Sweat Sodium ConcentrationMASTNCT07490756
Methods of Assessing Sweat-Electrolyte Testing (MAST)
A study testing Wearing the hDrop hydration sensor in people with Sweat Sodium Concentration, run by University of Arkansas, Fayetteville at 1 site in United States.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 39 yearsHealthy volunteers can take part
- Conditions the study is for
- Sweat Sodium Concentration
- What is being tested?
- Wearing the hDrop hydration sensor
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- 1 siteUnited States
- Study dates
- 7 Mar 2025to 13 Feb 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 39 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Healthy exercisers
- No orthopedic injury
- No chronic conditions
- Able to exercise for 60min in the heat
Who cannot join
- Chronic conditions
- Not 18y or over 39y
- Taking medications that alter fluid balance or thermoregulation
- Current orthopedic injury
Trial locations and contacts
1 site in 1 country.
United States1 site
University of Arkansas Exercise Science Research Center
Fayetteville, Arkansas, 72701
About this study
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.
Read the 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.
- Conditions
- Sweat Sodium Concentration
- Being tested
- Wearing the hDrop hydration sensor
- Keywords
- Sweat rate, Sweat sodium, Exercise dehydration
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Wearing the hDrop hydration sensorDevice
Participants wore the hDrop sensor during exercise in the heat.
| Study group | Role | What they receive |
|---|---|---|
| Exercise in the heat | Experimental | Not described Receives: Device: Wearing the hDrop hydration sensor |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 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.
Measured: 60 minutes of exercise
Secondary outcomes (2)
Reliability of hDrop output [sweat rate (Liters/hour)]
Data for 2 matched trials will be compared to determine repeatability/reliability between trials for sweat rate (Liters/hour).
Measured: Trial 1 compared to trial 2 (both 60 minutes of exercise)
Sweat-sodium reliability
Trial data for sweat-sodium concentration (millimoles/Liter) will be compared between trials for hDrop to determine reliability/repeatability of the device.
Measured: Trial 1 compared to trial 2 (60 minutes of exercise)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Mar 2026
- Study start7 Mar 2025
- Primary completion20 Jun 2025
- Study completion13 Feb 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Sweat Sodium ConcentrationStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Diagnosis
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 20 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Arkansas, Fayetteville
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Brendon P. McDermott, University of Arkansas, Fayetteville
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07490756
- Sponsor's protocol ID
- 2502587094
- Acronym
- MAST
- Status last verified
- Mar 2026
- First submitted
- 2 Mar 2026
- Last updated
- 24 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Deidentified data will be shared according to reasonable requests made to the corresponding contact here, or within peer-reviewed publications.
Publications
Zhao X, McKenna Z, Wierick S, Perez R, Sellner R, Allen B, McDermott B. Reliability and validity of portable sweat sodium analyzers during exercise in the heat. Appl Physiol Nutr Metab. 2026 Jan 1;51:1-9. doi: 10.1139/apnm-2025-0482.
PubMed 42190283
Study at a glance
From the registry record, last updated by the sponsor on 24 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Methods of Assessing Sweat-Electrolyte Testing (MAST)
- ClinicalTrials.gov ID
- NCT07490756
- Acronym / sponsor ID
- MAST / 2502587094
- Conditions
- Sweat Sodium Concentration
- Keywords
- Sweat rate, Sweat sodium, Exercise dehydration
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 20 participants (actual)
- Lead sponsor
- University of Arkansas, FayettevilleUniversity, hospital or other
- Study start
- 7 Mar 2025 (actual)
- Primary completion
- 20 Jun 2025 (actual)
- Study completion
- 13 Feb 2026 (actual)
- First posted
- 24 Mar 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
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 design
- Primary purpose
- Diagnosis
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Exercise in the heat | Experimental | Device: Wearing the hDrop hydration sensor |
Who may qualify
- Ages
- 18 to 39 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- Healthy exercisers
- No orthopedic injury
- No chronic conditions
- Able to exercise for 60min in the heat
Key exclusion criteria (4 listed)
- Chronic conditions
- Not 18y or over 39y
- Taking medications that alter fluid balance or thermoregulation
- Current orthopedic injury
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Wearing the hDrop hydration sensorParticipants wore the hDrop sensor during exercise in the heat. | Device | Exercise in the heat |
Primary outcome
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.
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.
2 secondary outcomes
Reliability of hDrop output [sweat rate (Liters/hour)]
Time frame: 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)
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Mar 2026.
- Derived from this study: PubMed 42190283Zhao X, McKenna Z, Wierick S, Perez R, Sellner R, Allen B, McDermott B. Reliability and validity of portable sweat sodium analyzers during exercise in the heat. Appl Physiol Nutr Metab. 2026 Jan 1;51:1-9. doi: 10.1139/apnm-2025-0482.
- Individual participant dataSharing planned: Yes. Deidentified data will be shared according to reasonable requests made to the corresponding contact here, or within peer-reviewed publications.
Related trials for Sweat Sodium Concentration
Not yet recruiting
Time Onset Sweat Sodium (TOSS) Study
Sweat Rate, Heat Effect
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Wearing the hDrop hydration sensor in people with Sweat Sodium Concentration, run by University of Arkansas, Fayetteville at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 24 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Validity of hDrop for sweat rate (Liters/hour) (time frame: 60 minutes). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07490756, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 24 Mar 2026.