Drink composition, voluntary drinking, and fluid balance in exercising, trained, heat-acclimatized boys

1999 ◽  
Vol 86 (1) ◽  
pp. 78-84 ◽  
Author(s):  
Anita M. Rivera-Brown ◽  
Randall Gutiérrez ◽  
Juan Carlos Gutiérrez ◽  
Walter R. Frontera ◽  
Oded Bar-Or
Keyword(s):  
Fluid Balance ◽  
Aerobic Power ◽  
Maximal Aerobic Power ◽  
Sweat Loss ◽  
Wet Bulb Globe Temperature ◽  
Flavored Water ◽  
Voluntary Dehydration ◽  
Ad Libitum ◽  
Globe Temperature ◽  
Body Fluid Balance

This study examined the effects of beverage composition on the voluntary drinking pattern, body fluid balance, and thermoregulation of heat-acclimatized trained boys exercising intermittently in outdoor conditions (wet bulb globe temperature 30.4 ± 1.0°C). Twelve boys (age 13.4 ± 0.4 yr) performed two 3-h sessions, each consisting of four 20-min cycling bouts at 60% maximal aerobic power alternating with 25-min rest. One of two beverages was assigned: unflavored water (W) or flavored water plus 6% carbohydrate and 18 mmol/l Na (CNa). Drinking was ad libitum. Total intake was higher ( P < 0.05) during CNa (1,943 ± 190 g) compared with W (1,470 ± 143 g). Euhydration was maintained with CNa (+0.18% body wt), but a mild dehydration resulted with W (−0.94% body wt; P < 0.05). Sweat loss, much higher than previously published for children of similar age, was similar between conditions (CNa = 1,644.7 ± 117.5; W = 1,750.2 ± 152.7 g). The increase in rectal temperature (CNa = 0.86 ± 0.3; W = 0.76 ± 0.1°C), heart rate, and all perceptual variables did not differ between conditions. In conclusion, a flavored carbohydrate-electrolyte drink prevents voluntary dehydration in trained heat-acclimatized boys exercising in a tropical climate despite their large sweat losses. Because hydration changes were minor, the thermoregulatory strain observed was similar between conditions.

Effect of Beverage Flavor on Body Hydration in Hong Kong Chinese Children Exercising in a Hot Environment

2014 ◽  
Vol 26 (2) ◽  
pp. 177-186 ◽  
Author(s):  
Stephen Heung-Sang Wong ◽  
Feng-Hua Sun
Keyword(s):  
Intermittent Exercise ◽  
Latin Square ◽  
Rest Period ◽  
Chinese Children ◽  
Total Fluid Intake ◽  
Hot Environment ◽  
Humid Environment ◽  
Flavored Water ◽  
Ad Libitum ◽  
Body Fluid Balance

The purpose of the current study was to examine the effect of flavor on voluntary drinking and thermoregulatory responses in Chinese boys and girls exercising intermittently in a hot environment. Fourteen boys and girls (9 to 11 years old) performed four 3-hour intermittent exercise sessions (20-min walking sessions at 50% VO2peak followed by a 25-minute rest period) in a hot and humid environment (~30 °C ambient temperature and ~70% relative humidity). The participants consumed 1 of 4 beverages ad libitum in a randomized sequence by using a Latin-square principle: unflavored water (W), orange-flavored water (OF), lemon-flavored water (LF), and grape-flavored water (GF). No differences were observed in the total fluid intake (W vs. OF vs. LF vs. GF: Boys, 441 ± 114 vs. 493 ± 106 vs. 387 ± 83 vs. 568 ± 146 ml; Girls, 613 ± 131 vs. 923 ± 204 vs. 825 ± 157 vs. 790 ± 166 ml), urine and sweat output, and physiological perceptual variables among trials and between sexes. The results suggested that Chinese children can maintain body fluid balance while exercising moderately in a hot and humid environment by ad libitum drinking. The flavor of the beverages had no impact on the voluntary drinking and the state of hydration in the current study.

