The article describes the case of a young athlete aged 22 years old who, at the medical examination for non-competitive sports fitness, presented, on the baseline ECG, flattened T waves in leads D2, V5, and V6 and negative in leads D3, aVF, V4. Initiated to a second level cardiological screening, including echocardiogram, ECG Holter, and exercise test on the cycle ergometer, she was negative for structural heart disease. Although asymptomatic, she showed, during the stress test, an accentuation of the negativity of the T wave, especially in V4, V5, and V6, with a slight lowering of the ST segment, indicating reduced coronary reserve. The girl then underwent a negative stress myocardial scan. Coronary CT angiography and MRI with contrast media were also performed without any diagnosis of heart disease. Therefore, considering the age, the lack of symptoms, and the absence of structural coronary abnormalities, in the presence of a silent coronary reactivity to effort, she was deemed suitable for non-competitive sports with limitation of loads to a submaximal heart rate. The objective of this work is to contribute to the case history of electrocardiographic abnormalities during a medical examination for non-competitive sports fitness, focusing on the evident electrocardio-graphic alteration detected in a structurally intact heart compatible with a silent coronary microvascular dysfunction (ischemia with no obstructive coronary arteries [INOCA]).