Abstract P247: Higher Habitual Physical Activity is Associated with Enhanced Left Ventricular Diastolic Function and Exercise Capacity and Lower Wave Reflection in Healthy Adolescents Independent of Time in Sedentary Activities
Background: Higher volume of habitual physical activity (PA) is associated with greater cardiac and vascular health in youth, but whether the amount of time spent in sedentary activities (e.g., television viewing, computers, video games, etc.) attenuates these cardiovascular benefits is unknown. We hypothesized that higher volume of PA in the past year would be associated with better left ventricular (LV) filling/relaxation dynamics and exercise capacity, and lower aortic stiffness/wave reflection in adolescents independent of time in sedentary activities.
Methods: Sixty healthy adolescents (age16.4 ± 0.2 yrs; 42% male; 53% black) had LV diastolic function (2D echo: mitral E/A ratio; tissue Doppler e’ velocity; isovolumetric relaxation time, IVRT), aortic stiffness (carotid-femoral pulse wave velocity, CFPWV), wave reflection (carotid augmentation index, AI), exercise tolerance (VO2peak; exercise duration Bruce treadmill test), body composition and serum metabolic factors measured. Time spent in PA and sedentary activities (hrs/week) during the previous 12 months was assessed by the Youth Adolescent Activity Questionnaire seasonal format.
Results: Subjects with higher (HIGHPA, n=30, age 16.4 ± 0.3 yrs, 25.7 ± 2.3 hrs/week) vs. lower (LOWPA, n=30, age 16.3 ± 0.3 yrs, 6.9 ± 0.7 hrs/week) volume of PA (above and below median hrs/week) demonstrated greater E/A (2.20 ± 0.07 vs. 1.90 ± 0.06, P<0.01), e’ (0.19 ± 0.1 vs. 0.17 ± 0.1 m/s, P=0.03), VO2peak (40 ± 2 vs. 31 ± 2 ml/kg/min, p<0.01), exercise test duration (11.9 ± 0.5 vs.10.1 ± 0.4 min, P<0.01) and lower AI (-11.83 ± 2.6% vs. -4.77 ± 2.2%, P<0.05), compared with LOWPA. Subjects did not differ in metabolic factors, body mass index/fat%, CFPWV or time in sedentary activities (all P>0.05). In the entire cohort, PA was associated with E/A (r=0.31, P<0.02), e’ (r=0.30,P=0.05), IVRT (r=0.27, P<0.05), carotid AI (r=-0.29, P<0.05), VO2peak (r=0.27, P<0.05) and exercise test duration (r=0.39, P<0.01). All relations except e’ remained after adjustment for sedentary activity time.
Conclusions: Higher volume of PA in the past year is associated with enhanced cardiac diastolic function and exercise tolerance and lower pressure wave reflection in healthy adolescents independent of time in sedentary activities.
- © 2013 by American Heart Association, Inc.