Effects of Pre-Cooling on Thermophysiological Responses in Elite Eventing Horses

In this study, we examined the effects of pre-cooling on thermophysiological responses in horses exercising in moderate environmental conditions (average wet bulb globe temperature: 18.5 ± 3.8 °C). Ten international eventing horses performed moderate intensity canter training on two separate days, and were either pre-cooled with cold-water rinsing (5–9 °C for 8 ± 3 min; cooling) or were not pre-cooled (control). We determined velocity (V), heart rate (HR), rectal temperature (Tre,), shoulder and rump skin temperature (Tshoulder and Trump), plasma lactate concentration (LA), gross sweat loss (GSL), and local sweat rate (LSR), as well as sweat sodium, chloride and potassium concentrations. The effect of pre-cooling on Tre was dependent on time; after 20 min of exercise the effect was the largest (estimate: 0.990, 95% likelihood confidence intervals (95% CI): 0.987, 0.993) compared to the control condition, resulting in a lower median Tre of 0.3 °C. Skin temperature was also affected by pre-cooling compared to the control condition (Tshoulder: −3.30 °C, 95% CI: −3.739, −2.867; Trump: −2.31 °C, 95% CI: −2.661, −1.967). V, HR, LA, GSL, LSR and sweat composition were not affected by pre-cooling. In conclusion, pre-cooling by cold-water rinsing could increase the margin for heat storage, allowing a longer exercise time before a critical Tre is reached and, therefore, could potentially improve equine welfare during competition.

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Consistency Assessment of Heat Stress Monitoring of Outdoor Workers Using Sweat Rate Measurement and Wet Bulb Globe Temperature WBGT in Arid and Semi-Arid Climates

Health Scope ◽

10.5812/jhealthscope.12910 ◽

2018 ◽

Vol In Press (In Press) ◽

Author(s):

Hamidreza Heidari ◽

Farideh Golbabaei ◽

Aliakbar Shamsipour ◽

Abbas Rahimi Forushani ◽

Abbasali Gaeini

Keyword(s):

Heat Stress ◽

Sweat Rate ◽

Rate Measurement ◽

Stress Monitoring ◽

Wet Bulb Globe Temperature ◽

Outdoor Workers ◽

Globe Temperature ◽

Semi Arid

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

Journal of Athletic Training ◽

10.4085/1062-6050-43.2.184 ◽

2008 ◽

Vol 43 (2) ◽

pp. 184-189 ◽

Cited By ~ 24

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 < .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.

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Collegiate Marching Band Artists Experience High Core Body Temperatures during Rehearsals and Performances

Journal of Athletic Training ◽

10.4085/jat0245-20 ◽

2020 ◽

Vol 2020 (preprint) ◽

pp. 0000-0000

Author(s):

Dawn M. Emerson ◽

Toni M. Torres-McGehee ◽

Susan W. Yeargin ◽

Melani R. Kelly ◽

Nancy Uriegas ◽

...

Keyword(s):

Risk Factors ◽

Sweat Rate ◽

Management Strategies ◽

Ground Surface ◽

Urine Specific Gravity ◽

Marching Band ◽

Wet Bulb Globe Temperature ◽

Exertional Heat Illness ◽

Globe Temperature ◽

Hydration Characteristics

Abstract Context: No research has investigated thermoregulatory responses and exertional heat illness (EHI) risk factors in marching band (MB) artists performing physical activity in high environmental temperatures. Objective: Examine core temperature (Tc) and EHI risk factors in MB artists. Design: Descriptive epidemiology study. Setting: Three rehearsals and 2 football games for 2 NCAA Division I MBs. Participants: Nineteen volunteers completed the study (female = 13, males = 6; age = 20.5 ± 0.9 years; weight = 75.0 ± 19.1 kg; height = 165.1 ± 7.1 cm). Main Outcome Measures: We measured Tc pre-, post-, and every 15 minutes during activity and recorded wet-bulb globe temperature (WBGT) and relative humidity (RH) every 15 minutes. Other variables included activity time and intensity, ground surface, hydration characteristics (fluid volume, sweat rate, urine specific gravity, percent body mass loss [%BM]), and medical history (eg, previous EHI, medications). Statistical analysis included descriptives (mean ± standard deviation), comparative analyses determined differences within and between days, and linear regression identified variables that significantly explained Tc. Results: Mean rehearsal time = 102.8 ± 19.8 minutes and game time = 260.5 ± 47.7 minutes. Max game Tc (39.1 ± 1.1°C) was significantly higher than rehearsal (38.4 ± 0.7°C, P = .003). The highest max game Tc = 41.2°C. Participants consumed significantly more fluid than their sweat rates (P < .003), which minimized %BM loss, particularly during rehearsals (−0.4 ± 0.6%). Mean game %BM loss = −0.9 ± 2.0%; however, 63.6% of the time, participants reported hypohydrated to game day. Max Tc was significantly predicted by max WBGT, max RH, ground surface, using mental health medications, and hours of sleep (adjusted R2 = 0.542, P < .001). Conclusions: Marching band artists experience high Tc during activity and should have access to athletic trainers who can implement EHI prevention and management strategies.

