Wearable Photoplethysmography for Non-invasive Hydration Assessment

April 3, 2026 updated by: PepsiCo Global R&D
Hydration status during exercise is often determined by measuring body mass change, fluid intake and urine output. However, obtaining these measurements can be an invasive, time-consuming process. Hydration status may be detectable by analyzing blood flow patterns of the superficial (just under the skin) blood vessels. Wearable devices are now abundant among the general population, and despite attempts from several groups, a hydration status metric based on noninvasive wearable device metrics has not been developed. With wearables, a light source connected to an optical sensor transmits and reflects light through the body. The light sensor detects absorption of the light based on wavelength measurements of the detected light. Absorption of specific wavelengths of light energy is dependent upon the amount of oxygenated blood in the vessels. When the vessels expand and relax, the amount of blood volume in the observed tissue increases and decreases potentially causing a shift in the photoplethysmography (PPG) wave detected by the wearable. The shift in the shape of the PPG wave may be detected in a way that indicates the relative change in tissue hydration levels. However, to our knowledge, no wrist worn device that utilizes PPG has been successfully able to predict hydration status. Therefore, this study aims to utilize photoplethysmography (PPG) technology in a wearable device to accomplish this approach to hydration monitoring.

Study Overview

Status

Status

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

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.

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 (Estimated)

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.
30

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 Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

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:

  • Study subject is 18-45 years of age, inclusive
  • Subject is male or female
  • If female, subject is not pregnant, planning to get pregnant, or currently breast feeding
  • Subject is willing to avoid alcohol consumption 24 hours prior to visit(s)
  • Able to speak, write, and read English
  • Provision of written consent to participate
  • Subject is not taking medication that may interfere with the study, as indicated on the general health questionnaire (GHQ)
  • Subject has no health conditions that would prevent completion of the trial, as indicated on the GHQ
  • Subject is willing to fast overnight (no food or beverage, only water, ~8- 10 hours)
  • Subject is willing to refrain from vigorous exercise for 24 hours
  • Subject is willing to eat the exact same food the day prior to each visit to the testing site
  • Subject is willing to undergo fluid restriction to induce dehydration
  • Subject is willing to wear a wrist worn wearable device for the duration of the study

Exclusion Criteria:

  • Subject has participated or currently enrolled in a clinical trial within the past 30 days
  • Subject has participated in any PepsiCo trial within the past 3 months
  • Subject has a condition or is taking medication that the investigator believes would interfere with his/her ability to provide informed consent, comply with the study protocol, which might confound the interpretation of the study results, or put the person at undue risk, as indicated on the GHQ
  • Subject is employed by, or has a parent, guardian, or other immediate family member employed by a company that manufactures any products that compete with any Gatorade product. If subject is unsure if a company would be considered a competitor to Gatorade, they will be asked to please let the study investigator know the name of the other company and the nature of their relationship to that company before they sign the informed consent.
  • Subject has a health condition or is taking medication that can be worsened by fluid restriction, as indicated on the GHQ

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: Other
  • Allocation: Randomized
  • Interventional Model: Crossover 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.
Other: Euhydrated Group
Water provided to account for sweat loss during exercise and to maintain hydration over the 24-hour period
Other: Exercise
Perform stationary cycling exercise in the laboratory for 2 30- minute bouts at a standardized exercise intensity (wattage) that elicits 50-80% heart rate max determined by equation (208-(70% of age))
Experimental: Dehydrated Group
Fluid restriction during exercise and the remaining 24 hours
Other: Exercise
Perform stationary cycling exercise in the laboratory for 2 30- minute bouts at a standardized exercise intensity (wattage) that elicits 50-80% heart rate max determined by equation (208-(70% of age))

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
Wearable Sensr Data
Time Frame: Continuous data collection over 24 hours from start of exercise trial through completion of Day 2 measurements.
photoplethysmogram (PPG) waveform data- optical signals obtained from photoplethysmography, which measure blood volume changes in the microvascular bed of tissue.
Continuous data collection over 24 hours from start of exercise trial through completion of Day 2 measurements.
Body Mass Change
Time Frame: Change in body mass during 60 min exercise bout and over 24 hours from baseline
Change in body mass during 60 min exercise bout and over 24 hours from baseline

