The Effect of Hydration Status on Substrate Oxidation at Rest and During Light and Moderate Exercise

NCT07298863 | Active Not Recruiting

• 1 other identifier: PEP-2507
• Study Type: interventional
• Target: 104
• Locations: 2 countries
• Sites: 2

Brief Summary

Metabolic flexibility is the ability to properly switch between fat and carbohydrate stores to use for energy under different conditions (rest, feeding, exercise). Impairments in metabolic flexibility, also known as metabolic inflexibility, have been suggested to be an underlying cause of metabolic disease, like type 2 diabetes. Long-term low fluid intake may increase the risk of type 2 diabetes due to insulin resistance, a form of metabolic inflexibility. Further, low fluid intake has been shown to impair the ability to switch fuel preference during exercise. While there is some evidence that low fluid intake may lead to impaired metabolic flexibility, more information is needed. Therefore, the purpose of this study is to evaluate the impact of hydration status on substrate preference at rest and during exercise at varying intensities (light and moderate). Further, we will examine whether biological sex and menstrual cycle phase impact hydration and metabolism under these same conditions.

Conditions

Hydration Status; Substrate Metabolism During Exercise

Keywords

hydration; metabolism; fluid retention

Outcome Measures

Primary Outcomes (2)

• Respiratory Exchange Ratio

  Part 1 only. VCO2 / VO2 measured using indirect calorimetry measured by metabolic cart (Moxus or similar device) while exercising on cycle ergometer.

  Measured over the course of exercise bouts performed during the exercise and experimental trials. Compared across DEH, EUH-H2O, and EUH-Electrolyte arms.

• Blood glucose levels

  Part 2 only. mg/dL

  baseline and 120-minutes following glucose ingestion for both the dehydration and euhydrated interventions

Secondary Outcomes (28)

• Body Mass

  Exercise - after bladder void at baseline, post 1st and 2nd 30 min exercise sessions, and post 20 min rest. Experimental -after bladder void at baseline, post 10 min rest, post 1st and 2nd 30 min exercise sessions, and post 20 min rest. OGTT- pre & post

• Plasma copeptin concentration

  Exercise trial- Post 10 min rest, pre-exercise bout. Experimental trial- Post 10 min rest, pre indirect calorimetry; post 1st and 2nd 30 min exercise bout; post 20 min rest. OGTT- every 30 min over 2 hour OGTT.

• Plasma osmolality

  Exercise trial- Post 10 min rest, pre-exercise bout. Experimental trial- Post 10 min rest, pre indirect calorimetry; post 1st and 2nd 30 min exercise bout; post 20 min rest. OGTT- every 30 min over 2 hour OGTT.

• Blood glucose

  At medical screening to determine eligibility. Exercise trial- Post 10 min rest, pre-exercise bout. Experimental trial- Post 10 min rest, pre indirect calorimetry; post 1st and 2nd 30 min exercise bout; post 20 min rest.

• Blood lactate

  Exercise trial- Post 10 min rest, pre-exercise bout. Experimental trial- Post 10 min rest, pre indirect calorimetry; post 1st and 2nd 30 min exercise bout; post 20 min rest. OGTT- every 30 min over 2 hour OGTT.

Study Arms (5)

Part 1- Dehydrated control trial

OTHER

Fluid restriction during exercise and for remaining 24 hours

Other: Part 1 - Exercise Trial; Other: Part 1 - Experimental Trial

Part 1 - Euhydrated with water

OTHER

Euhydrated with water to account for sweat loss and to maintain hydration over 24-hour period

Other: Part 1 - Exercise Trial; Other: Part 1 - Experimental Trial

Part 1 - Euhydrated with electrolyte beverage

EXPERIMENTAL

Euhydrated with electrolyte beverage (220 mg sodium in 20 oz) to account for sweat loss and to maintain hydration over 24-hour period

Other: Part 1 - Exercise Trial; Other: Part 1 - Experimental Trial

Part 2 - Euhydrated with water and electrolyte beverage

EXPERIMENTAL

Euhydrated with water and electrolyte beverage to maintain euhydration status over 3-day study period

Other: Part 2 - Oral Glucose Tolerance Test

Part 2 - Dehydration

OTHER

fluid restriction during experimental period (3 days),

Other: Part 2 - Oral Glucose Tolerance Test

Interventions

Part 1 - Exercise Trial OTHER

Perform steady-state cycling exercise for approximately 1 hour at 70-80% of maximal heart rate

Part 1 - Euhydrated with electrolyte beverage; Part 1 - Euhydrated with water; Part 1- Dehydrated control trial

Part 1 - Experimental Trial OTHER

24h after exercise trial, following assigned 24h hydration plan, perform indirect calorimetry followed by 30 min of light cycling (\~50% VO2 max) then 30 min of moderate-high cycling (\~80% VO2 max).

Part 1 - Euhydrated with electrolyte beverage; Part 1 - Euhydrated with water; Part 1- Dehydrated control trial

Part 2 - Oral Glucose Tolerance Test OTHER

a 2-hour oral glucose tolerance test

Part 2 - Dehydration; Part 2 - Euhydrated with water and electrolyte beverage

Eligibility Criteria

• Age: 18 Years - 35 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Subject is male or female
• If female, subject is not pregnant
• If female, subject has stopped taking birth control medication or removed long-acting reversible contraceptive \>6 months at start of the study
• If female, subject has normal menstrual cycle (25-35 days)
• If female, subject is currently tracking their menstrual cycle using a smartphone application
• If female subject is taking iron supplement, they are willing to continue supplementation during entire study
• If female, subject has a smartphone compatible for application to track menstrual cycle
• Subject is 18-35 years of age, inclusive
• Subject body mass index (BMI) is between 18.5-25 kg/m2
• Subject is at least recreationally active (engaged in moderate-intensity, intermittent, or steady-state exercise at least 3 days per week for at least 60 min at a time)
• Subject is accustomed to cycling for at least 60 min (Part 1 only)
• Subject does not smoke (or has quit for at least 6 months)
• Subject is not taking medication that may interfere with the study (e.g., diuretics, laxatives, or weight loss drugs)
• Subject has no health conditions that would interfere with the study
• As indicated on the general health questionnaire (GHQ)

You may not qualify if:

• Subject has participated in a clinical trial within the past 30 days
• Subject has participated in any PepsiCo trial within past 3 months (with the exception of Part 1 participants)
• 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
• Subject is allergic to alcohol (alcohol prep pads are used for blood draws).
• If female, subject is taking birth control medication or has long-acting reversible contraceptive
• If female, subject is anemic
• If male, subject is undergoing hormone therapy to alter testosterone levels (injections, transdermal patch, pill, etc.)
• 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.

Sponsors & Collaborators

• PepsiCo Global R&D: lead
• PeakGenics Innovation Inc.: collaborator

Study Sites (2)

Gatorade Sports Science Institute

Valhalla, New York, 10595, United States

Location

PeakGenics Innovation InPeakGenics Innovation Incc

Newcastle, Ontario, L1B0A9, Canada

Location

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: Randomized, controlled, cross-over study (counterbalanced).

Study Record Dates

• First Submitted: November 24, 2025
• First Posted: December 23, 2025
• Study Start: November 5, 2025
• Primary Completion: September 1, 2026
• Study Completion: September 1, 2026
• Last Updated: August 27, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

US (1); CA (1)