Study participants will report to the Human Performance/Clinical Research Laboratory (HPCRL) on 6 separate occasions. On visit 1 study participants will undergo screening (e.g. medical history and 12-lead electrocardiogram and blood pressure at rest and during incremental exercise to volitional exhaustion), and will be instructed to avoid foods and drinks high in 5-HMF (e.g., coffee, malt, barley, dried fruits, and caramel) for at least 3 days before each subsequent visit. Visit 2 will comprise of a habituation visit during which subjects will be given the opportunity to rehearse the exercise test. Visits 3, 4, 5 and 6, will occur in a random order and be almost identical in nature. Study participants will abstain from vigorous physical exercise and alcohol consumption during the 24-hours prior to each visit. In addition, study participants will abstain from all food and beverages, except water, during the 4-hours prior to visits 3, 4, 5 and 6. On arrival subjects will be instrumented for measurement of heart rate, blood pressure and blood oxygen saturation. Following baseline determination subjects will consume either: a placebo, 1000 mg of Aes-103 or 3000 mg of Aes-103. 45 minutes after consumption, participants will enter our environmental chamber, adjusted randomly to either normoxia (21% oxygen) or hypoxia (15% oxygen). The pairing of normoxia/hypoxia and supplement will be as follows: placebo + normoxia, placebo + hypoxia, 1000 mg + hypoxia, and 3000 mg + hypoxia. Participants will remain seated in the environmental chamber for 15 minutes, after which they will complete a standardized warm-up bout of exercise (100 W for 30 minutes) followed by a brief time trial (time taken to cycle 12.5 km (~7.75 miles)). Heart rate, blood pressure and blood oxygen saturation will be recorded every 5 minutes. During exercise, subjective ratings of perceived exertion (Borg Scale) will be recorded every 10 minutes, and at end-exercise.