Body clock vs. workout clock: can exercising at the 'wrong' time weaken your legs?
NCT ID NCT07711340
First seen Jul 17, 2026 · Last updated Jul 17, 2026
Summary
This study looks at whether exercising at an unexpected time of day affects leg strength and performance. Healthy adults aged 18-25 who usually exercise at the same time each day will be asked to work out three hours earlier or later than normal. Researchers will measure their leg muscle strength to see if the change in timing makes a difference.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- time-driven dosing (behavioral intervention: exercising three hours earlier or later than usual)
- What this could lead to
- If it works, this could help athletes and coaches optimize training schedules for better performance.
- What could go wrong
- This is a small, early-stage study with only 20 participants, so results may not apply to everyone. The effect of timing on performance may be small or absent.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Not a phased trial
Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.
- Participants
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About 20 people
The number the study aims to enrol. It can still change while the study runs.
- Expected to start
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Aug 2026
An estimate. Start dates often move.
- Expected to finish
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Dec 2026
An estimate. End dates often move.
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 to 25 years
- Sex
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Anyone
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: * Healthy * 18-25 years old * Lower body exercise three or more times per week, all at the same time of day (within 2 hour window) * Regular meal times (±1 hour window) * Regular sleep times (±1 hour window) Exclusion Criteria: * Active or uncontrolled mental or physical health issues * Current musculoskeletal injury
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The places running it
1 site. The list below names each one and where it is.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Locations
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Stanford University
Stanford, California, 94305, United States
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