Pieles GE, Gowing L, Forsey J, Ramanujam P, Miller F, Stuart AG, Williams CA. The relationship between biventricular myocardial performance and metabolic parameters during incremental exercise and recovery in healthy adolescents. Am J Physiol Heart Circ Physiol 309: H2067-H2076, 2015. First published October 23, 2015 doi:10.1152/ajpheart.00627.2015 and right ventricular (RV) myocardial reserve during exercise in adolescents has not been directly characterized. The aim of this study was to quantify myocardial performance response to exercise by using two-dimensional (2-D) speckle tracking echocardiography and describe the relationship between myocardial reserve, respiratory, and metabolic exercise parameters. A total of 23 healthy boys and girls (mean age 13.2 Ϯ 2.7 yr; stature 159.1 Ϯ 16.4 cm; body mass 49.5 Ϯ 16.6 kg; BSA 1.47 Ϯ 0.33 m 2 ) completed an incremental cardiopulmonary exercise test (25 W·3 min increments) with simultaneous acquisition of 2-D transthoracic echocardiography at rest, each exercise stage up to 100 W, and in recovery at 2 min and 10 min. Two-dimensional LV (LV Sl) and RV (RV Sl) longitudinal strain and LV circumferential strain (LV Sc) were analyzed to define the relationship between myocardial performance reserve and metabolic exercise parameters. Participants achieved a peak oxygen uptake (V O2peak) of 40.6 Ϯ 8.9 ml·kg Ϫ1 ·min Ϫ1 and a work rate of 154 Ϯ 42 W. LV Sl and LV Sc and RV Sl increased significantly across work rates (P Ͻ 0.05). LV Sl during exercise was significantly correlated to resting strain, V O2peak, oxygen pulse, and work rate (0.530 Յ r Յ 0.784, P Ͻ 0.05). This study identifies a positive and moderate relationship between LV and RV myocardial performance and metabolic parameters during exercise by using a novel methodology. Relationships detected present novel data directly describing myocardial adaptation at different stages of exercise and recovery that in the future can help directly assess cardiac reserve in patients with cardiac pathology. CARDIOVASCULAR EXERCISE RESPONSE is a complex interplay between respiratory, metabolic, cardiac, and muscular adaptations and is traditionally assessed in children by using cardiopulmonary exercise testing (CPET) (1, 34). CPET has been used in diagnosis and risk stratification in children with heart disease (38) as it can impose physiological stress on the cardiovascular system to determine submaximal and maximal capacity, while numerous studies in adults with cardiovascular disease have shown CPET is a strong predictor of clinical outcome (2). Two methodological limitations of CPET are, however, the inability to provide data on myocardial function in response to the imposed exercise stress, the dominant process being to increase cardiac output to enhance oxygen delivery (3), and its limited and indirect inferences of cardiac reserve.Over the last decade these methodological constraints have led to several pilot studies directly investigating cardiac function during exercise in the healthy pediatric population by using echoca...

25Background: Physical activity and exercise have important health benefits for children and

Purpose Few data exist on the descriptions of LV myocardial mechanics and reserve during dynamic exercise of adolescent athletes. The aim of this study was to describe the LV myocardial and cardiopulmonary changes during exercise using 2-D strain deformation imaging. Methods Elite adolescent male football players (n = 42) completed simultaneous cardiopulmonary exercise testing (CPET) and exercise echocardiography measurement of LV myocardial deformation by 2-D strain imaging. LV longitudinal and circumferential 2-D strain and strain rates were analyzed at each stage during incremental exercise to a work rate of 150 W. Additionally, exercise LV myocardial deformation and its relation to metabolic exercise parameters were evaluated at each exercise stage and in recovery using repeated measures ANOVA, linear regression and paired t tests. Results LV peak systolic baseline 2-D strain (longitudinal: − 15.4 ± 2.5%, circumferential: − 22.5 ± 3.1%) increased with each exercise stage, but longitudinal strain plateaued at 50 W (mean strain reserve − 7.8 ± 3.0) and did not significantly increase compared to subsequent exercise stages (P > 0.05), whilst circumferential strain (mean strain reserve − 11.6 ± 3.3) significantly increased (P < 0.05) throughout exercise up to 150 W as the dominant mechanism of exercise LV contractility increase. Regression analyses showed LV myocardial strain increased linearly relative to HR, VO2 and O2 pulse (P < 0.05) for circumferential deformation, but showed attenuation for longitudinal deformation. Conclusion This study describes LV myocardial deformation dynamics by 2-D strain and provides reference values for LV myocardial strain and strain rate during exercise in adolescent footballers. It found important differences between LV longitudinal and circumferential myocardial mechanics during exercise and introduces a methodology that can be used to quantify LV function and cardiac reserve during exercise in adolescent athletes.

The authors apologise for a missing label for one of the graphs in their published paper. It is missing from Figure 2-the green label 'concern about risks associated with exercise' is missing.