Low water intake and underhydration are public health issues that may increase risk for diseases such as Type 2 Diabetes Mellitus. Studies suggest that high vasopressin (AVP) levels associated with low water intake may contribute to hyperglycemia. This study explored the physiological system by which AVP impairs glucose regulation through a single-blind randomized, counterbalanced, crossover design. This is a pilot and feasibility study of AVP infusion at increasing incremental rates, which was completed to determine the rate of infusion for the cross-over study. Participants completed a control and experimental trial. The experimental trial included a 3-hour AVP infusion and a 2-hour euglycemic-hyper insulinemic clamp at the end of the first hour versus control of 0.9% sodium chloride replacing AVP. In both trials, blood samples were taken every 5 minutes to measure glucose, as well as 7 other time points of insulin infusion. Two participants completed the pilot (47.5±3.5 years, 172.5 ±7.5cm, 82.5±17.7kg, 27.5±3.5 kg/m2, 5.1±0.64% HbA1c), and 3 participants completed the cross-over study (49±1.7 years, 173.7±6.7cm, 80.4±150kg, 26.5±3.2kg/m2, 5.3±0.2% HbA1c), all females. The rate of AVP infusion for the cross-over study was 12.5 mU/min. Compared to the control, the AVP trial blood glucose trended higher towards the end of the experiment, as did glucose metabolism, plasma osmolality, and plasma volume. Blood pressure was slightly higher in the AVP trial versus the saline, while plasma sodium and potassium levels did not differ. Total plasma protein seemed higher in the saline trials than in the AVP trials. This study supports the notion that increased levels of vasopressin over time may increase blood glucose. This could lead to supplementation of type 2 diabetes interventions with increased water intake.

Type 2 diabetes mellitus is the most common form that exists and has many variables that play into its development and diagnosis. This study looks at some of the factors that may have played an impact on people who are pre-diabetic or at risk of being pre-diabetic. Pre-diabetes can often serve as a warning sign for people and presents them with an opportunity for intervention before their condition worsens. However, it often goes unnoticed due to the lack of education regarding healthy living and making better quality-of-life decisions in Hispanic communities. The purpose of this study was to help identify patterns in how people from these communities manage their conditions and find techniques that can be replicated by others in order to improve health outcomes. This study followed a mixed methods approach in order to gain a full understanding of the quantitative (QUAN) and qualitative (QUAL) aspects that may have an impact on diabetes. Data was collected using a questionnaire to analyze different aspects and lifestyles of the participants and an interview with probing questions regarding life decisions, beliefs, and expectations. The overarching research question was “How did varying levels of health motivation and healthful eating habits affect glycosylated hemoglobin levels (HbA1c) in Hispanic/Latinx populations who are at risk of or are pre-diabetic?”. With this, we can obtain a better understanding of certain key aspects that play a role in the development of diabetes. A correlations matrix analysis was run to test how certain variables related and caused changes with one another. To analyze how these variables related specifically to HbA1c, our dependent variable, a multiple regression model analysis was used. It was found that the main contributors to elevated HbA1c levels were health motivation and age. A joint display analysis combined different levels of health motivation, QUAN data, and the responses to a focus question regarding efforts taken to improve one's condition, QUAL. This displayed a pattern of participants with higher health motivation showing efforts to reduce their diabetes risk and by contrast, low health motivation participants showing minimal to no efforts in changing behavior. This study found that elevated HbA1c levels also come with higher health motivation which normally wouldn’t make sense. However, the participants from this study knew about their HbA1c levels before this survey was conducted which means that these people already knew about the dangers of their condition and may have been taking steps to mitigate further risk. This demonstrates the importance of developing education systems to help inform people about risk factors and symptoms to alert them of their condition. It is common in Hispanic areas for people to cook high-fat foods, lard, or oil which often lead to an increased risk of diabetes. There is also a great difference in the amount of resources that Hispanic communities have for practicing healthy lifestyle habits and less effective self-monitoring that makes it difficult to recognize early signs of diabetes. Promoting interventions that help educate about the risks of diabetes could encourage great change in eating habits, activity levels, and overall health outcomes for people from Hispanic communities.

