DYNAMIC TESTING OF THE MOTOR STEREOTYPE IN PRONE HIP EXTENSION FROM NEUTRAL POSITION

Objective. The purpose of the study was to identify a sequential activ ation of lumbar and hip muscles in active prone hip extension from neu tral position in subjects without a history of low back pain. Design. Using surface electromyography, the myoelectric activity onsets of ago nistic and antagonistic hip muscles were recorded. Background. The dev elopment of low back pain is ascribed to changes of the muscle firing order in prone hip extension. There appeared to be no normative data o n muscle firing order of the lumbar and hip musculature to provide a b asis for recognizing variations. Methods. Fifteen healthy subjects per formed standardized right hip extensions. Time-normalized onset of EMG activity in each muscle was measured for each trial. Results. A MANOV A revealed significant (P < 0.01) differences between the activity ons ets of synergistic muscles in hip extension. Conclusions. On the resul ts it was concluded that the consistent muscle firing order of ipsilat eral lumbar erector spinae, semitendinosus, contralateral lumbar erect or spinae, tensor fasciae latae, and gluteus maximus demonstrate the c haracteristic pattern in prone hip extension. In future studies it is essential to evaluate also the hip extension pattern in functional upr ight conditions during gait and their relationship to spinal mechanics . Relevance Hip extension is discussed in relation to the development of locomotor stereotypes and vertebral dysfunctions. This study identi fied the synergistic muscle firing order as an indication for the dyna mic motor stereotype in prone hip extension from neutral position of h uman healthy controls. (C) 1997 Elsevier Science Ltd.