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This study compared the immune and stress response of oral contraceptive users (WomenOC; n = 9) to normally-menstruating women (WomenNM; n = 9) at rest and during exercise in temperate (TEMP; 22°C) and hot (HEAT; 35°C) conditions. Participants performed a 3-stage cycling trial in each condition at 90% (Stage 1; 30 min), 135% (Stage 2; 15 min), and 180% (Stage 3; 7.5 min) of lactate threshold 1. C-reactive protein (CRP) and immune cell counts were measured at rest, and serum cytokines (IL-1β, IL-1RA, IL-6, IL-8, IL-10, and TNF-α) and salivary cortisol were evaluated before and after exercise in both the TEMP and HEAT conditions. There were no differences in resting immune cell counts between groups, nor any differences in cortisol or any of the pro- or anti-inflammatory cytokines measured at rest or after completion of the exercise trials (p > 0.05). However, a trend for a higher resting CRP concentration was observed in WomenOC relative to WomenNM (1.102 ± 1.182 and 0.326 ± 0.228, respectively, p = 0.07). The results obtained in the current study indicate similar immunoendocrine function in WomenOC and WomenNM both at rest and after exercise in temperate and hot environments. [ABSTRACT FROM AUTHOR]

Purpose: To compare the response of long-term oral contraceptive users (WomenOC; n = 8) to naturally menstruating women (WomenNM; n = 8) at rest and during exercise in temperate (TEMP; 22 °C) and hot (HEAT; 35 °C) conditions.Methods: Participants performed a three-stage cycling trial in each condition at 90, 135, and 180% of lactate threshold 1 (total = 52.5 min). Heart rate (HR) and core temperature (T c) were recorded continuously, whereas blood pressure (BP), ratings of perceived exertion (RPE), blood lactate [La-], and skin blood flow (BFsk) were recorded every 7.5 min.Results: Baseline T c was higher in WomenOC (37.5 ± 0.2, 37.6 ± 0.3 °C) than WomenNM (37.2 ± 0.2, 37.0 ± 0.4 °C) before the TEMP (p = 0.03) and HEAT (p < 0.01) trials, respectively. This difference remained for 22.5 min into both trials (p ≤ 0.05), after which time no between-group differences were found (p > 0.05). BFsk measured in WomenNM plateaued from 7.5 min in the HEAT, whereas BFsk measured in WomenOC increased for 15.0 min (p = 0.02) before plateauing. There were no between-group differences in HR, BP, or blood [La-] before or throughout either trial (p > 0.05). WomenOC had higher (p ≤ 0.04) RPE values than WomenNM in the HEAT, reporting 8 ± 1 and 6 ± 2 at the end of Stage 3, respectively.Conclusions: WomenOC concluded both trials with a comparable T c to WomenNM, but had a prolonged BFsk response and elevated RPE in the HEAT. Changes to BFsk and RPE observed in women using OC may have implications for exercise tolerance in hot conditions. [ABSTRACT FROM AUTHOR]

The effects on dehydration and cognitive performance from heat and/or physical activity are well established in the laboratory, although have not yet been studied for personnel working in occupations such as wildland firefighting regularly exposed to these types of conditions. This study aimed to investigate the effects of temperature and dehydration on seventy-three volunteer firefighters (35.7 ± 13.7 years, mean ± standard deviation) during a simulation of wildfire suppression under either control or hot (18-20; or 33-35 °C) temperature conditions. Results showed cognitive performance on the psychomotor vigilance task declined when participants were dehydrated in the heat and Stroop task performance was impaired when dehydrated late in the afternoon. Firefighters may be at risk of deteriorations in simple cognitive functions in the heat whilst dehydrated, although may also experience impairments in complex cognitive functions if dehydrated late in the day, irrespective of the environmental temperature. [ABSTRACT FROM AUTHOR]