Patients' pulmonary functions and diffusion capacity worsen following lung cancer surgery. Diaphragmatic activity and lung compliance decrease due to surgery. Peripheral and respiratory muscle functions are impaired in patients with lung cancer, exercise capacity and physical activity level decreased. Patients have postural instability and balance problems. Inspiratory muscle training has increased inspiratory muscle strength in patients with lung cancer. However, there is no study investigating functional inspiratory muscle training in patients with lung cancer.