scholarly journals Sweat Rates and Fluid Turnover in Professional Football Players: A Comparison of National Football League Linemen and Backs

2008 ◽  
Vol 43 (2) ◽  
pp. 184-189 ◽  
Author(s):  
Sandra Fowkes Godek ◽  
Arthur R. Bartolozzi ◽  
Richard Burkholder ◽  
Eric Sugarman ◽  
Chris Peduzzi
Keyword(s):  
Weight Loss ◽  
National Football League ◽  
Sweat Rate ◽  
Large Body ◽  
Football Players ◽  
Practice Session ◽  
Mass Measurements ◽  
Sweat Loss ◽  
Wet Bulb Globe Temperature ◽  
Globe Temperature

Abstract Context: Many National Football League (NFL) teams practice 2 times per day over consecutive days in a hot and humid environment. Large body surface area (BSA) and use of protective equipment result in high sweat rates and total sweat loss in these football players. Objective: To compare sweat rate, sweat loss, fluid consumption, and weight loss between NFL linemen and backs during preseason practices. Design: Between-groups design. Setting: Preseason training camp with wet bulb globe temperature between 19°C and 25°C. Patients or Other Participants: Eight linemen and 4 backs and receivers participated. Main Outcome Measure(s): Data were collected during both practice sessions on 2 separate days during the first week of August. Sweat rate was calculated as change in mass adjusted for all fluids consumed between prepractice and postpractice body mass measurements and the urine produced during practice divided by the length of the practice session. Gross daily sweat losses also were calculated. Results: Height, mass, and BSA were higher in linemen than in backs. Sweat rate was also higher in linemen (2385 ± 520 mL/h) than in backs (1410 ± 660 mL/h, P &lt; .001), as was the total volume of sweat lost during both practices in 1 day (6870 ± 1034 mL/d versus 4110 ± 2287 mL/d, P  =  .014). Compared with backs, linemen consumed more fluids during practice (2030 ± 849 mL versus 1179 ± 753 mL, P  =  .025) but produced less urine (53 ± 73 mL versus 163 ± 141 mL, P  =  .018). There was no difference in postpractice weight loss (linemen  =  −1.15 ± 0.83%, backs  =  −1.06 ± 0.76%). Conclusions: Linemen sweated at higher rates, lost larger volumes of sweat, consumed more fluids, and produced less urine during practice compared with the physically smaller backs, but they did not lose a greater percentage of body weight. Sodium losses could be considerable in NFL players during the preseason because of high daily sweat losses in backs and in linemen.

Effect of drink flavor and NaCL on voluntary drinking and hydration in boys exercising in the heat

1996 ◽  
Vol 80 (4) ◽  
pp. 1112-1117 ◽  
Author(s):  
B. Wilk ◽  
O. Bar-Or
Keyword(s):  
Heart Rate ◽  
Body Weight ◽  
Latin Square ◽  
Hydration Status ◽  
Stomach Fullness ◽  
O2 Uptake ◽  
Flavored Water ◽  
Voluntary Dehydration ◽  
Ad Libitum ◽  
Skin Temperatures

This study was intended to assess the influence of drink flavor and composition on voluntary drinking and hydration status in children exercising intermittently at 35 +/- 1 degrees C and 45-50% relative humidity. Twelve boys (9-12 yr) performed three 3-h identical sessions (four 20-min cycling bouts at 50% maximal O2 uptake followed by 25-min rest). One of three beverages (chilled to 8-10 degrees C) was assigned to each session in a Latin-square sequence: unflavored water (W), grape-flavored water (FW), and grape-flavored water plus 6% carbohydrate and 18 mmol/l NaCl (CNa). Drinking was ad libitum. Body weight, heart rate, rectal and skin temperatures, and thirst and stomach fullness perceptions were monitored periodically. Total intake was 610, 882, and 1,157 g in W, FW, and CNa, respectively (CNa-W and CNa-FW; P < 0.05). Hypohydration was observed with W (-0.65% body wt) and FW (-0.32% body wt), but drinking CNa resulted in slight overhydration (+0.47% body wt, CNa-W, CNa-FW; P < 0.05). Other physiological and all perceptual variables were insignificantly different among trails. In conclusion, while flavoring of water reduces children's voluntary dehydration, further addition of 6% carbohydrates and 18 mmol/l NaCl prevents it altogether.

