Analysis of the outdoor training effects on fatigue performance and thermal comfort in summer

Tianwei Tang; Yongcheng Zhu; Shaodong Huang; Zhang Lin; Zhaosong Fang

doi:10.1016/j.csite.2025.106341

Analysis of the outdoor training effects on fatigue performance and thermal comfort in summer

Tianwei Tang, Yongcheng Zhu, Shaodong Huang, Zhang Lin, Zhaosong Fang^*

^*Corresponding author for this work

Department of Architecture and Civil Engineering

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

1 Citation (Scopus)

33 Downloads (CityUHK Scholars)

Abstract

Climate change and rising global temperatures have raised concerns regarding outdoor activities and physical training. These issues require special attention in China, where physical training is common for university students. This study was conducted in Guangzhou, China, from September 2 to September 17, 2022, where students were trained for approximately two weeks, and 1180 valid questionnaires were collected to investigate the correlation between fatigue and training time by evaluating thermal sensations during physical training and analyzing changes in physiological parameters and fatigue levels throughout the training. The fatigue level and its correlates were discussed using Kaplan-Meier (KM) survival analysis and hazard analysis. The results revealed a substantial correlation and significant relationship between the mean thermal sensation vote and thermal index. Total fatigue scores were significantly correlated with the universal thermal climate index (UTCI), and fatigue levels were positively correlated with UTCI. According to the percentage distribution of each fatigue level with training time, more than 15 % of the subjects should rest after 11 a.m. Additionally, hot weather accelerated fatigue events. The increased caloric index exacerbated physical fatigue and symptomatic performance. Additionally, the proportion of negative emotions among students increased in hot environments, consequently, increasing mental fatigue. Fatigue was studied using KM survival and hazard analyses related to training time by incorporating several factors. UTCI, heart rate, tympanic temperature, and Tskin were found to produce a greater risk of fatigue events when they reached certain values. Based on the results, training time was recommended to be adjusted to 3.0 h and 2.5 h in the morning and afternoon, respectively. The results of this study will assist in adjusting student training time, reducing the occurrence of heat strokes in students during training, and maintaining overall student health.

© 2025 The Authors. Published by Elsevier Ltd.

Original language	English
Article number	106341
Journal	Case Studies in Thermal Engineering
Volume	72
Online published	15 May 2025
DOIs	https://doi.org/10.1016/j.csite.2025.106341
Publication status	Published - Aug 2025

Funding

This study was supported by the National Natural Science Foundation of China (Project No. 52278097). The authors express their gratitude to all the subjects who participated in the survey.

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 3 Good Health and Well-being

Research Keywords

Universal thermal climate index
Thermal stress
Heat strokes
Kaplan-meier survival analysis

Publisher's Copyright Statement

This full text is made available under CC-BY-NC 4.0. https://creativecommons.org/licenses/by-nc/4.0/

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10.1016/j.csite.2025.106341

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title = "Analysis of the outdoor training effects on fatigue performance and thermal comfort in summer",

abstract = "Climate change and rising global temperatures have raised concerns regarding outdoor activities and physical training. These issues require special attention in China, where physical training is common for university students. This study was conducted in Guangzhou, China, from September 2 to September 17, 2022, where students were trained for approximately two weeks, and 1180 valid questionnaires were collected to investigate the correlation between fatigue and training time by evaluating thermal sensations during physical training and analyzing changes in physiological parameters and fatigue levels throughout the training. The fatigue level and its correlates were discussed using Kaplan-Meier (KM) survival analysis and hazard analysis. The results revealed a substantial correlation and significant relationship between the mean thermal sensation vote and thermal index. Total fatigue scores were significantly correlated with the universal thermal climate index (UTCI), and fatigue levels were positively correlated with UTCI. According to the percentage distribution of each fatigue level with training time, more than 15 % of the subjects should rest after 11 a.m. Additionally, hot weather accelerated fatigue events. The increased caloric index exacerbated physical fatigue and symptomatic performance. Additionally, the proportion of negative emotions among students increased in hot environments, consequently, increasing mental fatigue. Fatigue was studied using KM survival and hazard analyses related to training time by incorporating several factors. UTCI, heart rate, tympanic temperature, and Tskin were found to produce a greater risk of fatigue events when they reached certain values. Based on the results, training time was recommended to be adjusted to 3.0 h and 2.5 h in the morning and afternoon, respectively. The results of this study will assist in adjusting student training time, reducing the occurrence of heat strokes in students during training, and maintaining overall student health.{\textcopyright} 2025 The Authors. Published by Elsevier Ltd.",

