Age-related longitudinal changes in metabolic energy expenditure during walking in boys with Duchenne muscular dystrophy

The aim of this study was to evaluate age-related changes in metabolic walking energy expenditure in ambulant boys affected by Duchenne muscular dystrophy over a follow-up period of 12 months. At baseline (T1) and 12 months later (T2), metabolic walking energy expenditure was assessed during a 6-minute walk test at comfortable speed in 14 ambulant boys with Duchenne (age range: 6.0-12.5 years, mean 8.2). Outcome measures derived from the assessment included the 6-minute comfortable walking distance (m) and net-nondimensional energy cost relative to speed-matched control cost (SMC-EC, %). Statistical comparisons were made using a two-way repeated measures ANOVA (factors: time (T1 versus T2) and age ( 0.158), and also there were no interaction effects (p>0.248). The results of our small study suggest that the natural course of walking performance in ambulant boys with Duchenne is characterized by a decrease in comfortable walking distance and an increase in walking energy cost. The rate of energy cost seems to increase with age, while walking distance decreases, which is opposite from the trend in typically developing childre

One-year changes in WECT outcomes.

<p>One-year changes in WECT outcomes.</p

One-year change in (A) comfortable walking distance; (B) walking effort; and (C) walking efficiency, as measured with the WECT.

<p>One-year change in (A) comfortable walking distance; (B) walking effort; and (C) walking efficiency, as measured with the WECT.</p

Subject demographics.

<p>Subject demographics.</p

One-year change in maximal walking distance, as measured with the 6MWT.

<p>One-year change in maximal walking distance, as measured with the 6MWT.</p

One-year change in walking cost in typically developing children (straight line) and in boys with DMD (dashed line).

<p>Reference data of typically developing children are based on Thomas et al <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115200#pone.0115200-Thomas1" target="_blank">[23]</a>.</p