Cardiorespiratory optimal point in monozygotics twins
Cardiopulmonary exercise testing, heritability, Oxygen uptake, anthropometry.
The Cardiorespiratory Optimal Point (COP) is a parameter that can add prognostic value to the cardiopulmonary exercise test, with particular utility in adults unable or not motivated to reach maximum exercise. To date, the influence of genetic / environmental factors on COP is unknown. Objective: to analyze the heritability of the optimal cardiorespiratory point and its relationship with anthropometric variables. Methods: A sample composed of 46 monozygotic twin pairs with a mean age of 25.4 ± 5.69. The Cardiopulmonary exercise testing was evaluated through a treadmill ramp protocol. The twins were separated into A and B and the intrapar ratio was calculated to observe the phenotypic differences. Comparisons between the siblings were performed by Student's t test for independent samples and the association between the anthropometric variables and the exercise testing was performed by the Pearson correlation. Results and conclusions: the variables mass, height, body mass index, waist circumference, perimeter of abdomen, perimeter of hip, COP time, COP, RER_COP and VO2_COP (l / min-1) did not differ in monozygotic twins, indicating a high heritability, with the exception of METS and VO2_COP (ml.kg-1.min-1). Anthropometric variables were not related to COP. This work presents a new statistical strategy for studies with twins by calculating the ratios, as well as providing an initial indication of the genetic and environmental contribution on the POC variable.