Familial relationships, including twins and siblings, demonstrated less intrapair variation in cardiac size than nonrelated subjects (p<0.05), even after 14 weeks of exercise training.
Observational (n=124)
Does genetic endowment or exercise training have a greater influence on cardiac size in college-age twins and siblings?
Cultural familial influences appear more important in determining cardiac size than nonfamilial influences or genetic influences alone.
p-value: p=<0.05
Because of the uncertainty as to the extent to which cardiac size is determined by exercise training vs genetic endowment, this study investigated familial (genetic plus common family environment) vs nonfamilial influences on cardiac size. College-age monozygotic twins (group 1, 31 sets), dizygotic twins (group 2, 10 sets), siblings of like sex (group 3, six sets), and nonrelated subjects (group 4, 15 sets) underwent echocardiographic and electrocardiographic tests, measurement of maximum oxygen uptake (VO2max), and evaluation of pulmonary and body composition; mean intrapair differences of the four groups were compared. Mean intrapair differences in cardiac size varied as much for subjects in group 1 as for those in groups 2 and 3. However, subjects in groups 1, 2, and 3 had less variation (p less than .05) than those in group 4. After the initial testing, 14 pairs of monozygotic twins, five sets of dizygotic twins, and six sets of siblings underwent 14 weeks of exercise training (both members participated) and all tests were repeated. After exercise training, subjects in group 1 still had as much intrapair variability in cardiac size as those in groups 2 and 3. The data suggest cultural familial influences are more important in determining cardiac size than nonfamilial influences or even genetic influences alone.
Adams et al. (Tue,) conducted a observational in Healthy subjects (n=124). Exercise training and familial relationship comparison vs. Nonrelated subjects and different degrees of relation was evaluated on Mean intrapair differences in cardiac size (p=<0.05). Familial relationships, including twins and siblings, demonstrated less intrapair variation in cardiac size than nonrelated subjects (p<0.05), even after 14 weeks of exercise training.