Effects of Creatine and Heat Exposure on Exercise Performance and Body Water Distribution
Creatine Monohydrate Supplementation During Repeated Heat Exposure: Effects on Fluid Balance and Exercise Performance in a Randomized Double-Blind, Placebo-Controlled Trial
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
研究概览
地位
详细说明
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.
研究类型
注册 (估计的)
阶段
- 不适用
联系人和位置
学习联系方式
- 姓名：Andrew S Perrotta, Phd
- 电话号码：604 679 7172
- 邮箱：Andrew.Perrotta@uwindsor.ca
研究联系人备份
- 姓名：Benjamin R Tilson, (BSc)
- 电话号码：519 819 7732
- 邮箱：tilsonb@uwindsor.ca
参与标准
资格标准
适合学习的年龄
- 成人
接受健康志愿者
描述
Inclusion Criteria:
- 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
Exclusion Criteria:
- 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
学习计划
研究是如何设计的？
设计细节
- 主要用途：基础科学
- 分配：随机化
- 介入模型：并行分配
- 屏蔽：双倍的
武器和干预
参与者组/臂 |
干预/治疗 |
|---|---|
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实验性的：Creatine Monohydrate + Heat Exposure
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.
|
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.
|
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安慰剂比较：Placebo + Heat Exposure
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.
|
Participants will consume maltodextrin matched to creatine supplementation appearance and dosing schedule during the loading and maintenance phases of the study.
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研究衡量的是什么？
主要结果指标
结果测量 |
措施说明 |
大体时间 |
|---|---|---|
|
Plasma Volume Change Following Heat Acclimation and Creatine Supplementation
大体时间：Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
|
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.
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Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
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次要结果测量
结果测量 |
措施说明 |
大体时间 |
|---|---|---|
|
Change in Total Body Water
大体时间：Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
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Total body water measured using bioelectrical impedance analysis (InBody 230).
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Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
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Change in Intracellular Water
大体时间：Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
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Intracellular water estimated using bioelectrical impedance analysis.
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Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
|
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Change in Extracellular Water
大体时间：Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
|
Extracellular water estimated using bioelectrical impedance analysis.
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Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
|
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Change in VO₂ Peak
大体时间：Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
|
VO₂ peak assessed during supramaximal cycling exercise using breath-by-breath metabolic gas analysis.
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Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
|
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Change in Musculoskeletal Performance
大体时间：Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
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Musculoskeletal performance assessed during supramaximal cycling exercise using peak and mean power output measures.
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Measured at baseline (pre-supplementation), after 7 days of creatine/placebo loading, and after 7 days of heat acclimation.
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合作者和调查者
出版物和有用的链接
一般刊物
- 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.
- 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.
- 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.
- 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.
- 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
- 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.
研究记录日期
研究主要日期
学习开始 (估计的)
初级完成 (估计的)
研究完成 (估计的)
研究注册日期
首次提交
首先提交符合 QC 标准的
首次发布 (实际的)
研究记录更新
最后更新发布 (实际的)
上次提交的符合 QC 标准的更新
最后验证
更多信息
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关键字
其他研究编号
- #26-057
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