It can start with unusual discomfort or breathlessness during a workout or an uphill walk—a feeling many of us experience, and dismiss, the older we get. But medical researchers are learning more ...

A new study suggests preload deficiency could be the underlying cause of fatigue and exercise intolerance in people with systemic lupus erythematosus (SLE). Preload deficiency is a condition where the ...

Exercise intolerance, or the inability to perform physical activity at the expected or desired level, is one of the many symptoms associated with long COVID. In a study, Yale researchers help explain ...

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Bradycardia does not often cause symptoms. If symptoms of bradycardia do occur, they may include fatigue, lightheadedness, and exercise intolerance. A slow heart rate in young people or athletes or ...