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author = "Tianwei Tang and Yongcheng Zhu and Shaodong Huang and Zhang Lin and Zhaosong Fang",

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doi = "10.1016/j.csite.2025.106341",

language = "English",

volume = "72",

journal = "Case Studies in Thermal Engineering",

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AU - Zhu, Yongcheng

AU - Huang, Shaodong

AU - Lin, Zhang

AU - Fang, Zhaosong

PY - 2025/8

Y1 - 2025/8

N2 - Climate change and rising global temperatures have raised concerns regarding outdoor activities and physical training. These issues require special attention in China, where physical training is common for university students. This study was conducted in Guangzhou, China, from September 2 to September 17, 2022, where students were trained for approximately two weeks, and 1180 valid questionnaires were collected to investigate the correlation between fatigue and training time by evaluating thermal sensations during physical training and analyzing changes in physiological parameters and fatigue levels throughout the training. The fatigue level and its correlates were discussed using Kaplan-Meier (KM) survival analysis and hazard analysis. The results revealed a substantial correlation and significant relationship between the mean thermal sensation vote and thermal index. Total fatigue scores were significantly correlated with the universal thermal climate index (UTCI), and fatigue levels were positively correlated with UTCI. According to the percentage distribution of each fatigue level with training time, more than 15 % of the subjects should rest after 11 a.m. Additionally, hot weather accelerated fatigue events. The increased caloric index exacerbated physical fatigue and symptomatic performance. Additionally, the proportion of negative emotions among students increased in hot environments, consequently, increasing mental fatigue. Fatigue was studied using KM survival and hazard analyses related to training time by incorporating several factors. UTCI, heart rate, tympanic temperature, and Tskin were found to produce a greater risk of fatigue events when they reached certain values. Based on the results, training time was recommended to be adjusted to 3.0 h and 2.5 h in the morning and afternoon, respectively. The results of this study will assist in adjusting student training time, reducing the occurrence of heat strokes in students during training, and maintaining overall student health.© 2025 The Authors. Published by Elsevier Ltd.

AB - Climate change and rising global temperatures have raised concerns regarding outdoor activities and physical training. These issues require special attention in China, where physical training is common for university students. This study was conducted in Guangzhou, China, from September 2 to September 17, 2022, where students were trained for approximately two weeks, and 1180 valid questionnaires were collected to investigate the correlation between fatigue and training time by evaluating thermal sensations during physical training and analyzing changes in physiological parameters and fatigue levels throughout the training. The fatigue level and its correlates were discussed using Kaplan-Meier (KM) survival analysis and hazard analysis. The results revealed a substantial correlation and significant relationship between the mean thermal sensation vote and thermal index. Total fatigue scores were significantly correlated with the universal thermal climate index (UTCI), and fatigue levels were positively correlated with UTCI. According to the percentage distribution of each fatigue level with training time, more than 15 % of the subjects should rest after 11 a.m. Additionally, hot weather accelerated fatigue events. The increased caloric index exacerbated physical fatigue and symptomatic performance. Additionally, the proportion of negative emotions among students increased in hot environments, consequently, increasing mental fatigue. Fatigue was studied using KM survival and hazard analyses related to training time by incorporating several factors. UTCI, heart rate, tympanic temperature, and Tskin were found to produce a greater risk of fatigue events when they reached certain values. Based on the results, training time was recommended to be adjusted to 3.0 h and 2.5 h in the morning and afternoon, respectively. The results of this study will assist in adjusting student training time, reducing the occurrence of heat strokes in students during training, and maintaining overall student health.© 2025 The Authors. Published by Elsevier Ltd.

KW - Universal thermal climate index

KW - Thermal stress

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KW - Kaplan-meier survival analysis

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DO - 10.1016/j.csite.2025.106341

M3 - RGC 21 - Publication in refereed journal

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VL - 72

JO - Case Studies in Thermal Engineering

JF - Case Studies in Thermal Engineering

M1 - 106341

ER -

Analysis of the outdoor training effects on fatigue performance and thermal comfort in summer

Abstract

Funding

UN SDGs

Research Keywords

Publisher's Copyright Statement

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