Methods of Assessing Sweat-Electrolyte Testing (MAST) (MAST)

March 18, 2026 updated by: Brendon P. McDermott, University of Arkansas, Fayetteville
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.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Prior to each trial, participants will be provided with urine jugs and food/fluid logs to record food and drink intake for 24hr. They will be asked to log food/fluid intake. They will provide a small urine sample to verify hydration prior to exercise in the heat. If participants arrive dehydrated, they will be provided and asked to consume 16oz (a bottle) of water. Next, Participants will be seated, have 2 electrodes placed on their inner forearm and then get iontophoresis (direct current electrical stimulation) applied for about 5min. This is a passive way of eliciting a local sweat response. Sweat will then be collected via a small disc applied to their forearm. Immediately following this, participants will have their nude body mass measured and they 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 their left upper arm. These devices will all be synced with electronic applications (phone apps) to assure data collection. Participants will then self-insert a rectal thermistor ~15cm past the anal sphincter to monitor core temperature throughout exercise. They will also be fitted with a heart rate strap across their chest. They will then enter the chamber and exercise for 60min. The environmental chamber will maintain a consistent temperature (80 degrees F) and humidity (~45% relative humidity). Participants will be monitored for safety throughout exercise and they will be allowed to cycle (stationary bike) or run or walk (treadmill) at their 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. Exercise will be arrested if participants experience signs/symptoms of heat illness, get exhausted, or no longer want to continue. Following exercise, sweat collection devices will be collected and analyzed for sweat electrolyte concentration and/or sweat rate detection. Upon completion of exercise, participants will towel dry and have nude body mass measured again. They will be provided fluids and snacks following exercise while monitored for 15min post-exercise. Following this, they will be allowed to leave once they have been scheduled for their second trial. Following their second trial, they will be compensated for their participation.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
20

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Arkansas
      • Fayetteville, Arkansas, United States, 72701
        • University of Arkansas Exercise Science Research Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

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

Exclusion Criteria:

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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Exercise in the heat
Device: Wearing the hDrop hydration sensor
Participants wore the hDrop sensor during exercise in the heat.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Validity of hDrop for sweat rate (Liters/hour)
Time Frame: 60 minutes
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)
Time Frame: 60 minutes of exercise
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 Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Reliability of hDrop output [sweat rate (Liters/hour)]
Time Frame: Trial 1 compared to trial 2 (both 60 minutes of exercise)
Data for 2 matched trials will be compared to determine repeatability/reliability between trials for sweat rate (Liters/hour).
Trial 1 compared to trial 2 (both 60 minutes of exercise)
Sweat-sodium reliability
Time Frame: Trial 1 compared to trial 2 (60 minutes of exercise)
Trial data for sweat-sodium concentration (millimoles/Liter) will be compared between trials for hDrop to determine reliability/repeatability of the device.
Trial 1 compared to trial 2 (60 minutes of exercise)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Arkansas, Fayetteville

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
March 7, 2025

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
June 20, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
February 13, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
March 2, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 18, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 24, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 24, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 18, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2502587094

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Deidentified data will be shared according to reasonable requests made to the corresponding contact here, or within peer-reviewed publications.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • ICF

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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