Hot Water Immersion Research Articles

Application of hot water and cold air to reduce bacterial contamination on broiler carcasses.

Two physical treatments (heat via water bath and cold air) with various temperatures (20/70/75/80°C and - 80/-90°C) and exposure times (20, 30, 40 s) were carried out to identify a decontaminating effect on zoonotic pathogens on broiler carcasses. Subsequently, carcasses were analyzed for thermotolerant Campylobacter (C.), Salmonella, Escherichia (E.). coli and total colony count (TCC). Moreover, for the hot water treatment, qPCR with viable/dead differentiation (v-qPCR) was applied to detect viable but non-culturable cells (VBNC) of Campylobacter, referred to as intact but putatively infectious units (IPIU). Hot water immersion was tested on carcasses inoculated with C. jejuni and Salmonella, while cold air treatment was evaluated for naturally contaminated carcasses of broiler flocks colonized with Campylobacter. For hot water treatment, the statistically significant reducing effect was about 1 log10 CFU/ml for both Salmonella and Campylobacter for 70-80°C and 20/30 s treatments. The effect of heat treatment for Campylobacter was smaller when samples were analyzed with v-qPCR with reductions of 0.5-0.8 log10 IPIU/ml in mean. Cold air treatments at -90°C were effective in reducing the mean contamination level of Campylobacter by 0.4-0.5 log10 CFU/ml at all exposure times (p < 0.05). Hot water treatments showed a decreasing trend on TCC by 0.6-0.9 log10 CFU/ml (p < 0.05). TCC counts were not significantly affected by cold air treatment. For E. coli no statistically significant reductions were observed by hot water treatment. The cold air treatment at -90°C for 20 and 40 s led to a reduction of E. coli by 0.4 and 0.8 log10 CFU/ml (p < 0.05), respectively. Treatment of carcasses with higher bacterial levels tended to show higher reduction. The research demonstrated that the efficacy of physical treatments for decontamination of broiler carcasses was more pronounced for hot water immersion than for cold air exposure. In conclusion, the results shed light on the potential application of these physical treatments in practice to reduce the quantitative load of contaminating pathogens to enhance food safety in the broiler meat production.

Traconia Fish Sting in a City without a Sea.

The traconia fish fish poisons people it comes into contact with using the spiny structure on its back. In this case, we report the exposure of a 62-year-old housewife to a dead traconia fish while cleaning the fish. The patient came to the emergency room with unbearable pain and burning sensation in his hand. He was not relieved by the analgesia given after the examination in the emergency room and the hot water immersion methods applied. Local anesthesia-analgesia was provided by the orthopedist using the regional block technique. It should not be forgotten that such rare cases may occur in places that are not connected to the sea and/or even when the fish is dead.

Post-exercise hot or cold water immersion does not alter perception of effort or neuroendocrine responses during subsequent moderate-intensity exercise.

Post-exercise hot (HWI) and cold (CWI) water immersion are popular strategies used by athletes in a range of sporting contexts, such as enhancing recovery or adaptation. However, prolonged heating bouts increase neuroendocrine responses that are associated with perceptions of fatigue. Fourteen endurance-trained runners performed three trials consisting of two 45-min runs at 95% lactate threshold on a treadmill separated by 6h of recovery. Following the first run, participants completed one of HWI (30min, 40°C), CWI (15min, 14°C) or control (CON, 30min rest in ambient conditions) in a randomised order. Perceived effort and recovery were measured using ratings of perceived exertion (RPE) and the Acute Recovery and Stress Scale (ARSS), whilst physiological responses including venous concentrations of a range of neuroendocrine markers, superficial femoral blood flow, heart rate and rectal temperature were measured. Exercise increased neuroendocrine responses of interleukin-6, adrenaline and noradrenaline (all P <0.001). Additionally, perceptions of overall recovery (P <0.001), mental performance capacity (P =0.02), physical performance capability (P =0.01) and emotional balance (P =0.03) were reduced prior to the second run. However, there was no effect of condition on these variables (P>0.05), nor RPE (P =0.68), despite differences in rectal temperature, superficial femoral blood flow following the first run, and participants' expected recovery prior to the intervention (all P <0.001). Therefore, athletes may engage in post-exercise hot or cold-water immersion without negatively impacting moderate-intensity training sessions performed later the same day.

