The effects of different air velocities on heat storage and body temperature in humans cycling in a hot, humid environment

Saunders, Arron; Dugas, Jonathan P.; Tucker, Ross; Lambert, Mike; Noakes, Timothy D.

doi:10.1111/j.1365-201x.2004.01400.x

Cited by 170 publications

(140 citation statements)

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“…However, T sk was elevated at 2.8 m/s. 33 Therefore, with a more appropriate air velocity in our study, skin temperature and body temperature probably would have been lower in both conditions, and this might have reduced the efficacy of our intervention. Further research is needed to test the efficacy of our intervention in laboratory studies using more realistic air velocities or studies undertaken in the field.…”

Section: Future Directionsmentioning

confidence: 99%

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Self-Paced Exercise Performance in the Heat After Pre-Exercise Cold-Fluid Ingestion

Byrne

Owen

Cosnefroy

et al. 2011

Journal of Athletic Training

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Context:Precooling is the pre-exercise reduction of body temperature and is an effective method of improving physiologic function and exercise performance in environmental heat. A practical and effective method of precooling suitable for application at athletic venues has not been demonstrated.Objective: To confirm the effectiveness of pre-exercise ingestion of cold fluid without fluid ingestion during exercise on pre-exercise core temperature and to determine whether pre-exercise ingestion of cold fluid alone without continued provision of cold fluid during exercise can improve exercise performance in the heat.Design: Randomized controlled clinical trial. Setting: Environmental chamber at an exercise physiology laboratory that was maintained at 32°C, 60% relative humidity, and 3.2 m/s facing air velocity.Patients or Other Participants: Seven male recreational cyclists (age = 21 ± 1.5 years, height = 1.81 ± 0.07 m, mass = 78.4 ± 9.2 kg) participated.Intervention(s): Participants ingested 900 mL of cold (2°C) or control (37°C) flavored water in 3 300-mL aliquots over 35 minutes of pre-exercise rest.Main Outcome Measure(s): Rectal temperature and thermal comfort before exercise and distance cycled, power output, pacing, rectal temperature, mean skin temperature, heart rate, blood lactate, thermal comfort, perceived exertion, and sweat loss during exercise.Results: During rest, a greater decrease in rectal temperature was observed with ingestion of the cold fluid (0.41 ± 0.16°C) than the control fluid (0.17 ± 0.17°C) over 35 to 5 minutes before exercise (t 6 = -3.47, P = .01). During exercise, rectal temperature was lower after ingestion of the cold fluid at 5 to 25 minutes (t 6 range, 2.53-3.38, P ≤ .05). Distance cycled was greater after ingestion of the cold fluid (19.26 ± 2.91 km) than after ingestion of the control fluid (18.72 ± 2.59 km; t 6 = -2.80, P = .03). Mean power output also was greater after ingestion of the cold fluid (275 ± 27 W) than the control fluid (261 ± 22 W; t 6 = -2.13, P = .05). No differences were observed for pacing, mean skin temperature, heart rate, blood lactate, thermal comfort, perceived exertion, and sweat loss (P > .05).Conclusions: We demonstrated that pre-exercise ingestion of cold fluid is a simple, effective precooling method suitable for field-based application.Key Words: precooling, hyperthermia, time trialKey Points • Ingestion of 900 mL of cold fluid over 35 minutes of pre-exercise rest produced a mean 0.4°C reduction in pre-exercise rectal temperature and resulted in lower rectal temperature during exercise.• Self-paced endurance performance in the heat was improved after pre-exercise ingestion of cold fluid.• Ingesting cold fluid before exercise was a simple, effective precooling method that might be applied at athletic venues before athletes train or compete in the heat.P recooling is the lowering of body temperature before exercise and consistently has been demonstrated as an effective method of improving physiologic function and exercise performance in environmental h...

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Section: Future Directionsmentioning

confidence: 99%

“…Saunders et al 33 reported that core temperature, heart rate, sweat rate, and perceived exertion were not different between air velocities of 2.8 m/s (9.9 km/h) and the more appropriate 9.3 m/s (33 km/h) during 2 hours of cycling at 60% peak power in a 33°C and 59% relative humidity environment. However, T sk was elevated at 2.8 m/s.…”

Section: Future Directionsmentioning

confidence: 99%

Self-Paced Exercise Performance in the Heat After Pre-Exercise Cold-Fluid Ingestion

Byrne

Owen

Cosnefroy

et al. 2011

Journal of Athletic Training

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“…Despite this, the two-compartment model is still extensively used for the estimation of ⌬T b and ⌬H b , both as an analytical tool for assessing individual heat load status for a wide range of subpopulations (1,7,36,49) and extensively as a physiological criterion for maximal heat exposure (2,16,17,19,22).…”

mentioning

confidence: 99%

A three-compartment thermometry model for the improved estimation of changes in body heat content

