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The purpose of this study was to examine the effect of heat acclimation (HA) on thirst levels, sweat rate, and percentage of body mass loss (%BML), and changes in fluid intake factors throughout HA induction. Twenty-eight male endurance athletes (mean ± SD; age, 35 ± 12 years; body mass, 73.0 ± 8.9 kg; maximal oxygen consumption, 57.4 ± 6.8 ml·kg−1·min−1) completed 60 min of exercise in a euhydrated state at 58.9 ± 2.3% velocity of maximal oxygen consumption in the heat (ambient temperature, 35.0 ± 1.3 °C; relative humidity, 48.0 ± 1.3%) prior to and following HA where thirst levels, sweat rate, and %BML were measured. Then, participants performed 5 days of HA while held at hyperthermia (38.50–39.75 °C) for 60 min with fluid provided ad libitum. Sweat volume, %BML, thirst levels, and fluid intake were measured for each session. Thirst levels were significantly lower following HA (pre, 4 ± 1; post, 3 ± 1, p p = .039) and %BML (pre, 2.66 ± 0.53%; post, 2.98 ± 0.83%, p = .049) were significantly greater following HA. During HA, thirst levels decreased (Day 1, 4 ± 1; Day 2, 3 ± 2; Day 3, 3 ± 2; Day 4, 3 ± 1; Day 5, 3 ± 1; p p = .010) and fluid intake (Day 1, 1.20 ± 0.45 L; Day 2, 1.52 ± 0.58 L; Day 3, 1.69 ± 0.63 L; Day 4, 1.65 ± 0.58 L; Day 5, 1.74 ± 0.51 L; p

Background: A Venn diagram consisting of percentage body mass loss, urine color, and thirst perception (weight, urine, thirst [WUT]) has been suggested as a practical method to assess hydration status. However, no study to date has examined relationships between WUT and urine hydration indices. Thus, the purpose of this study was to investigate relationships between urine specific gravity, urine osmolality, and the WUT criteria. Hypothesis: Urine specific gravity and urine osmolality indicate hypohydration when the WUT criteria demonstrate hypohydration (≥2 markers). Study Design: Laboratory cohort study. Level of Evidence: Level 3. Methods: A total of 22 women (mean ± SD; age, 20 ± 1 years; mass, 65.4 ± 12.6 kg) and 21 men (age, 21 ± 1 years; body mass, 78.7 ± 14.6 kg) participated in this study. First morning body mass, urine color, urine specific gravity, urine osmolality, and thirst level were collected for 10 consecutive days in a free-living situation. Body mass loss >1%, urine color >5, and thirst level ≥5 were used as the dehydration thresholds. The number of markers that indicated dehydration levels were counted and categorized into either 3, 2, 1, or 0 WUT markers that indicated dehydration. One-way analysis of variance with Tukey pairwise comparisons was used to assess the differences in urine specific gravity and urine osmolality between the different number of WUT markers. Results: Urine specific gravity in 3 WUT markers (mean ± SD [effect size], 1.021 ± 0.007 [0.57]; P = 0.025) and 2 WUT markers (1.019 ± 0.010 [0.31]; P = 0.026) was significantly higher than 1 WUT marker (1.016 ± 0.009). Urine mosmolality in 2 WUT markers (705 ± 253 mOsmol [0.43]; P = 0.018) was significantly higher than 1 WUT (597 ± 253 mOsmol). Meeting at 3 WUT resulted in specificity of 0.956 and at 0 WUT resulted in sensitivity of 0.937 for urine osmolality>700mOsm. Conclusion: These results suggest that when 3 WUT markers are met, urine specific gravity and urine osmolality indicated hypohydration and 0 WUT represents a high likelihood of euhydration. 1 and 2 WUT values are indeterminate of hydration status. The WUT criterion is a useful tool to use in field settings to assess hydration status when first morning urine sample was used. Clinical Relevance: Athletes, coaches, sports scientists, and medical professionals can use WUT criteria to monitor dehydration with reduced cost and time.

