Different regions of the central nervous system activate the neuromuscular system. Nowadays, artificial systems are employed to imitate physiological tasks lost due to neurological injuries. The electrical stimulation of in vivo human tissues, as a way of treatment, has been developed by means of research and technological enhancements. People who have suffered spinal cord injury can lose partial or total motor function. The electrical stimulation of neuromuscular tissue generates artificial movements that can afford long term health improvements by means of neuronal plasticity. Functional electrical stimulation can use diverse parameters, electrodes and application sites in the body. When the adjustments and corrections of stimulatory parameters are performed manually, the system is called open loop control; whereas when it is automatic, the system is closed-loop control. Both ways (open- and closed-loop) contribute to physical rehabilitation of spinal cord injury patients. Closed-loop control systems present advantages in comparison to open-loop systems like automatic correction of electrical stimulation parameters. Therefore, with the development of artificial motor control strategies and the creation of user-friendly interfaces, the activation of software and hardware for producing movements artificially can be performed by the users of the system (spinal cord injury patients), resembling the human physiological system.193530541Fodstad, H., Hariz, M., Electricity in the treatment of nervous system disease (2007) Acta Neurochir Suppl, 97, p. 11. , http://dx.doi.org/10.1007/978-3-211-33079-1_2Popovic, M.R., Thrasher, T.A., Neuroprostheses (2004) Encyclopedia of Biomaterials and Biomedical Engineering, pp. 1056-1065. , In: Bowlin GL, Wnek G, eds, New York: Informa HealthcareGalvani, L., De viribus electricitatis in motu musculari commentarius (1791) Bon Sci Art Inst Acad Comm, pp. 363-418Verkhratsky, A., Krishtal, O.A., Petersen, O.H., From Galvani to patch clamp: The development of electrophysiology (2006) Pflugers Arch - Eur J Physiol, 453, pp. 233-247Duchenne, G.B., (1855) De L'Electrisation Localisee Et De Son Application a La Pathologie Et a La Therapeutique, p. 900. , Paris: J-B BaillièreDilorenzo, D.J., Bronzino, J.D., (2007) Neuroengineering, p. 408. , http://dx.doi.org/10.1201/9780849381850, Boca Raton: CRC PressHe, B., (2005) Neural Engineering, p. 488. , http://dx.doi.org/10.1007/b112182, Dordrecht: Kluwer/PlenumDeluze, C., Bosia, L., Zirbs, A., Chantraine, A., Vischer, T.L., Electroacupuncture in fibromyalgia: Results of a controlled trial (1992) Br Med J, 305, pp. 1249-1252. , http://dx.doi.org/10.1136/bmj.305.6864.1249Song, J.W., Yang, L.J., Russell, S.M., Peripheral nerve: What's new in basic science laboratories (2009) Neurosurg Clin N Am, 20, pp. 121-131. , http://dx.doi.org/10.1016/j.nec.2008.07.026Popovic, M.R., Curt, A., Keller, T., Dietz, V., Functional electrical stimulation for grasping and walking: Indications and limitations (2001) Spinal Cord, 39, pp. 403-412. , http://dx.doi.org/10.1038/sj.sc.3101191O'Donovan, K.J., O'Keeffe, D.T., (2001) Movement Monitoring FES System, pp. 1-3. , Annual Conference of the International Functional Electrical Stimulation Society, ClevelandGraupe, D., Kohn, K.H., (1994) Functional Electrical Stimulation for Ambulation by Paraplegics: Twelve Years of Clinical Observations and System Studies, p. 194. , Malabar: Krieger Publishing CompanyIsakov, E., Mizrahi, J., Najenson, T., Biomechanical and physiological evaluation of FES-activated paraplegic patients (1986) J Rehabil Res Dev, 23, pp. 9-19McNeil, C.J., Murray, B.J., Rice, C.L., Differential changes in muscle oxygenation between voluntary and stimulated isometric fatigue of human dorsiflexors (2006) J Appl Physiol, 100, pp. 890-895. , http://dx.doi.org/10.1152/japplphysiol.00921.2005Hamada, T., Hayashi, T., Kimura, T., Nakao, K., Moritani, T., Electrical stimulation of human lower extremities enhances energy consumption, carbohydrate oxidation, and whole body glucose uptake (2004) J Appl Physiol, 96, pp. 911-916. , http://dx.doi.org/10.1152/japplphysiol.00664.2003Packman-Braun, R., Relationship between functional electrical stimulation duty cycle and fatigue in wrist extensor muscles of patients with hemiparesis (1988) Phys Ther, 68, pp. 51-56Thorsen, R., Spadone, R., Ferrarin, M., A pilot study of myoelectrically controlled FES of upper extremity (2001) IEEE Trans Neural Syst Rehabil Eng, 9, pp. 161-168. , http://dx.doi.org/10.1109/7333.928576Hoshimiya, N., Naito, A., Yajima, M., Handa, Y., A multichannel FES system for the restoration of motor functions in high spinal cord injury patients: A respiration-controlled system for multijoint upper extremity (1989) IEEE Trans Biomed Eng, 36, pp. 754-760. , http://dx.doi.org/10.1109/10.32108Crago, P.E., Memberg, W.D., Usey, M.K., Keith, M.W., Kirsch, R.F., Chapman, G.J., An