Genetic Risk Factor for Heat Stroke

PROCEDURE

Heat Challenge

Participants will be asked to arrive well-hydrated and to refrain from exercise, alcohol, caffeine, and smoking for 24 hours prior to the visit. Height, weight, blood pressure, and body fat percentage will be measured. Blood (15.5 ml) and urine will be collected. Participants will wear a heart rate monitor and sit in a heat chamber at 62-63 degrees Celsius for 45 minutes. Heart rate will be measured continuously. Body temperature and a self-report of their comfort (1-4 scale) and thermosensation (1-7 scale) will be measured before the challenge, every 15 minutes during the challenge, and after the challenge. During the challenge, a sample of sweat will be collected to measure electrolyte loss. Participants will consume 16 ounces of water at their own pace during the 45 minutes. If they become too uncomfortable to continue or their body temperature rises above 39 degrees Celsius, the challenge will be stopped. All baseline measures except body fat percentage will be measured again.

Participant Scores for Temperature Sensitivity and Regulation Survey

Time frame: Baseline

Individual and composite scores for 5 components of the Temperature Sensitivity Survey (Heat- and Activity-Induced Autonomic Thermoregulation; Heat-Induced Behavioral Thermoregulation; Heat Perception; and Heat- and Activity-Induced Fatigue). For these 5 components, there are a total of 25 questions. All questions are on a 7-point scale, with the highest representing the most sensitive to heat and the lowest being the least sensitive. We will add up the scores for each question to arrive at a composite score for each component and the component scores will be added to arrive at a total score. Scores will be compared between groups.

Change in Weight

Time frame: Up to 45 minutes

Weight will be measured in kilograms pre- and post-heat challenge. We will compare change in weight between groups.

Change in Sodium Concentration

Time frame: Up to 45 minutes

Sodium concentration will be measured pre- and post-heat challenge by blood draw and urine sample. Sodium concentration will be compared between groups.

Change in Potassium Concentration

Time frame: Up to 45 minutes

Potassium concentration will be measured pre- and post-heat challenge by blood draw and urine sample. Potassium concentration will be compared between groups.

Concentration of Sweat Chloride

Time frame: Up to 45 minutes

Sweat chloride will be measured pre- and post-heat challenge by sweat collection. Sweat chloride will be compared between groups.

Final Score on Comfort Scale

Time frame: Up to 45 minutes

Participants will rate their level of comfort on a scale of 1-4 at the end of the heat challenge. Scores will be compared between groups.

Final Score on Thermosensation Scale

Time frame: Up to 45 minutes

Participants will rate their level of thermosensation on a scale of 1-7 at the end of the heat challenge. Scores will be compared between groups.

What is a clinical trial?

A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.

Is it safe to participate?

Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.

Will I be compensated?

Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.

Will I receive a placebo instead of treatment?

When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.

Can I leave a trial if I change my mind?

Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.

How long does a clinical trial last?

Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.