James Aggett, Joe Page, Jenny Peel, Kevin John, Guilherme Matta, Jamie Tallent, Shane Heffernan, Owen Jeffries, Mark Waldron
{"title":"Acute Effects of Caffeine and Taurine Co-Ingestion on Time to Exhaustion and Thermoregulatory Responses to Cycling in the Heat","authors":"James Aggett, Joe Page, Jenny Peel, Kevin John, Guilherme Matta, Jamie Tallent, Shane Heffernan, Owen Jeffries, Mark Waldron","doi":"10.1002/ejsc.70044","DOIUrl":null,"url":null,"abstract":"<p>Caffeine and taurine are commonly co-ingested pre-exercise but elicit different thermoregulatory responses; however, their combined effect on thermoregulation is unknown. Therefore, we evaluated the effects of oral caffeine and taurine co-ingestion on time to exhaustion (TTE) and thermoregulatory responses to cycling in the heat at the gas exchange threshold (GET). Ten healthy nonheat acclimated participants took part in a double-blind crossover study, completing a TTE in the heat (35°C; 40% relative humidity), cycling at a power output associated with the GET and 1 h after ingesting: caffeine (5 mg/kg) and taurine (50 mg/kg) combined or placebo. Pulmonary gas exchange, core and mean skin temperatures and whole-body sweat rate (WBSR) were recorded throughout. Heat production was determined using partitional calorimetry. There were no differences in TTE between conditions (<i>p</i> = 0.608); however, the rate of oxygen consumption (<i>p</i> = 0.017), minute ventilation (<i>p</i> = 0.029) and heat production (<i>p</i> = 0.019) were higher following the supplement. There were no differences between conditions for skin (<i>p</i> = 0.539) and core temperature (<i>p</i> = 0.699), mean skin blood flow (<i>p</i> = 0.119), respiratory exchange ratio (<i>p</i> = 0.546) and WBSR (<i>p</i> = 0.897). Pre-exercise co-ingestion of caffeine and taurine in the heat had no ergogenic effect despite increasing the ventilatory and metabolic demand. Collectively, these data indicate minimal effects on whole-body thermoregulation.</p>","PeriodicalId":93999,"journal":{"name":"European journal of sport science","volume":"25 10","pages":""},"PeriodicalIF":3.0000,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12439788/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"European journal of sport science","FirstCategoryId":"1085","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/ejsc.70044","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
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Abstract
Caffeine and taurine are commonly co-ingested pre-exercise but elicit different thermoregulatory responses; however, their combined effect on thermoregulation is unknown. Therefore, we evaluated the effects of oral caffeine and taurine co-ingestion on time to exhaustion (TTE) and thermoregulatory responses to cycling in the heat at the gas exchange threshold (GET). Ten healthy nonheat acclimated participants took part in a double-blind crossover study, completing a TTE in the heat (35°C; 40% relative humidity), cycling at a power output associated with the GET and 1 h after ingesting: caffeine (5 mg/kg) and taurine (50 mg/kg) combined or placebo. Pulmonary gas exchange, core and mean skin temperatures and whole-body sweat rate (WBSR) were recorded throughout. Heat production was determined using partitional calorimetry. There were no differences in TTE between conditions (p = 0.608); however, the rate of oxygen consumption (p = 0.017), minute ventilation (p = 0.029) and heat production (p = 0.019) were higher following the supplement. There were no differences between conditions for skin (p = 0.539) and core temperature (p = 0.699), mean skin blood flow (p = 0.119), respiratory exchange ratio (p = 0.546) and WBSR (p = 0.897). Pre-exercise co-ingestion of caffeine and taurine in the heat had no ergogenic effect despite increasing the ventilatory and metabolic demand. Collectively, these data indicate minimal effects on whole-body thermoregulation.