An interventional study of Creatine Monohydrate and Maltodextrin (Placebo) in Heat Exposure, Exercise Performance and Hydration, sponsored by University of Windsor. Not yet recruiting. Open to male participants aged 18 Years to 27 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-05-18.
Sponsored by University of Windsor · Not applicable, Interventional, and Basic science
The goal of this clinical trial is to learn whether creatine supplementation changes how the body adapts to repeated exercise in the heat in healthy recreationally active adults and varsity athletes. The study will also examine whether creatine affects fluid balance, blood volume changes and exercise performance.
The main questions it aims to answer are:
Does creatine supplementation increase plasma volume and total body water during repeated heat exposure more than placebo? Does creatine supplementation improve exercise performance after heat acclimation more than placebo? Does creatine supplementation influence cardiovascular responses to heat stress?
Researchers will compare a creatine supplementation group to a placebo group to determine whether creatine changes the magnitude of heat acclimation adaptations.
Participants will:
Complete baseline measurements of body composition, hydration, blood markers, and exercise performance.
Consume either creatine monohydrate or a placebo supplement daily Complete repeated supervised exercise sessions in a controlled heated environment Undergo repeated assessments of body water, temperature, heart rate, and exercise performance throughout the study
Heat acclimation (HA) is a physiological adaptation process that occurs following repeated exposure to hot environmental conditions. HA is associated with several beneficial cardiovascular and thermoregulatory adaptations, including plasma volume expansion, improved heat tolerance, lower physiological strain during exercise, and improved exercise performance in hot and temperate environments. However, substantial variability exists in the magnitude and rate of adaptation between individuals.
Creatine monohydrate supplementation is widely used to improve high-intensity exercise performance and is known to increase intracellular water retention within skeletal muscle. Because HA also influences fluid regulation and plasma volume expansion, creatine supplementation may alter fluid distribution and cardiovascular responses during repeated heat exposure. Despite this theoretical interaction, limited research has investigated the combined effects of creatine supplementation and HA on fluid balance and exercise performance.
The purpose of this randomized, double-blind, placebo-controlled trial is to examine whether creatine monohydrate supplementation influences body-fluid distribution, plasma volume expansion, and exercise performance during repeated heat exposure in healthy recreationally active males and varsity athletes.
Participants will complete baseline testing consisting of body composition assessment, body water measurement, capillary blood sampling, resting temperature assessment, and cardiorespiratory and musculoskeletal performance testing using cycle ergometry. Participants will then be randomly assigned to receive either creatine monohydrate or a placebo supplement under double-blind conditions.
The supplementation protocol will include a 7-day loading phase followed by a maintenance phase throughout the remainder of the study. Following supplementation, participants will complete 7 consecutive days of supervised heat exposure consisting of moderate-intensity cycling in a heated environment designed to elevate body temperature and induce heat acclimation adaptations.
Throughout the study, researchers will assess changes in plasma volume, total body water, resting temperature, heart rate responses, and exercise performance. Physiological monitoring will occur during all heat exposure sessions to support participant safety.
The findings from this study may improve understanding of how creatine supplementation influences fluid regulation and adaptation to heat stress. Results may have implications for athletes, physically active individuals, and occupational populations exposed to hot environmental conditions.
Exclusion Criteria:
Participants assigned to this arm will complete a 7-day creatine monohydrate loading phase followed by daily maintenance supplementation during a 7-day heat acclimation protocol. Participants will complete daily supervised heat exposure sessions consisting of cycling exercise in a controlled hot environment.
Dietary Supplement: Creatine Monohydrate
Participants assigned to this arm will consume a placebo supplement (maltodextrin) matched in appearance and dosing schedule to the creatine condition during a 7-day heat acclimation protocol. Participants will complete daily supervised heat exposure sessions consisting of cycling exercise in a controlled hot environment.
Dietary Supplement: Maltodextrin (Placebo)
Participants assigned to this intervention will consume micronized creatine monohydrate during a 7-day loading phase at 0.3 g·kg-¹·day-¹ followed by a maintenance dose of 0.03 g·kg-¹·day-¹ during the heat acclimation protocol. Supplements will be dissolved in orange juice and consumed under supervision during laboratory visits. Creatine supplementation will continue throughout the heat acclimation period.
Participants will consume maltodextrin matched to creatine supplementation appearance and dosing schedule during the loading and maintenance phases of the study.
Plasma Volume Change Following Heat Acclimation and Creatine Supplementation
Percent change in plasma volume estimated from capillary blood hematocrit measurements. Following centrifugation, packed red blood cell volume and plasma layers will be measured using a microhematocrit reader, and hematocrit will be expressed as a percentage of total blood volume. Relative changes in blood volume and plasma volume will be inferred from repeated hematological measurements obtained at standardized time points throughout the study.
Time frame: Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
Change in Total Body Water
Total body water measured using bioelectrical impedance analysis (InBody 230).
Time frame: Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
Change in Intracellular Water
Intracellular water estimated using bioelectrical impedance analysis.
Time frame: Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
Change in Extracellular Water
Extracellular water estimated using bioelectrical impedance analysis.
Time frame: Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
Change in VO₂ Peak
VO₂ peak assessed during supramaximal cycling exercise using breath-by-breath metabolic gas analysis.
Time frame: Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
Change in Musculoskeletal Performance
Musculoskeletal performance assessed during supramaximal cycling exercise using peak and mean power output measures.
Time frame: Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
No study locations are listed for this record.
Plan to share: No
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University of Windsor