Short-term Maximal-Intensity Resistance Training Increases Volitional Function and Strength in Chronic Incomplete Spinal Cord Injury

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BACKGROUND AND PURPOSE: Recent research shows that individuals with an incomplete spinal cord injury (SCI) have a reserve of force-generating capability that is observable during repeated intermittent maximal volitional effort contractions. Previous studies suggest that increased neural drive contributes to the enhanced short-term force-generating capabilities. Whether this reserve can be harnessed with repeated training is unclear. The purpose of this pilot study was to investigate the effects of 4 weeks of maximal-intensity resistance training, compared with conventional progressive resistance training, on lower extremity function and strength in chronic incomplete SCI. METHODS: Using a randomized crossover design, 5 individuals with chronic (> 1 year postinjury) SCI American Spinal Injury Association Impairment Scale classification C or D were tested before and after 4 weeks of both maximal-intensity training and progressive resistance training paradigms. Outcomes measures included the 6-Minute Walk Test, the Berg Balance Scale, and peak isometric torque for strength of lower extremity muscles. RESULTS: Maximal-intensity resistance training was associated with an average increase of 12.19 ± 8.29 m on the 6-Minute Walk Test, 4 ± 1.9 points on the Berg Balance Scale, 4 ± 4.5 points on the lower extremity motor score), while no changes on the above scores were seen with conventional training. Furthermore, significant increases in peak volitional isometric torques (mean increase = 20 ± 8 Nm) were observed following maximal-intensity resistance training when compared with conventional training (mean increase = 0.12 ± 3 Nm, P = 0.03). DISCUSSION AND CONCLUSIONS: Maximal-intensity training paradigm may facilitate rapid gains in volitional function and strength in persons with chronic motor-incomplete SCI, using a simple short-term training paradigm.