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Hematological and acid-base changes in men during prolonged exercise with and without sodium-lactate infusion

Journal of Applied Physiology ◽

10.1152/japplphysiol.00753.2004 ◽

2005 ◽

Vol 98 (3) ◽

pp. 856-865 ◽

Cited By ~ 25

Author(s):

Benjamin F. Miller ◽

Michael I. Lindinger ◽

Jill A. Fattor ◽

Kevin A. Jacobs ◽

Paul J. LeBlanc ◽

...

Keyword(s):

Metabolic Regulation ◽

Prolonged Exercise ◽

Lactate Concentration ◽

Sodium Lactate ◽

Weak Acid ◽

Moderate Intensity ◽

Strong Ion Difference ◽

Acid Base ◽

Plasma Lactate Concentration ◽

Lactate Infusion

An emerging technique used for the study of metabolic regulation is the elevation of lactate concentration with a sodium-lactate infusion, the lactate clamp (LC). However, hematological and acid-base properties affected by the infusion of hypertonic solutions containing the osmotically active strong ions sodium (Na+) and lactate (Lac−) are a concern for clinical and research applications of LC. In the present study, we characterized the hematological and plasma acid-base changes during rest and prolonged, light- to moderate-intensity (55% V̇o2 peak) exercise with and without LC. During the control (Con) trial, subjects were administered an isotonic, isovolumetric saline infusion. During LC, plasma lactate concentration ([Lac−]) was elevated to 4 meq/l during rest and to 4–7 meq/l during exercise. During LC at rest, there were rapid and transient changes in plasma, erythrocyte, and blood volumes. LC resulted in decreased plasma [H+] (from 39.6 to 29.6 neq/l) at the end of exercise while plasma [HCO3−] increased from 26 to 32.9 meq/l. Increased plasma strong ion difference [SID], due to increased [Na+], was the primary contributor to decreased [H+] and increased [HCO3−]. A decrease in plasma total weak acid concentration also contributed to these changes, whereas Pco2 contributed little. The infusion of hypertonic LC caused only minor volume, acid-base, and CO2 storage responses. We conclude that an LC infusion is appropriate for studies of metabolic regulation.

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Thermoregulatory Responses and Hydration Practices in Heat-Acclimatized Adolescents During Preseason High School Football

Journal of Athletic Training ◽

10.4085/1062-6050-45.2.136 ◽

2010 ◽

Vol 45 (2) ◽

pp. 136-146 ◽

Cited By ~ 36

Author(s):

Susan Walker Yeargin ◽

Douglas J. Casa ◽

Daniel A. Judelson ◽

Brendon P. McDermott ◽

Matthew S. Ganio ◽

...

Keyword(s):

