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.

Study Overview

• Status: Recruiting
• Conditions: Hydration Status
• Intervention / Treatment: Other: Exercise

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Anthony Wolfe; Phone Number: 574-315-5901; Email: anthony.wolfe@pepsico.com

Study Locations

• United States
  • Texas
    • Frisco, Texas, United States, 75034
      • Recruiting
      • PepsiCo R&D
      • Contact: Anthony Wolfe; Phone Number: 574-315-5901; Email: anthony.wolfe@pepsico.com
    • Plano, Texas, United States, 75024
      • Recruiting
      • PepsiCo R&D
      • Contact: Anthony Wolfe; Phone Number: 574-315-5901; Email: anthony.wolfe@pepsico.com

Participation Criteria

Eligibility Criteria

• 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

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
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

Outcome Measure	Measure Description	Time Frame
Wearable Sensr Data	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		Change in body mass during 60 min exercise bout and over 24 hours from baseline

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Urine Specific Gravity	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	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	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	[Body mass loss (kg) + fluid intake (mL)]/Duration of exercise (hr)	Throughout entire duration of 60 min exercise bout
Fluid Intake	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	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	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	systolic/diastolic (mmHg)	Medical Screening to determine eligibility
Subject Demographics	Age, Sex, Race, and Ethnicity	At baseline
Dietary Intake	Food intake logs	Completed for 24 hours prior to baseline and between visits.
Standardized Exercise Intensity	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	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

• Sponsor: PepsiCo Global R&D

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): September 1, 2026
• Study Completion (Estimated): October 1, 2026

Study Registration Dates

• First Submitted: April 3, 2026
• First Submitted That Met QC Criteria: April 3, 2026
• First Posted (Actual): April 9, 2026

Study Record Updates

• Last Update Posted (Actual): April 9, 2026
• Last Update Submitted That Met QC Criteria: April 3, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Motor Activity; Movement; Musculoskeletal Physiological Phenomena; Musculoskeletal and Neural Physiological Phenomena; Exercise
• Other Study ID 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