Fabrication and analysis of a novel and sustainable set-up for safe and economic hydrotherapy

Hot water immersion therapy has been found a promising therapy that offers several potential benefits to the human body, including pain relief, wound healing, improved blood circulation, stress relief, and improved sleep. However, the therapy is not widely used by the general population, especially the middle-class and lower-middle-class populations. The reasons for this could be the accessibility and cost of the therapy. This article introduces an innovative hot water immersion therapy set-up designed to increase the therapy's accessibility to a broader audience. The proposed set-up is engineered for easy home fabrication and installation without requiring special tools or skills, ensuring user safety through the use of electrically leak-proof components. A significant benefit of this set-up is its integration with a standard household geyser for water heating, which obviates the need for a dedicated geyser typically associated with commercial hot water immersion therapy systems, thereby reducing the overall initial, operational, and maintenance costs. The set-up has been successfully fabricated, installed, and tested, proving its effectiveness and efficiency. Among the four modes experimentally analyzed, Mode 4, a mix of regular and hot water with a combined flow rate of 8.06 L/min, leads to minimum waiting and geyser on-time of 19.85 min. In addition to the direct benefit of reduced liquid petroleum gas consumption, choosing Mode 4 contributes to an overall lower environmental footprint. This study aims to raise awareness of hydrotherapy and make it accessible to the general public.

Hot Water Immersion as a Means to Prevent Cardiovascular Disease and Associated Mortality.

Hot Water Immersion as a Means to Prevent Cardiovascular Disease and Associated Mortality.

Acute exposure to carbon monoxide inhalation and/or hot water immersion transiently increases erythropoietin in females but not in males.

The use of acute carbon monoxide inhalation (COi) and hot water immersion (HWI) are of growing interest as interventions to stimulate erythropoietin (EPO) production. However, whether EPO production is further augmented when combining these stressors and whether there are sex differences in this response are poorly understood. Therefore, we measured circulating EPO concentration in response to acute COi and HWI independently and in combination and determined whether the responses were altered by sex. Participants completed three study visits-COi, HWI, and combined COi and HWI-separated by 1 week in a randomized, balanced, crossover design. Renal blood velocity was measured during all interventions, and carboxyhaemoglobin was measured during and after COi. Serum samples were analysed every hour for 6h post-intervention for EPO concentration. HWI decreased renal blood velocity (46.2cm/s to 36.2cm/s) (P<0.0001), and COi increased carboxyhaemoglobin (1.5%-12.8%) (P<0.0001) without changing renal blood velocity (46.4-45.2cm/s) (P=0.4456). All three interventions increased peak EPO concentration from baseline (COi: 6.02-9.74mIU/mL; HWI: 6.80-11.10mIU/mL; COi + HWI: 6.71-10.91mIU/mL) (P=0.0048) and to the same extent (P=0.3505). On average, females increased EPO while males did not in response to COi (females: 6.17mIU/mL; males: 1.27mIU/mL) (P=0.0010), HWI (females: 6.47mIU/mL; males: 2.14mIU/mL) (P=0.0104), and COi and HWI (females: 6.65mIU/mL; males: 1.76mIU/mL) (P=0.0256). These data emphasize that combining these interventions does not augment EPO secretion and that these interventions may work better in females.

Effects of sodium bicarbonate ingestion on ventilatory and cerebrovascular responses in resting heated humans.

Hyperthermia stimulates ventilation in humans. This hyperthermia-induced hyperventilation may be mediated by the activation of peripheral chemoreceptors implicated in the regulation of respiration in reaction to various chemical stimuli, including reductions in arterial pH. Here, we investigated the hypothesis that during passive heating at rest, the increases in arterial pH achieved with sodium bicarbonate ingestion, which could attenuate peripheral chemoreceptors activity, mitigate hyperthermia-induced hyperventilation. We also assessed that the effect of sodium bicarbonate ingestion on cerebral blood flow responses, which are associated with hyperthermia-induced hyperventilation. Twelve healthy men ingested a sodium bicarbonate (0.3 g/kg body weight) or sodium chloride (0.208 g/kg). One hundred minutes after the ingestion, the participants were passively heated using hot-water immersion (42°C) combined with a water-perfused suit. Increases in esophageal temperature (an index of core temperature) and minute ventilation (VE) during the heating were similar in the two trials. Moreover, when VE is expressed as a function of esophageal temperature, there were no between-trial differences in the core temperature threshold for hyperventilation (37.9 ± 0.3 vs. 38.0 ± 0.4°C, P = 0.338), and sensitivity of hyperthermia-induced hyperventilation as assessed by the slope of the core temperature-VE relation (13.7 ± 14.9 vs. 15.8 ± 15.6 L/min/°C, P = 0.748). Furthermore, middle cerebral artery mean blood velocity (an index of cerebral blood flow) decreased similarly with heating duration in both trials. These results suggest that sodium bicarbonate ingestion does not mitigate hyperthermia-induced hyperventilation and the reductions in cerebral blood flow index in resting heated humans.

