Neurological disorders * Multiple sclerosis Respiratory disorders * Cystic fibrosis: CF can cause skeletal muscle atrophy, however more commonly it can cause<unk> . The<unk>  is associated with reduced pulmonary function that is the origin of CF. * Bronchiectasis Chronic fatigue syndrome (CFS) * Post-exertional malaise is one of the main symptoms of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). PEM can be described as "a delayed and significant exacerbation of ME/CFS symptoms that always follows physical activity and often follows cognitive activity". * Orthostatic<unk>  (OI) occurs in CFS. OI includes<unk>  as one of the main symptoms. It also includes fatigue, nausea, headaches, cognitive problems and visual disturbances as other less major symptoms. Post-concussion syndrome (PCS) *<unk>  is present in those with PCS however their<unk>  to<unk>  may reduce over time. * Individuals with postconcussion syndrome may also experience a level of<unk> , however there is little known comparatively about<unk>  in PCS patients. Heart conditions * Angina pectoris * Heart failure:<unk>  is a primary symptom of chronic diastolic heart failure. * Cardiac arrhythmia * Aortic valve insufficiency * Pulmonary artery hypertension: PAH has the following symptoms; dyspnea and fatigue, these systems consequently contribute to<unk> . * Asymptomatic atrial septal defects; In the heart the right ventricular (RV) can have a volume overload which ultimately produces a pressure overload in the RV resulting in<unk>  as the RV is no longer able to control high pressure associated with<unk> . * Chronic heart failure Musculoskeletal disorders * Spinal muscular atrophy: symptoms include<unk> , cognitive impairment and fatigue. * Rhabdomyolysis: a condition in which muscle degrades, releasing intracellular muscle content into the blood as reflected by elevated blood levels of creatine kinase.<unk>  tolerance is significantly compromised. Mutations * Mitochondrial complex III: Currently it is suggested that there are 27 different mutations identified in cytochrome b (mitochondrial complex III is one of those mutations). This mutation can often lead to skeletal muscle weakness and as a result<unk> . * A complex of Coenzyme Q10: * Skeletal muscle respiratory chain defect (electron transport chain ETC): This can result in severe<unk>  which is manifested by the following symptoms of Skeletal muscle respiratory chain defect; muscle fatigue and lactic acidosis. *<unk>  tolerance reflects the combined capacity of components in the oxygen cascade to supply adequate oxygen for ATP resynthesis. In individuals with diseases such as cancer, certain therapies can affect one or more components of this cascade and therefore reduce the body's ability to utilise or deliver oxygen, leading to temporary<unk> . Cytochrome b mutations Cytochrome b mutations can frequently cause isolated<unk>  and myopathy and in some cases multisystem disorders. The mitochondrial respiratory chain complex III catalyses electron transfer to cytochrome c. Complex III is embedded in the inner membrane of the mitochondria and consists of 11 subunits. Cytochrome b is encoded by the mitochondrial DNA which differs from all other subunits which are encoded in the nucleus. Cytochrome b plays a major part in the correct fabrication and function of complex III. This mutation occurred in an 18-year-old man who had experienced<unk>  for most of his adolescence. Symptoms included extreme fatigue, nausea, a decline in physical activity ability and myalgia. Intracranial hypertension Individuals with elevated levels of cerebrospinal fluid can experience increased head pain, throbbing, pulsatile tinnitus, nausea and vomiting, faintness and weakness and even loss of consciousness after<unk>  or exertion. General physical problems A person who is not physically fit due to a sedentary lifestyle may find that vigorous<unk>  is unpleasant.
Exercise intolerance
Paroxysmal nocturnal dyspnoea
Heat intolerance
Alarm fatigue
Palpitations
Platypnea
Myxedema
Tachypnea