Abstract
Introduction Deficits in control of the trunk muscles have been demonstrated in people with recurrent low back pain (LBP) (1,2). These changes can persist despite resolution of symptoms (1) and is thought to be associated with recurrence and chronicity. One approach that has been shown to reduce symptoms and prevent recurrence involves rehabilitation of trunk muscle control, rather than training the strength and endurance of the trunk muscles. Although we have recently shown that this rehabilitation strategy induces immediate changes in coordination (3), no study has investigated whether improvement can be maintained in the long-term. Using the model of changes in control of the deep abdominal muscle, transversus abdominis (TrA), in people with LBP(1), this study aimed to investigate whether four weeks of training of repeated voluntary TrA contractions could induce long-term changes in control of the trunk muscles.
Methods Nine volunteers with recurrent LBP trained isolated voluntary TrA contractions twice per day for four weeks. Coordination of the abdominal muscles was assessed during single rapid arm movements and walking. Measures were made before and after initial training, before and after training at week two, at week four, and at six months. Recordings of electromyographic activity (EMG) were made from trunk and deltoid muscles. Feedback of contraction during training was provided during training at the initial session and at 2 weeks with real-time ultrasound. TrA EMG activity was maintained at 5% maximum root-mean-square EMG. Onsets of trunk muscle EMG was identified during arm movement and coefficient of EMG variation (CV) was calculated during walking.
Results Onset of TrA EMG was earlier during arm flexion and extension immediately after a single session of training, and was further improved with four weeks of training (p< 0.05). In addition, the CV of the TrA EMG (indicating more sustained activity) during walking were found over four weeks of training (p< 0.05). Changes in motor control were retained at six months follow-up despite cessation of training. Changes in other trunk muscles were not significant (p> 0.05).
Discussion The results suggest that four weeks specific motor control training is associated with consistent changes in motor control of the trained muscle during functional tasks. Although improvements in symptoms were also identified, future randomized clinical trials are required to confirm these changes and their association with the changes in coordination of the trunk muscles.
The abstracts were prepared by Assoc Prof Bruce McPhee. Correspondence should be addressed to him at the Division of Orthopaedics, The University of Queensland, Clinical Sciences Building, Royal Brisbane Hospital, Herston, Brisbane, 4029, Australia.
References
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