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

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.

Description

Eligibility

Age range

18–35 years

Sex

All

Healthy volunteers

Yes

Interventions

• 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).

Location