Association of body size and muscle strength with incidence of coronary heart disease and cerebrovascular diseases: a population-based cohort study of one million Swedish men

BACKGROUND: Muscle strength and body size may be associated with coronary heart disease (CHD) and stroke risk. However, perhaps because of a low number of cases, existing evidence is inconsistent. METHODS: Height, weight, systolic (SBP) and diastolic blood pressure (DBP), elbow flexion, hand grip and knee extension strength were measured in young adulthood in 1 145 467 Swedish men born between 1951 and 1976. Information on own and parental social position was derived from censuses. During the register-based follow-up until the end of 2006, 12 323 CHD and 8865 stroke cases emerged, including 1431 intracerebral haemorrhage, 1316 subarachoid haemorrhage and 2944 intracerebral infarction cases. Hazard ratios (HR) per 1 SD in the exposures of interest were computed using Cox proportional hazard model. RESULTS: Body mass index (BMI, kg/m(2)) showed increased risk with CHD and intracerebral infarction, whereas for intracerebral and subarachoid haemorrhage both under- and overweight was associated with increased risk. Height was inversely associated with CHD and all types of stroke. After adjustment for height, BMI, SBP, DBP and social position, all strength indicators were inversely associated with disease risk. For CHD and intracerebral infarction, grip strength showed the strongest association (HR = 0.89 and 0.91, respectively) whereas for intracerebral and subarachoid haemorrhage, knee extension strength was the best predictor (HR = 0.88 and 0.92, respectively). CONCLUSION: Body size and muscle strength in young adulthood are important predictors of risk of CHD and stroke in later life. In addition to adiposity, underweight needs attention since it may predispose to cerebrovascular complications.