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Limiting factors in peak oxygen uptake and the relationship with functional ambulation in ambulating children with
J F De Groot1, T Takken, M A G C Schoenmakers
1Research Group Lifestyle and Health, University of Applied Sciences, Utrecht, The Netherlands. J.F.degroot-16@umcutrecht.nl
Insights
Peak oxygen uptake (VO2peak) is lower in children with spina bifida (SB), often limited by deconditioning and muscular factors. Community ambulators show greater impairment in functional ambulation and higher exercise strain than normal ambulators.
Area of Science:
- Pediatric Exercise Physiology
- Neuromuscular Rehabilitation
- Spina Bifida Research
Background:
- Children with spina bifida (SB) often exhibit reduced cardiorespiratory fitness.
- Understanding limitations in peak oxygen uptake (VO2peak) is crucial for optimizing physical function in ambulatory children with SB.
- Functional ambulation is a key outcome measure for this population.
Purpose of the Study:
- To interpret peak oxygen uptake (VO2peak) outcomes in children with spina bifida (SB).
- To explore the relationship between VO2peak and functional ambulation.
- To identify factors limiting VO2peak and assess exercise strain during locomotion.
Main Methods:
- Retrospective cross-sectional study of 23 ambulatory children with SB.
- VO2peak measured via graded treadmill testing; limiting factors analyzed using algorithms.
- Energy expenditure (O2 rate, O2 cost) and %VO2peak/%HRpeak assessed during 6-minute walk test (6MWT).
Main Results:
- VO2peak and related cardiorespiratory parameters were significantly lower than reference values.
- Community ambulators demonstrated significantly lower VO2peak and greater impairment in 6MWT distance, O2 cost, %VO2peak, and %HRpeak compared to normal ambulators.
- Primary limiting factors for VO2peak were 'muscular and/or deconditioning' (47%) and 'gas exchange' (35%).
Conclusions:
- VO2peak in ambulatory children with SB is primarily limited by deconditioning, muscular factors, and potentially ventilatory issues.
- Community ambulators experience higher physiological strain during ambulation, indicating greater functional limitations.
- Future interventions should focus on enhancing cardiorespiratory fitness, muscular endurance, and reducing locomotion energy costs in this population.
Abstract:
The objective of this study is to interpret the outcomes of peak oxygen uptake (VO(2peak)) in children with SB and explore the relationship between VO(2peak) and functional ambulation using retrospective cross-sectional study. Twenty-three ambulating children with SB participated at Wilhelmina's Children's Hospital Utrecht, the Netherlands. VO(2peak) was measured during a graded treadmill-test. Eschenbacher's and Maninna's algorithm was used to determine limiting factors in reaching low VO(2peak) values. Energy expenditure during locomotion (both O(2) rate and O(2) cost) and percentage of VO(2peak) and HR(peak) were determined during a 6-min walking test (6MWT). Differences between community and normal ambulators were analyzed. VO(2peak), VO(2peak)/kg, HR(peak), RER(peak) and VE (peak) were significantly lower compared to reference values, with significant differences between normal and community ambulators. Limiting factors according to the algorithm were mostly "muscular and/or deconditioning" (47%) and ventilatory "gasexchange" (35%). Distance walked during 6MWT was 48.5% of predicted distance. Both O(2) rate and O(2) cost were high with significant differences between normal and community ambulators [17.6 vs. 21.9 ml/(kg min) and 0.27 vs 0.43 ml/(kg m)]. Also %HR(peak) and %VO(2peak) were significantly higher in community ambulators when compared to normal ambulators (resp. 97.6 vs. 75% and 90.2 vs. 55.9%). VO(2peak) seems to be mostly limited by deconditioning and/or muscular components and possible ventilatory factors. For both peak values and functional ambulation, community ambulators were significantly more impaired than normal ambulators. High energy expenditure, %VO(2peak) and %HR(peak) reflect high level of strain during ambulation in the community ambulators. Future exercise testing in children with SB should include assessment of ventilatory reserve. Exercise training in ambulatory children should focus on increasing both VO(2peak) and muscular endurance, as well as decreasing energy cost of locomotion.
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