Table 5. Mean and standard deviation from nonlinear indices in both groups.

Index	TD		DMD
	Rest seated	Cognitive task	Rest seated	Cognitive task
SD1 (ms)	37.88 ± 20.85	36.98 ± 23.01	26.33 ± 14.84	22.11 ± 14.41
SD2 (ms)	105.21 ± 43.69	80.73 ± 45.27	71.99 ± 32.86	46.46 ± 20.24
SD1/SD2 (ms)	0.35 ± 0.11	0.46 ± 0.18	0.36 ± 0.10	0.45 ± 0.16

TD: Typical Development; DMD: Duchenne Muscular Dystrophy; SD1: standard deviation of instantaneous beat-to-beat variability; SD2: standard deviation of long-term continuous RR intervals; ms: milliseconds.

There was significant difference between cognitive task vs rest seated in both groups for all frequency domain indexes. For SD1/SD2 there was no significant difference between groups.