NCT05919979

Brief Summary

This study explores the impact of high-intensity exercise during fasting on energy metabolism and cognitive function in healthy adults. Changes in respiratory exchange ratio, blood substances, and cognitive performance will be measured after 24 and 34 hours of fasting with and without exercise in a randomized crossover design.

Trial Health

87
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
25

participants targeted

Target at below P25 for not_applicable

Timeline
Completed

Started May 2023

Typical duration for not_applicable

Geographic Reach
1 country

1 active site

Status
completed

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

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Study Timeline

Key milestones and dates

Study Start

First participant enrolled

May 29, 2023

Completed
7 days until next milestone

First Submitted

Initial submission to the registry

June 5, 2023

Completed
22 days until next milestone

First Posted

Study publicly available on registry

June 27, 2023

Completed
2 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

June 11, 2025

Completed
7 days until next milestone

Study Completion

Last participant's last visit for all outcomes

June 18, 2025

Completed
Last Updated

December 26, 2025

Status Verified

December 1, 2025

Enrollment Period

2 years

First QC Date

June 5, 2023

Last Update Submit

December 18, 2025

Conditions

Energy Metabolism

Outcome Measures

Primary Outcomes (1)

  • Respiratory Exchange Ratio

    24-hour after starting the fasting period

Secondary Outcomes (11)

  • Respiratory Exchange Ratio

    34-hour after starting the fasting period

  • Serum insulin concentration

    24-hour after starting the fasting period

  • Serum insulin concentration

    34-hour after starting the fasting period

  • Serum glucose concentration

    24-hour after starting the fasting period

  • Serum glucose concentration

    34-hour after starting the fasting period

  • +6 more secondary outcomes

Study Arms (2)

Fasting, then fasting+exercise

EXPERIMENTAL
Behavioral: 34-hour fasting in sedentary conditionsBehavioral: 34-hour fasting with high-intensity exercise

Fasting + Exercise, then fasting

EXPERIMENTAL
Behavioral: 34-hour fasting in sedentary conditionsBehavioral: 34-hour fasting with high-intensity exercise

Interventions

34-hour fasting in sedentary conditionsBEHAVIORAL

Participants will fast for 34h after a standardized breakfast, refraining from physical activity.

Fasting + Exercise, then fastingFasting, then fasting+exercise
34-hour fasting with high-intensity exerciseBEHAVIORAL

Participants will fast for 34h after a standardized breakfast, performing a high-intensity exercise session 6-10 hours aprox. after starting the fasting period.

Fasting + Exercise, then fastingFasting, then fasting+exercise

Eligibility Criteria

Age18 Years - 40 Years
Sexall
Healthy VolunteersYes
Age GroupsAdult (18-64)

You may qualify if:

  • years old.
  • Body mass index: 18.5-30.0 Kg/m2.
  • Stable body weight (5kg range within the last 3 months)
  • Being able to consume all the food items provided as part of the study.
  • Not having change the time zone or have shifted sleeping hours equivalent to more than 3 hours on the previous 2 weeks.

You may not qualify if:

  • Diagnosed with any chronic condition that, in the research team's opinion or based on the American College of Sports Medicine guidelines, could contraindicate the implementation of 34-hour fasting periods and/or high-intensity exercise.
  • Diagnosed with a chronic endocrine, digestive, rheumatic, neurological, cardiac, pulmonary, autoimmune, or infectious condition that affects energy metabolism.
  • Presenting any signs or symptoms of illness that, in the research team's opinion or based on the American College of Sports Medicine guidelines, could contraindicate the implementation of 34-hour fasting periods and/or high-intensity exercise.
  • Pregnant or breastfeeding.
  • Using medications or supplements that may alter energy metabolism.
  • Currently undergoing or having undergone any type of nutritional intervention or treatment in the past 3 months.
  • Engaging in more than 5 hours per week of habitual moderate-to-vigorous cycling.
  • Any other condition that, in the research team's opinion, discourages participation in the study.

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (1)

Instiuto Mixto Universitario Deporte y Salud

Granada, Granada, 18007, Spain

Location

Study Design

Study Type
interventional
Phase
not applicable
Allocation
RANDOMIZED
Masking
NONE
Purpose
BASIC SCIENCE
Intervention Model
CROSSOVER
Sponsor Type
OTHER
Responsible Party
PRINCIPAL INVESTIGATOR
PI Title
Principal Investigator

Study Record Dates

First Submitted

June 5, 2023

First Posted

June 27, 2023

Study Start

May 29, 2023

Primary Completion

June 11, 2025

Study Completion

June 18, 2025

Last Updated

December 26, 2025

Record last verified: 2025-12

Locations

ES(1)