NCT07298863

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

• Status: Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 74 (estimated)
• Sponsor: PepsiCo Global R&D · Industry
• Sex: All
• Age: 18 Years – 35 Years
• Healthy volunteers: Accepted

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.

Detailed description

The 3-arm intervention will be completed in females during both the follicular and luteal phases for a total of 13 visits including the medical screening. In males, the 3-arm intervention will be completed once for a total of 7 visits including the medical screening.

Conditions

• Hydration Status
• Substrate Metabolism During Exercise

Interventions

Type	Name	Description
OTHER	Exercise Trial	Perform steady-state cycling exercise for approximately 1 hour at 70-80% of maximal heart rate
OTHER	Experimental Trial	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).

Timeline

• Start date: 2025-11-05
• Primary completion: 2026-04-01
• Completion: 2026-04-30
• First posted: 2025-12-23
• Last updated: 2026-03-03

Locations

1 site across 1 country: United States