CaffeineNCT07129200
The Effects of Caffeine on Exercise Physiology and Time-trial Performance in a Hot Environment
A study testing Hot environment and Thermoneutral environment in people with Caffeine and Thermoregulation, run by St. Mary's University, Twickenham.
Trial summary
Maintaining a stable core temperature is vital for physiological function; yet, exercise in heat can be problematic, and there is risk of exertional heat-related illness (Flouris \& Schlader, 2015; Leyk et al., 2019; Périard et al., 2021; Tyler et al., 2016; Veltmeijer et al., 2015). Read more about this study
- Who is it for?
- Ages 18 to 45 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Caffeine, Thermoregulation
- What is being tested?
- Hot environment and Thermoneutral environment
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 15 participants
- Where
- No sites listed yet
- Study dates
- 22 Aug 2025to 30 Jun 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 45 years
- Men only
- Healthy volunteers accepted
- Adult
Who may be able to join
- Healthy trained runners
Who cannot join
- -
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: The Effects of Caffeine Supplementation on Exercise Physiology and Time-trial Performance in a Hot Environment
Maintaining a stable core temperature is vital for physiological function; yet, exercise in heat can be problematic, and there is risk of exertional heat-related illness (Flouris \& Schlader, 2015; Leyk et al., 2019; Périard et al., 2021; Tyler et al., 2016; Veltmeijer et al., 2015). While aerobic fitness improves heat tolerance (Alhadad et al., 2019), strategies like acclimation and pre-cooling also mitigate heat stress (Casadio et al., 2016; Lorenzo et al., 2010; Ross et al., 2013; Siegel et al., 2010). Caffeine, an ergogenic aid (Del Corso et al., 2011; John et al., 2024), is known to enhance performance via adenosine antagonism and increased catecholamines in normothermic environments (Fredholm et al., 1999; Graham \& Spriet, 1991). However, effects in heat are inconsistent (Ganio et al., 2009; Zhang et al., 2014), possibly due to caffeine reducing the ability to thermoregulate effectively. Therefore, the aim of this study is to investigate the effects of a moderate dose of caffeine (5 mg/kg) on thermoregulation during a 30-minute running time trial in 35°C heat.
- Conditions
- Caffeine, Thermoregulation
- Being tested
- Hot environment, Thermoneutral environment
- Keywords
- caffeine, thermoregulation, time trial, exercise physiology
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Hot environmentOther
Hot environment of 35 degrees Celsius
Thermoneutral environmentOther
Thermoneutral environment of 18 degrees Celsius
| Study group | Role | What they receive |
|---|---|---|
| Caffeine | Experimental | 5 mg/kg dose of caffeine (in pill form) Receives: Other: Hot environment; Other: Thermoneutral environment |
| Placebo | Placebo comparator | 5 mg/kg dose of placebo (maltodextrin - in pill form) Receives: Other: Hot environment; Other: Thermoneutral environment |
What is being measured
The primary outcome is the main question the study is designed to answer.
Blood lactate concentration
Change from baseline in blood lactate concentration measured at rest and at five different exercise intensities (65, 70, 75, 80, and 85% percent of maximal oxygen uptake) on a treadmill.
Measured: From baseline to completion, up to 31 days
Heart rate
Change from baseline in heart rate measured at rest and at five different exercise intensities (65, 70, 75, 80, and 85% percent of maximal oxygen uptake) on a treadmill.
Measured: From baseline to completion, up to 31 days
Rating of perceived exertion
Change from baseline in rating of perceived exertion measured (using the 6-20 Borg scale) at five different exercise intensities (65, 70, 75, 80, and 85% percent of maximal oxygen uptake) on a treadmill.
Measured: From baseline to completion, up to 31 days
Oxygen uptake
Change from baseline in oxygen uptake measured at five different exercise intensities (65, 70, 75, 80, and 85% percent of maximal oxygen uptake) on a treadmill.
Measured: From baseline to completion, up to 31 days
Time trial performance
Change from baseline in distance covered during a 30 minute time trial on a treadmill.
