Influence of gait analysis on decision-marketing for lower extremity surgery

Changes in EMG activation patterns following a strength training programme for adolescents with cerebral palsy


  • 1. School of Human Movement and Exercise Science, University of Western Australia;
  • 2. School of Physiotherapy, University of Notre Dame, Pertb, Western Australia, Australia

Objective: To determine the effects of an upper limb eccentric strength training programme on electromyographic (EMG) activation characteristics of adolescents with cerebral palsy (CP), relative to typically developing peers. The hypothesis are that: (1) those with CP will show decreased flexor EMG activation compared with those without CP; and (2) EMG flexor activity will increase following strengthening  for those with CP.

Design: An intervention study with a matched normative comparison population.

Participants: A volunteer sample of 14 adolescents with hemiplegia, aged 9 to 15 years (mean age 11y 4 mo [SD 1y 10mo]), completed the eccentric strength-training programme. Exclusion criteria included upper limb surgical or botulinum toxin A intervention within the past 12 months. An age- and sex-matched sample of 14 typically developing adolescents, were recruited as the comparative population.

Method: Participants with CP completed the eccentric training with a specifically designed training rig to exercise eccentrically the elbow flexors pf their affected upper limb. Participants commenced training at a load equivalent to 50% of their maximum eccentric capacity and progressed up to 70% by week 6 of training. Participants exercise three times a week, performing three sets of 10 repetitions at each session. Pre- and post-training biceps brachii and brachioradialis EMG activation was assessed during maximum eccentric and concentric isokinetic actions on a Biodex Dynamometer. Comparative data was collected on participants without CP using the same protocol.

Results: EMG activation was normalized to individual maximum and the activity of biceps and brachioradialis averaged to provide overall `flexor activation’. Flexor activation was analyzed over three phases of elbow range of motion: 60 to 69 0, 70 to 79 0, and 80 to 100 0. Before training, children with CP displayed significantly greater flexor EMG that those without CP in the concentric tasks (F(1,23)=6.894,p=0.015). Following training these group differences no longer existed. Flexor activation in the eccentric task decreased significantly (F(1,11)=9.334, p=0.011), from pre- (mean 56%  [SD8] ) to post-training (mean 41% of [SD 17] for children with CP.

Conclusions: Before training, EMG activity was overactive in those with CP compared with the typically developing comparison group.Following training, EMG activity decreased to normative levels across the phases. Therefore, it appears that eccentric training increased neural efficiency of the elbow flexors. These results suggest that eccentric exercises may have an important role in the area of motor control, having significant implication for the prescription of strength-training programmes for those with CP.

Acknowledgements: The authors wish to acknowledge the endorsement of The Cerebral Palsy Association of Western Australia (ltd) and Therapy Focus.

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