NCT07129200

The Effects of Caffeine on Exercise Physiology and Time-trial Performance in a Hot Environment

The Effects of Caffeine Supplementation on Exercise Physiology and Time-trial Performance in a Hot Environment

• Status: Not Yet Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 15 (estimated)
• Sponsor: St. Mary's University, Twickenham · Academic / Other
• Sex: Male
• Age: 18 Years – 45 Years
• Healthy volunteers: Accepted

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). 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

Interventions

Type	Name	Description
OTHER	Hot environment	Hot environment of 35 degrees Celsius
OTHER	Thermoneutral environment	Thermoneutral environment of 18 degrees Celsius

Timeline

• Start date: 2025-08-22
• Primary completion: 2026-04-30
• Completion: 2026-06-30
• First posted: 2025-08-19
• Last updated: 2025-08-19