CARDIAC STRAIN DURING UPRIGHT CYCLE ERGOMETRY IN ADOLESCENT MALES

Little evidence exists with regard to changes in cardiac strain that occur during submaximal exercise in young males. The aims of the study were to evaluate the changes that occur in longitudinal (L), radial (R) and endocardial circumferential (EC) strain during submaximal upright cycle ergometry and to examine the test-retest reproducibility of these measurements. Fourteen recreationally active, adolescent (age: 17.9 ± 0.7 years), males volunteered for the study. All subjects underwent an incremental (40W) submaximal cycle ergometer test. L, R, and EC strain values were obtained using speckle tracking, from two-dimensional B-mode images of the left ventricle (LV) during rest and the initial stages of submaximal exercise (40W and 80W). The average of 6 LV segments was used to determine both peak wall deformation (%) and the time to peak deformation (ms). There was a statistically (P<0.05) significant increase from rest to submaximal exercise for peak deformation for L, R and EC strain. There was a statistically significant (P<0.05) decrease from rest to submaximal exercise for time to peak for L and R and EC strain and between submaximal workloads for time to peak for L strain and EC strain. Coefficients of variation demonstrated reproducibility for upright strain and strain rate measurements similar to published supine measurements. This study has demonstrated that changes in left ventricular wall deformation (L, R and EC strain) that occur during the transition from rest to submaximal exercise can be reliably measured and confirm that a healthy left ventricle has a hyperdynamic response to exercise.