Peak oxygen uptake (VO(2peak)) across childhood, adolescence and young adulthood in Barth syndrome: Data from cross-sectional and longitudinal studies

Barth syndrome (BTHS) is an ultra-rare, X-linked recessive disorder characterized by cardio-skeletal myopathy, exercise intolerance, and growth delay. Oxygen uptake during peak exercise (VO(2peak)) has been shown to be severely limited in individuals with BTHS however; the trajectory of VO(2peak) from childhood to young adulthood is unknown. The objective of this study was to describe VO(2peak) from childhood through young adulthood in BTHS. Methods and Materials: VO(2peak) over time was presented through cross-sectional (n = 33 participants) and a longitudinal analyses (n = 12 participants). Retrospective data were obtained through maximal exercise testing on a cycle ergometer from individuals with BTHS who were or are currently enrolled in a research study during July 2006-September 2017. Participants included in the cross-sectional analysis were divided into 3 groups for analysis: 1) children (n = 13), 2) adolescents (n = 8), and 3) young adults (n = 12). Participants in the longitudinal analysis had at least two exercise tests over a span of 2–9 years. Results: VO(2peak) relative to body weight (ml/kgBW/min), fat-free mass (FFM) and by percent of predicted VO(2peak) obtained were not significantly different between children, adolescents and young adults. VO(2peak) did not longitudinally change over a mean time of ~5 years in late adolescent and young adult participants with repeated tests. A model including both cardiac and skeletal muscle variables best predicted VO(2peak). Conclusions: In conclusion, VO(2peak) relative to body weight and fat-free mass demonstrates short- and long-term stability from childhood to young adulthood in BTHS with some variability among individuals.