Bradycardia is a medical condition characterized by a slower than normal heart rate, typically defined as fewer than 60 beats per minute in adults. It can occur in healthy individuals, especially athletes, but may also indicate underlying health issues such as heart disease, hypothyroidism, or electrolyte imbalances. Symptoms of bradycardia can include fatigue, dizziness, shortness of breath, and fainting. In some cases, it may not cause any noticeable symptoms. Treatment depends on the underlying cause and severity, and may involve lifestyle changes, medication, or the use of a pacemaker to regulate the heart rate.