Dehydration during and after exercise is prevalent in athletes. Due to a thirst mechanism that does not entirely replenish total body water lost during exercise, it is crucial to rehydrate efficiently with sufficient fluids and electrolytes to retain fluid intake. The study aimed to observe the effectiveness of rehydration with different commercially available drinks and plain water. The rehydration was assessed over 4 hours after a 2% exercise-induced dehydration in the heat. Rehydration was equal to 150% of fluid loss via exercise and was administered in four equal doses during the first 60 minutes of the rehydration period. The average exercise-induced dehydration was 2.11 ± 0.4%. The high sodium and potassium-containing drink, GoodSport, had significantly better rehydration at the four-hour time point (-0.44 ± .21) than in Gatorade (-0.71 ± 0.16; P = 0.0273), Body Armor (-1.00 ± 0.5; P < 0.0001), and water (-0.88 ± 0.39; P = 0.0015). Similarly, GoodSport resulted in lower urinary output than the other drinks. Results from this study indicate that the intake of a high sodium and potassium-containing sports drink after exercise improves net fluid balance more than drinks with lower electrolyte concentrations.

Sweat evaporation is fundamental to human thermoregulation, yet our knowledge of the microscale sweat droplet evaporation dynamics is very limited. To study sweat droplet evaporation, a reliable way to measure sweat evaporation rate from skin and simultaneously image the droplet dynamics through midwave infrared thermography (MWIR) or optical coherence tomography (OCT) is required. Ventilated capsule is a common device employed for measuring sweat evaporation rates in physiological studies. However, existing designs of ventilated capsules with cylindrical flow chambers create unrealistic flow conditions that include flow separation and swirling. To address this problem, this thesis introduces a ventilated capsule with rectangular sweat evaporation area preceded by a diffuser section with geometry based on wind tunnel design guidelines. To allow for OCT or MWIR imaging, a provision to install an acrylic or a sapphire window directly over the exposed skin surface being measured is incorporated in the design. In addition to the capsule, a simplified artificial sweating surface that can supply water in a filmwise, single or multiple droplet form was developed. The performance of the capsule is demonstrated using the artificial sweating surface along with example MWIR imaging.

The human body has temperature-regulating mechanisms working to maintain body core temperature around 37°C. This ensures optimal bodily function. Disruption to core temperature however, initiates a cascade of events to return to baseline. The objective of this study is to evaluate the efficacy of cooling strategies to induce the fastest reductions in core temperature. The study was set up as a randomized field study. Core temperature was measured using an E-Celsius core temperature capsule. Environmental conditions were measured using a Kestrel heat stress tracker. Following completion of a heat-stress protocol, participants underwent one of the four randomized cooling protocols. These cooling protocols consisted of: 1) wearing an ice vest (18°C), 2) applying an icy towel directly to the back of the neck (24°C) in combination with hand/forearm water immersion (15°C), 3) a combination of ice vest, icy towel and hand/forearm water immersion, or 4) sitting in a thermoneutral room (20°C). In all cooling interventions, participants consumed 16oz of an ice slurry (0°C) within 10 minutes of the initiation of the protocol. The control group consumed only room temperature water- ad libitum. A total of 10 active males (25 ± 3 years old) reported no difference between baseline body core temperatures after each heating intervention (P=0.23). Average core temperature and heart rate differed, though not statistically significant between treatments (P>0.05). No significant differences were noted between cooling rates (P=0.51). Skin temperature (Tsk) average and decrement was found to be statistically significant (P<0.001).