Durable Superhydrophobic Aluminum Surfaces against Immersion and Hot Steam Impact: A Comparative Evaluation of Different Hydrophobization Methods and Coatings

Controlling the wettability properties of metallic materials and surfaces can enhance their applicability and improve their performance and durability in several fields, such as corrosion protection, heat transfer applications, self-cleaning, and friction reduction. Here, we present and compare some versatile fabrication methods that can provide aluminum surfaces with durable superhydrophobic performance which are suitable for heat transfer applications. To probe their stability in heat transfer applications, two evaluation protocols are designed, one which suggests immersion in hot water for several hours, and a second testing against the harsh conditions of hot steam impact. The superhydrophobic aluminum surfaces are fabricated by first creating micro or micro-nano roughness on an initially flat surface, followed by the minimization of its surface energy through two hydrophobization methods, one wet and one dry, thus creating a series of different coating materials. Surfaces are then evaluated by immersing them in hot water and exposing them to steam impact. It is demonstrated that despite the fact that all hydrophobization methods tested resulted in surfaces exhibiting superhydrophobic properties, only the ultra-thin Teflon-like coating, obtained after plasma deposition using C4F8 plasma, exhibited robust superhydrophobicity with hysteresis lower than 8° when immersed in water at 90 °C for 10 h. This surface also showed minimal wettability changes and was the only one to retain its hysteresis below 6° after 4 h of exposure to hot steam.

Hot But Not Cold Water Immersion Mitigates the Decline in Rate of Force Development following Exercise-Induced Muscle Damage.

In recent years, there has been significant advancement in the guidelines for recovery protocols involving heat or cold water immersion. Yet, comparison between the effects of hot and cold water immersion on key markers of neuromuscular recovery following exercise-induced muscle damage (EIMD) is lacking. Thirty physically active males completed an individualized and tailored EIMD protocol immediately followed by one of the following recovery interventions: cold water immersion (11 °C, CWI11), hot water immersion (41 °C, HWI41) or warm-bath control (36 °C, CON36). Gastrointestinal temperature was tracked throughout HWI41. Knee extensors' maximal isokinetic strength [peak torque (Tpeak)] and explosive strength [late-phase rate of force development, (RFD100-200)] were measured prior to EIMD (pre-), 24 h (post-24 h) and 48 h (post-48 h) post-EIMD. In addition, pressure pain threshold (PPT) was measured to quantify the recovery from muscle soreness. Surface electromyography signals (sEMG) from the vastus lateralis were captured to extract the rates of electromyography rise (REMGR) and the spectral power in the low-frequency band. At post-48 h, Tpeak returned to baseline values following both CWI11 (-8.3 ± 6.8 %, p = 0.079) and HWI41 (-1.4 ± 4.1%, p = 1). In contrast, RFD100-200 (-2.3 ± 29.3%, p = 1) and PPT (+5.6 ± 14.6%, p = 1) returned to baseline values at post-48 h only following HWI41. Spectral analysis of the sEMG signal revealed that the low-frequency band was significantly increased following CWI11 (+9.0 ± 0.52%, p = 0.012). REMGR was unchanged regardless of the condition (all p > 0.05). A single session of HWI41, rather than CWI11, improved the recovery of the late-phase rate of force development following EIMD in physically active males. This suggests that in athletic contexts where a rapid force development is a key performance determinant, hot bath should be preferred over cold bath.

Hot-Water Immersion (HWI) or Ice-Pack Treatment (IPT) as First Aid for Human Envenomation by Marine Animals? Review of Literature.

