Solar radiation and the validity of infrared tympanic temperature during exercise in the heat
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We investigated the validity of infrared tympanic temperature (IR-Tty) during exercise in the heat with variations in solar radiation. Eight healthy males completed stationary cycling trials at 70% peak oxygen uptake until exhaustion in an environmental chamber maintained at 30°C with 50% relative humidity. Three solar radiation conditions, 0, 250 and 500 W/m2, were tested using a ceiling-mounted solar simulator (metal-halide lamps) over a 3 × 2 m irradiated area. IR-Tty and rectal temperature (Tre) were similar before and during exercise in each trial (P > 0.05). Spearman’s rank correlation coefficient (rs) demonstrated very strong (250 W/m2, rs = 0.87) and strong (0 W/m2, rs = 0.73; 500 W/m2, rs = 0.78) correlations between IR-Tty and Tre in all trials (P < 0.001). A Bland-Altman plot showed that mean differences (SD; 95% limits of agreement; root mean square error) between IR-Tty and Tre were − 0.11°C (0.46; − 1.00 to 0.78°C; 0.43 ± 0.16°C) in 0 W/m2, − 0.13°C (0.32; − 0.77 to 0.50°C; 0.32 ± 0.10°C) in 250 W/m2 and − 0.03°C (0.60; − 1.21 to 1.14°C; 0.46 ± 0.27°C) in 500 W/m2. A positive correlation was found in 500 W/m2 (rs = 0.51; P < 0.001) but not in 250 W/m2 (rs = 0.04; P = 0.762) and 0 W/m2 (rs = 0.04; P = 0.732), indicating a greater elevation in IR-Tty than Tre in 500 W/m2. Percentage of target attainment within ± 0.3°C between IR-Tty and Tre was higher in 250 W/m2 (100 ± 0%) than 0 (93 ± 7%) and 500 (90 ± 10%; P < 0.05) W/m2. IR-Tty is acceptable for core temperature monitoring during exercise in the heat when solar radiation is ≤ 500 W/m2, and its accuracy increases when solar radiation is 250 W/m2 under our study conditions.
KeywordsCore temperature Heat stress Physical activity Sunlight
The authors thank the participants who gave their time and effort to participate in the present study.
This study was funded by the Japan Society for the Promotion of Science KAKENHI (grant number 26870759).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
- Casa DJ, Becker SM, Ganio MS, Brown CM, Yeargin SW, Roti MW, Siegler J, Blowers JA, Glaviano NR, Huggins RA, Armstrong LE, Maresh CM (2007) Validity of devices that assess body temperature during outdoor exercise in the heat. J Athl Train 42:333–342Google Scholar
- Cohen J (1988) Statistical power analysis for the behavioral sciences, 2nd edn. Lawrence Erlbaum Associates, HillsdaleGoogle Scholar
- Ganio MS, Brown CM, Casa DJ, Becker SM, Yeargin SW, McDermott BP, Boots LM, Boyd PW, Armstrong LE, Maresh CM (2009) Validity and reliability of devices that assess body temperature during indoor exercise in the heat. J Athl Train 44:124–135. https://doi.org/10.4085/1062-6050-44.2.124 CrossRefGoogle Scholar
- Guo J, Chen Y, Fan PWP, Lee MSH, Ong JX, Tan PL, Law LYL, Lee JKW, Seng KY (2018) Kalman filter models for the prediction of individualised thermal work strain In book: Kalman Filters - Theory for Advanced Applications. InTechOpenGoogle Scholar
- Hansen RD, Amos D, Leake B (1996) Infrared tympanic temperature as a predictor of rectal temperature in warm and hot conditions. Aviat Space Environ Med 67:1048–1052Google Scholar
- Magee S (2010) Solar radiation—a cause of illness and cancer? Createspace, New YorkGoogle Scholar
- Morán-Navarro R, Courel-Ibáñez J, Martínez-Cava A, Conesa-Ros E, Sánchez-Pay A, Mora-Rodriguez R, Pallarés JG (2019) Validity of skin, oral and tympanic temperatures during exercise in the heat: effects of wind and sweat. Ann Biomed Eng 47:317–331. https://doi.org/10.1007/s10439-018-02115-x CrossRefGoogle Scholar
- Nassiri P, Monazzam MR, Golbabaei F, Dehghan SF, Rafieepour A, Mortezapour AR, Asghari M (2017) Application of universal thermal climate index (UTCI) for assessment of occupational heat stress in open-pit mines. Ind Health 55:437–443. https://doi.org/10.2486/indhealth.2017-0018 CrossRefGoogle Scholar