Treatment with oral corticosteroids, clinical symptoms of depression, myositis, self-reported complaints of fatigue and high circulating levels of tumour necrosis factor-α (TNF-α) are all present in patients with sarcoidosis and can all affect skeletal muscle force and exercise capacity. Additionally, low levels of circulating insulin-like growth factor I (IGF-I), which can be induced by high levels of TNF-α, and high circulating levels of interleukin (IL)-6 and IL-8 (CXCL8) have been associated with skeletal muscle weakness. These interleukins are part of the current concept of the immunopathogenesis of sarcoidosis16 and may be raised in patients with stable sarcoidosis.