Short-term progressive resistance exercise may not be effective at increasing wrist strength in people with tetraplegia: a randomised controlled trial

Questions: Is an 8-week progressive resistance exercise program effective for increasing strength in the wrist muscles of people with tetraplegia? Is it effective for improving muscle endurance and participants' perceptions about use of their hands for activities of daily living? Design: Randomised controlled trial with concealed allocation, assessor blinding, and intention-to-treat analysis. Participants: Thirty-two people with tetraplegia and neurological weakness of their wrist flexor or extensor muscles. Intervention: The wrist muscles of one randomly-chosen hand were trained 3 times a week for 8 weeks. The control group received no intervention. Outcome measures: The primary outcome was strength measured as maximal voluntary isometric torque in Nm. The secondary outcomes were muscle endurance measured as fatigue resistance and participants' perceptions about use of their hands using the Canadian Occupational Performance Measure. Results: The mean effect on maximal voluntary isometric torque was 0.2 Nm (95% CI -0.5 to 0.8). This represents an 8% increase of mean initial strength; less than the 20% deemed clinically worthwhile at the commencement of the study. The mean effect on fatigue resistance was 0.1 (95% CI 0.0 to 0.2). The mean effect on participants' perceptions of performance was -0.3 (95% CI -1.9 to 1.2) and satisfaction was -0.3 (95% CI -1.6 to 1.0). Conclusion: The results indicate that progressive resistance exercise has no effect on participants' perceptions about hand function. However, it is not yet clear whether progressive resistance exercise programs improve strength and endurance in muscles with neurologically-induced weakness following tetraplegia.