Gastrointestinal Temperature Research Articles

Real‐Time Monitoring of the Core Body Temperature of Endurance Horses During Field Exercise

IntroductionContinuous monitoring of core body temperature may provide useful information about the thermal response to metabolic heat load and environmental challenges. The aim of this study was to evaluate a telemetric gastrointestinal (GI) pill (Equivital®) measuring gastrointestinal temperature (GT) during endurance exercise. It was hypothesised that a temperature and metabolic heat profile could be established.MethodsThe GI pill was administered to 6 horses by nasogastric tube (n = 3) or modified‐drench gun (n = 3), the day before competition. During competition, GT, skin temperature and heart rate (HR) were recorded (by Equivital® belt). Other data collected included body weight and rectal temperature (RT), GPS/HR monitor information, and environmental conditions using a data logger. Metabolic heat production was calculated [1] and GT correlations were explored using simple correlation estimates (P<0.05).ResultsData were collected from 6 horses during 80 km (n = 4 horses) and 100 km (n = 2) competition days with mean data loss of 7.4% (±2.4%). GT profiles showed increasing temperature with cumulative metabolic heat production, and time to reach maximum GT was 2.14–6.29 h (maximum GT range: 38.4–39.5°C). During exercise (7 h 6 min ± 1 h 3 min duration), mean and maximum speeds ranged from 10.1–14.5 km/h and 23.5–30.8 km/h, respectively. No correlation was found between GT and HR, skin, or environment temperature. Maximum GT increased with bodyweight (r = 0.775, P = 0.08). GT was systematically higher than RT (mean difference +0.46°C).ConclusionsGT was recorded successfully during competition with minimal data loss. The GI pill has great potential as a method to further investigate thermoregulation in horses under field conditions.Ethical Animal ResearchAll studies were performed under the Adelaide Animal Ethics Committee, University of Adelaide. Explicit owner informed consent for participation in this study is not stated. Sources of funding: The equipment for the project was funded by the Faculty of Science ‘Grant for minor equipment’, University of Adelaide, Australia. Competing interests: none.

Physiological And Perceived Effects Of Forearm Cooling During Simulated Firefighting Activity

Accessory cooling devices have been developed to protect firefighters (FF) from suffering an exertional heat illness by attenuating the rise in core body temperature. Head cooling (HC) via a cold gel pack placed inside the helmet is one cooling mechanism marketed to FF, but the research regarding its efficacy is limited. PURPOSE: To investigate the physiological and perceived effects of HC during simulated firefighting activity (FFA). METHODS: Participants (males; 40±8 y; 168±7 cm; 91.8±14.2 kg) were randomly assigned to either the HC group (n=9), who completed FFA while wearing a cold gel pack inside their helmet, or the control (CON) group (n=10), who received no accessory cooling during FFA. FF completed four FFA stations in full turnout gear and self-contained breathing apparatus (SCBA) (23.3±1.4 kg). FFA stations lasted 15 min and included an obstacle course, a high-rise drill, a two-story search and rescue drill, and car extrication. Stations were completed in random order. After each station, FF replaced their air cylinder and HC replaced their gel pack; FF then completed a different station. After every two stations, the FF rested for 15 min in the shade by removing their turnout gear and SCBA and drinking water ad libitum. Gastrointestinal temperature (GI), heart rate (HR), Stroop Test interference score (ST), rating of perceived exertion (RPE), perceived thermal strain (PTS), and hydration status were measured. Repeated measures ANOVAs were used to compare groups across time. RESULTS: No significant demographic differences were found between groups (p>0.05). GI (39.18±0.49°C) and HR (163±22bpm) increased during FFA. No significant interactions were found for GI, HR, ST, PTS, or RPE (p>0.05). There were no differences in sweat loss (2.5±0.8 L), hypohydration (0.9±0.8%), or post FFA urine specific gravity (1.020±0.008) between groups (p>0.05). Weak relationships were noted between perceived thermal sensation and gastrointestinal temperature (r=.248). CONCLUSION: HC did not attenuate the rise in GI or reduce HR during FFA. The discrepancy between perception and actual body temperature may be dangerous for FF, as it may allow them to work beyond their central drive and the critical GI threshold.