Effects of obesity on body temperature in otherwise-healthy females when controlling hydration and heat production during exercise in the heat

• Published in: European journal of applied physiology Vol. 115; no. 1; pp. 167 - 176
• Main Authors: Adams, J. D., Ganio, Matthew S., Burchfield, Jenna M., Matthews, Andy C., Werner, Rachel N., Chokbengboun, Amanda J., Dougherty, Erin K., LaChance, Alex A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-01-2015; Springer Nature B.V
• Subjects: Adolescent; Adult; Biomedical and Life Sciences; Biomedicine; Body fat; Body temperature; Case-Control Studies; Exercise; Female; Heat; Hot Temperature; Human Physiology; Humans; Hydration; Hyperthermia; Metabolism; Obesity; Obesity - physiopathology; Occupational Medicine/Industrial Medicine; Original Article; Physical fitness; Skin; Sports Medicine; Thermogenesis; Variance analysis; Water-Electrolyte Balance; Thermoregulation; Obesity; Sweating; Core temperature
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-014-3002-y

Background
Previous studies investigating body temperature responses in obese individuals during exercise in the heat fail to control metabolic heat production or hydration status during exercise.
Purpose
To determine if there are differences in body temperature responses between obese and non-obese females when controlling metabolic heat production during exercise.
Methods
Twenty healthy females, ten obese (43.5 ± 4.5 % fat, 77.5 ± 14.4 kg) and ten non-obese (26.3 ± 6.2 % fat, 53.7 ± 6.4 kg), cycled for 60 min in a warm environment (40 °C, 30 % humidity) at a work load that elicited either 300 W of metabolic heat production (fixed heat production; FHP) or 175 W/m
2
of skin surface area (body surface area, BSA). Before and during exercise, rectal temperature (
T
re
), mean skin temperature (
T
sk
), oxygen uptake (
V
O
2
), and sweat rate were measured. Fluid was provided throughout exercise so that euhydration was maintained throughout.
Results
In the FHP trial, when absolute heat production was similar between obese (287 ± 15 W) and non-obese (295 ± 18 W) individuals (
P
 > 0.05), there were no differences at the end of exercise in
T
re
(38.26 ± 0.40 vs. 38.30 ± 0.30 °C, respectively) or
T
sk
(36.94 ± 1.65 vs. 35.85 ± 0.67 °C) (all
P
 > 0.05). In the BSA trials, relative heat production was similar between obese and non-obese individuals (168 ± 8 vs. 176 ± 5 W/m
2
, respectively;
P
 > 0.05). Similar to the FHP trials, there were no differences between obese and non-obese
T
re
(38.45 ± 0.33 vs. 38.08 ± 0.29 °C, respectively) or
T
sk
(36.82 ± 1.04 vs. 36.11 ± 0.64 °C) at the end of exercise (all
P
 > 0.05).
Conclusions
When obese and non-obese females exercised at a fixed metabolic heat production and euhydration was maintained, there were no differences in body temperature between groups.