Envenomation by marine animals poses a significant health concern globally, affecting both local residents and tourists in coastal regions. The primary objective of this review is to critically evaluate the existing scientific literature to determine the most effective first-aid treatment for envenomations caused by marine animals, specifically whether hot-water immersion (HWI) or ice-pack treatment (IPT) provides the best immediate care. This comprehensive review covers a wide range of marine envenomations, from jellyfish stings to stingray injuries. While our focus is primarily on the efficacy of HWI and IPT, we also explore the role of cold-water treatment as a result of its relevance and similarity to ice-pack applications. In addition, we examine other treatments mentioned in the literature, such as medications or vinegar, and highlight their findings where applicable. To provide a clear and structured overview, we summarised the articles in separate tables. These tables categorise the type of research conducted, the marine species studied, the region of origin of the marine species, and the key findings of each study. Our analysis of the available evidence indicates a general consensus in the scientific community on the effectiveness of HWI or IPT for envenomation by marine animals. However, when treating those injuries, it is crucial to consider all factors since there is no universally superior treatment due to the diverse nature of marine habitats.

Hydrotherapy in Pain Management in Pregnant Women: A Meta-Analysis of Randomized Clinical Trials.

Background: the benefits of water are significant during the birth process. Improved maternal experience of labor, less use of epidurals, better pain management, shorter labor, and a greater sense of control are observed during the birth process. Objective: This report aims to determine the benefits of hydrotherapy in clinical childbirth approaches and its applicability in pain control. Methods: A meta-analysis of randomized clinical trials selected from various databases with no publication date limits was conducted, comparing groups that did not use hydrotherapy with groups that did during labor. Results: Seven articles met the inclusion criteria, with five articles using hot water immersion and two using hot water shower as hydrotherapy treatments. This study identified 840 participants, with the intervention groups including 417 term pregnant women and the control groups including 423 pregnant women. The effect size of hydrotherapy on pain was calculated using the visual analog scale in five articles and analgesic use in the other two articles. Hydrotherapy significantly reduced pain during labor with a mean difference of -0.97 (95% CI: -1.91 to -0.03; I2 = 97.32%, p < 0.001). The duration of the first stage of labor was not significantly affected, with a mean difference of -0.17 h (95% CI: -0.55 to 0.21; I2 = 56.75%, p = 0.059). Additionally, hydrotherapy did not significantly impact the newborns' Apgar scores at 5 min, with a mean difference of 0.18 (95% CI: -0.48 to 0.85; I2 = 2.15%, p = 0.939). Conclusions: Hydrotherapy is beneficial for pain control in the first stage of labor and does not increase its duration or negatively affect the Apgar score of newborns.

External auricle temperature enhances ear-based wearable accuracy during physiological strain monitoring in the heat

Body core temperature (Tc) monitoring is crucial for minimizing heat injury risk. However, validated strategies are invasive and expensive. Although promising, aural canal temperature (Tac) is susceptible to environmental influences. This study investigated whether incorporation of external auricle temperature (Tea) into an ear-based Tc algorithm enhances its accuracy during multiple heat stress conditions. Twenty males (mean ± SD; age = 25 ± 3 years, BMI = 21.7 ± 1.8, body fat = 12 ± 3%, maximal aerobic capacity (VO2max) = 64 ± 7 ml/kg/min) donned an ear-based wearable and performed a passive heating (PAH), running (RUN) and brisk walking trial (WALK). PAH comprised of immersion in hot water (42.0 ± 0.3 °C). RUN (70 ± 3%VO2max) and WALK (50 ± 10%VO2max) were conducted in an environmental chamber (Tdb = 30.0 ± 0.2 °C, RH = 71 ± 2%). Several Tc models, developed using Tac, Tea and heart rate, were validated against gastrointestinal temperature. Inclusion of Tea as a model input improved the accuracy of the ear-based Tc algorithm. Our best performing model (Trf3) displayed good group prediction errors (mean bias error = − 0.02 ± 0.26 °C) but exhibited individual prediction errors (percentage target attainment ± 0.40 °C = 88%) that marginally exceeded our validity criterion. Therefore, Trf3 demonstrates potential utility for group-based Tc monitoring, with additional refinement needed to extend its applicability to personalized heat strain monitoring.

Use of Ozone as a Substrate Treatment for the Control of Trichoderma in the Production of Pleurotus ostreatus.