Measured: From baseline to completion, up to 31 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Aug 2025
- Study start22 Aug 2025 (estimated)
- Primary completion30 Apr 2026 (estimated)
- Study completion30 Jun 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for CaffeineStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 15 participants (estimated)
Sponsor and investigators
- Lead sponsor
- St. Mary's University, Twickenham
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07129200
- Sponsor's protocol ID
- SMU_ETHICS_2024-25_1111
- Status last verified
- Aug 2025
- First submitted
- 12 Aug 2025
- Last updated
- 19 Aug 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 19 Aug 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effects of Caffeine Supplementation on Exercise Physiology and Time-trial Performance in a Hot Environment
- ClinicalTrials.gov ID
- NCT07129200
- Acronym / sponsor ID
- SMU_ETHICS_2024-25_1111
- Conditions
- Caffeine, Thermoregulation
- Keywords
- caffeine, thermoregulation, time trial, exercise physiology
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 15 participants (estimated)
- Lead sponsor
- St. Mary's University, TwickenhamUniversity, hospital or other
- Study start
- 22 Aug 2025 (estimated)
- Primary completion
- 30 Apr 2026 (estimated)
- Study completion
- 30 Jun 2026 (estimated)
- First posted
- 19 Aug 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Maintaining a stable core temperature is vital for physiological function; yet, exercise in heat can be problematic, and there is risk of exertional heat-related illness (Flouris \& Schlader, 2015; Leyk et al., 2019; Périard et al., 2021; Tyler et al., 2016; Veltmeijer et al., 2015). While aerobic fitness improves heat tolerance (Alhadad et al., 2019), strategies like acclimation and pre-cooling also mitigate heat stress (Casadio et al., 2016; Lorenzo et al., 2010; Ross et al., 2013; Siegel et al., 2010). Caffeine, an ergogenic aid (Del Corso et al., 2011; John et al., 2024), is known to enhance performance via adenosine antagonism and increased catecholamines in normothermic environments (Fredholm et al., 1999; Graham \& Spriet, 1991). However, effects in heat are inconsistent (Ganio et al., 2009; Zhang et al., 2014), possibly due to caffeine reducing the ability to thermoregulate effectively. Therefore, the aim of this study is to investigate the effects of a moderate dose of caffeine (5 mg/kg) on thermoregulation during a 30-minute running time trial in 35°C heat.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Caffeine | Experimental | Other: Hot environment, Other: Thermoneutral environment5 mg/kg dose of caffeine (in pill form) |
| Placebo | Placebo comparator | Other: Hot environment, Other: Thermoneutral environment5 mg/kg dose of placebo (maltodextrin - in pill form) |
Who may qualify
- Ages
- 18 to 45 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (1 listed)
- Healthy trained runners
Key exclusion criteria (1 listed)
- -
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Hot environmentHot environment of 35 degrees Celsius | Other | Caffeine, Placebo |
| Thermoneutral environmentThermoneutral environment of 18 degrees Celsius | Other | Caffeine, Placebo |
Primary outcome
Blood lactate concentration
Time frame: From baseline to completion, up to 31 days
Change from baseline in blood lactate concentration measured at rest and at five different exercise intensities (65, 70, 75, 80, and 85% percent of maximal oxygen uptake) on a treadmill.
Heart rate
Time frame: From baseline to completion, up to 31 days
Change from baseline in heart rate measured at rest and at five different exercise intensities (65, 70, 75, 80, and 85% percent of maximal oxygen uptake) on a treadmill.
Rating of perceived exertion
Time frame: From baseline to completion, up to 31 days
Change from baseline in rating of perceived exertion measured (using the 6-20 Borg scale) at five different exercise intensities (65, 70, 75, 80, and 85% percent of maximal oxygen uptake) on a treadmill.
Oxygen uptake
Time frame: From baseline to completion, up to 31 days
Change from baseline in oxygen uptake measured at five different exercise intensities (65, 70, 75, 80, and 85% percent of maximal oxygen uptake) on a treadmill.
Time trial performance
Time frame: From baseline to completion, up to 31 days
Change from baseline in distance covered during a 30 minute time trial on a treadmill.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 19 Aug 2025.
Related trials for Caffeine
RecruitingPhase 4
Improving Morning Strength and Cognitive Performance Using Caffeine or Whole-body Vibration.
Vibration Therapy, Caffeine
Active, not recruiting
The REVIVE-PEEP Trial: Positive End-expiratory Pressure Versus Sham Valve/Zero End-expiratory Pressure in Cardiopulmonary Resuscitation During Manual Ventilation to Improve Neurological Outcomes at Discharge in Adult Patients Suffering an Out-of-hospital Cardiac Arrest
Cardiac Arrest, Out-Of-Hospital
Recruiting
The Effect of Short-term Supplementation of OliPhenolia® on Fat Oxidation
Healthy
Active, not recruitingPhase 4
A Study to See if an Energy Drink With Caffeine and Green Tea Increases Fat Burning When Exercising
Exercise
Not yet recruitingPhase 2
CAffeine Use in Prolonged Oxygen Use in meConium aspIration Syndrome in Neonatal Outcomes (CAPUCINO)
Meconium Aspiration Syndrome
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Questions about this trial
What is this clinical trial studying?
A study testing Hot environment and Thermoneutral environment in people with Caffeine and Thermoregulation, run by St. Mary's University, Twickenham.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 19 Aug 2025. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Mark Glaister (+447957616552, mark.glaister@stmarys.ac.uk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Blood lactate concentration (time frame: From baseline to completion, up to 31 days). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 19 Aug 2025.