Reliability of intestinal temperature using an ingestible telemetry pill system during exercise in a hot environment

Reliability of a 60-min treadmill running protocol in the heat: The journal Temperature toolbox

We determined the reliability of a 60-min treadmill protocol in the heat when spaced >4 weeks apart, longer than the test-retest duration of 1 week found in the literature. Nine unacclimated, trained males (age: 31 ± 8 y; VO2peak: 60 ± 6 ml∙kg-1∙min-1) undertook a 15 min self-paced time-trial pre-loaded with 45 min of running at 70% of individual ventilatory threshold (11.2 ± 0.3 km∙h-1) in 30 ± 1°C (53 ± 5% relative humidity). They repeated this following 40 ± 14 and 76 ± 26 days, with pre-trial standardization of diet and exercise for 48 h. When considering trial 1 as a familiarization, change in core temperature (∆Tcore) during the first 45 min (∆2.0 ± 0.2°C) between trials 2 and 3 yielded bias and 95% limits of agreement (LoA) of -0.10 ± 0.43°C, standard error of measurement (SEM) of 0.13°C and intraclass correlation coefficient (ICC) of 0.75, more reliable than measures of baseline Tcore (36.9 ± 0.2°C; LoA: -0.23 ± 0.90°C; SEM: 0.22°C; ICC: 0.03) and Tcore at 45 min during exercise (38.9 ± 0.4°C; LoA: 0.32 ± 1.12°C; SEM: 0.28°C; ICC: 0.15). The coefficient of variation (CV) between trials 2 and 3 for distance run during the 15 min time-trial was 2.1 ± 2.0% with LoA of 0.001 ± 0.253 km and SEM of 0.037 km. This protocol is reliable spaced ~5 weeks apart when considering the most commonly accepted limit of <5% CV for performance, reinforced by reliability of the ΔTcore being 0.1 ± 0.4°C.

Reliability and Validity of the CORE Sensor to Assess Core Body Temperature during Cycling Exercise

Monitoring core body temperature (T_c) during training and competitions, especially in a hot environment, can help enhance an athlete's performance, as well as lower the risk for heat stroke. Accordingly, a noninvasive sensor that allows reliable monitoring of T_c would be highly beneficial in this context. One such novel non-invasive sensor was recently introduced onto the market (CORE, greenTEG, Rümlang, Switzerland), but, to our knowledge, a validation study of this device has not yet been reported. Therefore, the purpose of this study was to evaluate the validity and reliability of the CORE sensor. In Study I, 12 males were subjected to a low-to-moderate heat load by performing, on two separate occasions several days apart, two identical 60-min bouts of steady-state cycling in the laboratory at 19 °C and 30% relative humidity. In Study II, 13 males were subjected to moderate-to-high heat load by performing 90 min of cycling in the laboratory at 31 °C and 39% relative humidity. In both cases the core body temperatures indicated by the CORE sensor were compared to the corresponding values obtained using a rectal sensor (T_rec). The first major finding was that the reliability of the CORE sensor is acceptable, since the mean bias between the two identical trials of exercise (0.02 °C) was not statistically significant. However, under both levels of heat load, the body temperature indicated by the CORE sensor did not agree well with T_rec, with approximately 50% of all paired measurements differing by more than the predefined threshold for validity of ≤0.3 °C. In conclusion, the results obtained do not support the manufacturer's claim that the CORE sensor provides a valid measure of core body temperature.

Practical Cooling Strategies During Continuous Exercise in Hot Environments: A Systematic Review and Meta-Analysis

Background

Performing exercise in thermally stressful environments impairs exercise capacity and performance. Cooling during exercise has the potential to attenuate detrimental increases in body temperature and improve exercise capacity and performance.

Objective

The objective of this review was to assess the effectiveness of practical cooling strategies applied during continuous exercise in hot environments on body temperature, heart rate, whole body sweat production, rating of perceived exertion (RPE), thermal perception and exercise performance.