Pleurotus ostreatus is one of the most widely cultivated species in the world. It can be produced in many lignocellulosic substrates after carrying out a treatment to eliminate competing microorganisms. The most commonly used is pasteurization by steam or by immersion in hot water. The aim of this work is to evaluate if ozone can be employed as treatment for decontamination of the substrate used for the production of the edible mushroom P. ostreatus to control of green mold Trichoderma. Wheat straw was employed as a substrate. We used two different methodologies: bubbling ozone into a tank with water and the substrate, and injecting ozone into a closed tank with the substrate inside. Ten treatments were carried out including two treatments with inoculation by a spray of conidia of Trichoderma. The effect of ozone on the conidia was also evaluated. We found that the treatment of the substrate with ozone in immersed water resulted more effective (lower growth of Trichoderma) than injecting ozone into a closed tank. Anyway, we found that the contaminant fungi could grow on the substrate in both treatments with ozone. We observed that although ozone affected the conidia when it was bubbled into water, some of them still managed to survive and could germinate 72h later. P. ostreatus could grow and produce fruiting bodies on a substrate that was previously treated with ozone and yields were not affected. Based on the results obtained, we conclude that ozone may not be an effective agent to control Trichoderma in highly contaminated substrates, at least in the experimental conditions that we used, for the production of P. ostreatus.

Comparison of Acute Physiological Responses to Different Passive Heating Modalities

The repeated use of passive heating has gained popularity as a therapeutic approach toward promoting health and wellness. Passive heating elicits a rise in core body temperature and subsequent cardiovascular demand that can result in physiological adaptations beneficial to health. Hot water immersion, traditional sauna, and far-infrared sauna are three common modalities of passive heating; however, current literature lacks a direct comparison between these modalities. The purpose of this study is to characterize and compare the acute thermoregulatory and cardiovascular responses to a single bout of hot water immersion (HWI), traditional sauna (TRAD), and far-infrared sauna (FIR). We hypothesized that HWI will induce more pronounced thermoregulatory and cardiovascular responses when compared to both TRAD and FIR. In a randomized cross-over study design, nineteen healthy adults (9 F; age 24±4 years; body mass index 26.47±5 kg/m2) completed three bouts of acute passive heating: HWI (45 minutes at 40°C), TRAD (3x10 minutes at 80°C, separated by 5 min of thermoneutral rest), and FIR (45 minutes at 45-65°C) separated by at least 1 week. These temperatures and durations were chosen based on previous research and reflect typical use of these modalities. Measurements of arterial pressure, core temperature (Tc), and heart rate (HR) were collected at pre-heating baseline and at 5-min intervals during passive heating. Cardiac output (Q) was measured before, halfway, and at the end of heating using the open-circuit acetylene wash-in method. Mean arterial pressure (MAP) was calculated as 1/3 systolic + 2/3 diastolic and stroke volume (SV) and systemic vascular resistance (SVR) were calculated by Q/HR and MAP/Q. Data were analyzed using one-way ANOVAs to compare the changes from baseline to end of heating and are presented as mean with 95% confidence intervals. The change in Tc from baseline to end of heating was greater in HWI [+1.1°C (1.0, 1.3)] vs TRAD [+0.4°C (0.2, 0.6), p&lt;0.0001], HWI vs FIR [+0.1°C (-0.1,0.2), P &lt;0.0001], and TRAD vs FIR (P=0.0291). The increase in HR was greater in HWI [+39 bpm (35, 43)] vs. FIR [+26 bpm (21, 32), P=0.0017], with no differences in HWI vs. TRAD [+34 bpm (28, 40), P=0.4247] or TRAD vs. FIR (P=0.0793). Cardiac output increased to a greater extent in HWI [+3.9 L (3.3, 4.4)] vs. TRAD [+2.4 L (1.8, 2.9), P=0.0003)] and HWI vs. FIR [+1.7 L (1.2, 2.1), p&lt;0.0001], with no difference between TRAD vs FIR (P=0.1379). MAP decreased in HWI [-14 mmHg (-20, -9)] vs TRAD [-3 mmHg (-8, 1), P=0.0058] and HWI vs FIR [-0.5 mmHg (-5, 4), P=0.0003], with no difference between TRAD vs FIR (P= 0.7506). Conclusion: A single bout of HWI elicits the greatest thermoregulatory challenge and cardiovascular strain compared to both TRAD and FIR. Funded by American Heart Association (19TPA34890033) and NIH (R01HL144128). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Proteomic Changes during Human Heat Stress and Heat Acclimation