Objectives To assess the effects of hydration status and ice-water dousing on physiological and performance parameters. Design Randomized, crossover. Methods Twelve athletes (mean[M] ± standard deviation[SD]; age, 20 ± 1 years; height, 174 ± 8 cm; body mass, 72.1 ± 11.0 kg; VO2max 53.9 ± 7.3 mL⋅kg−1⋅min−1) completed four trials (euhydrated without dousing, hypohydrated without dousing, euhydrated with dousing, and hypohydrated with dousing), which involved intermittent treadmill running (five 15-minute bouts) in the heat (M ± SD; ambient temperature, 34.7 ± 2.1 °C; relative humidity, 46 ± 3%; wet-bulb globe temperature, 28.0 ± 0.4 °C). Participants also completed four cognitive, power, agility, reaction time, and repeated sprint performance tests throughout each trial. Heart rate (HR) and rectal temperature (Trec) were measured continuously. Repeated measures ANOVAs were performed to assess differences between physiological and performance variables. Alpha was set at ≤0.05, a priori. Data are reported as mean difference ± standard error (MD ± SE). Results HR was significantly lower in euhydrated trials compared to hypohydrated trials, irrespective of dousing (8 ± 2 bpm; p = 0.001). Dousing did not significantly impact HR (p = 0.455) and there was no interaction between hydration and dousing (p = 0.893). Trec was significantly lower in euhydrated trials compared to hypohydrated trials (0.39 ± 0.05 °C, p Conclusions Athletes should aim to maintain euhydration during exercise in the heat for improved physiological function and cooling with ice-water dousing elicits additional performance benefits.

Assessing the adaptation of rectal temperature (Trec) is critical following heat acclimatization (HAz) and heat acclimation (HA) because it is associated with exercise performance and safety; however, more feasible and valid methods need to be identified. The purpose of this study was to predict adaptations in Trec from heart rate (HR), sweat rate (SR), and thermal sensation (TS) using predictive modeling techniques. Twenty-five male endurance athletes (age, 36 ± 12 y; VO2max, 57.5 ± 7.0 mL⋅kg−1⋅min−1) completed three trials consisting of 60 min running at 59.3 ± 1.7% vVO2max in a hot environment. During trials, the highest HR and TS, SR, and Trec at the end of trials were recorded. Following a baseline trial, participants performed HAz followed by a post-HAz trial and then completed five days HA, followed by a post-HA trial. A decision tree indicated cut-points of HR (0.3 L·h−1), and TS (≤−0.5) to predict lower Trec. When two or three variables met cut-points, the probability of accuracy of showing lower Trec was 95.7%. Greater adaptations in Trec were observed when two or three variables met cut-points (−0.71 ± 0.50 °C) compared to one (−0.13 ± 0.36 °C, p < 0.001) or zero (0.0 3 ± 0.38 °C, p < 0.001). Specificity was 0.96 when two or three variables met cut-points to predict lower Trec. These results suggest using heart rate, sweat rate, and thermal sensation adaptations to indicate that the adaptations in Trec is beneficial following heat adaptations, especially in field settings, as a practical and noninvasive method.

Clinical Scenario: Exercise in the heat can lead to performance decrements and increase the risk of heat illness. Heat acclimation refers to the systematic and gradual increase in exercise in a controlled, laboratory environment. Increased duration and intensity of exercise in the heat positively affects physiological responses, such as higher sweat rate, plasma volume expansion, decreased heart rate, and lower internal body temperature. Many heat acclimation studies have examined the hydration status of the subjects exercising in the heat. Some of the physiological responses that are desired to elicit heat acclimation (ie, higher heart rate and internal body temperature) are exacerbated in a dehydrated state. Thus, euhydration (optimal hydration) and dehydration trials during heat acclimation induction have been conducted to determine if there are additional benefits to dehydrated exercise trials on physiological adaptations. However, there is still much debate over hydration status and its effect on heat acclimation. Clinical Question: Does dehydration affect the adaptations of plasma volume, heart rate, internal body temperature, skin temperature, and sweat rate during the induction phase of heat acclimation? Summary of Findings: There were no observed differences in plasma volume, internal body temperature, and skin temperature following heat acclimation in this critically appraised topic. One study found an increase in sweat rate and another study indicated greater changes in heart rate following heat acclimation with dehydration. Aside from these findings, all 4 trials did not observe statistically significant differences in euhydrated and dehydrated heat acclimation trials. Clinical Bottom Line: There is minimal evidence to suggest that hydration status affects heat acclimation induction. In the studies that met the inclusion criteria, there were no differences in plasma volume concentrations, internal body temperature, and skin temperature. Strength of Recommendation: Based on the Oxford Centre for Evidence-Based Medicine Scale, Level 2 evidence exists.

