Which of the following is an absolute contraindication for exercise?

An absolute contraindication for exercise is a condition that poses such a significant risk that exercise should not be performed under any circumstances until the condition is resolved. A recent change in ECG indicates that there may be a new or worsening cardiovascular issue, such as arrhythmias or ischemia, which could increase the likelihood of a serious event occurring during physical activity. In this case, exercising could exacerbate the underlying condition, leading to potential harm. Therefore, it is crucial to identify and resolve the issue indicated by the change in ECG before resuming any form of exercise.

In contrast, while electrolyte abnormalities, stable angina, and severe resting arterial hypertension can also pose significant risks, they may allow for certain modifications to be made in a tailored exercise program under medical supervision, rather than being classified as absolute contraindications.