The Effects of Caffeine on Exercise Physiology and Time-trial Performance in a Hot Environment
Trial statusNot yet recruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexMale
Age18-45
SponsorSt. Mary's University, Twickenham
About this trial
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.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Healthy trained runners
Disqualifiers
None
Trial design
Design model
Crossover
Treatments tested in this trial
Hot environment
Other interventionHot environment of 35 degrees Celsius
Thermoneutral environment
Other interventionThermoneutral environment of 18 degrees Celsius
Treatment groups
15 Participants
are divided into 2 treatment groupsGroup A: CaffeineExperimental treatment 2 interventions
Group B: PlaceboPlacebo comparator 2 interventions
Trial outcomes
Primary outcomes
1
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.
Time frame
From baseline to completion, up to 31 days2
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.
Time frame
From baseline to completion, up to 31 days3
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.
Time frame
From baseline to completion, up to 31 days4
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.
Time frame
From baseline to completion, up to 31 daysLocations
Sponsors and contacts
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Source ClinicalTrials.gov
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