Influence of coronary artery disease on cardiolocomotor coupling during walking: a preliminary study

Abstract

The mechanisms involved in the coupling between cardiac and locomotor rhythms in patients with heart disease remain unclear. It was speculated that reduced function of the cardiovascular and/or locomotor systems would increase the coupling of these systems to increase energy efficiency in response to increased energy demand during exercise. We investigated the development of cardiolocomotor coupling (CLC) in patients with coronary artery disease. Eight outpatients with coronary artery disease (CAD group) and eight healthy individuals (control group) underwent cardiopulmonary exercise testing involving a cycle ergometer ramp protocol and treadmill walk test to record CLC strength. The coefficient of determination (R2 value) of the interval between R waves on the electrocardiograph and step interval reflects CLC strength intensity. The Student’s t-test was used to compare cardiopulmonary exercise testing data and R2 values between the study groups. The R2 value was significantly higher in the CAD group than the control group. Peak oxygen uptake and oxygen uptake at the anaerobic threshold were significantly lower in the CAD group than the control group. Our findings showed that CLC intensity was higher in patients with CAD, suggesting that CLC is more likely to occur in individuals with reduced exercise tolerance due to cardiorespiratory deterioration. Key highlights Eight outpatients with coronary artery disease and eight healthy individuals underwent cardiopulmonary exercise and treadmill walk tests to determine cardiolocomotor coupling strength and physiological characteristics. This study reports a stronger cardiolocomotor coupling during exercise in patients with coronary artery disease compared with healthy individuals, suggesting that cardiolocomotor coupling is more likely to occur in people with reduced exercise tolerance attributed to impaired cardiorespiratory function. Our results support the theory that patients with cardiorespiratory impairment due to coronary artery disease have greater dynamic interaction between the locomotor and cardiovascular systems during exercise, which is concurrent with the hypothesis that cardiolocomotor coupling is a compensatory phenomenon for exercise maintenance.