Effects of Creatine and Heat Exposure on Exercise Performance and Body Water Distribution

NCT07593014 | Not Yet Recruiting

• 1 other identifier: #26-057
• Study Type: interventional
• Target: 25
• Locations: 0 countries
• Sites: N/A

Brief Summary

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

Conditions

Hydration; Body Fluid Compartments; Placebo - Control; Plasma Volume; Heat Exposure; Creatine Supplementation; Exercise Performance

Keywords

Creatine Monohydrate; Heat Exposure; Heat Acclimation; Short Term Heat Acclimation; Plasma Volume; Fluid Balance; Body Fluid Compartments; Wingate Test; VO2 Max; Cardiorespiratory Performance; Musculoskeletal Performance

Outcome Measures

Primary Outcomes (1)

• 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.

  Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.

Secondary Outcomes (5)

• Change in Total Body Water

  Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.

• Change in Intracellular Water

  Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.

• Change in Extracellular Water

  Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.

• Change in VO₂ Peak

  Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.

• Change in Musculoskeletal Performance

  Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.

Study Arms (2)

Creatine Monohydrate + Heat Exposure

EXPERIMENTAL

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

Placebo + Heat Exposure

PLACEBO COMPARATOR

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)

Interventions

Creatine Monohydrate DIETARY_SUPPLEMENT

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.

Creatine Monohydrate + Heat Exposure

Maltodextrin (Placebo) DIETARY_SUPPLEMENT

Participants will consume maltodextrin matched to creatine supplementation appearance and dosing schedule during the loading and maintenance phases of the study.

Placebo + Heat Exposure

Eligibility Criteria

• Age: 18 Years - 27 Years
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy biological males between 18 and 27 years of age
• Recreationally active males and varsity athletes
• Able to safely participate in moderate-intensity exercise and heat exposure
• Willing to maintain habitual diet and physical activity throughout the study
• Willing to refrain from additional dietary supplementation during study participation
• Able to attend all required laboratory visits and heat exposure sessions
• Able to provide informed consent

You may not qualify if:

• History of cardiovascular, metabolic, respiratory, renal, neurological, or heat-related illness
• Contraindications to exercise testing or heat exposure identified during health screening
• Current musculoskeletal injury limiting exercise participation
• Current use of creatine supplementation or inability to complete the required washout period
• Current use of medications or supplements known to affect hydration, thermoregulation, cardiovascular function, or exercise performance
• Known allergy or intolerance to creatine monohydrate, maltodextrin, or orange juice
• Inability to comply with study procedures or supplementation protocol
• Resting tympanic temperature ≥38.0°C prior to a heat exposure session
• Participation in another research study that may interfere with this protocol

Sponsors & Collaborators

• University of Windsor: lead

Related Publications (6)

• Wenger CB (2003). Human adaptation to hot environments. In K. B. Pandolf, M. N. Sawka, & R. R. Gonzalez (Eds.), Human performance physiology and environmental medicine at terrestrial extremes (pp. 379-438). Benchmark Press.

  BACKGROUND

• Mack, G.W. and Nadel, E.R. (1994), Body Fluid Balance During Heat Stress in Humans. Comprehensive Physiology, 1994: 187-214. https://doi.org/10.1002/j.2040-4603.1994.tb01156.x

  BACKGROUND

• Periard JD, Racinais S, Sawka MN. Adaptations and mechanisms of human heat acclimation: Applications for competitive athletes and sports. Scand J Med Sci Sports. 2015 Jun;25 Suppl 1:20-38. doi: 10.1111/sms.12408.

  PMID: 25943654 BACKGROUND

• Lorenzo S, Halliwill JR, Sawka MN, Minson CT. Heat acclimation improves exercise performance. J Appl Physiol (1985). 2010 Oct;109(4):1140-7. doi: 10.1152/japplphysiol.00495.2010. Epub 2010 Aug 19.

  PMID: 20724560 BACKGROUND

• Kreider RB, Kalman DS, Antonio J, Ziegenfuss TN, Wildman R, Collins R, Candow DG, Kleiner SM, Almada AL, Lopez HL. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr. 2017 Jun 13;14:18. doi: 10.1186/s12970-017-0173-z. eCollection 2017.

  PMID: 28615996 BACKGROUND

• Dill DB, Costill DL. Calculation of percentage changes in volumes of blood, plasma, and red cells in dehydration. J Appl Physiol. 1974 Aug;37(2):247-8. doi: 10.1152/jappl.1974.37.2.247. No abstract available.

  PMID: 4850854 BACKGROUND

MeSH Terms

Interventions

Creatine; maltodextrin

Intervention Hierarchy (Ancestors)

Guanidines; Amidines; Organic Chemicals; Amino Acids; Amino Acids, Peptides, and Proteins

Central Study Contacts

Andrew S Perrotta, Phd

CONTACT

604 679 7172; Andrew.Perrotta@uwindsor.ca

Benjamin R Tilson, (BSc)

CONTACT

519 819 7732; tilsonb@uwindsor.ca

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Masking Details: This study uses a double-blind design. Participants and investigators involved in data collection and testing procedures will be blinded to supplement allocation. Creatine monohydrate and placebo supplements will be prepared in identical containers and mixed with orange juice to maintain blinding. Group allocation codes will remain concealed until completion of data collection and primary analyses.
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor, Department of Kinesiology, University of Windsor

Study Record Dates

• First Submitted: May 11, 2026
• First Posted: May 18, 2026
• Study Start (Estimated): July 30, 2026
• Primary Completion (Estimated): April 30, 2027
• Study Completion (Estimated): August 30, 2027
• Last Updated: May 18, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will not share