High School ◽

Thermal Sensation ◽

Sweat Rate ◽

Urine Osmolality ◽

Tanner Stage ◽

American Football ◽

Adolescent Boys ◽

Wet Bulb Globe Temperature ◽

Thermoregulatory Responses ◽

Globe Temperature

Abstract Context: Previous researchers have not investigated the thermoregulatory responses to multiple consecutive days of American football in adolescents. Objective: To examine the thermoregulatory and hydration responses of high school players during formal preseason football practices. Design: Observational study. Setting: Players practiced outdoors in late August once per day on days 1 through 5, twice per day on days 6 and 7, and once per day on days 8 through 10. Maximum wet bulb globe temperature averaged 23 ± 4°C. Patients or Other Participants: Twenty-five heat-acclimatized adolescent boys (age = 15 ± 1 years, height = 180 ± 8 cm, mass = 81.4 ± 15.8 kg, body fat = 12 ± 5%, Tanner stage = 4 ± 1). Main Outcome Measure(s): We observed participants within and across preseason practices of football. Measures included gastrointestinal temperature (TGI), urine osmolality, sweat rate, forearm sweat composition, fluid consumption, testosterone to cortisol ratio, perceptual measures of thirst, perceptual measures of thermal sensation, a modified Environmental Symptoms Questionnaire, and knowledge questionnaires assessing the participants' understanding of heat illnesses and hydration. Results were analyzed for differences across time and were compared between younger (14–15 years, n = 13) and older (16–17 years, n = 12) participants. Results: Maximum daily TGI values remained less than 40°C and were correlated with maximum wet bulb globe temperature (r = 0.59, P = .009). Average urine osmolality indicated that participants generally experienced minimal to moderate hypohydration before (881 ± 285 mOsmol/kg) and after (856 ± 259 mOsmol/kg) each practice as a result of replacing approximately two-thirds of their sweat losses during exercise but inadequately rehydrating between practices. Age did not affect most variables; however, sweat rate was lower in younger participants (0.6 ± 0.2 L/h) than in older participants (0.8 ± 0.1 L/h) (F1,18 = 8.774, P = .008). Conclusions: Previously heat-acclimatized adolescent boys (TGI < 40°C) can safely complete the initial days of preseason football practice in moderate environmental conditions using well-designed practice guidelines. Adolescent boys replaced most sweat lost during practice but remained mildly hypohydrated throughout data collection, indicating inadequate hydration habits when they were not at practice.

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Additional Clothing Increases Heat Load in Elite Female Rugby Sevens Players

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2020-0620 ◽

2020 ◽

pp. 1-8

Author(s):

Mitchell J. Henderson ◽

Bryna C.R. Chrismas ◽

Christopher J. Stevens ◽

Andrew Novak ◽

Job Fransen ◽

...

Keyword(s):

Heat Load ◽

Perceived Exertion ◽

Sweat Rate ◽

Training Session ◽

Rating Of Perceived Exertion ◽

Compression Garments ◽

Wet Bulb Globe Temperature ◽

Parallel Group ◽

Globe Temperature ◽

Hot Environments

Purpose: To determine whether elite female rugby sevens players are exposed to core temperatures (Tc) during training in the heat that replicate the temperate match demands previously reported and to investigate whether additional clothing worn during a hot training session meaningfully increases the heat load experienced. Methods: A randomized parallel-group study design was employed, with all players completing the same approximately 70-minute training session (27.5°C–34.8°C wet bulb globe temperature) and wearing a standardized training ensemble (synthetic rugby shorts and training tee [control (CON); n = 8]) or additional clothing (standardized training ensemble plus compression garments and full tracksuit [additional clothing (AC); n = 6]). Groupwise differences in Tc, sweat rate, GPS-measured external locomotive output, rating of perceived exertion, and perceptual thermal load were compared. Results: Mean (P = .006, ) and peak (P < .001, ) Tc were higher in AC compared with CON during the training session. There were no differences in external load (F4,9 = 0.155, P = .956, Wilks Λ = 0.935, ) or sweat rate (P = .054, Cohen d = 1.09). A higher rating of perceived exertion (P = .016, Cohen d = 1.49) was observed in AC compared with CON. No exertional-heat-illness symptomology was reported in either group. Conclusions: Player Tc is similar between training performed in hot environments and match play in temperate conditions when involved for >6 minutes. Additional clothing is a viable and effective method to increase heat strain in female rugby sevens players without compromising training specificity or external locomotive capacity.

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Metabolism- and sex-dependent critical WBGT limits at rest and during exercise in the heat

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00101.2021 ◽

2021 ◽

Author(s):

S. Tony Wolf ◽

Mireille A. Folkerts ◽

Rachel M. Cottle ◽

Hein A.M. Daanen ◽

W. Larry Kenney

Keyword(s):

