C-26 Free Communication/Poster - Objective Measures: Accelerometry and Pedometry: JUNE 3, 2010 7:30 AM - 12:30 PM: ROOM: Hall C
Recent work has demonstrated that boys with Duchenne muscular dystrophy (DMD) are less active and take fewer steps/day than healthy boys. However, little information is known regarding what factors may contribute to this decrease in physical activity.
PURPOSE: The purpose of this study was to examine gait parameters, strength, and functional ability in boys with DMD whose daily step count was < 6000 steps/day compared to those who had a step count of > 6000 steps/day.
METHODS: Physical activity was assessed for 5-7 consecutive days with an activity monitor (accelerometer) to obtain average daily step count and METs (determined by the Freedson child energy expenditure prediction equation). Fifteen ambulatory boys with DMD (mean age 8.8 + 1.4 years) participated. Seven of these subjects had a daily step count < 6000 steps/day (4850 +/- 1059) (INACTIVE), and eight had > 6000 steps/day (7436 +/- 1402) (ACTIVE). Subjects also participated in gait assessment for spatiotemporal parameters, strength testing (isometric knee extension and plantarflexion on a dynamometer), and a timed functional test (30 foot fast walk). T-tests were used to determine differences between the two groups, and relationships were examined using Pearson correlation coefficients (alpha = 0.05).
RESULTS: No differences were noted between the groups for age, METs, or strength (p > 0.30). A difference in gait parameters was noted for step length (m) (INACTIVE 0.46 +/- 0.05, ACTIVE 0.54 +/- 0.06; p < 0.01). Trends were noted for base of support (cm) (INACTIVE 5.6 +/- 3.0, ACTIVE 2.9 +/- 2.1; p = 0.08) and functional ability as evidenced by the 30 foot walk (s) (INACTIVE 7.04 +/- 2.0, ACTIVE 5.60 +/- 0.6; p = 0.07). There was an inverse relationship found between daily step count and the 30 foot walk for all 15 subjects (r = -0.66, p < 0.01).
CONCLUSIONS: The preliminary data collected in this study suggest that functional ability and gait characteristics appear to be more important than strength in distinguishing activity level in children with DMD. Further research is warranted to explore these variables to determine if addressing these functional limitations may improve a child's daily activity.
Funded by the Muscular Dystrophy Association (MDA4170), Wellstone Muscular Dystrophy Center Grant (1U54RO52646-01A1), and Parent Project Muscular Dystrophy.