Here, the investigators propose an early intervention of combined NMES (Comb-NMES). This program couples electrically induced resistance and aerobic exercise on the knee extensor muscle group (quadriceps) with the goal of maintaining or even improving muscle mass and metabolic function. The proposed Comb-NMES program repetitively stresses the paralyzed knee extensor muscles with both low frequency electrical stimulation (aerobic training) to improve oxidative metabolism and retain Type I fibers and high frequency (resistance training) electrical stimulation with dynamic contractions to prevent atrophy and retain Type IIa fibers.