Comparison of Muscle Strength and Cardiorespiratory Fitness in Relation to Cardiovascular and All-Cause Mortality: The Copenhagen City Heart Study

Abstract

Objective: To compare the association between muscle strength (MS), cardiorespiratory fitness (CRF), and all-cause and cardiovascular disease (CVD) mortality.

Methods: The Copenhagen City Heart Study is a prospective longitudinal study comprising a random sample of adults; we excluded participants with a history of coronary heart disease or cancer, leaving 9896 men and women for analyses. A self-administered questionnaire at baseline (from October 10, 1991, to September 16, 1994) documented self-rated MS and CRF, categorized as low, moderate, or high. MS was measured in 3299 participants by a hand grip strength of the dominant hand with isometric dynamometry. Multivariable adjusted analyses were performed adjusting for potential confounders.

Results: During follow-up of 27 years, 4971 all-cause deaths and 2128 CVD deaths occurred. Compared with moderate CRF, high CRF was associated with lower all-cause mortality (hazard ratio, 0.82; 95% CI, 0.75 to 0.90) and lower CVD mortality (hazard ratio, 0.81; 95% CI, 0.70 to 0.93). There were approximately 10% higher risk reductions for CRF than for MS in comparing high with moderate levels for both all-cause and CVD mortality; comparing moderate with low levels, CRF was 19% (95% CI, -5% to 48%) better than MS for decreasing risk of all-cause mortality and 33% (95% CI, -6% to 89%) better for reducing CVD mortality. The self-rated MS reports corresponded well with the hand grip results.

Conclusion: Both CRF and MS are inversely associated with CVD mortality and all-cause mortality, but of the 2, CRF confers stronger protection.