The purpose of this consensus document was to develop feasible, evidence‐based occupational heat safety recommendations to protect the US workers that experience heat stress. Heat safety recommendations were created to protect worker health and to avoid productivity losses associated with occupational heat stress. Recommendations were tailored to be utilized by safety managers, industrial hygienists, and the employers who bear responsibility for implementing heat safety plans. An interdisciplinary roundtable comprised of 51 experts was assembled to create a narrative review summarizing current data and gaps in knowledge within eight heat safety topics: (a) heat hygiene, (b) hydration, (c) heat acclimatization, (d) environmental monitoring, (e) physiological monitoring, (f) body cooling, (g) textiles and personal protective gear, and (h) emergency action plan implementation. The consensus‐based recommendations for each topic were created using the Delphi method and evaluated based on scientific evidence, feasibility, and clarity. The current document presents 40 occupational heat safety recommendations across all eight topics. Establishing these recommendations will help organizations and employers create effective heat safety plans for their workplaces, address factors that limit the implementation of heat safety best‐practices and protect worker health and productivity., Key Points This document presents feasible, evidenced‐based occupational heat safety recommendations to protect workers from the dangers of heatA roundtable of 51 experts created 40 heat safety recommendations within eight heat safety topics: heat hygiene, hydration, heat acclimatization, environmental monitoring, physiological monitoring, body cooling, textiles and personal protective gear, and emergency action plan implementationImplementing feasible and effective heat safety plans in the workplace will protect worker health and mitigate productivity losses

Background: Mentorship is a critical aspect of the professional development of the doctoral student who wishes to pursue a role in higher education. Continued understanding is needed regarding the needs of the doctoral student when it comes to mentorship. Purpose: The purpose of this study is to describe the needs of a doctoral student from their mentoring relationships, as they work towards their terminal degree. Methods: This is a descriptive, phenomenological qualitative research study within universities that offer doctoral education. One-on-one, semi-structured interviews were conducted using Zoom video conference technology. Each interview, after transcribed, was analyzed following the step-wise approach of a phenomenological study. Credibility was established by 1) research triangulation, 2) bracketing/reflexivity, and 3) peer review. Results: Twelve doctoral students (7 females, 5 males) who were enrolled in doctoral programs with a focus on allied health or exercise science completed the Zoom interviews. Our participants were an average age of 28 3 years, and all twelve had graduate assistantship positions in association with their doctoral programs. Three main themes materialized from the data analyses including 1) guided autonomy, 2) humanistic nature, and 3) professional advocate. Doctoral students want guidance to develop the technical skills necessary for success by providing opportunities to perform with the chance to gain feedback. Mentors were identified as needing to demonstrate humanistic qualities that were rooted in being interpersonal. The importance of a mentor serving as a professional advocate to help the student grow and develop as a professional was also discussed. Conclusions: Doctoral students need their mentors to demonstrate both personal and professional attributes in the mentor relationship. Specifically, they are looking for guidance and feedback through independent learning, as well as a mentor who values them, is relatable, and is invested in their development as a professional.

Exertional heat illnesses (EHIs) are common among athletes, with the most severe form, exertional heat stroke (EHS), being one of the top three causes of death in athletes. Many risk factors for EHI are known and prevention strategies are available to decrease the risk of EHI. While EHS can be deadly, it is 100% survivable if recognized early and treated appropriately in a prompt manner. Cold water immersion (CWI) is considered the gold standard method of cooling with tarp-assisted cooling with oscillation (TaCO) being the only other accepted method of cooling appropriately. While little scientific evidence exists to guide return to play following EHS, consensus recommendations are available and are recommended when guiding athletes back to activities after EHS.