The purpose of this investigation was to evaluate the influence of tap water safety perceptions on plain water intake (PWI) and hydration status in US Latinx adults. Participants (n=492; age, 28±7 y; 37.4% female) completed an Adapted Survey of Water Issues in Arizona and household watersecurity experience-based scales. A sub-sample (n=55; age, 33±14 y; body mass index, 27.77±6.60 kg·m2) completed dietary recalls on two weekdays and one weekend day via Automated Self-Administered 24-hour Dietary Assessment Tool to determine average PWI and total water intake (TWI). A 24-h urine sample was collected on one recall day and analyzed for urine osmolality (UOsm). Binary logistic regression determined odds ratios (OR) for the odds of perceiving tap water to be unsafe. Hierarchical linear regression was employed with 24-h UOsm and PWI as primary outcomes for the sub-sample. Overall, 51.2% of all participants and 52.7% of the sub-sample mistrust their tap water safety. The odds of mistrusting tap water were significantly greater (P<0.05) for each additional favorable perception of bottled over tap water (OR=1.94, 95% CI=1.50, 2.50), each additional negative home tap water experience (OR=1.32, 95% CI=1.12, 1.56), each additional use of alternatives and/or modifications to home tap water (OR=1.25, 95% CI=1.04, 1.51), and decreased water quality and acceptability (OR=1.21, 95% CI=1.01, 1.45). The odds of mistrusting tap water were significantly lower (P<0.05) for those whose primary source of drinking water is the public supply (municipal) (OR=0.07, 95% CI=0.01, 0.63) and for those with decreased water access (OR=0.56, 95% CI=0.48, 0.66). There were no differences (n=55, P>0.05) in TWI (2,678±1,139 mL), PWI (1,357±971), or 24-h UOsm (460±234 mosm·kg-1). Tap water safety perceptions did not significantly explain variance in PWI or 24-h UOsm (P > 0.05). In conclusion, Latinx mistrust in tap water safety is prevalent. Mistrust appears to be influenced by organoleptic perceptions and to lead to reliance on alternatives to the home drinking water system. Perceptions of tap water safety do not appear to be related to PWI, TWI, or hydration status in Latinx adults.

Heat acclimatization can be induced by targeting a core temperature 38.5°C for at least 60 minutes per day lasting 5 to 21 days, complementary to normal exercise activity. However, consistently meeting this threshold on consecutive days may be difficult for athletes. The objective of this study was to evaluate the efficacy of four single-bout heating protocols to reach a core temperature 38.5°C. The study was set up as a non-randomized field study, factoring in the September-October outdoor desert conditions, Tempe, AZ, USA. Environmental conditions were measured using a Kestrel heat stress tracker. Protocols were constituted out of 3 elements: PAS – passive heat exposure in a tent (54±1°C), EH - exercise in hot condition with high intensity interval training (HIIT) outdoors in the heat in a tent with a ventilator (43±1°C), EM – exercise in moderate conditions with HIIT indoors (22±0.4°C). All participants performed protocols in the following order: 1) PAS 60-min; 2) EH-PAS (EH 30-min + PAS 30-min); 3) EH 60-min, and 4) EM 60-min. A cycle ergometer was used for HIIT (2-min warm-up followed by 7x2-min sprints with 2-min relative rest between sprints during the first 30 min and stationary cycling for the second 30 min), with a self-selected workload at 80-100 rpm and similar heart rate (HR) response during exercise testing for EH: 146±10, EM: 142±13, and EH-PAS: 142±13 (P>0.05). A total of 10 active male students (25±3 years old) reported no difference between protocols for baseline Tc (P=0.37) and HR (P=0.28). During the first 30-min, Tc was significantly different between protocols (average ranging from 37.3-37.6°C, P=0.01), but from a practical perspective, differences were limited. During the second 30-min session, the Tc for EH (38.5±0.4°C) and EH-PAS (38.6±0.4°C) were significantly higher from EM (38.1±0.4°C) and PAS alone (37.8±0.4°C), P<0.001. The average HR (bpm) was significantly lower in PAS (110±17) and EH (136±13) during the second half of the protocols compared to the EH (151±10) and EM (149±16), P<0.001. In conclusion, exercise alone vs. a combination of exercise and passive heating in hot conditions resulted both in a body temperature 38.5°C, but the combination was more efficient since participants exercised for only 30-minutes.

