Quantifying Exercise Heat Acclimatisation in Athletes and Military Personnel: A Systematic Review and Meta-analysis

Brown, Harry A.; Topham, Thomas H.; Clark, Brad; Ioannou, Leonidas G.; Flouris, Andreas D.; Smallcombe, James W.; Telford, Richard D.; Jay, Ollie; Périard, Julien D.

doi:10.1007/s40279-023-01972-4

Cited by 4 publications

(1 citation statement)

References 79 publications

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“…Moreover, 95% LoA of the MX3 hydration testing system suggests that it is sufficiently accurate to detect adaptations associated with both heat acclimatisation (i.e. ~ 15 mmoL·L −1 ; Brown et al ( 2023 )) and heat acclimation (i.e. ~ 22 mmoL·L −1 ; Tyler et al ( 2016 )), as well as changes in sweat [Na + ] associated with the development of hyponatremia (i.e.…”

Section: Discussionmentioning

confidence: 99%

Reliability and validity of the MX3 portable sweat sodium analyser during exercise in warm conditions

Brown,

Clark,

Périard

2024

Eur J Appl Physiol

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Purpose Accurately measuring sweat sodium concentration ([Na+]) in the field is advantageous for coaches, scientists, and dieticians looking to tailor hydration strategies. The MX3 hydration testing system is a new portable analyser that uses pre-calibrated biosensors to measure sweat [Na+]. This study aimed to assess the validity and reliability of the MX3 hydration testing system. Methods Thirty-one (11 females) recreationally active participants completed one experimental trial. During this trial, participants exercised at a self-selected pace for 45 min in a warm environment (31.5 ± 0.8 °C, 63.2 ± 1.3% relative humidity). Sweat samples were collected from three measurement sites using absorbent patches. The samples were then analysed for sweat [Na+] using both the MX3 hydration testing system and the Horiba LAQUAtwin-NA-11. The reliability of the MX3 hydration testing system was determined following two measurements of the same sweat sample. Results The mean difference between measurements was 0.1 mmoL·L−1 (95% limits of agreement (LoA): − 9.2, 9.4). The analyser demonstrated a coefficient of variation (CV) of 5.6% and the standard error of measurement was 3.3 mmoL·L−1. When compared to the Horiba LAQUAtwin-NA-11, there was a mean difference of − 1.7 mmoL·L−1 (95% LoA: − 0.25$${\overline{\text{X}}}$$ X ¯ , 0.25$${\overline{\text{X}}}$$ X ¯ ) and the CV was 9.8%. Conclusion The MX3 hydration testing system demonstrated very good single-trial reliability, moderate agreement and a very good CV relative to the Horiba LAQUAtwin-Na-11. To further validate its performance, the MX3 hydration testing system should be compared with analytical techniques known for superior reliability and validity.

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Section: Discussionmentioning

confidence: 99%

Reliability and validity of the MX3 portable sweat sodium analyser during exercise in warm conditions

Brown,

Clark,

Périard

2024

Eur J Appl Physiol

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A High‐Performance Passive Radiative Cooling Metafabric with Janus Wettability and Thermal Conduction

Du,

Zhao,

Zhan

et al. 2024

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With the development of industry and global warming, passive radiative cooling textiles have recently drawn great interest owing to saving energy consumption and preventing heat‐related illnesses. Nevertheless, existing cooling textiles often lack efficient sweat management capacity and wearable comfort under many practical conditions. Herein, a hierarchical cooling metafabric that integrates passive radiation, thermal conduction, sweat evaporation, and excellent wearable comfort is reported through an electrospinning strategy. The metafabric presents excellent solar reflectivity (99.7%, 0.3–2.5 µm) and selective infrared radiation (92.4%, 8–13 µm), given that the unique optical nature of materials and wettability gradient/micro‐nano hierarchical structure design. The strong moisture‐wicking effect (water vapor transmission (WVT) of 2985 g m−2 d−1 and directional water transport index (R) of 1029.8%) and high heat‐conduction capacity can synergistically enhance the radiative cooling efficiency of the metafabric. The outdoor experiment reveals that the metafabric can obtain cooling temperatures of 13.8 °C and 19.3 °C in the dry and sweating state, respectively. Meanwhile, the metafabric saves ≈19.3% of annual energy consumption compared with the buildings with HAVC systems in Shanghai. The metafabric also demonstrates desirable breathability, mechanical strength, and washability. The cost‐effective and high‐performance metafabric may offer a novel avenue for developing next‐generation personal cooling textiles.

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Thermal and cardiovascular heat adaptations in active adolescents following summer

Brown,

Topham,

Clark

et al. 2024

Temperature

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This study aimed to investigate seasonal heat acclimatization in active adolescents following summer. Fifteen (5 females) active adolescents (14.6 ± 1.0 y) completed a 45-min heat response test (HRT) walking at 60% O 2peak in 40°C and 30% relative humidity before and after summer (i.e. November 2022 and March 2023). During the HRT, gastro-intestinal temperature (T gi ), skin temperature (T sk ), heart rate, local sweat rate (LSR) and whole-body sweat loss (WBSL) were recorded. Carbon monoxide rebreathing and dual-energy X-ray absorptiometry scans determined resting hematological measures and body composition. Participants completed physical activity (PA) diaries and wore an accelerometer for two one-week periods (pre- and post-summer). Daytime wet-bulb globe temperature (WBGT) was calculated for each summer day. Data are presented as posterior mean and 90% credible intervals. Participants reported 7 ± 4 h·wk −1 of outdoor PA, and daytime WBGT was 21.2 ± 4.6°C. Following summer, resting T gi and heart rate were reduced by 0.2°C [−0.3, −0.1; probability of direction = 99%] and 7 beats·min −1 [−10, −3; 100%], respectively. During the HRT, there was an earlier onset of sweating (−0.2°C [−0.3, −0.0; 98%]), an attenuated rise of T gi (0.2°C [−0.5, 0.0; 92%]) and mean T sk changed by −0.2°C [−0.5, 0.1; 86%]. There was minimal evidence for heat adaptations in LSR or WBSL, hematological parameters or perceptual measures. This is the first study to demonstrate seasonal heat adaptations in active adolescents. Reductions in resting T gi and exercising T sk and a lower T gi at the onset of sweating were associated with a smaller rise in T gi during the HRT following summer.

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Quantifying Exercise Heat Acclimatisation in Athletes and Military Personnel: A Systematic Review and Meta-analysis

Cited by 4 publications

References 79 publications

Reliability and validity of the MX3 portable sweat sodium analyser during exercise in warm conditions

Reliability and validity of the MX3 portable sweat sodium analyser during exercise in warm conditions

A High‐Performance Passive Radiative Cooling Metafabric with Janus Wettability and Thermal Conduction

Thermal and cardiovascular heat adaptations in active adolescents following summer

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