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
Urine Specific Gravity
Time Frame: Day 1: Baseline, post 1st and 2nd 30 min exercise sessions Day 2: 1st morning void collected at home and upon arrival at laboratory
au
Day 1: Baseline, post 1st and 2nd 30 min exercise sessions Day 2: 1st morning void collected at home and upon arrival at laboratory
Urine Volume
Time Frame: Day 1: Baseline, post 1st and 2nd 30 min exercise sessions Day 2: 1st morning void collected at home and upon arrival at laboratory
g
Day 1: Baseline, post 1st and 2nd 30 min exercise sessions Day 2: 1st morning void collected at home and upon arrival at laboratory
Urine Color
Time Frame: Day 1: Baseline, post 1st and 2nd 30 min exercise sessions Day 2: 1st morning void collected at home and upon arrival at laboratory
Scale of 1 (most hydrated) to 7 (most dehydrated)
Day 1: Baseline, post 1st and 2nd 30 min exercise sessions Day 2: 1st morning void collected at home and upon arrival at laboratory
Sweat Rate
Time Frame: Throughout entire duration of 60 min exercise bout
[Body mass loss (kg) + fluid intake (mL)]/Duration of exercise (hr)
Throughout entire duration of 60 min exercise bout
Fluid Intake
Time Frame: documented by subject on provided log for 24 hours prior to exercise and experimental trials. Exercise bouts- DEH group restricted from fluid intake. EUH group fluid measured over duration of exercise bout (60 minutes).
mL
documented by subject on provided log for 24 hours prior to exercise and experimental trials. Exercise bouts- DEH group restricted from fluid intake. EUH group fluid measured over duration of exercise bout (60 minutes).
Subjective Feelings of Thirst
Time Frame: Day 1 & 2: Following 5 min of rest
Categorical Thirst Scale, on a scale of 1 (Not thirsty at all) to 7 (very, very thirsty).
Day 1 & 2: Following 5 min of rest
Heart Rate
Time Frame: At medical screening to determine eligibility. Day 1: Prior to start of exercise bouts during 5 min rest and every 10 min throughout entire duration of each 60 min exercise trial. Day 2: During 5 min rest, prior to body weight measurement.
bpm
At medical screening to determine eligibility. Day 1: Prior to start of exercise bouts during 5 min rest and every 10 min throughout entire duration of each 60 min exercise trial. Day 2: During 5 min rest, prior to body weight measurement.
Blood pressure
Time Frame: Medical Screening to determine eligibility
systolic/diastolic (mmHg)
Medical Screening to determine eligibility
Subject Demographics
Time Frame: At baseline
Age, Sex, Race, and Ethnicity
At baseline
Dietary Intake
Time Frame: Completed for 24 hours prior to baseline and between visits.
Food intake logs
Completed for 24 hours prior to baseline and between visits.
Standardized Exercise Intensity
Time Frame: Every 10 min throughout entire duration of each 30 min exercise bout to reach 50-80% of heart rate max.
W
Every 10 min throughout entire duration of each 30 min exercise bout to reach 50-80% of heart rate max.
Rate of Perceived Exertion
Time Frame: Every 10 min throughout entire duration of each 30 min exercise bout
Borg Scale, a scale of 6 (No exertion at all) to 20 (maximal exertion)
Every 10 min throughout entire duration of each 30 min exercise bout

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.
PepsiCo Global R&D

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 (Estimated)

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.
April 1, 2026

Primary Completion (Estimated)

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.
September 1, 2026

Study Completion (Estimated)

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.
October 1, 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).
April 3, 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.
April 3, 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.
April 9, 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.
April 9, 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.
April 3, 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.
April 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

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.
  • PEP-2516

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

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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Conditions

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