If systolic blood pressure exceeds _____mmHg while exercising, it should be monitored by a physician.

The correct indication for when systolic blood pressure should be monitored by a physician during exercise is 220 mmHg. This threshold is established based on guidelines for safe exercise participation, particularly for those individuals who may have pre-existing hypertension or other cardiovascular conditions.

During physical exertion, it is normal for systolic blood pressure to rise due to increased demand for oxygenated blood by the muscles. However, when it reaches around 220 mmHg, it can signify that the cardiovascular system is under excessive strain, raising concerns about increased risks for adverse events such as cardiovascular complications.

Monitoring at this level allows for proactive management of the individual's health status and implementation of necessary precautions. Lower thresholds, such as 180 or 200 mmHg, while also indicative of elevated blood pressure, do not specifically identify the critical point where immediate professional observation is warranted. Thus, 220 mmHg is acknowledged as a more definitive level at which further medical assessment is advisable.