INTRODUCTION. To thrive in a warmer climate, humans will need to adapt physiologically. Improved thermoregulatory and cardiovascular responses during heat acclimation have been widely described. However, the cellular and molecular mechanisms mediating these improvements remain understudied in humans. The aim of this study was to perform a broad-spectrum, non-targeted proteomic analysis to determine how plasma protein levels change in response to moderate heat stress and heat acclimation. METHODS. Ten healthy adults (4F/6H, age: 25 ± 3 years) attended two laboratory visits performed before and after a 7-day heat acclimation protocol (hot water immersion, 60 min at a rectal temperature ≥38.5°C). During the visits, blood samples were drawn before and during passive heat stress (~1.5°C increase in esophageal temperature, water-perfused suit). Proteomic analyses were performed on 2938 plasma proteins using the Olink Explore 3072 assay. We quantified the number of proteins that changed by more than one log2(fold change) in concentration. RESULTS. Prior to acclimation, ~1% of the proteins (n=29) changed in concentration during heat stress. The change in concentration for 9 of these proteins reached the p value threshold. After acclimation, 54 proteins changed in concentration under a normothermic state. During subsequent heat stress, 175 proteins (~6%) increased in concentration and 19 (~0.6%) decreased. For 180 of these proteins, the change in concentration during heat stress was unique to the post-acclimation visit. The genes for proteins that changed in concentration during heat stress prior to acclimation are more highly expressed in brain (FGFBP3), arterial (TIMP4), skin (OBP2B), lung/salivary gland/esophageal (CXCL17) tissue. The genes for proteins that changed concentration in response to heat acclimation are highly expressed in skin (MMP7, CA6, KLK14) and brain tissue (DNER). The genes for proteins that only changed in concentration during heat stress post-acclimation are more highly expressed in brain (MOG, SMOC1, PTPRN2), and arterial (TNC, C1QTNF1, MATN2, NTF3, SMOC1) tissue. CONCLUSION. This untargeted and large-scale proteomic analysis identified novel plasma proteins that change in concentration during human heat stress and subsequent heat acclimation. The individual protein results can be utilized as external validation for other studies, as the basis of further data analysis explorations, and/or to guide targeted investigations of the biological responses and adaptations to heat exposure. Natural Sciences and Engineering Research Council of Canada. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Feasibility of Improving Glycemic Control via Heat Therapy in individuals at risk for Alzheimer’s Disease (FIGHT-AD): a pilot study

Impaired glycemic control increases the risk for type 2 diabetes and Alzheimer’s Disease (AD). Mechanisms such as impaired energy metabolism, cellular bioenergetic function, reduced intracellular protein homeostasis, and inflammation are all potential contributors to AD pathology. Heat therapy, via hot water immersion, has been shown to improve blood glucose regulation, insulin resistance, and inflammation. Given the potential contribution of these factors to brain health, heat therapy could offer immense clinical benefit to individuals at risk for AD. We performed a pilot study to test the feasibility of utilizing heat therapy in older individuals at risk for AD due to metabolic risk. The study intervention involved two pre-visits which included a cognitive function screen, sleep, diet, and physical activity questionnaires, as well as a glucose tolerance test and MRI scan. The intervention consisted of four weeks of heat therapy (3 visits/wk) for a total of 12 visits, followed by two post-intervention study visits identical to the pre-study visits. A total of 18 individuals (9 male, 9 female), average age 71.1 ± 3.9 y completed the intervention. Participants demonstrated metabolic risk based on average HbA1c values of 6.6 ± 0.67, Body Mass Index (BMI) of 29.1 ± 5.4, and 15 of the 18 participants were on hypertensive medications. Our cohort was highly diverse, with 33% underrepresented minority group representation. We had 96% participant adherence for the study (8 missed visits out of 216 total visits), and 1 study related Adverse Event (mild dizziness/nausea) that was mild. Overall, the research participants responded to a post-intervention survey saying they enjoyed participating in the study and it was not a burden on their schedules. In addition, we obtained preliminary data demonstrating a significant effect of the heat therapy intervention on body mass index, mean arterial pressure, and cerebral perfusion (p&lt;0.05), and a trend for improved self-reported sleep quality (Pittsburgh Sleep Quality Index; p=0.06). Future studies of longer duration are needed to provide a comprehensive understanding of the impact of heat therapy on glucose homeostasis and brain health. NIH P30 AG035982 (KU ADRC), pilot funds to PCG. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Hot head-out water immersion increases internal carotid artery shear rate but does not alter intracranial vascular reactivity to carbon dioxide

