Protection against muscle damage exerted by oestrogen: hormonal or antioxidant action?

Introduction In the early 1980s it was felt necessary to develop diagnostic tests for a population of patients who attended the Neuromuscular Diseases Clinic of the university hospital. Their complaints were often vague and difficult to objectify, and for a large group the complaints were often triggered by some form of exercise. Exercise, in this context, is to be taken quite broadly, and varied from going up the stairs, vacuum cleaning the house, cycling or walking home with heavy groceries, to extremes such as an army sports instructor, who only experienced complaints after strenuous physical (sports) exercise El]. At rest, these patients as a rule showed no signs of weakness or indeed any abnormality, but the most common complaint was ‘fatigue’, i.e. not being able to complete a physical activity, be it vacuum cleaning the room or a half marathon. Biochemically, these patients hardly ever showed any abnormalities, except sometimes a high creatine kinase (CK) activity or a slightly raised lactate concentration in plasma. Increased CK activity in plasma is usually interpreted as a sign of muscle damage, but this interpretation should be made with care, as there is no clear relationship between CK activity and the ‘gold standard’ for muscle damage, histological assessment. Strictly speaking, increased vulnerability or increased permeability would be better terms, but muscle damage is commonly used. This aspect is discussed in more detail in [2]. Most patients did not show any sign of their complaints at rest, and we therefore decided to develop tests that might trigger the complaints in a laboratory setting during or after carefully controlled exercise and with biochemical monitoring of blood variables. In doing so, we hoped to be able to detect possible metabolic disorders caused by enzyme deficiencies, such as mitochondrial myopathies, McArdle’s disease, carnitine palmitoyltransferase deficiency and others [3].