Sex Differences ◽

Thermal Environment ◽

Water Vapor Pressure ◽

Absolute Intensity ◽

Body Core Temperature ◽

Moderate Intensity ◽

Moderate Intensity Exercise ◽

Wet Bulb Globe Temperature ◽

Globe Temperature ◽

Environmental Limits

Critical environmental limits are environmental thresholds above which heat gain exceeds heat loss and body core temperature (Tc) cannot be maintained at equilibrium. Those limits can be represented as critical wet-bulb globe temperature (WBGTcrit), a validated index that represents the overall thermal environment. Little is known about WBGTcrit at rest and during low-to-moderate intensity exercise, or sex differences in WBGTcrit, in unacclimated young adults. The following hypotheses were tested: (1) WBGTcrit progressively decreases as metabolic heat production (Mnet) increases, (2) no sex differences in WBGTcrit occur at rest, and (3) WBGTcrit is lower during absolute-intensity exercise but higher at relative intensities in women compared to men. Thirty-six participants (19M/17W; 23±4 yr) were tested at rest, during light, absolute-intensity exercise (10 W), or during moderate, relative-intensity exercise (30% V̇O2max) in an environmental chamber. Dry-bulb temperature was clamped as relative humidity or ambient water vapor pressure was increased until an upward inflection was observed in Tc (rectal or esophageal temperature). Sex-aggregated WBGTcrit was lower during 10 W (32.9±1.7°C, P<0.0001) and 30% V̇O2max (31.6±1.1°C, P<0.0001) exercise vs. rest (35.3±0.8°C), and lower at 30% V̇O2max vs. 10 W (P=0.01). WBGTcrit was similar between sexes at rest (35.6±0.8°C vs. 35.0±0.8°C, P=0.83), but lower during 10 W (31.9±1.7°C vs. 34.1±0.3°C, P<0 .01) and higher during 30% V̇O2max (32.4±0.8°C vs. 30.8±0.9°C, P=0.03) exercise in women vs. men. These findings suggest that WBGTcrit decreases as Mnet increases, no sex differences occur in WBGTcrit at rest, and sex differences in WBGTcrit during exercise depend upon absolute vs. relative intensities.

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Temperature of Ingested Water and Thermoregulation During Moderate-Intensity Exercise

Canadian Journal of Applied Physiology ◽

10.1139/h97-031 ◽

1997 ◽

Vol 22 (5) ◽

pp. 479-493 ◽

Cited By ~ 34

Author(s):

Gregory S. Wimer ◽

David R. Lamb ◽

William M. Sherman ◽

Scott C. Swanson

Keyword(s):

Blood Flow ◽

Cold Water ◽

Sweat Rate ◽

Fluid Replacement ◽

Whole Body ◽

Moderate Intensity ◽

Moderate Intensity Exercise ◽

Radiative Heat Loss ◽

Trained Subjects ◽

Water Ingestion

The effect of the temperature of ingested water on the rise in core temperature (TCO) during exercise is not clear. Seven trained subjects were recruited to complete 2 hr of recumbent cycling at 51% VO2 peak in a temperate environment (Ta = 26 °C, relative humidity = 40%) on four occasions, while ingesting either no fluid (trial NF26), cold water (0.5 °C; trial CD26), cool water (19 °C; trial CL26), or warm water (38 °C; trial WA26) during the second hour of exercise. A fifth trial was conducted during which convective and radiative heat loss were reduced by raising Ta to 31 °C. During this trial, subjects ingested cold water (0.5 °C; trial CD31). When compared to WA26, over the second hour of exercise, CD26 attenuated the time-averaged changes in (TCO) and forearm blood flow and decreased whole-body sweat rate and forearm sweat rate (p < .05). Similarly, relative to WA26, the CL26 trial attenuated the time-averaged changes in TCO and reduced whole-body sweat rate (p < .05) during the second hour of exercise, but CL26 had no significant effect on forearm sweat rate or blood flow. Finally, regardless of beverage temperature, water ingestion (vs. NF26) reduced the time-averaged changes in TCO and in heat storage during the second hour of exercise (p < .05). Key words: exertion, temperature regulation, skin blood flow, body temperatures, fluid replacement

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Core Body Temperatures in Collegiate Marching Band Artists During Rehearsals and Performances

Journal of Athletic Training ◽

10.4085/1062-6050-0245.20 ◽

2021 ◽

Vol 56 (3) ◽

pp. 302-310

Author(s):

Dawn M. Emerson ◽

Toni Marie Torres-McGehee ◽

Susan W. Yeargin ◽

Melani R. Kelly ◽

Nancy Uriegas ◽

...

