Effects of neuromuscular electrical stimulation in people with spinal cord injury

INTRODUCTION: Muscle force production is usually impaired in people with spinal cord injury (SCI). The use of high-intensity neuromuscular electrical stimulation (NMES) strength training can help promote metabolically active lean muscle mass and thus, increase muscle mass and improve physical health and quality of life (QoL). Nonetheless, NMES is usually used at low-stimulation intensities and there is limited evidence on the effects of high-intensity NMES strength training into improving muscle force and mass, symptoms of spasticity or physical health and quality of life (QoL) in people with SCI. METHODS: Five individuals with chronic SCI completed five 10-repetition sets of high-intensity knee extension NMES strength training sessions for 12 weeks in both quadriceps muscles. Quadriceps femoris (QF) knee extensor torque was measured on a dynamometer and cross-sectional area (CSAQF) was measured with extended-field-of-view ultrasonography. Venous blood samples were collected for blood lipid profiling and c-reactive protein (CRP) analyses. The Spinal Cord Injury Spasticity Evaluation Tool (SCI-SET) was used to assess symptoms of spasticity and the quality of life index (QLI) SCI version III was used for QoL measures. RESULTS: QF tetanic knee extensor torque increased on average by 35% (2 - 92%) and CSAQF increased by 47% (14 - 145%). A significant increase in the HDL/LDL cholesterol ratio (p < 0.001), a mean significant improvement of 4.8% ± 2.3% (absolute value = 0.26) in SCI-SET score was observed, whilst QoL showed a near-significant improvement in the health & functioning domain (15.0 ± 4.2; 17.3 ± 5.1; p = 0.07). CONCLUSIONS: High-intensity NMES-strength training in people with SCI may improve muscle strength, mass, physical health and QoL. However, replication of these results is necessary before clinical implementation.