Methods of Assessing Sweat-Electrolyte Testing (MAST)

NCT07490756 | Completed

• 1 other identifier: 2502587094
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief Summary

If you agree to be in this study, you will be asked to report to our exercise science research center for two total visits (2 separate trials separated by at least 4 days) and the total time commitment for this study will be approximately 5 hours. Prior to each trial, you will be provided with urine jugs and food/fluid logs to record food and drink intake for 24hr. You will be asked to log food/fluid intake 24hr leading into trials. We ask that you match your diet for both trials, as much as possible. Also, we ask that you match caffeine consumption prior to trials. Lastly, we ask that you refrain from strenuous exercise and alcohol consumption for at least 12hrs leading into trials. Either of these exclude your participation in the study for safety reasons. You will be asked to provide a small urine sample upon arrival to the lab before trials. The purpose of this is to verify hydration prior to exercise in the heat. If you are not hydrated upon arrival, you will be provided and asked to drink 16oz (a bottle) of water prior to the trial. Next, you will be seated, have 2 electrodes placed on your inner forearm and researchers will apply electrical stimulation for about 5min. Typically, people feel slight tingling or nothing at all during this procedure. This is a passive way of making you sweat on your forearm. Sweat will then be collected via a small disc applied to your forearm. Immediately following this, you will have your nude body mass measured and you will be instrumented with a lab-based sweat collection patch (large band-aid on the forearm), a Gatorade sweat collection patch on the opposite forearm, and the Hdrop sweat detection device on your left upper arm. the hDrop device is non-FDA approved device because it does not provide a medical diagnosis, but serves as an education and recovery tool. These devices will all be synced with electronic applications (phone apps) to assure data collection. You will then self-insert a rectal thermistor \~15cm past the anal sphincter to monitor core temperature throughout exercise (for safety purposes). You will also be fitted with a heart rate strap that goes around your chest. You will then be asked to enter the environmental chamber and exercise for 60min. The environmental chamber will maintain a consistent temperature (80 degrees F) and humidity (\~45% relative humidity). You will be monitored for safety throughout exercise and you will be allowed to cycle (stationary bike) or run or walk (treadmill) at your own pace/intensity. Pace and intensity will be recorded during the first trial and matched for the second trial. Because fluid consumption may impair accuracy of sweat collection devices, participants will not be allowed to consume fluids during exercise.

Conditions

Sweat Sodium Concentration

Keywords

Sweat rate; Sweat sodium; Exercise dehydration

Outcome Measures

Primary Outcomes (2)

• Validity of hDrop for sweat rate (Liters/hour)

  Data will be compared between lab-based and hDrop sweat rate. Sweat rate (Liters/hourr) will be quantified during exercise. At the conclusion of 60 minutes of exercise, lab-based sweat rate and hDrop sweat rate data will be compared to determine validity.

  60 minutes

• Validity of sweat electrolyte losses from hDrop (millimoles/Liter)

  Lab-based and hDrop sweat-sodium concentration (millimoles/Liter). The data between methods will be compared to determine accuracy/validity of the hDrop device.

  60 minutes of exercise

Secondary Outcomes (2)

• Reliability of hDrop output [sweat rate (Liters/hour)]

  Trial 1 compared to trial 2 (both 60 minutes of exercise)

• Sweat-sodium reliability

  Trial 1 compared to trial 2 (60 minutes of exercise)

Study Arms (1)

Exercise in the heat

EXPERIMENTAL

Device: Wearing the hDrop hydration sensor

Interventions

Wearing the hDrop hydration sensor DEVICE

Participants wore the hDrop sensor during exercise in the heat.

Exercise in the heat

Eligibility Criteria

• Age: 18 Years - 39 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy exercisers
• No orthopedic injury
• No chronic conditions
• Able to exercise for 60min in the heat

You may not qualify if:

• Chronic conditions
• Not 18y or over 39y
• Taking medications that alter fluid balance or thermoregulation
• Current orthopedic injury

Sponsors & Collaborators

• University of Arkansas, Fayetteville: lead

Study Sites (1)

University of Arkansas Exercise Science Research Center

Fayetteville, Arkansas, 72701, United States

Location

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: DIAGNOSTIC
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Study Record Dates

• First Submitted: March 2, 2026
• First Posted: March 24, 2026
• Study Start: March 7, 2025
• Primary Completion: June 20, 2025
• Study Completion: February 13, 2026
• Last Updated: March 24, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, ICF

Locations

US (1)