Jay¹,

Gariépy²,

Reardon³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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Jay, O, Gariépy LM, Reardon FD, Webb P, Ducharme MB, Ramsay T, Kenny GP. A three-compartment thermometry model for the improved estimation of changes in body heat content. Am J Physiol Regul Integr Comp Physiol 292: R167-R175, 2007. First published August 24, 2006; doi:10.1152/ajpregu.00338.2006.-The aim of this study was to use whole body calorimetry to directly measure the change in body heat content (⌬Hb) during steady-state exercise and compare these values with those estimated using thermometry. The thermometry models tested were the traditional twocompartment model of "core" and "shell" temperatures, and a threecompartment model of "core," "muscle," and "shell" temperatures; with individual compartments within each model weighted for their relative influence upon ⌬Hb by coefficients subject to a nonnegative and a sum-to-one constraint. Fifty-two participants performed 90 min of moderate-intensity exercise (40% of V O2 peak) on a cycle ergometer in the Snellen air calorimeter, at regulated air temperatures of 24°C or 30°C and a relative humidity of either 30% or 60%. The "core" compartment was represented by temperatures measured in the esophagus (Tes), rectum (Tre), and aural canal (Tau), while the "muscle" compartment was represented by regional muscle temperature measured in the vastus lateralis (Tvl), triceps brachii (Ttb), and upper trapezius (Tut). The "shell" compartment was represented by the weighted mean of 12 skin temperatures (T sk). The whole body calorimetry data were used to derive optimally fitting two-and three-compartment thermometry models. The traditional two-compartment model was found to be statistically biased, systematically underestimating ⌬Hb by 15.5% (SD 31.3) at 24°C and by 35.5% (SD 21.9) at 30°C. The three-compartment model showed no such bias, yielding a more precise estimate of ⌬Hb as evidenced by a mean estimation error of 1.1% (SD 29.5) at 24°C and 5.4% (SD 30.0) at 30°C with an adjusted R 2 of 0.48 and 0.51, respectively. It is concluded that a major source of error in the estimation of ⌬Hb using the traditional two-compartment thermometry model is the lack of an expression independently representing the heat storage in muscle during exercise. body heat storage; calorimetry; muscle temperature; thermoregulation THE DERIVATION OF THE CHANGE in body heat content (⌬H b ) is of fundamental importance to the physiologist assessing the exposure of the human body to environmental conditions that result in thermal imbalance. In theory, the measurement of body heat exchange using simultaneous measures of direct and indirect calorimetry is the only method whereby ⌬H b can be directly determined. Thus the difference between metabolic heat production using the stoichiometric relationship of the products and reactants of oxidative metabolism (indirect calorimetry) and the total heat lost from the body can be used to estimate ⌬H b . By definition, ⌬H b is the product of the change of the mean temperature of the tissues of the body (⌬T b ), the total body mass (b m ), and the average sp...

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“…The results of the study Saunders et al 15 an increase in BT at a relative humidity of 80% compared with 59% relative humidity to nine subjects after cycling for two hours. This statement was in accordance with the results of research Yashasi et al 16 physical exercise at high relative humidity causes the core body temperature was higher than the low relative humidity.…”

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confidence: 93%

Relative Humidity of 40% Inhibiting the Increase of Pulse Rate, Body Temperature, and Blood Lactic Acid During Exercise

2016

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Background: Excessive sweating of the body is a reaction to decrease the heat caused by prolonged exercise at high relative humidity (RH). This situation may cause an increase in pulse rate (PR), body temperature (BT), and blood lactic acid (BLA) workout. Objective: This study aimed to prove that a RH of 40% better than a RH of 50% and 60% RH in inhibiting the increase of PR, BT, and BLA during exercise. Methods: The study was conducted on 54 samples randomly selected from the IKIP PGRI Bali students. The samples were divided into three groups, and each group was given cycling exercise with a load of 80 Watt for 2 x 30 minutes with rest between sets for five minutes. Group-1 of cycling at 40% of RH, Group-2 at a RH of 50%, and the Group-3 at a RH of 60%. Data PR, BT, and BLA taken before and during exercise.The mean difference between groups before and during exercise were analyzed by One-way Anova and a further test used Least Significant Difference (LSD). Significance used was α = 0.05. Results: The mean of PR during exercise was significantly different between groups with p = 0.045, the mean of BT during exercises was significantly different between groups with p = 0.006, and the mean of BLA during exercises was significantly different between groups with p = 0.005 (p <0.05). Also found that PR, BT, and BLA during exercise at 40% RH was lower than 50% RH and 60% RH (p <0.05). Conclusion: Thus, the RH of 40% was better than RH of 50% and 60 % in inhibiting the increase of PR, BT, and BLA during exercise. Therefore, when practiced in a closed room is expected at 40% relative humidity.Keywords: relative humidity, pulse rate, body temperature, blood lactic acid. Cite This Article: Sandi, N., Pangkahila, A., Adiatmika, P.2016. Relative humidity of 40% inhibiting the increase of pulse rate, body temperature, and blood lactic acid during exercise.

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The effects of different air velocities on heat storage and body temperature in humans cycling in a hot, humid environment

Cited by 170 publications

References 50 publications

Self-Paced Exercise Performance in the Heat After Pre-Exercise Cold-Fluid Ingestion

Self-Paced Exercise Performance in the Heat After Pre-Exercise Cold-Fluid Ingestion

A three-compartment thermometry model for the improved estimation of changes in body heat content

Relative Humidity of 40% Inhibiting the Increase of Pulse Rate, Body Temperature, and Blood Lactic Acid During Exercise

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