What does electrocardiography (ECG) primarily record?

Electrocardiography (ECG) primarily focuses on recording the electrical activity of the heart. This technique measures the electrical impulses that trigger each heartbeat. By placing electrodes on the skin, an ECG provides a graphical representation of the heart's electrical activity over time, allowing healthcare professionals to assess the heart’s rhythm, identify abnormalities, and diagnose various cardiac conditions.

Understanding heart health is crucial, as the electrical signals indicate not just the pace of the heart but also the coordination of heart muscle contractions. This can help detect arrhythmias, heart attacks, and other cardiac issues. The other options, while important in their respective fields, do not pertain to what ECG measures, making the understanding of the heart’s electrical activity a fundamental aspect of cardiology and athletic training.