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

Conditions

• Hydration Status
• Substrate Metabolism During Exercise

Eligibility Criteria

Sex

ALL

Age

18 Years - 35 Years

Healthy Volunteers

Accepted

Interventions

• Exercise Trial — OTHER
  Perform steady-state cycling exercise for approximately 1 hour at 70-80% of maximal heart rate
• 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).

Study Details

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.

Key Dates

Start date

Nov 5, 2025

Status verified

Feb 2026

Primary completion

Apr 1, 2026

Completion

Apr 30, 2026

Study Design

Enrollment

74 participants (estimated)

Allocation

RANDOMIZED

Intervention model

CROSSOVER

Primary purpose

OTHER

Arms

• Other: Dehydrated control trial
  Fluid restriction during exercise and for remaining 24 hours
• Other: Euhydrated with water
  Euhydrated with water to account for sweat loss and to maintain hydration over 24-hour period
• Experimental: Euhydrated with electrolyte beverage
  Euhydrated with electrolyte beverage (220 mg sodium in 20 oz) to account for sweat loss and to maintain hydration over 24-hour period

Primary Outcome Measure

Respiratory Exchange Ratio [ Time Frame: Measured over the course of exercise bouts performed during the exercise and experimental trials. Compared across DEH, EUH-H2O, and EUH-Electrolyte arms. ]

Central Contacts

• Matt Hinkley
  570-574-1858
  [email protected]

Locations (1)

Find similar trials in Valhalla, NY

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