Arabia. Out of the total, 51⋅8 % were male and 48⋅2 % were females. Good knowledge of dehydration definition and prevention and recommended minimum water intake was observed in 98, 95 and 75 % of the participants, respectively. Fifty-nine percent of the participants met the minimum daily requirement of 3 l or more per day. The age (95 % CI 1⋅003, 1⋅017, P value = 0⋅006), diabetes (95 % CI 1⋅028, 1⋅459, P value = 0⋅023) and prior hospitalisation due to dehydration (95 % CI 1⋅010, 1⋅378, P value = 0⋅037) were associated with higher water intake. Additional glasses of coffee (95 % CI 1⋅02, 1⋅115, P value = 0⋅004) and juice (95 % CI 1⋅039, 1⋅098, P value < 0⋅001) were associated with more water intake. The participants exhibited good knowledge of dehydration definition, symptoms and consequences. Intake of fluids such as ‘juice and coffee’ enhances more water intake. Although two-thirds of the participants met the recommended daily water intake, still one-third of them did not meet this level. Innovative approaches to enhance healthy drinking are warranted and may include partnering with patients to take an active role in hydration monitoring and increasing communication with the different healthcare providers.

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