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NCT Number: NCT07520344

Wearable Photoplethysmography for Non-invasive Hydration Assessment

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.

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Key information

Conditions

Hydration Status

Age range

18 year–45 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

PepsiCo R&D, Frisco, Texas, United States

Loading trial locations.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Exercise

Other

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))

Primary outcomes

  1. 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.

  2. Body Mass Change

    Time frame: Change in body mass during 60 min exercise bout and over 24 hours from baseline

Secondary outcomes

  1. 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

  2. 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

  3. 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)

  4. Sweat Rate

    Time frame: Throughout entire duration of 60 min exercise bout

    [Body mass loss (kg) + fluid intake (mL)]/Duration of exercise (hr)

  5. 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

  6. 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).

  7. 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

  8. Blood pressure

    Time frame: Medical Screening to determine eligibility

    systolic/diastolic (mmHg)

  9. Subject Demographics

    Time frame: At baseline

    Age, Sex, Race, and Ethnicity

  10. Dietary Intake

    Time frame: Completed for 24 hours prior to baseline and between visits.

    Food intake logs

  11. 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

  12. 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)

Study contacts

Contact information is provided by the study sponsor or research team.

Anthony Wolfe

CONTACT

[email protected]

574-315-5901

Sponsors and collaborators

Lead sponsor

PepsiCo Global R&D

Industry

Registry information

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Apr 9, 2026
Registry last updated
Apr 9, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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