Resistance training and locomotor recovery after incomplete spinal cord injury: a case series

Study design: Longitudinal intervention case series. Objective: To determine if a 12- week resistance and plyometric training program results in improved muscle function and locomotor speed after incomplete spinal cord injury ( SCI). Setting: University research setting. Methods: Three ambulatory individuals with chronic ( 18.7 +/- 2.2 months post injury) motor incomplete SCI completed 12 weeks of lower extremity resistance training combined with plyometric training ( RPT). Muscle maximum cross- sectional area ( max- CSA) of the knee extensor ( KE) and plantar flexor ( PF) muscle groups was determined using magnetic resonance imaging ( MRI). In addition, peak isometric torque, time to peak torque ( T-20 - 80), torque developed within the initial 220 ms of contraction ( torque(220)) and average rate of torque development ( ARTD) were calculated as indices of muscle function. Maximal as well as self-selected gait speeds were determined pre- and post- RPT during which the spatio- temporal characteristics, kinematics and kinetics of gait were measured. Results: RPT resulted in improved peak torque production in the KE ( 28.9 +/- 4.4%) and PF ( 35.0 +/- 79.1%) muscle groups, as well as a decrease in T20 - 80, an increased torque220 and an increase ARTD in both muscle groups. In addition, an increase in self- selected ( pre- RPT = 0.77 m/ s; post- RPT = 1.03 m/ s) and maximum ( pre- RPT = 1.08 m/ s; post-RPT = 1.47 m/ s) gait speed was realized. Increased gait speeds were accompanied by bilateral increases in propulsion and hip excursion as well as increased lower extremity joint powers. Conclusions: The combination of lower extremity RPT can attenuate existing neuromuscular impairments and improve gait speed in persons after incomplete SCI.