Inclusion Criteria:

• Healthy males and females aged 19-39 years, and 60-79 years
• Engaging in regular aerobic exercise (e.g., running, cycling, swimming, hiking, field, ice, or racquet sports) at least once per week

Exclusion Criteria:

• History of any cardiovascular condition, including hypertension
• Use of any chronic medication
• History of any respiratory condition, including asthma
• Smoking, including cannabis or vaping in the past year
• History of diabetes mellitus, cancer, hepatic, renal or any other chronic illness
• Seated blood pressure ≥130/90 or <100/60 mmHg
• Body mass index <20 or >32 kg/m2
• Non-sinus rhythm or abnormalities on 12-lead electrocardiogram (ECG)
• Pregnant, breastfeeding, or women of childbearing potential not using appropriate contraception
• Current or recent (past year) participation in >150 minutes per week of moderate-vigorous intensity exercise (to avoid endurance training-related bradycardia)
• Any condition that prevents vigorous exercise from being performed safely
• Seated resting heart rate <60 beats per minute
• Prolonged QT interval (e.g., long QT syndrome)
• Sick sinus syndrome, sino-atrial block or third-degree atrio-ventricular block
• Use of strong cytochrome P450 (CYP3A4) inhibitors (e.g., nirmatrelvir and ritonavir, ketoconazole), which can increase ivabradine levels in the blood to potentially unsafe levels
• Use of verapamil or diltiazem, which are moderate CYP3A4 inhibitors and also lower heart rate, posing a risk of excessive bradycardia when combined with ivabradine
• Lactose intolerance, as ivabradine contains lactose
• Known allergy/hypersensitivity to ivabradine or to any ingredient in the formulation or component of the container