Methods

Electronic database searches of MEDLINE, SPORTDiscus, Scopus and Physiotherapy Evidence Database (PEDro) were conducted using medical subject headings, indexing terms and keywords. Studies were eligible if participants were defined as ‘healthy’, the exercise task was conducted in an environment ≥25 °C, it used a cooling strategy that would be practical for athletes to use during competition, cooling was applied during a self-paced or fixed-intensity trial, participants exercised continuously, and the study was a randomised controlled trial with the comparator either a thermoneutral equivalent or no cooling. Data for experimental and comparator groups were meta-analysed and expressed as a standardised mean difference and 95 % confidence interval.

Results

Fourteen studies including 135 participants met the eligibility criteria. Confidence intervals for meta-analysed data included beneficial and detrimental effects for cooling during exercise on core temperature, mean skin temperature, heart rate and sweat production during fixed-intensity exercise. Cooling benefited RPE and thermal perception during fixed-intensity exercise and improved self-paced exercise performance.

Conclusion

Cooling during fixed-intensity exercise, particularly before a self-paced exercise trial, improves endurance performance in hot environments by benefiting RPE and thermal perception, but does not appear to attenuate increases in body temperature.

The Systematic Bias of Ingestible Core Temperature Sensors Requires a Correction by Linear Regression

An accurate measure of core body temperature is critical for monitoring individuals, groups and teams undertaking physical activity in situations of high heat stress or prolonged cold exposure. This study examined the range in systematic bias of ingestible temperature sensors compared to a certified and traceable reference thermometer. A total of 119 ingestible temperature sensors were immersed in a circulated water bath at five water temperatures (TEMP A: 35.12 ± 0.60°C, TEMP B: 37.33 ± 0.56°C, TEMP C: 39.48 ± 0.73°C, TEMP D: 41.58 ± 0.97°C, and TEMP E: 43.47 ± 1.07°C) along with a certified traceable reference thermometer. Thirteen sensors (10.9%) demonstrated a systematic bias > ±0.1°C, of which 4 (3.3%) were > ± 0.5°C. Limits of agreement (95%) indicated that systematic bias would likely fall in the range of −0.14 to 0.26°C, highlighting that it is possible for temperatures measured between sensors to differ by more than 0.4°C. The proportion of sensors with systematic bias > ±0.1°C (10.9%) confirms that ingestible temperature sensors require correction to ensure their accuracy. An individualized linear correction achieved a mean systematic bias of 0.00°C, and limits of agreement (95%) to 0.00–0.00°C, with 100% of sensors achieving ±0.1°C accuracy. Alternatively, a generalized linear function (Corrected Temperature (°C) = 1.00375 × Sensor Temperature (°C) − 0.205549), produced as the average slope and intercept of a sub-set of 51 sensors and excluding sensors with accuracy outside ±0.5°C, reduced the systematic bias to < ±0.1°C in 98.4% of the remaining sensors (n = 64). In conclusion, these data show that using an uncalibrated ingestible temperature sensor may provide inaccurate data that still appears to be statistically, physiologically, and clinically meaningful. Correction of sensor temperature to a reference thermometer by linear function eliminates this systematic bias (individualized functions) or ensures systematic bias is within ±0.1°C in 98% of the sensors (generalized function).

