TABLE V.

Electromyographic Data for Normal Subjects and Before and After Muscle-Tendon Lengthening in Patients with Cerebral Palsy

	Muscle Activity (percent of mean)
	Effect Size^*	Normal Subjects	Patients with Cerebral Palsy^†
	Effect Size^*	Normal Subjects	Preop.	Postop.
Gastrocnemius
Range	0.35	3.00	2.14	1.89
Mean	—	1	1	1
Maximum	0.33	3.17	2.54	2.24
Minimum	0.06	0.17	0.39	0.36
At foot contact	0.13	0.79	1.38	1.25
At mid-stance	0.17	1.75	1.14	1.31^‡
At toe-off	0.19	0.48	0.63	0.55
Tibialis anterior
Range	0.28	2.06	1.41	1.62
Mean	—	1	1	1
Maximum	0.26	2.37	1.93	2.05
Minimum	0.06	0.30	0.52	0.43^‡
At foot contact	0.20	1.56	1.16	1.26
At mid-stance	0.09	0.69	0.97	0.97
At toe-off	0.18	1.13	0.97	0.98
Hamstrings
Range	0.27	2.77	1.47	1.71
Mean	—	1	1	1
Maximum	0.25	2.93	1.95	2.08
Minimum	0.05	0.16	0.49	0.37^‡
At foot contact	0.35	1.73	1.57	1.39
At mid-stance	0.12	0.73	0.92	1.06
At toe-off	0.19	0.72	0.78	0.58
Quadriceps
Range	0.31	2.62	1.50	1.66
Mean	—	1	1	1
Maximum	0.28	2.86	2.02	2.09
Minimum	0.06	0.24	0.51	0.43^‡
At foot contact	0.21	1.66	1.25	1.22
At mid-stance	0.10	0.58	0.93	0.99
At toe-off	0.24	1.62	0.87	0.97

Effect size = the difference required for significance at α < 0.05 with a statistical power of 0.9.

^†

Boldface type indicates that the data were significantly different from the value for normally developing subjects (p < 0.05).

^‡

These postoperative data were significantly different from the preoperative values (p < 0.05). The results suggest that muscle-tendon lengthening has little effect on knee or hip muscle activities but can modify myoactivity of stance-phase ankle dynamics.