Postural orthostatic tachycardia syndrome (POTS) is a disorder of unknown origin characterized by orthostatic intolerance and increased heart rate (HR) of ≥ 30 beats/minute during orthostasis in the absence of orthostatic hypotension. In addition to the orthostatic intolerance and tachycardia, patients with POTS experience several debilitating symptoms including light-headedness, nausea, blurred vision, fatigue, mental confusion (brain-fog), chest pain and gastrointestinal problems. Several potential underlying mechanisms have been suggested for POTS including autonomic denervation, hypovolemia, hyperadrenergic stimulation and autoantibodies against adrenergic receptors. However, none of these proposed mechanisms has yet led to an effective treatment. Physical activity is recommended as a complimentary treatment in POTS in international guidelines. However, less is known regarding how physical activity could successfully be implemented in clinical practice in patients with POTS. Thus, in the current study, we aim to assess the effect of a 16-week specialized physical activity program in POTS.