What could indicate a drug reaction in an athlete?

A racing heartbeat without physical exertion could indicate a drug reaction in an athlete because it suggests a significant change in physiological response that is inconsistent with the athlete's usual level of activity. Drug reactions can produce various symptoms, including changes in heart rate due to the effects of stimulants or other substances on the cardiovascular system. This symptom could point to an adverse effect or an allergic reaction resulting from medication or performance-enhancing drugs. Monitoring heart rate is crucial in identifying such reactions, particularly when athletes are at rest and not experiencing physical exertion.

The other options do not specifically indicate a drug reaction. Inability to speak after exercise may suggest a serious health issue such as a stroke or extreme exhaustion rather than a direct drug reaction. Increased appetite and energy could result from normal physiological responses to exercise or diet changes, rather than indicating a drug reaction. Loss of coordination during practice may signal neurological issues or the effects of fatigue but does not directly correlate with drug reactions as clearly as the racing heartbeat does.