Contrary to general believe, in one case of 18month cauda equina lesion four-month electrical stimulation of thigh muscles (impulse energy 1.92 Joule) increased stimulation frequency from 2 to 20 Hz, i. e., up to tetanic contractions. After 2 years of treatment, CT-cross sectional area of quadriceps improved 58.3% (right) and 44.4% (left) with increased muscle density. Mean myofiber size was 37.2 ± 24.8 µm (right) and 40.5 ± 24.9 µm (left). Improvement of stimulated knee torque, from zero to 12.0 Nm and 10.5 Nm, respectively, enabled to stand up trials. Surviving myofibers undergo re-growth (they show the chess board appearance of normal muscle), and dying myofibers continuously regenerate (up to 3% are embryonic myosin positive 3-year post-FES). Regeneration events are essential components of the FES rehabilitation protocol due to superior excitability of regenerated myofibers in comparison to long-term denervated, degenerated myofibers, which were almost not excitable before FES training.