The effects of dorso-lumbar motion restriction on EMG activity of selected muscles during running.

The effects of restricting dorso-lumbar spine mobility on electromyographic activity of the erector spinae, quadriceps femoris, hamstrings and gastrocnemius muscles in runners was investigated. Thermoplastic casting material was fashioned into a rigid orthosis and used to restrict spinal motion during running. Volunteers ran on a treadmill at 2.78 m/sec, under normal conditions and with spinal motion restricted. Surface electromyographic data was collected during both sets of trials. Normal electromyographic data was also compared with previous authors to determine similarity with their electromyographic data.

RESULTS: Casted running resulted in an increase in erector spinae (p < 0.01) and quadriceps femoris (p = 0.02) electromyography activity. Total stride time and swing time of gait were decreased during casted running (p < 0.01), indicating a shift towards shorter and thus more frequent steps to run the same distance. The normal electromyographic data collected was in agreement with previously reported work.

CONCLUSIONS: Neurological control over muscle and the fascia surrounding it is responsible for joint movement and load transfer. Experimentally restricting spinal motion during running demonstrated an increase in erector spinae and rectus femoris electromyographic activity. This lends support to the hypothesis that decreased spinal mobility may be a contributing factor to overuse muscle injuries in runners.