What is the direct measurement of the heart's electrical activity called?

The direct measurement of the heart's electrical activity is referred to as an electrocardiogram (ECG). An ECG records the electrical signals that trigger heartbeats, allowing healthcare providers and fitness professionals to assess the heart's rhythm, identify potential issues, and monitor heart health. It showcases the timing and duration of each electrical phase in the heartbeat, which is crucial for diagnosing various cardiac conditions.

In contrast, a heart rate monitor primarily tracks the number of heartbeats over a specific time period and may not provide detailed insights into the electrical activity of the heart. A cardiac output test measures the amount of blood the heart pumps in a minute, focusing on the volume rather than the electrical signals. Blood pressure measurement indicates the force of blood against artery walls, which is important for cardiovascular health but does not directly assess electrical activity. Thus, the electrocardiogram is the correct choice as it specifically captures the heart's electrical dynamics.