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Purpose: This study aimed to characterize core-temperature (Tc) responses of swimmers competing at the 2024 3-km World Aquatics Masters Open Water Swimming Championships. Methods: Within a cross-sectional observational study design, swimmers (n = 48 [23 male, 25 female]) ingested a telemetric Tc pill 4 hours before their race. Water temperatures were 20.9 °C (male; mean wet-bulb-globe temperature 25.9 °C) and 20.5 °C (female; mean wet-bulb-globe temperature: 25.4 °C). Linear mixed models determined differences between males and females for race-start, mean in-race, and peak Tc. Random coefficient models determined relationships between (1) sex, race time, body mass index (BMI), body-mass change or age, and Tc peak; (2) sex, race time, BMI, body-mass change or age, and Tc nadir; (3) sex, Tc peak, BMI, body-mass change or age, and race time, and (4) sex, Tc peak, BMI, body-mass change, or age and race ranking. Results: The mean in-race Tc was 37.8 °C (36.1–38.8 °C); however, there were highly variable individual Tc responses (−3.1 to +2.7 °C). One swimmer experienced mild hypothermia (Tc ≤ 35.0 °C), and 5 exceeded 39.0 °C, a risk factor for heat-related illness. There were no statistical differences between males and females for race-start, mean, and peak Tc (P ≥.243). Higher peak Tc was associated with faster race time (P =.05), higher race rank (P =.027), and higher BMI (P =.001). Conclusions: Highly variable Tc responses (−3.1 to +2.7 °C) were observed, demonstrating that organizers of mass-participation open-water swimming events should always be prepared for, and provide facilities to treat, swimmers experiencing cold-/heat-related health incidents during competition. [ABSTRACT FROM AUTHOR]

Objectives: Assess the effect of water dousing on heat strain and performance during self- and fixed-paced exercise in the heat. Design: Crossover, block-randomized controlled trial. Methods: Thirteen trained runners completed a 10-km time trial (TT) and 60-minute fixed-pace run (60% velocity of V ˙ O 2 max) in a 30.4 °C, 47.4% relative humidity environment using either water dousing (DOUSE) or no dousing (CON). Results: Ten-kilometer TT performance was faster in DOUSE compared to CON (44:11 [40:48, 47:34] vs 44:38 [41:21, 47:56] min:s; P =.033). Change in core temperature (Tc) was not different between groups during the TT (+0.02 [−0.04, 0.07] °C in DOUSE; P =.853) or fixed-pace run (+0.02 [−0.15, 0.18] °C; P =.848). Change in mean skin temperature was lower in DOUSE during the TT (−1.80 [−2.15, −1.46] °C; P <.001) and fixed-pace run (−1.38 [−1.81, −0.96] °C; P <.001). Heart rate was lower for DOUSE during the fixed-pace run (−3.5 [−6.8, −0.2] beats/min; P =.041) but not during the TT (−0.2 [−2.5, 2.1] beats/min; P =.853). Thermal sensation was lower for DOUSE during the TT (−49.3 [−72.1, −26.1] mm; P <.001) and fixed-pace run (−44.7 [−59.7, −29.6] mm; P <.001). Rating of perceived exertion was not different between groups for the TT (−0.2 [−0.7, 0.3]; P =.390) or fixed-pace run (−0.2 [−0.8, 0.4]; P =.480). Sweat rate was lower for DOUSE for the TT (−0.37 [−0.53, −0.22] L/h; P <.001) and fixed-pace run (−0.37 [−0.48, −0.26] L/h; P <.001). Conclusion: Water dousing improves 10-km TT performance in the heat but does not affect Tc. The positive change in thermal perception (via lower skin temperature) during the TT likely drives this benefit. [ABSTRACT FROM AUTHOR]

The detrimental impact of extreme heat exposure on the health and well-being of children is widely acknowledged. The direct and indirect effects of climate change have led to an increased risk of certain cardiovascular events which may be particularly harmful to children who are born with, or develop, heart disease. Purpose: To highlight the worrying paucity of investigative research aimed at differentiating how higher ambient temperatures further tax an already compromised cardiovascular system in children. Methods: This commentary describes basic thermoregulatory concepts relevant to the healthy pediatric population and summarizes common heart diseases observed in this population. Results: We describe how heat stress and exercise are important factors clinicians should more readily consider when treating children with heart disease. Countermeasures to physical inactivity are suggested for children, parents, clinicians, and policymakers to consider. Conclusions: As sudden, excessive heat exposures continue to impact our rapidly warming world, vulnerable populations like children with underlying heart conditions are at greater heat health risk, especially when coupled with the negative physical activity and fitness trends observed worldwide. [ABSTRACT FROM AUTHOR]

ObjectivesTo investigate image-guided volumetric hyperthermia strategies using the ExAblate Body MR-guided focused ultrasound ablation system, involving mechanical transducer movement and sector-vortex beamforming.Materials and methodsAcoustic and thermal simulations were performed to investigate volumetric hyperthermia using mechanical transducer movement combined with sector-vortex beamforming, specifically for the ExAblate Body transducer. The system control in the ExAblate Body system was modified to achieve fast transducer movement and MR thermometry-based hyperthermia control, mechanical transducer movements and electronic sector-vortex beamforming were combined to optimize hyperthermia delivery. The experimental validation was performed using a tissue-mimicking phantom.ResultsThe developed simulation framework allowed for a parametric study with varying numbers of heating spots, sonication durations, and transducer movement times to evaluate the hyperthermia characteristics for mechanical transducer movement and sector-vortex beamforming. Hyperthermic patterns involving 2-4 sequential focal spots were analyzed. To demonstrate the feasibility of volumetric hyperthermia in the system, a tissue-mimicking phantom was sonicated with two distinct spots through mechanical transducer movement and sector-vortex beamforming. During hyperthermia, the average values of Tmax, T10, Tavg, T90, and Tmin over 200 s were measured within a circular ROI with a diameter of 10 pixels. These values were found to be 8.6, 7.9, 6.6, 5.2, and 4.5 °C, respectively, compared to the baseline temperature.ConclusionsThis study demonstrated the volumetric hyperthermia capabilities of the ExAblate Body system. The simulation framework developed in this study allowed for the evaluation of hyperthermia characteristics that could be implemented with the ExAblate MRgFUS system.