Daily Fluid Turnover during Preseason Training in U.S. College Football

2007 ◽  
Vol 17 (4) ◽  
pp. 340-351 ◽  
Author(s):  
John R. Stofan ◽  
Kris L. Osterberg ◽  
Craig A. Horswill ◽  
Magie Lacambra ◽  
E. Randy Eichner ◽  
...  
Keyword(s):  
Body Mass ◽  
Deuterium Oxide ◽  
College Football ◽  
Football Players ◽  
Sweat Loss ◽  
Body Mass Change ◽  
Wet Bulb Globe Temperature ◽  
Urine Production ◽  
Globe Temperature ◽  
Football Training

The authors measured 24-h fluid-turnover (FTO) rate during 6 d of preseason training in U.S. college football players. Players, training (T, n = 9, full gear and contact drills) and reference (R, n = 4, conditioning without gear or contact), ingested a deuterium oxide (D2O) dose and provided urine samples every 24 h for analysis of D2O. During one ~2.3–h practice (wet-bulb globe temperature 24.6 °C), body-mass change, urine production, and voluntary fluid intake were measured to calculate gross sweat loss (GSL). Average FTO was 10.3 ± 2.2 L/d for T and 7.0 ± 1.0 L/d for R. GSL was 3.4 ± 1.5 L for T and 1.7 ± 1.3 for R (P > 0.05). By Day 6, body mass decreased significantly in T (–2.4 ± 1.3 kg, P < 0.05) but not in R (0.38 ± 0.95 kg). With preseason training under moderate environmental stress, football players had high FTO and sweat rates, which might have contributed to a loss of body mass during preseason football training.

Runners Greatly Underestimate Sweat Losses Before and After a 1-hr Summer Run

2012 ◽  
Vol 22 (5) ◽  
pp. 353-362 ◽  
Author(s):  
Eric K. O’Neal ◽  
Brett A. Davis ◽  
Lauren K. Thigpen ◽  
Christina R. Caufield ◽  
Anthony D. Horton ◽  
...  
Keyword(s):  
Body Weight ◽  
Fluid Intake ◽  
Late Summer ◽  
Volume Of Fluid ◽  
Estimation Accuracy ◽  
Sweat Loss ◽  
Wet Bulb Globe Temperature ◽  
Loss Calculation ◽  
Before And After ◽  
Globe Temperature

The purpose of this study was to determine how accurately runners estimate their sweat losses. Male (n = 19) and female (n = 20) runners (41 ± 10 yr, VO2max 57 ± 9 ml · kg−1 · min−1) from the southeastern U.S. completed an ~1-hr run during late summer on a challenging outdoor road course (wet bulb globe temperature 24.1 ± 1.5 °C). Runs began at ~6:45 a.m. or p.m. Before and after running, participants filled race-aid-station paper cups with a volume of fluid they felt would be equivalent to their sweat losses. Total sweat losses and losses by percent body weight differed (p < .01) between men (1,797 ± 449 ml, 2.3% ± 0.6%) and women (1,155 ± 258 ml, 1.9% ± 0.4%). Postrun estimates (738 ± 470 ml) were lower (p < .001) than sweat losses (1,468 ± 484 ml), equaling underestimations of 50% ± 23%, with no differences in estimation accuracy by percentage between genders. Runners who reported measuring changes in pre- and postrun weight to assess sweat losses within the previous month (n = 9, –54% ± 18%) were no more accurate (p = .55) than runners who had not (n = 30, –48% ± 24%). These results suggest that inadequate fluid intake during runs or between runs may stem from underestimations of sweat losses and that runners who do assess sweat-loss changes may be making sweat-loss calculation errors or do not accurately translate changes in body weight to physical volumes of water.

