Using an Ingestible Telemetric Temperature Pill to Assess Gastrointestinal Temperature During Exercise

Summary

This study describes an accurate, reliable and non-invasive technique to continuously measure gastrointestinal temperature during exercise. The ingestible telemetric temperature pill is suitable to measure gastrointestinal temperature in laboratory settings as well as in field based settings.

Abstract

Exercise results in an increase in core body temperature (Tc), which may reduce exercise performance and eventually can lead to the development of heat-related disorders. Therefore, accurate measurement of Tc during exercise is of great importance, especially in athletes who have to perform in challenging ambient conditions. In the current literature a number of methods have been described to measure the Tc (esophageal, external tympanic membrane, mouth or rectum). However, these methods are suboptimal to measure Tc during exercise since they are invasive, have a slow response or are influenced by environmental conditions. Studies described the use of an ingestible telemetric temperature pill as a reliable and valid method to assess gastrointestinal temperature (Tgi), which is a representative measurement of Tc. Therefore, the goal of this study was to provide a detailed description of the measurement of Tgi using an ingestible telemetric temperature pill. This study addresses important methodological factors that must be taken into account for an accurate measurement. It is recommended to read the instructions carefully in order to ensure that the ingestible telemetric temperature pill is a reliable method to assess Tgi at rest and during exercise.

Introduction

The oxidation of substrates during muscle contractions, necessary to perform exercise and physical activity, importantly impacts our thermoregulatory system as only 20% is used for muscle power¹, whilst the majority of the energy is released as heat (80%)^2,3. As a consequence, the elevated metabolic heat production during physical activity and exercise typically exceeds the heat dissipation capacity^4,5, resulting in an increase in core body temperature (Tc). Accordingly, Tc rises above the hypothalamic set point, which is defined as hyperthermia⁶, and may even result in an attenuated exercise performance^5,7,8 and/....

Protocol

The steps described in the following section are in line with and accepted by the medical ethical committee of the Radboud University Medical Center in Nijmegen, The Netherlands. To our knowledge, 3 different commercial systems of ingestible temperature pills are currently available for researchers. The user manual of the ingestible temperature pills is brand-specific (Table of Specific Materials), but all systems are suitable for measurements during exercise and under resting conditions.

1. Exclusion Criteria and Subject Instruction

1. Ask subjects in written or verbal form for the exclusion criteria for using the telemetric tempe....

Results

Representative results from our previous work demonstrating the methods are presented in the next section, in which an example of a cross sectional (Figure 3A) and a continuous measurement (Figure 3B) are given.

Cross sectional measurement of Tgi

An example of data from a cross sectional measurement is shown in Figure 3A. After obtaining baseline Tgi, subjects walked 30 km at a self-selected pace. During exercise th.......

Discussion

The ingestible telemetric temperature pill has the ability to provide a continuous, valid and non-invasive measurement of the Tgi. Furthermore, an advantage of the temperature pill is the fact that once ingested, the subjects are unaware of the presence of the pill in the body or that the measurements are performed. Therefore, this method is easily applicable under resting conditions as well as during exercise, a minimal burden for study participants, and can therefore be used in field and laboratory settings. Another ad.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
CorTemp data recorder	CorTemp system, HQ Inc., Florida, USA	Not applicable	http://www.hqinc.net/cortemp-data-recorder/
Cortemp ingestible telemetric temperature pill	CorTemp system, HQ Inc., Florida, USA	HT150002	http://www.hqinc.net/cortemp-sensor-2/
CorTrack II software (Data processing for a PC only)	CorTemp system, HQ Inc., Florida, USA	Not applicable	http://www.hqinc.net/cortrack-ii-data-graphing-software/