Acute head-out water immersion (HOWI) in hot water increases cerebral blood flow (CBF) until core temperature rises by ~1.0°C. The increase in CBF may promote increases in arterial shear rate that could enhance cerebrovascular reactivity to CO2 (CVRCO2) as a result of elevated nitric oxide (NO) bioavailability. An increase in NO bioavailability improves peripheral vasodilator function, and therefore, a similar response may occur in the cerebral vasculature. This likely only aids in cerebral vasodilation during hypercapnia, and not cerebral vasoconstriction during hypocapnia. However, it is unclear if a single session of hot HOWI alters cerebral artery shear rate and CVRCO2 to hyper- and hypocapnia. Purpose: We tested the hypotheses that during a single session of hot HOWI (39°C), cerebral artery shear rate and hypercapnic CVRCO2 would be greater and hypocapnic CVRCO2 would be lower compared to temperate HOWI (35°C). Methods: Eighteen healthy participants (age: 25±5 y, 6 women) completed two experimental visits. Middle and posterior cerebral artery blood velocities (transcranial Doppler; MCAv and PCAv) were continuously recorded. Blood velocities and diameters of the right internal carotid artery (ICA) and vertebral artery (VA) were obtained via dual-mode Doppler ultrasound to calculate shear rate. Hypocapnic and hypercapnic CVRCO2 were assessed in the MCA and PCA during self-paced hyperventilation (until PETCO2 decreased by 10 mmHg from baseline) and during 30 s of 7% CO2 inhalation, respectively. Measures were completed before immersion (PRE) and after a +1.0°C increase in core temperature during hot HOWI and time-matched during temperate HOWI. Data are reported as mean ± SD. Results: There were no differences between conditions at PRE. MCAv (55±9 vs. 64±12 cm/s; P=0.01) and PCAv (29±5 vs. 39±7 cm/s; p&lt;0.01) were lower in hot vs. temperate HOWI at +1.0°C. ICA shear rate was greater in hot vs. temperate HOWI at +1.0°C (247±51 vs. 180±43 s−1; p&lt;0.01) but VA shear rate did not differ between conditions (P=0.78). There were no differences between conditions for hypercapnic CVRCO2 (MCA: P =0.48, PCA: P=0.43) or hypocapnic CVRCO2 (MCA: P=0.18). A condition effect was observed for PCA hypocapnic CVRCO2 (p&lt;0.01), but multiple comparisons did not reveal where differences occurred (all P≥0.10). Conclusion: Hot head out water immersion elicits similar changes in hemodynamics and CVRCO2 in intracranial arteries (i.e., MCA and PCA) as temperate head out water immersion. Hot head out water immersion produces a greater shear rate in the ICA compared to temperate water, which may be beneficial for cerebrovascular health if done recurrently. This study was partially supported by the Mark Diamond Research Fund at the University at Buffalo and the Offce of Naval Research Director of Research Early Career Grant (N00014-17-1-2878). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Home-Based Heat Therapy and Vascular Function of Adults Living with Type 2 Diabetes: Preliminary Analyses of a Randomized Controlled Trial

Background: Several studies indicate that various heat exposure interventions improve peripheral endothelial function and microvascular reactivity, as well as reduce central arterial stiffness and blood pressure in various populations. Nonetheless, few studies have considered the potential therapeutic effects of heat exposure for people living with type 2 diabetes mellitus (T2DM), who are at high cardiovascular risk. In addition, all heat therapy interventions investigated to date have been laboratory-based, which may limit long-term adherence. HYPOTHESES: This study aims is to determine the effects of a 12-week home-based heat therapy intervention on markers of vascular function in adults living with T2DM. The primary hypothesis is that heat therapy improves peripheral endothelial function relative to a sham intervention. Secondary hypotheses include improved microvascular reactivity, central arterial stiffness, and 24h blood pressure. METHODS: Thirteen adults (66 ± 10 years, 28.9 ± 6.0 kg/m2, 9 men/ 4 women) living with TD2M were randomized to 12 weeks of home-based heat therapy (n=7, lower leg immersion in 42°C water) or a thermoneutral sham intervention (n=6, lower leg immersion in 36°C water). Peripheral endothelial function (brachial artery flow-mediated dilation, FMD), microvascular reactivity (post-occlusive reactive hyperemia), arterial stiffness (carotid-femoral pulse wave velocity), and 24h blood pressure (ambulatory blood pressure monitoring), were measured before and after the intervention. RESULTS: Brachial artery FMD changed by 1.72% [95%CI, 0.06; 3.37] in response to heat therapy compared to 0.41% [-1.38; +2.20] in response to the sham intervention. Peak and total reactive hyperemia changed by 0.79 mL/min/mmHg [-0.27; 1.86] and by 1.77 mL/mmHg [0.73; 2.81], respectively, in response to heat therapy compared with 0.76 mL/min/mmHg [-0.38; 1.91] and 1.68 mL/mmHg [0.56; 2.80] in response to the sham intervention. Arterial stiffness changed by 0.55 m/s [-1.62; 2.71] in response to heat therapy compared with -1.60 m/s [-3.75; 0.57] in response to the sham intervention. The 24h-systolic and diastolic blood pressure changed by 6 mmHg [-1; +12] and 2 mmHg [-3; +7], respectively, in response to heat therapy compared with -2 mmHg [-10; +6] and -3 mmHg [-9; +3] in response to the sham intervention. CONCLUSION: These preliminary results suggest that 12 weeks of home-based lower leg hot water immersion improves brachial artery FMD in adults with T2DM. In contrast, the heat therapy intervention does not appear to improve microvascular reactivity, central arterial stiffness, or 24h blood pressure. Cardiometabolic Health Diabetes and Obesity Research Network and Diabète Quebec. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Solvent-tolerant lignosulfonate-attapulgite/calcium carbonate coating on nylon filter mesh for oily water treatment

