DOI: 10.1097/01.hjh.0000379279.90011.ca
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Issn Print: 0263-6352
Publication Date: 2010/06/01
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Abstract
Aim:To investigate relations of muscle morphology to risk of cardiovascular disease.
Background:While it's well known that physical inactivity is a major risk factor for cardiovascular disease, there is still a search for the mechanisms by which exercise exerts its positive effect. Skeletal muscle fiber type can be affected to some extent by exercise, and different fiber types possess different anti-inflammatory and glucometabolic properties. Relations of muscle fiber composition to risk of cardiovascular events may therefore depend on level of physical activity.
Design:Population-based cohort study with up to 15.3 (median 12.3) years of follow-up.
Participants:Four-hundred and sixty-two 71-year-old men without myocardial infarction, stroke or heart failure, of which 283 were physically active (engaged in strenuous physical activity at least three hours per week).
Main Outcome Measure:Major cardiovascular events (fatal and non-fatal myocardial infarction or stroke, a first hospitalization for heart failure, or cardiovascular death).
Results:During follow-up, 142 cardiovascular events occurred (84 among the physically active). Relations of muscle fiber composition to risk of cardiovascular events were dependent on physical activity status. Among physically active men, those with type 2X as the dominant muscle fiber type had higher risk of cardiovascular events than men with type 1 as dominant fiber type (Cox proportional hazard ratio [HR] 3.69, 95% confidence interval [CI] 1.92–7.09, in age-adjusted models; HR 2.54, 95% CI 1.19–5.46, in models adjusting for smoking, alcohol intake, socioeconomic status, systolic blood pressure, antihypertensive treatment, diabetes mellitus, body mass index, and total cholesterol). No association of muscle fiber type with risk of cardiovascular events was observed among physically inactive men.
Conclusion:In physically active healthy elderly men, the risk of cardiovascular events is higher in those with type 2X-dominant than those with type 1-dominant skeletal muscles. Possible explanations include different cytokine profiles or glucometabolic properties between skeletal muscles with different predominant fiber types.
