title: A comparison of rectal, oesophageal and gastro-intestinal tract temperatures during moderate-intensity cycling in temperate and hot conditions.
abstract: The purpose of this study was to compare three of the most commonly used methods of core temperature (Tcore) measurement during cycling under different environmental conditions as there are practical problems associated with each method and, sometimes, uncertainty as to which is the appropriate measure. Eight trained males (VO2 max: 60 ± 7 ml kg(-1) min(-1)) completed two 60-min cycling trials at ~70% VO2 max at 20°C (MOD) and 35°C (HOT). Measures of Tcore were made every 5 min with oesophageal (Toes) and rectal (Trec) thermistors and of the gastro-intestinal tract temperature (Tgi ) with a temperature-sensitive disposable radio pill. During MOD Toes initially plateaued after 10 min, Tgi after 25 min and Trec after 50 min, whereas during HOT these times had increased to 25 min for Toes and 55 min for both Tgi and Trec. Toes consistently provided lower readings than Trec (0·24-0·26°C) and Tgi (0·26-0·28°C) with Tgi and Trec similar (0·02°C). Readings for Tgi displayed closer agreement with Trec (ICC = 0·92) than Toes (ICC = 0·86) with less agreement between Trec and Toes (ICC = 0·84). 95% of all Tgi readings were within ±0·5°C of Trec and within ±0·6°C of Toes with 95% of all Toes readings being within ±0·7°C of Trec . These results demonstrate distinct response times, absolute values and agreement between Tcore measured at different body locations under different ambient conditions. Implications and considerations are discussed.
authors.affiliation: School of Sport and Exercise, Massey University, Palmerston North, New Zealand.
authors.forename: Toby
authors.initials: T
authors.lastname: Mündel
authors.affiliation: Gatorade Sport Science Institute UK, Loughborough, UK.
authors.forename: James M
authors.initials: JM
authors.lastname: Carter
authors.affiliation: Sport Performance and Rehabilitation Unit, University of Chichester, Chichester, UK.
authors.forename: David M
authors.initials: DM
authors.lastname: Wilkinson
authors.affiliation: School of Healthcare Science, Manchester Metropolitan University, Manchester, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: Jones
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D001831:Body Temperature / Q000502:physiology*; D001833:Body Temperature Regulation / Q000502:physiology*; D004947:Esophagus / Q000502:physiology*; D005080:Exercise Test; D041981:Gastrointestinal Tract / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D008297:Male; D005082:Physical Exertion / Q000502:physiology; D012007:Rectum / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013817:Thermography
keywords: ambient temperature; core temperature; exercise; hyperthermia; measurement