Exercise and statins
Exercise and statins are both prescribed for cardiovascular health, but they may not work well together. It is known that statins can cause breakdown of muscle fiber - mild or more severe. In some cases these side effects make it impossible for the patient to continue. Most patients do not have such visible side effects, but the muscular changes may be subtle and the person might not be conscious of them. They could result in an overall decline in physical fitness, which might go unnoticed or thought of as a natural consequence of aging.
Disentangling the effects of statins for the general population from natural decline in fitness is tough, but researchers from the University of Missouri have taken a shot at it.
Two groups of people were followed as they undertook an exercise program designed to increase aerobic fitness. One group also took simvastatin. After three months the people who did not take the drug had demonstrably better capacity on tests of physical ability.
It was a small sample size, but the differences between those who took simvasstatin and those who did not was statistically significant. More work on this question is probably needed.
Previous work in animals found atorvastatin reduces physical abilities in rats.
And a previous study found that marathon runners who are on statins tend to develop higher creatine levels over the course of a race than non-medicated runners. Creatine kinase is important in the energy production process and its presence in bodily fluids is an indicator of muscle fiber breakdown. Levels of myoglobin - another blood serum indicator of injury - was not different between statin users and non-users.
There is also evidence that taking statins results in lower levels of aerobic fitness.
Scientists hypothesize that the statins affect the functioning of the mitochondria - the units within the cells that metabolize sugar to produce energy. A study of in vitro muscle cells exposed to simvastatin found that at a dose equivalent to 40 mg/day, new muscle cell growth was reduced by 50%. While this does not translate directly to how statins work inside the body, it does provide scientists proof that statins directly affect muscles.
This is an unfortunate finding. It affects the decision about whether to prescribe statins to medium risk overweight sedentary people. Those people would especially benefit from exercise to reduce risk of cardiovascular disease. If exercise exacerbates the toxicity of statins, which it seems to, that shifts the risk-benefit calculation backwards toward "no prescribe".
Researchers at the University of Connecticut looked at 15 studies on muscle strengh, exercise, and endurance and whether statins had a consistent effect. They concluded the data was not sufficient to show a relationship between statin use and muscle strength. They did find, however, some nonconclusive evidence that statins change energy metabolism markers in aerobic activity. Strenuous exercise increases levels of inflammatory markers and increases cardiovascular risk in the very short term. The anti-inflammatory effects of statins may mitigate this risk.