Responses of Obese and Lean Girls Exercising under Heat and Thermoneutral Conditions

doi:10.1016/j.jpeds.2012.10.047

The Journal of Pediatrics

Volume 162, Issue 5, May 2013, Pages 1054-1060

https://doi.org/10.1016/j.jpeds.2012.10.047 Get rights and content

Objective

To compare thermoregulatory and perceptual responses between lean and obese girls during and after exercise under heat (HC) and thermoneutral (TC) conditions.

Study design

In a randomized order, 27 girls (14 lean [16.6 ± 6.7% fat and 9.1 ± 1.3 years] and 13 obese [41.3 ± 6.7% fat and 9.4 ± 1.1 years]) cycled 30 minutes at ∼55% peak oxygen uptake in 2 sessions, which only differed in the thermal conditions (35°C and 40% relative humidity vs 24°C and 50% relative humidity).

Results

Initial rectal temperature (T_re) was higher in obese versus lean during HC (37.5 ± 0.3°C vs 37.3 ± 0.3°C, P = .03) and TC (37.6 ± 0.3°C vs 37.3 ± 0.2°C; P = .03) sessions. During cycling, T_re remained higher in the obese, but the rate of increase was greater in the lean. This change occurred mainly in the HC, when final T_re of the lean surpassed that of the obese (37.8 ± 0.2 vs 38.0 ± 0.2°C, P = .04). Sweat volume (in mL^.m⁻²) was similar between lean and obese in the HC (167 ± 119 and 120 ± 145) and TC (200 ± 196 vs 72 ± 20). Heart rate, rate of perceived exertion, and thermal sensation were similar between groups, independent of the thermal condition. Cycling in HC produced decreased thermal comfort (P = .009) and increased irritation (P = .02) within the lean girls.

Conclusion

Thermoregulatory and perceptual responses of prepubescent obese girls during 30 minutes of cycling at a similar relative intensity do not seem to be impaired when comparing with a lean group either in TC or HC.

Section snippets

Methods

A total of 27 prepubertal girls (14 lean and 13 obese) between 7 and 11 years of age participated in this study. Sample size was calculated with statistical power at 95% and level of significance at 5% (PEPI 4.0, Abramson JH, Gahlinger PM; Sagebrush: Salt Lake City, Utah) based on T_re from studies with obese and nonobese boys2, 5 and resulting in 12 participants per group. The body fat obtained from dual energy X-ray absorptiometry (Lunar GE Pencil Bin, SmartScan pediatric program, v. 4.7c; GE

Results

Initially, 44 girls were recruited, of whom 10 were excluded (9 had already reached puberty, 1 did not satisfy the criterion for obesity), 7 left the study (5 left after the preliminary assessment, and 2 left after the first experimental session) and 27 girls completed the study.

Groups arrived to both HC and TC sessions with similar hydration levels as observed from urine measures. In the HC, respective urine color and USG were 3.0 ± 1.6 and 1.016 ± 0.07 for the lean group, and 3.4 ± 1.3 and

Discussion

Although all girls of the present study were tested in the morning and were allowed to rest for 5 minutes before assessing T_re inside the environmental chamber, obese girls started at a T_re 0.2°C and 0.3°C (P = .03) higher in the HC and TC, respectively. In boys, a higher gastric temperature before exercise was also found in obese compared with their lean peers, whether they were heat-acclimated⁴ or not.³ It is intriguing why obese children presented a higher T_re and T_gastric at rest prior to

References (29)