EFFECTS OF INONIZING RADIATION CAUSED HEAT STRESS ON THE HUMAN BODY FOR STANDARD ISO 7243

2013 ◽  
pp. 47-57
Author(s):  
Van Trong Le ◽  
Thi Tuyet Mai Nguyen ◽  
Thi Xuan Duyen Nguyen ◽  
Ba Luan Nguyen ◽  
Tuyen Pham ◽  
...  
Keyword(s):  
Heat Stress ◽  
Risk Assessments ◽  
Management Systems ◽  
Temperature Index ◽  
Wet Bulb Globe Temperature ◽  
Simple Index ◽  
Simple Tool ◽  
Results Management ◽  
Globe Temperature ◽  
Hot Environments

Objectives: Presents heat stress Standard ISO 7243, which is based upon the wet bulb globe temperature index (WBGT), and considers its suitability for use worldwide. Materials and Methods: The WBGT index are considered and how it is used in ISO 7243 and across the world as a simple index for monitoring and assessing hot environments. Results: Management systems, involving risk assessments, that take account of context and culture, are required to ensure successful use of the standard and global applicability. For use outdoors, a WBGT equation that includes solar absorptivity is recommended. A ‘clothed WBGT’ is proposed to account for the effects of clothing. Conclusion: ISO 7243 is a simple tool to assess the heat stress and may be applicated worldwide.

scholarly journals Thermal Performance of Single-Story Air-Welled Terraced House in Malaysia: A Field Measurement Approach

2020 ◽  
Vol 13 (1) ◽  
pp. 201
Author(s):  
Pau Chung Leng ◽  
Gabriel Hoh Teck Ling ◽  
Mohd Hamdan Ahmad ◽  
Dilshan Remaz Ossen ◽  
Eeydzah Aminudin ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Air Temperature ◽  
Thermal Performance ◽  
Field Measurement ◽  
Natural Ventilation ◽  
Residential Buildings ◽  
Wet Bulb Globe Temperature ◽  
Natural Lighting ◽  
Ventilation Performance ◽  
Globe Temperature

The provision requirement of 10% openings of the total floor area stated in the Uniform Building By-Law 1984 Malaysia is essential for natural lighting and ventilation purposes. However, focusing on natural ventilation, the effectiveness of thermal performance in landed residential buildings has never been empirically measured and proven, as most of the research emphasized simulation modeling lacking sufficient empirical validation. Therefore, this paper drawing on field measurement investigates natural ventilation performance in terraced housing with an air-well system. The key concern as to what extent the current air-well system serving as a ventilator is effective to provide better thermal performance is to be addressed. By adopting an existing single-story air-welled terrace house, indoor environmental conditions and thermal performance were monitored and measured using HOBO U12 air temperature and humidity, the HOBO U12 anemometer, and the Delta Ohm HD32.3 Wet Bulb Globe Temperature meter for a six-month duration. The results show that the air temperature of the air well ranged from 27.48 °C to 30.92 °C, with a mean relative humidity of 72.67% to 79.25%. The mean air temperature for a test room (single-sided ventilation room) ranged from 28.04 °C to 30.92 °C, with a relative humidity of 70.16% to 76.00%. These empirical findings are of importance, offering novel policy insights and suggestions. Since the minimum provision of 10% openings has been revealed to be less effective to provide desirable thermal performance and comfort, mandatory compliance with and the necessity of the bylaw requirement should be revisited.

Maximal aerobic power in essential hypertension

1988 ◽  
Vol 6 (11) ◽  
pp. 859-865 ◽  
Author(s):  
Robert Fagard ◽  
Jan Staessen ◽  
Antoon Amery
Keyword(s):  
Essential Hypertension ◽  
Aerobic Power ◽  
Maximal Aerobic Power
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