Validity and Reliability of the CorTempTM Telemetric Pill during 50 h of Reuse in a Circulating Water Bath

Assessment of the Omius™ cooling headband effectiveness during a 70-min submaximal running effort followed by a 5-km time-trial in hot/humid conditions

Exercise performed under hot/humid conditions can hinder endurance performance. The Omius™ headband (OH) is purported to reduce the perception of heat and improve performance. We examined the impact of OH on selected thermal and cardiovascular functions, subjective perceptions and running performance. Using a randomized crossover protocol, 10 trained male athletes (28 ± 4 years) completed two trials (OH and sham headband (SH), 35.0 ± 0.3 °C, 56 ± 3% relative humidity) comprising 70 min of running (60% V˙ O2max) followed by a 5-km running time-trial (TT). Heart rate, perceived exertion and whole-body thermal comfort did not significantly differ between conditions during the submaximal running effort and TT. Rectal temperature was higher with OH (0.11 ± 0.16 °C, p = 0.052) than SH prior to the submaximal running effort, however, no significant differences were observed between conditions regarding the changes in rectal temperature from baseline during the submaximal running effort and TT. Forehead temperature was significantly lower with OH than SH during the submaximal running effort, but no significant differences were observed at the end of the TT. Scores of perceived forehead thermal comfort was only significantly lower with OH than SH during the submaximal running effort. TT performance did not significantly differ between OH (19.8 ± 1.2 min) and SH (20.2 ± 1.0 min). In conclusion, OH improves forehead thermal comfort and reduces forehead temperature but not rectal temperature, heart rate and perceived exertion during, nor 5-km TT performance following, 70 min of submaximal running in the heat.

An assessment of the validity and reliability of the P022-P version of e-Celsius core temperature capsules

Core temperature monitoring is a research tool used in many studies, though most popularly, heat strain. Ingestible core temperature capsules are a non-invasive and increasingly popular choice for measuring core body temperature, particularly considering the well-established validation of capsule systems. A newer version of the e-Celsius ingestible core temperature capsule has been released since the preceding validation study resulting in a paucity of validated research for the current version of capsules, P022-P, used by researchers. Using a 1:1 ratio of propylene glycol to water in a circulating water bath, and a reference thermometer with resolution and uncertainty of 0.01 °C, we assessed the validity and reliability of 24 P022-P e-Celsius capsules in three groups of eight, at seven temperature plateaus between 35 °C, and 42 °C in a test-retest format. The systematic bias of these capsules across all 3360 measurements was found to be -0.038 °C ± 0.086 °C (p < .001), The TEST-RETEST evaluation revealed excellent reliability by way of a minute overall mean difference of 0.0095 °C ± 0.048 °C (p < .001), and an intraclass correlation coefficient of 1.00 for each of TEST and RETEST conditions. Although quite small, differences in systematic bias across temperature plateaus were observed for both the OVERALL bias-between 0.00066 °C and 0.041°C-and TEST/RETEST bias-between 0.00010 °C and 0.016 °C. We found that the new capsule version outperforms manufacturer guarantees, with half of the systematic bias observed in a validation study of the previous capsule version. Though these capsules tend to slightly underestimate temperature, we find they possess excellent validity and reliability between 35 °C and 42 °C.

Programmed vs. Thirst-Driven Drinking during Prolonged Cycling in a Warm Environment

We compared the effect of programmed (PFI) and thirst-driven (TDFI) fluid intake on prolonged cycling performance and exercise associated muscle cramps (EAMC). Eight male endurance athletes (26 ± 6 years) completed two trials consisting of 5 h of cycling at 61% V˙O2peak followed by a 20 km time-trial (TT) in a randomized crossover sequence at 30 °C, 35% relative humidity. EAMC was assessed after the TT with maximal voluntary isometric contractions of the shortened right plantar flexors. Water intake was either programmed to limit body mass loss to 1% (PFI) or consumed based on perceived thirst (TDFI). Body mass loss reached 1.5 ± 1.0% for PFI and 2.5 ± 0.9% for TDFI (p = 0.10). Power output during the 20 km TT was higher (p < 0.05) for PFI (278 ± 41 W) than TDFI (263 ± 39 W), but the total performance time, including the breaks to urinate, was similar (p = 0.48) between conditions. The prevalence of EAMC of the plantar flexors was similar between the drinking conditions. Cyclists competing in the heat for over 5 h may benefit from PFI aiming to limit body mass loss to <2% when a high intensity effort is required in the later phase of the race and when time lost for urination is not a consideration.