Final answer:
Bradycardia, or a resting heart rate below 60 bpm, can be caused by issues within the heart or external factors. Symptoms suggest inadequate blood oxygenation, potentially needing medical treatment.
Step-by-step explanation:
An individual's heart rate may fall below 60 beats per minute (bpm) due to a condition known as bradycardia. Bradycardia can be caused by inherent factors such as abnormalities in the sinoatrial (SA) or atrioventricular (AV) nodes, or external factors including metabolic disorders, thyroid pathologies, electrolyte imbalances, or the use of certain medications like beta blockers.
In athletes, a low resting heart rate may be normal due to their high level of physical fitness. If bradycardia is accompanied by symptoms such as dizziness or fainting, it indicates that the heart is not supplying enough oxygenated blood to the body, which may require medical intervention such as a pacemaker or supplemental oxygen, depending on the underlying cause.