Academic Journal
Quantifying the time course of changes in maximal skin wettedness with 7 days of heat acclimation.
| العنوان: | Quantifying the time course of changes in maximal skin wettedness with 7 days of heat acclimation. |
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| المؤلفون: | Lynch, Grant P, Mavros, Yorgi, Jay, Ollie |
| المصدر: | J Appl Physiol (1985) ; ISSN:1522-1601 ; Volume:138 ; Issue:1 |
| بيانات النشر: | Atypon |
| سنة النشر: | 2025 |
| المجموعة: | PubMed Central (PMC) |
| مصطلحات موضوعية: | evaporation, heat adaptation, sweating, thermoregulation |
| الوصف: | The aim of the present study was to quantify the time course of changes in maximum skin wettedness (ωmax)-that is, the proportion of skin surface area covered in sweat at the point of uncompensable heat stress, throughout seven consecutive days of heat acclimation. Nine adults (6 M, 3 F) completed a humidity-ramp protocol (RAMP) on days 1, 3, 5, and 7 of seven consecutive days of heat acclimation. In each RAMP trial, participants cycled continuously at 275 W·m-2 for 120 min at 37°C: 60 min at a vapor pressure of 2.05 kPa followed by 60 min with vapor pressure increased by 0.045 kPa·min-1. An upward inflection in esophageal temperature (Teso) signaled a transition to uncompensable heat stress with the critical water vapor pressure at that point used to calculate ωmax. In days between RAMP assessments, participants cycled for 90 min at 75% HRmax at 37°C, 60% RH. Teso, whole body sweat rate (WBSR), local sweat rates on the back and forearm (LSRback and LSRarm, respectively), and activated sweat gland density (ASGD) were measured throughout. ωmax was progressively and significantly greater from day 1 (0.68 ± 0.10) to day 3 (0.75 ± 0.10; P = 0.002), to day 5 (0.79 ± 0.10; P = 0.004), and to day 7 (0.87 ± 0.06; P = 0.009). WBSR was higher on days 5 (1.11 ± 0.30 L·h-1; P = 0.01) and 7 (1.12 ± 0.19 L·h-1; P < 0.001) compared with day 1 (0.94 ± 0.21 L·h-1). ASGD was higher on day 5 (78 ± 15 glands·cm-2; P < 0.001) and day 7 (81 ± 17 glands·cm-2; P = 0.001) compared with day 1 (65 ± 12 glands·cm-2). There were no observed differences in sweat gland output (P = 0.21). In conclusion, ωmax significantly increased throughout 7 days of heat acclimation. These progressive increases in ωmax were predominantly mediated by an increase in the number of active sweat glands, not the output per gland.NEW & NOTEWORTHY Significant increases in ωmax were observed as early as 3 days into a 7-day heat acclimation protocol. These data are the first to report dynamic changes in ωmax with progressive heat acclimation and provide new information about ωmax levels between the standard "unacclimated" and "acclimated" states in existing heat stress models. |
| نوع الوثيقة: | article in journal/newspaper |
| اللغة: | English |
| Relation: | https://doi.org/10.1152/japplphysiol.00919.2023; https://pubmed.ncbi.nlm.nih.gov/39561019 |
| DOI: | 10.1152/japplphysiol.00919.2023 |
| الاتاحة: | https://doi.org/10.1152/japplphysiol.00919.2023 https://pubmed.ncbi.nlm.nih.gov/39561019 |
| رقم الانضمام: | edsbas.5DF0A5A7 |
| قاعدة البيانات: | BASE |
| DOI: | 10.1152/japplphysiol.00919.2023 |
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