Table 1.

Demographic data.

Age, mean (SD), y	12.1 (3.9)
Body mass, mean (SD), kg	44.9 (18.0)
Height, mean (SD), cm	149.8 (21.7)
Sex, female, n (%)	22 (44%)
Ambulatory status, ambulatory, n (%)	34 (68%)
MRC knee extensors, n	36
MRC 3, n (%)	11 (31%)
MRC ≥ 4, n (%)	25 (69%)
MRC knee flexors, n	37
MRC 3, n (%)	5 (14%)
MRC ≥ 4, n (%)	32 (86%)
MRC elbow extensors, n	40
MRC 3, n (%)	5 (12.5%)
MRC ≥ 4, n (%)	35 (87.5%)
MRC elbow flexors, n	49
MRC 3, n (%)	14 (29%)
MRC ≥ 4, n (%)	35 (71%)
Diagnosis, n (%)
Axonal motor neuropathy	1 (2%)
Axonal polyneuropathy	1 (2%)
Becker muscular dystrophy	3 (6%)
Carey Fineman Ziter syndrome	2 (4%)
Central core myopathy	1 (2%)
Duchenne muscular dystrophy	1 (2%)
Hereditary motor and sensory neuropathy	7 (14%)
Myotonic dystrophy	1 (2%)
Myasthenia gravis	2 (4%)
Myotonica congenita (type Becker)	2 (4%)
Nemaline myopathy	1 (2%)
Silver syndrome	1 (2%)
Spinal muscular atrophy	27 (54%)
1c	1 (2%)
2a	7 (14%)
2b	1 (2%)
3a	17 (34%)
3b	1 (2%)

MRC (Medical Research Council) scale.