a. With respect to the GMFM Dimensional performance, a significant difference was appreciated amongst the pediatric cohort, using a Friedman test with multiple comparisons. Children with GSD IIIa demonstrated poorer performance on Dimension D, standing tasks, and Dimension E, walking, running, and jumping tasks. Only significant results from the multiple comparisons are indicated. **= p<0.01. b. On the GSGC, a significant difference was found between overall performance on the GSGC subdomains using a Friedman test; however, no significant differences were present with review of the multiple comparisons. In general a higher proportion of individuals demonstrated a poorer performance, represented by a greater score, on the Gait and Gowers subdomains. Gait, Gowers, and Stairs are graded on a 1–7 range, with 7 indicating the inability to perform the maneuver. The chair maneuver is graded on 1 −6 range, with 6 meaning inability to arise from a chair15. No individual scored the maximum for any of the four maneuvers.