Functional capacity during exercise in very-low-birth-weight premature children

The functional capacity of children born prematurely with very-low-birth weight was compared with that of children born at full-term using the six-minute walk test (6MWT) and the ten-minutes shuttle walk test (10MSWT). The factors affecting walking distance were analyzed.

A cross-sectional study was conducted with two groups of children aged 6-9 years, matched by sex and age. One group included children born before 37 weeks of gestation weighing <1,500 g and the second group included children born at term. Both groups were submitted to the 6MWT and 10MWST, performed on the same day with an interval of 20 min between tests and the sequence of the tests was randomized, by sealed-envelope technique. Physiological parameters were measured at the beginning and end of each test. The walking distance and factors affecting the walking distance were analyzed.

Thirty-seven children born prematurely and 37 born at term were studied. The premature children walked shorter distances in the 6MWT (480.9 ± 80.5 m vs. 518.3 ± 51.8 m, P = 0.010) than term children, and both groups walked similar distances in the 10MSWT (391.5 ± 99.0 m vs. 406.1 ± 79.2 m, P = 0.487). By multiple linear regression analysis, adjusted for confounders, walking distance was associated with height (OR: 3.6) and oxygen dependency at 28 days (OR: -67.7) in the 6MWT (P < 0.001) and with height (OR: 4.9) and oxygen dependency at 28 days (OR: -91.0) in the 10MSWT (P < 0.001).

In conclusion, this study suggests that children born prematurely with very low birth weight, especially those who had bronchopulmonary dysplasia present limited functional capacity during exercise.