E. Arens et al.
Partial- and whole-body thermal sensation and comfort. Part I: uniform environmental conditions
J Therm Biol
(2006)
D.M. Savastano et al.
Adiposity and human regional body temperature
Am J Clin Nutr
(2009)
American Academy of Pediatrics
Policy statement. Climatic heat stress and exercising children and adolescents
Pediatrics
(2011)
E.M. Haymes et al.
Heat tolerance of exercising lean and heavy prepubertal girls
J Appl Physiol
(1974)
K.A. Dougherty et al.
Responses of lean and obese boys to repeated summer exercise in the heat bouts
Med Sci Sport Exerc
(2009)
K.A. Dougherty et al.
Critical environmental limits for exercising heat-acclimated lean and obese boys
Eur J Appl Physiol
(2010)
P.L. Sehl et al.
Responses of obese and non-obese boys cycling in the heat
Int J Sports Med
(2012)
E.M. Haymes et al.
Heat tolerance of exercising lean and heavy prepubertal boys
J Appl Physiol
(1975)
T.G. Lohman et al.
Body fat measurement goes high-tech: not all are created equal
ACSM Health Fitness J
(1997)
P.R. Crocker et al.
Measuring general levels of physical activity: preliminary evidence for the Physical Activity Questionnaire for Older Children
Med Sci Sport Exer
(1997)

J.M. Tanner

Growth at adolescence

(1962)

D. Dubois et al.

Clinical calorimetry: a formula to estimate the approximate surface area if height and weight be known

Arch Int Med

(1916)

O. Bar-Or et al.

Pediatric exercise medicine. From physiologic principles to health-care application

(2004)

G. Cunha et al.

Effect of biological maturation on maximal oxygen uptake and ventilatory thresholds in soccer players: an allometric approach

J Sports Sci

(2011)

Cited by (31)

