Electrical stimulation and blood flow restriction increase wrist extensor cross-sectional area and flow meditated dilatation following spinal cord injury

Purpose To examine the effects of neuromuscular electrical stimulation (NMES) and blood flow restricted (BFR) exercise on wrist extensors cross-sectional area (CSA), torque and hand functions compared NMES only in individuals with incomplete tetraplegia. The acute effect of an acute bout of NMES with BFR on flow mediated dilation (FMD) was compared with BFR only. Method Nine men completed 6 weeks twice weekly of bilateral NMES training of the wrist extensor muscles. The right forearm received NMES + BFR (30 % above the resting systolic blood pressure), while the left forearm received NMES only. The CSA of the extensor carpi radialis longus (ECRL) and extensor digitorum communis (EDC) muscles was measured on ultrasound images. Torque was measured isometrically and hand function with grasp and release test. Another eight men with SCI received NMES+BFR to the right forearm, while the left forearm received BFR only. Immediately, the FMD of the brachial artery was measured. Result Following training, the ECRL CSA was 17 % greater in the NMES+BFR forearm (mean difference = 0.6 cm 2 , p = 0.003) compared with the NMES only. The NMES+BFR had a 15 % increase in ECRL CSA (mean increase = 0.58 cm 2 , p = 0.048). FMD increased ( p = 0.05) in the exercise arm (12 ± 3 %) compared with the control arm (6.5 ± 6 %). Conclusion NMES training with BFR is a strategy that can increase skeletal muscle size. NMES with and without BFR can improve wrist strength and hand function. The acute effects of NMES+BFR may suggest that an increase in FMD may partially contribute to skeletal muscle hypertrophy.