Too Much Cardio?

Dr William J Rowe looks at the topic of 'Extraordinary unremitting endurance exercise and permanent injury to normal heart':

• "This hypothesis is that permanent cardiac injury could develop in some endurance athletes despite the absence of coronary atherosclerosis and ventricular hypertrophy. The proposed mechanism by which this injury could arise involves two physiological "vicious cycles". The first vicious cycle would occur between severe ischaemia and high catecholamines, the second would be between coronary vasospasm (induced by high catecholamines) and endothelial injury. The likelihood of the injury becoming permanent might increase if there is insufficient time between bouts of endurance exercise for regression of ischaemia and endotheliat repair. Furthermore, magnesium ion deficiency, which can be induced byexercise, could exacerbate these vicious cycles and also contribute to catecholamine-induced thrombogenesis. In addition to ischaemia, there are several mechanisms, including the effect of free fatty acids liberated by the lipolytic effect of high catecholamines, that could cause direct myocardial injury."

His site contains an interesting article on magnesium deficiency and athlete death. (Magnesium is one of the few supplements I take along with potassium and occasional D3).

I previously quoted one of his letters on the subject of iron in 'Our Ancestors Had it Right'.