Cedar Falls

Researchers are investigating whether one week of creatine monohydrate supplementation affects inflammation, markers of acute kidney injury (AKI) risk, and cognitive performance during exercise in the heat. The study focuses on active, young, healthy adults aged 18 to 45 and compares creatine supplementation to a placebo (maltodextrin). It aims to understand if creatine changes urinary inflammation markers, AKI risk markers, and cognitive function after heat exercise. Participants will undergo three visits: one baseline visit and two experimental trials. At baseline, fitness and cognitive assessments will be completed, including a maximal aerobic exercise test to determine workloads used during exercise. During the experimental trials, participants will consume 20 grams per day of creatine or placebo for seven days, followed by a 90-minute cycling session in a controlled hot environment (38°C, 40% humidity). During exercise, intensity alternates between low and high workloads, with continuous monitoring of heart rate and core temperature. Cognitive tests and urine samples will be collected before, during, and after exercise. Participant involvement includes urine collection for hydration and kidney injury markers, cognitive testing using the NIH toolbox, blood pressure and blood sample measurements, and body composition analysis. Monitoring includes heart rate, core and skin temperatures, perceived exertion, mood, fatigue, and gastrointestinal symptoms. After exercise, hydration assessment and cognitive testing continue, with a washout period of at least 21 days before the second supplementation phase. The primary outcome is the change in a urine biomarker of AKI risk from before to one hour after exercise in the heat.