Investigation of group differences in human perceptions of indoor environment in open-plan offices in a severe cold region
2022, Building and Environment
To investigate group differences in human perceptions, long-term and point-in-time measurements on indoor environmental parameters were conducted in 22 open-plan offices in Harbin, China and 1352 questionnaires were collected. The differences in human perceptions among gender, age, level of education, BMI and the location of subjects groups were analyzed. The comfort temperatures for the male subjects were 1.2 °C and 0.8 °C lower than those for the female subjects in summer and winter, which revealed the higher acceptance of female subjects to the higher indoor temperatures. The mean comfort vote for undergraduates was 0.7 higher than those for master and doctoral students in winter. The difference between Griffiths comfort temperatures and operative temperatures in the overweight group was 1.9 °C in summer and 2.5 °C in winter, higher than the normal weight group (1.8 °C and 2.1 °C) and the underweight group (1.3 °C and 1.7 °C), which revealed the lower tolerance of the overweight subjects to higher temperatures than other groups. The subjects who sat near windows had lower thermal comfort votes than the subjects at other locations in all seasons due to solar radiation, radiator heating and the draft caused by window opening. For indoor air quality, sound and light environment, the male subjects had higher comfort votes than those for female subjects, and undergraduates had higher comfort votes than master and doctoral students. Finally, the interaction of five groups on human comfort was also explored. This study can be used to take into account the difference between groups and decide the comfort systems.
Experimental investigation on the ventilation performance of diffuse ceiling ventilation in heating conditions
2021, Building and Environment
This paper aims to investigate the performance of diffuse ceiling ventilation (DCV) in heating mode by a full-scale chamber. Eleven cases combined with different exhaust positions, supply air change rates, internal heat source intensities, and the type and location of contaminant sources were tested. The contaminant removal effectiveness (CRE) and temperature effectiveness (TE) were utilized to evaluate the ventilation effectiveness of DCV. It is found that thermal discomfort due to vertical temperature differences or draught is negligible for all tested cases. The results demonstrate that the effect of exhaust positions on CRE depends on the existence of internal heat source. With the presence of heat source, the room air can reach a good mixing, and the effect of exhaust positions is therefore limited. Nevertheless, when there is no internal heat source, the lower position can force the supply air to enter the occupied zone and improve ventilation performance. Increased air change rates can significantly improve indoor air quality, but have a little influence on ventilation effectiveness. CRE is strongly influenced by the internal heat source intensity and the contaminant source type. With the increase of heat source intensity, CRE increases notably from 0.28 to 0.82. As for different contaminant source types, CRE is about 1.3 under the active source (with heat), but only 0.68 and 0.82 under the passive source (without heat). This study is beneficial to the further design and optimization of DCV for its broader heating application.
The impact of body fat on thermoregulation during exercise in the heat: A systematic review and meta-analysis
2021, Journal of Science and Medicine in Sport
Citation Excerpt :
Laboratory investigations have examined the effect of body fat on thermoregulation during exercise in the heat, but these studies are limited in number with small sample sizes with conflicting conclusions.5,9,13,14 Some studies reported significant differences in Tcore and Tsk between high-body fat (Hi-BF) and low-body fat (Lo-BF)15–17 where others suggest that there are no differences in any thermoregulatory outcome.18–21 Moreover, individuals with higher body fat tend to have lower fitness levels, greater body mass and a smaller body surface area to mass ratio compared to those with lower body fat, which makes it difficult to ascertain the independent influence of body fat on thermoregulatory responses during exercise in the heat.12
We performed a systematic review and meta-analysis to examine the effect of body fat on thermoregulatory responses to exercise in the heat.
Systematic Review and Meta-analysis.
We systematically searched databases (N = 8) for studies that included: healthy participants; an aerobic exercise intervention under heat stress; a measure of body fat by a high and low body fat group; pre- and post-exercise internal temperature, and/or post-exercise mean skin temperature and whole body sweat loss. Criteria to distinguish high body fat and low body fat were determined by each qualifying study. Out of 1222 potential studies, 10 qualified. Robust variance estimation models were utilized to determine the pooled effect size (ES, 95% CI) for interventions that performed unbias comparisons between groups.
Participants (n = 211) were mostly male (70%) and young (19.3 ± 7.1 years) with a maximal oxygen consumption of 50.42 ± 9.3 ml∙kg⁻¹∙min⁻¹ by high body fat (36.7 ± 11.8%) and low body fat (17.8 ± 5.7%). Exercise duration was between 30 and 60 min at moderate–high intensity (44.1–71.4% VO₂max) at 28–40.3 °C and 26–50% humidity. Of the 7 interventions that normalized metabolic heat production to body mass and 5 interventions that normalized to external workload, there were no differences in any of the three outcome variables between groups.
Many of the included studies did not control for confounding factors that may affect the relationship between body fat and thermoregulation during exercise in the heat such as metabolic heat production and body mass. Given the small number of interventions included, future work must make unbiased comparisons to appropriately assess the independent influence of body fat.
Revisiting individual and group differences in thermal comfort based on ASHRAE database
2020, Energy and Buildings
Citation Excerpt :
Wang et al.’s review [29] found there is no consistent conclusion on whether the age has statistically significant influence on thermal comfort. Other factors have been studied in previous studies include economic conditions [28], thermal history [30], physical disabilities [31], fitness [32,33], and climate zone and country [34]. However, a major constraint of existing studies is each study focus on only one or a few influential factors.
Different thermal demands and preferences between individuals lead to a low occupant satisfaction rate, despite the high energy consumption by HVAC system. This study aims to quantify the difference in thermal demands, and to compare the influential factors which might lead to those differences. With the recently released ASHRAE Database, we quantitatively answered the following two research questions: which factors would lead to marked individual difference, and what the magnitude of this difference is. Linear regression has been applied to describe the macro-trend of how people feel thermally under different temperatures. Three types of factors which might lead to different thermal demands have been studied and compared in this study, i.e. individual factors, building characteristics and geographical factors. It was found that the local climate has the most marked impact on the neutral temperature, with an effect size of 3.5 °C; followed by country, HVAC operation mode and body built, which lead to a difference of more than 1 °C. In terms of the thermal sensitivity, building type and local climate are the most influential factors. Subjects in residential buildings or coming from Dry climate zone could accept 2.5 °C wider temperature range than those in office, education buildings or from Continental climate zone. The findings of this research could help thermal comfort researchers and designers to identify influential factors that might lead to individual difference, and could shed light on the feature selection for the development of personal comfort models.
The Squeaky wheel: Machine learning for anomaly detection in subjective thermal comfort votes
2019, Building and Environment
Citation Excerpt :
It is generally acknowledged, however, that physical measurements alone may not reliably determine or predict occupants' thermal comfort due to the significant inter-individual differences in preference [11]. These differences have been observed across gender [12], age [13], physical fitness [14], and activity levels [15], and are partly influenced by clothing decisions (or corporate dress codes), basal metabolic rates, and a person's unique experience and perception of their thermal environment. These types of effects can result in some people feeling comfortable in the same ambient conditions while others expressing dissatisfaction with the environment.
Anomalous patterns in subjective votes can bias thermal comfort models built using data-driven approaches. A stochastic-based two-step framework to detect outliers in subjective thermal comfort data is proposed to address this problem. The anomaly detection technique involves defining similar conditions using a k-Nearest Neighbor (KNN) method and then quantifying the dissimilarity of the occupants’ votes from their peers under similar thermal conditions through a Multivariate Gaussian approach. This framework is used to detect outliers in the ASHRAE Global Thermal Comfort Database I & II. The resulting anomaly-free dataset produced more robust comfort models avoiding dubious predictions. The proposed method has been proven to effectively distinguish outliers from inter-individual variabilities in thermal demand. The proposed anomaly detection framework could easily be applied to other applications with different variables or subjective metrics. Such a tool holds great promise for use in the development of occupancy responsive controls for automated building HVAC systems.
Individual difference in thermal comfort: A literature review
2018, Building and Environment
Human individual differences widely and markedly affect thermal comfort and should be carefully considered in the design and operation of the built environment. This paper aims to list and examine the magnitude and significance of individual difference in the preferred/neutral/comfort temperature through reviewing previous climate chamber and field studies. Causal factors for individual differences are investigated, including sex, age and etc. There is no clear and consistent conclusions as to the significance and size of inter-group differences in thermal comfort (between females and males, or the young and the old). To address the issue of individual difference, a paradigm shift from centralized to personalized air condition is on the way with the following three steps: first, collecting individual physiological and psychological response; second, predict individual comfort with machine learning algorithms; and third, accommodating individual difference with Personalized Comfort Systems.

