Treadmill Testing of Children Who Have Spina Bifida and Are Ambulatory: Does Peak Oxygen Uptake Reflect Maximum Oxygen Uptake?

Background. Earlier studies have demonstrated low peak oxygen uptake ((V) over doto(2)peak) in children with spina bifida. Low peak heart rate and low peak respiratory exchange ratio in these studies raised questions regarding the true maximal character of (V) over doto(2)peak values obtained with treadmill testing. Objective. The aim of this study was to determine whether the (V) over doto(2)peak measured during an incremental treadmill test is a true reflection of the maximum oxygen uptake ((V) over doto(2)max) in children who have spina bifida and are ambulatory. Design. A cross-sectional design was used for this study. Methods. Twenty children who had spina bifida and were ambulatory participated. The (V) over doto(2)peak was measured during a graded treadmill exercise test. The validity of (V) over doto(2) peak measurements was evaluated by use of previously described guidelines for maximum exercise testing in children who are healthy, as well as differences between (V) over doto(2)peak and (V) over doto(2) during a supramaximal protocol ((V) over doto(2)supramaximal). Results. The average values for (V) over doto(2)peak and normalized (V) over doto(2)peak were, respectively, 1.23 L/min (SD=0.6) and 34.1 mL/kg/min (SD=8.3). Fifteen children met at least 2 of the 3 previously described criteria; one child failed to meet any criteria. Although there were no significant differences between (V) over doto(2)peak and (V) over doto(2)supramaximal, 5 children did show improvement during supramaximal testing. Limitations. These results apply to children who have spina bifida and are at least community ambulatory. Conclusions. The (V) over doto(2)peak measured during an incremental treadmill test seems to reflect the true (V) over doto(2)max in children who have spina bifida and are ambulatory, validating the use of a treadmill test for these children. When confirmation of maximal effort is needed, the addition of supramaximal testing of children with disability is an easy and well-tolerated method.