Keyword(s):

Risk Factors ◽

Surface Area ◽

Body Surface Area ◽

Body Surface ◽

National Collegiate Athletic Association ◽

Sweat Rate ◽

Urine Specific Gravity ◽

Marching Band ◽

Wet Bulb Globe Temperature ◽

Globe Temperature

Context To our knowledge, no researchers have investigated thermoregulatory responses and exertional heat illness (EHI) risk factors in marching band (MB) artists performing physical activity in high environmental temperatures. Objective To examine core temperature (Tc) and EHI risk factors in MB artists. Design Descriptive epidemiology study. Setting Three rehearsals and 2 football games for 2 National Collegiate Athletic Association Division I institution's MBs. Patients or Other Participants Nineteen volunteers (females = 13, males = 6; age = 20.5 ± 0.9 years, height = 165.1 ± 7.1 cm, mass = 75.0 ± 19.1 kg) completed the study. Main Outcome Measure(s) We measured Tc, wet bulb globe temperature, and relative humidity preactivity, during activity, and postactivity. Other variables were activity time and intensity, body surface area, hydration characteristics (fluid volume, sweat rate, urine specific gravity, percentage of body mass loss), and medical history (eg, previous EHI, medications). The statistical analysis consisted of descriptive information (mean ± standard deviation), comparative analyses that determined differences within days, and correlations that identified variables significantly associated with Tc. Results The mean time for rehearsals was 102.8 ± 19.8 minutes and for games was 260.5 ± 47.7 minutes. Mean maximum Tc was 39.1 ± 1.1°C for games and 38.4 ± 0.7°C for rehearsals; the highest Tc (41.2°C) occurred during a game. Fluid consumption did not match sweat rates (P < .001). Participants reported to games in a hypohydrated state 63.6% of the time. The maximum Tc correlated with the maximum wet bulb globe temperature (r = 0.618, P < .001) and was higher in individuals using mental health medications (rpb = −0.254, P = .022) and females (rpb = 0.330, P = .002). Body surface area (r = −0.449, P < .001) and instrument mass (r = −0.479, P < .001) were negatively correlated with Tc. Conclusions Marching band artists experienced high Tc during activity and should have access to athletic trainers who can implement EHI-prevention and -management strategies.

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Normative Data for Sweat Rate and Whole-Body Sodium Concentration in Athletes Indigenous to Tropical Climate

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.2019-0299 ◽

2020 ◽

Vol 30 (4) ◽

pp. 264-271

Author(s):

Anita M. Rivera-Brown ◽

José R. Quiñones-González

Keyword(s):

Normative Data ◽

Sweat Rate ◽

Sodium Concentration ◽

Tropical Climate ◽

Fluid Replacement ◽

Whole Body ◽

Adult Males ◽

Wet Bulb Globe Temperature ◽

Tropical Environments ◽

Globe Temperature

This study determined normative data for sweat rate (SR) and whole-body (WB) sweat sodium concentration [Na+] in athletes indigenous to a tropical climate, categorized by age, gender, and sport classification. We analyzed data from 556 athletes (386 adult and 170 young) in endurance (END), team/ball (TBA), and combat (COM) sports exercising in tropical environments (wet bulb globe temperature = 29.4 ± 2.1 °C). SR was calculated from change in body weight corrected for urine output and fluid/food intake. Sweat was collected using absorbent patches, and regional [Na+] was determined using an ion selective analyzer and normalized to WB sweat [Na+]. Data are expressed as mean ± SD. SR was higher in males compared with females in both young (24.2 ± 7.7 ml·kg−1·hr−1 vs. 16.7 ± 5.7 ml·kg−1·hr−1) and adult (22.8 ± 7.4 ml·kg−1·hr−1 vs. 18.6 ± 7.0 ml·kg−1·hr−1) athletes, in END sports in girls (END = 19.1 ± 6.0 ml·kg−1·hr−1; TBA = 14.6 ± 4.5 ml·kg−1·hr−1), and in adult males (END = 25.2 ± 6.3 ml·kg−1·hr−1; TBA = 19.1 ± 7.2 ml·kg−1·hr−1; COM = 18.4 ± 8.5 ml·kg−1·hr−1) and females (END = 23.5 ± 5.6 ml·kg−1·hr−1; TBA = 14.2 ± 5.2 ml·kg−1·hr−1; COM = 15.3 ± 5.2 ml·kg−1·hr−1); p < .05. WB sweat [Na+] was higher in adult athletes than in young athletes (43 ± 10 mmol/L vs. 40 ± 9 mmol/L, p < .05). These norms provide a reference range for low, low average, average high, and high SR and WB sweat [Na+], which serve as a guide for fluid replacement for athletes who live and train in the tropics.

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