View all citing articles on Scopus

: The authors declare no conflicts of interest.

View full text

Original ArticleResponses of Obese and Lean Girls Exercising under Heat and Thermoneutral Conditions

Objective

Study design

Results

Conclusion

Section snippets

Methods

Results

Discussion

J Therm Biol

Am J Clin Nutr

Policy statement. Climatic heat stress and exercising children and adolescents

Pediatrics

Heat tolerance of exercising lean and heavy prepubertal girls

J Appl Physiol

Responses of lean and obese boys to repeated summer exercise in the heat bouts

Med Sci Sport Exerc

Critical environmental limits for exercising heat-acclimated lean and obese boys

Eur J Appl Physiol

Responses of obese and non-obese boys cycling in the heat

Int J Sports Med

Heat tolerance of exercising lean and heavy prepubertal boys

J Appl Physiol

Body fat measurement goes high-tech: not all are created equal

ACSM Health Fitness J

Measuring general levels of physical activity: preliminary evidence for the Physical Activity Questionnaire for Older Children

Med Sci Sport Exer

Growth at adolescence

Clinical calorimetry: a formula to estimate the approximate surface area if height and weight be known

Arch Int Med

Pediatric exercise medicine. From physiologic principles to health-care application

Effect of biological maturation on maximal oxygen uptake and ventilatory thresholds in soccer players: an allometric approach

J Sports Sci

Original Article
Responses of Obese and Lean Girls Exercising under Heat and Thermoneutral Conditions