Clinical Research Directory

Effect of Thermoregulation Bundle Applied at Birth on Neonatal Physiological Parameters and Breastfeeding

Maintaining the infant's body temperature (thermoregulation), particularly in the first hour after birth, is critical for the newborn's survival and adaptation to the environment. It is hypothesized that the implementation of a thermoregulation bundle will lead to a faster stabilization of physiological parameters and will positively influence the initiation and overall success of breastfeeding. To this end, this study will examine the effects of a thermoregulation bundle applied at birth on the physiological parameters of newborns (vital signs such as body temperature, respiratory rate, heart rate, and oxygen saturation) and its impact on breastfeeding.

Identifying the Limits of Survivability in Heat-exposed Older Females

Climate change increases extreme heat events, elevating global heat-illness risk. Females have reduced heat loss capacity (\~5%) compared to males, driven by differences in skin blood flow and sweating responses. While findings on sex-mediated mortality are mixed, some studies suggest older females (≥65 years), face higher heat-related mortality/morbidity risks, evidenced by disproportionate female deaths in the 2021 Western Heat Dome. The effects of extreme uncompensable heat on older females remain understudied. Heat exposure initially causes net heat gain, raising core/skin temperatures and triggering heat-loss responses. Under compensable heat stress, heat loss balances gain, stabilizing core temperature. Uncompensable heat stress (exceeding maximal dissipation capacity) causes continuous core temperature rise, posing severe health risks. The specific temperature and relative humidity (RH) limits where compensability is lost are critical survival determinants, influenced by age and sex. Ramping protocols identify these limits: participants face progressively increasing heat stress (e.g., staged humidity rises) while core temperature is monitored. Core temperature typically stabilizes initially, then exhibits an abrupt rapid increase at an inflection point, operationally defined as the limit of compensability. Despite increasing use, ramping protocol validity for accurately identifying this threshold remains unverified. This project assesses ramping protocol validity for determining uncompensable conditions in older females and evaluates cumulative thermal and cardiovascular strain, as well as psychological and cognitive responses to both uncompensable and compensable heat. Participants will complete five trials. Trial 1 (Ramping): Rest at 42°C, 28% RH for 70min, then incremental RH increases (3% every 10min) to 70% RH. Individual core temperature (rectal) inflection points are identified from the ramping trial. Trials 2-5 (Fixed Conditions, Randomized): i) \~10% below inflection; ii) \~5% below inflection; iii) \~5% above inflection; iv) Thermo-neutral control (26°C, 45% RH). Comparing the rate of rectal temperature change and cumulative strain during prolonged fixed exposures (especially below vs. above inflection) will validate if the ramping inflection point represents the true limit of compensability for older females.

The Effects of Caffeine on Exercise Physiology and Time-trial Performance in a Hot Environment

Maintaining a stable core temperature is vital for physiological function; yet, exercise in heat can be problematic, and there is risk of exertional heat-related illness (Flouris \& Schlader, 2015; Leyk et al., 2019; Périard et al., 2021; Tyler et al., 2016; Veltmeijer et al., 2015). While aerobic fitness improves heat tolerance (Alhadad et al., 2019), strategies like acclimation and pre-cooling also mitigate heat stress (Casadio et al., 2016; Lorenzo et al., 2010; Ross et al., 2013; Siegel et al., 2010). Caffeine, an ergogenic aid (Del Corso et al., 2011; John et al., 2024), is known to enhance performance via adenosine antagonism and increased catecholamines in normothermic environments (Fredholm et al., 1999; Graham \& Spriet, 1991). However, effects in heat are inconsistent (Ganio et al., 2009; Zhang et al., 2014), possibly due to caffeine reducing the ability to thermoregulate effectively. Therefore, the aim of this study is to investigate the effects of a moderate dose of caffeine (5 mg/kg) on thermoregulation during a 30-minute running time trial in 35°C heat.

Enhancing Heat Resiliency in Older Adults During Indoor Overheating Via Heat Acclimation by Warm Water Immersion

As overheating in buildings is expected to increase as global warming continues, proactive measures to increase heat resiliency in heat-vulnerable older people are needed, especially for those without access to home cooling or reliable sources of electricity. While short-term heat acclimation through exercise in the heat has been shown to increase heat dissipation and decrease both the physical and mental stress imposed on individuals exposed to heat, such protocols are not tenable for older, sedentary adults. A recent report showed that seven consecutive days of warm-water immersion improved whole-body heat loss and reduced physiological strain as assessed during an exercise-heat stress in habitually active older men This represents a critical finding as an increase heat-loss capacity would serve as an important safeguard for older adults exposed to indoor overheating due to lack of air-conditioning. While this preliminary data highlights passive hot water immersion as a promising strategy for increasing heat-resilience in vulnerable adults, work is needed to confirm its efficacy in more "real-world" environments. Thus, this study aims to assess the effectiveness of a 7-day passive heating (warm-water immersion with core temperature clamped at \~38.5°C for the final 60 minutes) protocol in mitigating increases in thermal and cardiovascular strain in older females exposed to daylong (10-hours) indoor overheating (36°C, 45% relative humidity) prior to and following the passive heating intervention. Relative to males, females have a reduced heat loss capacity (\~5%), which is driven by differences in the activation of heat loss responses (i.e., skin blood flow and sweating). Although there have been mixed findings with regards to the influence of sex as a mediating factor for heat-related mortality, some studies suggest that females are at a higher risk of heat-related mortality and morbidity compared to males, especially amongst older individuals (≥65 years). Notably, a greater proportion of older females died compared to their male counterparts during the 2021 Western Heat Dome. While the underlying causes for these differences remain unclear, greater cardiovascular strain may place females at higher mortality risk during extreme heat.

Physiological Responses to Heat Stress During High-risk Events

Exertional heat stroke (EHS) affects \~500 Military Personnel and over 100 Soldiers every year, and it is believed that these numbers are underreported. EHS is the most severe form of exertional heat illness (EHI) and can result in substantial, long-lasting organ damage, and even death in severe cases. Based on current knowledge and training needs, it is impossible to prevent every EHS - which shifts the focus from exclusively prevention to a combination of prevention, treatment, and enhancing recovery as much as possible. While many risk factors have been identified and there are adequate treatments available, biomarkers associated with heat stroke risk, recovery, and return-to-duty (RTD) remain largely unclear. The purpose of the proposed study is to enhance knowledge surrounding biomarkers of EHS and long-term health consequences that result from EHS. The investigators will recruit research volunteers for a field study in order to collect pre-, post-, and follow-up measures from a high-risk EHS event (i.e. ruck marches, timed runs) this will allow us to have a basis for comparison between Soldiers who collapse with EHS (from previously collected data) and those that complete high-risk events, but do not collapse. This will allow for comparison between the groups to identify EHS-specific biomarkers that could aid in recovery and RTD decisions for Soldiers.