The effects of 10,000 voluntary contractions over 8 weeks on the strength of very weak muscles in people with spinal cord injury: a randomised controlled trial

Abstract

Study design: A multi-centred, single-blinded randomised controlled trial. Objectives: To determine the effect of 10,000 voluntary contractions over 8 weeks on the strength of very weak muscles in people with spinal cord injury (SCI). Settings: Seven hospitals in Australia and Asia. Methods: One hundred and twenty people with recent SCI undergoing inpatient rehabilitation were randomised to either a Treatment or Control Group. One major muscle group from an upper or lower limb was selected if the muscle had grade 1 or grade 2 strength on a standard six-point manual muscle test. Participants allocated to the Treatment Group performed 10,000 isolated contractions of the selected muscle group, as well as usual care in 48 sessions over 8 weeks. Participants allocated to the Control Group received usual care alone. Participants were assessed at baseline and 8 weeks by a blinded assessor. The primary outcome was voluntary muscle strength on a 13-point manual muscle test. There were three secondary outcomes capturing therapists’ and participants’ perceptions of strength and function. Results: The mean between-group difference of voluntary strength at 8 weeks was 0.4/13 points (95% confidence interval −0.5 to 1.4) in favour of the Treatment Group. There were no notable between-group differences on any secondary outcome. Conclusion: Ten thousand isolated contractions of very weak muscles in people with SCI over 8 weeks has either no or a very small effect on voluntary strength.