Effect of hand cooling on body temperature, cardiovascular and perceptual responses during recumbent cycling in a hot environment

The purpose of this study was to quantify physiological and perceptual responses to hand immersion in water during recumbent cycling in a hot environment. Seven physically active males (body mass 79.8 ± 6.3 kg; stature 182 ± 5 cm; age 23 ± 3 years) immersed their hands in 8, 14 and 34°C water whilst cycling at an intensity (W) equivalent to 50% [Formula: see text]O_2peak for 60 min in an environmental chamber (35°C, 50% relative humidity). 8 and 14°C water attenuated an increase in body temperature, and lowered cardiorespiratory and skin blood flow demands. These effects were considered to be practically beneficial (standardised effect size > 0.20). There was a tendency for 8 and 14°C to extend exercise duration versus 34°C (>7%). Heart rate, intestinal, mean skin and mean body temperature were less in 8°C compared to 14°C; these differences were considered practically beneficial. Augmented heat loss at the palm-water surface might enable cooler blood to return to the body and limit physiological strain. These findings provide a mechanistic basis for continuous hand cooling and indicate that endurance exercise in hot environments could be improved using this method. Future research should investigate its effectiveness during cycling and running performance.

Validation of an ingestible temperature data logging and telemetry system during exercise in the heat

Aim: Intestinal temperature telemetry systems are promising monitoring and research tools in athletes. However, the additional equipment that must be carried to continuously record temperature data limits their use to training. The purpose of this study was to assess the validity and reliability of a new gastrointestinal temperature data logging and telemetry system (e-Celsius™) during water bath experimentation and exercise trials. Materials and Methods: Temperature readings of 23 pairs of e-Celsius (T_eC) and VitalSense (T_VS) ingestible capsules were compared to rectal thermistor responses (T_rec) at 35, 38.5 and 42°C in a water bath. Devices were also assessed in vivo during steady-state cycling (n = 11) and intermittent running (n = 11) in hot conditions. Results: The water bath experiment showed T_VS and T_eC under-reported T_rec (P<0.001). This underestimation of T_rec also occurred during both cycling (mean bias vs T_VS: 0.21°C, ICC: 0.84, 95% CI: 0.66–0.91; mean bias vs. T_eC: 0.44°C, ICC: 0.68, 95% CI: 0.07–0.86, P<0.05) and running trials (mean bias vs. T_VS: 0.15°C, ICC: 0.92, 95% CI: 0.83–0.96; mean bias vs. T_eC: 0.25, ICC: 0.86, 95% CI: 0.61–0.94, P<0.05). However, calibrating the devices attenuated this difference during cycling and eliminated it during running. During recovery following cycling exercise, T_eC and T_VS were significantly lower than T_rec despite calibration (P<0.01). Conclusion: These results indicate that both T_eC and T_VS under-report T_rec during steady-state and intermittent exercise in the heat, with T_eC predicting T_rec with the least accuracy of the telemetry devices. It is therefore recommended to calibrate these devices at multiple temperatures prior to use.

Capsule endoscopy of the future: What's on the horizon?

Capsule endoscopes have evolved from passively moving diagnostic devices to actively moving systems with potential therapeutic capability. In this review, we will discuss the state of the art, define the current shortcomings of capsule endoscopy, and address research areas that aim to overcome said shortcomings. Developments in capsule mobility schemes are emphasized in this text, with magnetic actuation being the most promising endeavor. Research groups are working to integrate sensor data and fuse it with robotic control to outperform today's standard invasive procedures, but in a less intrusive manner. With recent advances in areas such as mobility, drug delivery, and therapeutics, we foresee a translation of interventional capsule technology from the bench-top to the clinical setting within the next 10 years.

Flexible and capsule endoscopy for screening, diagnosis and treatment

Endoscopy dates back to the 1860s, but many of the most significant advancements have been made within the past decade. With the integration of robotics, the ability to precisely steer and advance traditional flexible endoscopes has been realized, reducing patient pain and improving clinician ergonomics. Additionally, wireless capsule endoscopy, a revolutionary alternative to traditional scopes, enables inspection of the digestive system with minimal discomfort for the patient or the need for sedation, mitigating some of the risks of flexible endoscopy. This review presents a research update on robotic endoscopic systems, including both flexible scope and capsule technologies, detailing actuation methods and therapeutic capabilities. A future perspective on endoscopic potential for screening, diagnostic and therapeutic gastrointestinal procedures is also presented.