The purpose of this study was to evaluate the impact of improved hydration on endurance performance and mood in physically active adults. Participants (n = 72; age, 21.0 ± 3.0; 22.2% female) completed two two-mile run trials separated by exactly a week. Before each trial, participants provided a urine sample from the day before the run and a sample from the morning of the run. These samples were analyzed for urine osmolality (UOsm), urine specific gravity (USG), and urine color (Ucol). UOsm and USG levels determined if the participants were placed in either the euhydrated or underhydrated group after the first trial. Those assigned to the euhydrated group were instructed to maintain their current fluid intake levels and those in the underhydrated group were instructed to increase fluid intake levels before the second trial. However, results were grouped by if they improved or maintained their hydration or not. The subjects also completed a Profile of Mood States (POMS) questionnaire before and after each trial to determine mood. Based on conditioning requirements for group assignment, 38% of subjects were classified as underhydrated. There were significant differences between the two trials for both subjects that improved and worsened their hydration in UOsm, USG, Ucol, and thirst (P < 0.05). The group with improved hydration ran -15 ± 67 sec faster in the second trial, while the group that worsened hydration ran 4 ± 26 sec slower in the second trial. When these differences were compared between the two groups with a t-test, there was a trend for statistical differences with a one-way t-test analysis (P = 0.06). When results were split by sex no statistically significant differences were observed (male: -10.8 ± 63.6 sec; female: -29.4 ± 94.8 sec; P > 0.05). Improved hydration did not result in statistically significant difference in TMD or any of the individual mood sub-scales for either group for both males and females (P > 0.05). In conclusion, increased fluid intake to optimize hydration status may affect endurance exercise in young, healthy adults in a two-mile run, but no effect was seen on mood.

Urinary tract infections (UTIs) disrupt military women’s service obligations and health. Females are more susceptible to UTIs due to their unique anatomical features and hormone fluctuations affecting vaginal flora. During phase 1 of the menstrual cycle (onset of bleeding, menstrual cycle days 1-5), estrogen levels significantly decrease and inhibit the growth of lactobacilli, good bacteria that are essential in warding off harmful bacteria and infections, particularly pathogens of UTIs. To reduce UTI onset, it is recommended to frequently urinate with sufficient urine void volume to facilitate washing out harmful bacteria from the bladder and urethra. While menstruating, increased fluid consumption to support urination frequency and void volume may be critical, as the urethra and urinary tract are more predisposed to pathogenic bacteria found. Yet, there is a lack of research investigating the impact of hydration on urinary tract health during menstruation. The study sought to examine the effects of increased water fluid intake on the uropathogenic bacterial activity of underhydrated menstruating premenopausal females. Thirteen females underwent a 2x2 randomized crossover trial to evaluate the effectiveness of a) additional 1.89 L of water fluid intake and b) maintain habitual fluid intake on two subsequent phase 1 menses. At each phase 1 menses, fluid intake was gathered on days 2 and 5 to determine the fluid amount consumed. First-morning urinations on days 3 and 6 assessed urogenital bacterial activity. Combining data collection days 2 and 5 per intervention (INT) and control (CON), the mean±SD for total fluid intake was INT 2.99±1.05 and CON 1.85±0.89, resulting in a 62% increase, p< 0.001, η2= 0.459. For days 2 and 5, a 48% and 80% increase in total fluid in from CON to INT was found, ps< 0.01. However, only four cultures detected uropathogenic bacteria from four participants, with no patterns between conditions or days, making it difficult to determine the effectiveness of the intervention. Though the intervention results were undetermined, military women’s hydration, menstruation, and urinary tract health remain prominent health concerns. Efforts to assess their fluid consumption and urination behaviors during menstruation and UTI risks are warranted.