Due to the rapid increasing drainage of oily wastewater, robust and durable filtration materials with underwater superoleophobic coatings are highly desired. The existing underwater superoleophobic filter materials for oil/water separation are always subject to mechanical and chemical damages, causing the significant loss of superoleophobicity. Herein, a robust and tolerant nylon filter mesh (NFM) with underwater superoleophobicity was fabricated through simple layer-by-layer (LBL) assembly of lignosulfonate (LS), attapulgite (APT) nanorods, calcium ion, and carbonate on NFM. Compared with LS@CaCO3 assembly, the obtained LS-APT@CaCO3 assembly on NFM exhibits good micro/nano-structure, uniform distribution, and excellent underwater superoleophobicity (oil contact angle: > 156°). Moreover, after the fabricated mesh is subjected to the immersion in corrosive environments (acid, base, and salt aqueous solutions) and hot water as well as severe mechanical scratch, the oil contact angle are still higher than 147.5°, implying superb durability. More importantly, the as-obtained NFM is able to treat a variety of oil/pure water and oil/corrosive solution mixtures with separation efficiencies of over 98.2 %. Therefore, the as-prepared mesh has a huge application potential in oil-polluted water remediation due to the simple, facile, and eco-friendly preparation process.

Mixed-Method Heat Acclimation Induces Heat Adaptations in International Triathletes Without Training Modification

PurposeHeat acclimation (HA) kinetics often necessitates that the intervention is conducted in the weeks immediately preceding athletic competitions, potentially interfering with a training taper. Therefore, we investigated the efficacy of a mixed-method HA protocol, superimposed over planned external training loads, during the 3-weeks prior to the 2022 U23 World Triathlon Championships.MethodsSix international triathletes completed 8 pre-competition HA sessions (5 active: running/cycling, 3 passive: hot water immersion [HWI]), across 2-weeks. Outdoor high-intensity training sessions were followed by 30–60 min HWI, whilst low-intensity cycling/running sessions were completed in a hot, humid environmental chamber. To assess heat adaptations, participants completed three 25 min heat stress tests (HST) involving iso-speed treadmill running (session 1 = HST1, session 5 = HST2, and session 8 = HST3). Physiological, haematological and wellbeing monitoring were conducted throughout HA.ResultsReduced heart rate (~ − 6 beats/min) was observed within HST3 (P = 0.01, ηp2 = 0.64), versus HST1 and HST2. No changes in core temperature were observed across HSTs (P = 0.055,ηp2 = 0.44). Sweat sodium concentration was lower by HST2 at the arm (− 23 ± 16 mmol/L, P = 0.02) and back (− 27 ± 17 mmol/L, P = 0.01). White blood cell count reduced from baseline to the end of HA (P = 0.02, ηp2 = 0.27), but no changes were found in any other haematological markers (all P > 0.05). Perceptual wellbeing measures did not change across HA (all P > 0.05).ConclusionBy HST3, seven prior mixed-method HA sessions improved markers of heat adaptation (exercising HR and sweat concentration) within international triathletes. Mixed-method HA may be implemented without modifying training load, with no apparent detrimental effects on athlete health or training stress markers.