elbow extension neuroprosthesis for individuals with tetraplegia (1998) IEEE Trans Rehabil Eng, 6, pp. 1-6. , http://dx.doi.org/10.1109/86.662614Kilgore, K.L., Hart, R.L., Montague, F.W., Bryden, A.M., Keith, M.W., Hoyen, H.A., An implanted myoelectrically-controlled neuroprosthesis for upper extremity function in spinal cord injury (2006) Conf Proc IEEE Eng Med Biol Soc, 1, pp. 1630-1633. , http://dx.doi.org/10.1109/IEMBS.2006.259939Maynard, F.M., Bracken, M.B., Creasey, G., Ditunno, J.F., Donovan, W.H., Ducker, T.B., International standards for neurological and functional classification of spinal cord injury (1997) Spinal Cord, 35, pp. 266-274. , http://dx.doi.org/10.1038/sj.sc.3100432Burt, A.A., The epidemiology, natural history and prognosis of spinal cord injury (2004) Curr Orthop, 18, pp. 26-32. , http://dx.doi.org/10.1016/j.cuor.2004.01.001(2010) Lesão Medular: Principais Causas De Lesão Medular Traumática (Endereço Na Internet), , http://www.sarah.br/paginas/doencas/po/p_08_lesao_medular.htm, Brasília: SARAH - Rede Sarah Kubitschek de Hospitais, atualizado em: 01/2010acessado em: 01, Disponível emPetrofsky, J.S., Electrical stimulation: Neurophysiological basis and application (2004) Basic Appl Myol, 14, pp. 205-213Venkatasubramanian, G., Jung, R., Sweeney, J.D., Functional Electrical Stimulation (2006) Encyclopedia of Medical Devices and Instrumentation, pp. 347-366. , In: Webster JG, ed., 2 ed. New York, NY: John Wiley & SonsAgne, J.E., (2005) Eletroterapia: Teoria E Prática, p. 336. , Santa Maria: OriumHatzis, A., Stranjalis, G., Megapanos, C., Sdrolias, P.G., Panourias, I.G., Sakas, D.E., The current range of neuromodulatory devices and related technologies (2007) Acta Neurochir Suppl, 97, pp. 21-29. , http://dx.doi.org/10.1007/978-3-211-33079-1_3Ward, A.R., Shkuratova, N., Russian electrical stimulation: The early experiments (2002) Phys Ther, 82, p. 1019Audu, M., To, C., Kobetic, R., Triolo, R., Gait evaluation of a novel hip constraint orthosis with implication for walking in paraplegia (2010) IEEE Trans Neural Syst Rehabil Eng, , http://dx.doi.org/10.1109/TNSRE.2010.2047594, In PressTo, C.S., Kirsch, R.F., Kobetic, R., Triolo, R.J., Simulation of a functional neuromuscular stimulation powered mechanical gait orthosis with coordinated joint locking (2005) IEEE Trans Neural Syst Rehabil Eng, 13, pp. 227-235. , http://dx.doi.org/10.1109/TNSRE.2005.847384Marsolais, E.B., Kobetic, R., Functional electrical stimulation for walking in paraplegia (1987) J Bone Joint Surg, 69, pp. 728-733Thrasher, A., Graham, G.M., Popovic, M.R., Reducing muscle fatigue due to functional electrical stimulation using random modulation of stimulation parameters (2005) Artif Organs, 29, pp. 453-458. , http://dx.doi.org/10.1111/j.1525-1594.2005.29076.xBaker, L.L., Bowman, B.R., McNeal, D.R., Effects of waveform on comfort during neuromuscular electrical stimulation (1988) Clin Orthop Relat Res, 233, pp. 75-85Rabischong, E., Surface action potentials related to torque output in paraplegics' electrically stimulated quadriceps muscle (1996) Med Eng Phys, 18, pp. 538-547. , http://dx.doi.org/10.1016/1350-4533(96)00001-XRooney, J.G., Currier, D.P., Nitz, A.J., Effect of variation in the burst and carrier frequency modes of neuromuscular electrical stimulation on pain perception of healthy subjects (1992) Phys Ther, 72, pp. 800-806Geddes, L.A., Baker, L.E., (1989) Principles of Applied Biomedical Instrumentation, p. 961. , New York: Wiley-Interscience, 3 EdBronzino, J.D., (1992) Management of Medical Technology: A Primer for Clinical Engineers, p. 451. , Boston: Butterworth-HeinemannMarsolais, E.B., Kobetic, R., Development of a practical electrical stimulation system for restoring gait in the paralyzed patient (1988) Clin Orthop Relat Res, 233, pp. 64-74Shimada, Y., Sato, K., Kagaya, H., Konishi, N., Miyamoto, S., Matsunaga, T., Clinical use of percutaneous intramuscular electrodes for functional electrical stimulation (1996) Arch Phys Med Rehabil, 77, pp. 1014-1018. , http://dx.doi.org/10.1016/S0003-9993(96)90061-1Orizio, C., Gobbo, M., Diemont, B., Changes of the force-frequency relationship in human tibialis anterior at fatigue (2004) J Electromyogr Kinesiol, 14, pp. 523-530. , http://dx.doi.org/10.1016/j.jelekin.2004.03.009Castro, M.J., Apple, D.F., Staron, R.S., Campos, G.E.R., Dudley, G.A., Influence of complete spinal cord injury on skeletal muscle within 6 mo of injury (1999) J Appl Physiol, 86, pp. 350-358Valenga, M.H., Jorge, R.F., dos Santos, A., Schneider, B., Nohama, P., Sistema de estimulação elétrica gatilhado por sinal respiratório. 21o Congresso Brasileiro de Engenharia Biomédica (2008) Salvador, pp. 495-498Bear, M.F., Connors, B.W., Paradiso, M.A., (2002) Neurociências: Desvendando O Sistema Nervoso, p. 855. , 2 ed. Porto Alegre: ArtmedMachado, A.B.M., (2006) Neuroanatomia Funcional, p. 363. , 2ed. São Paulo: AtheneuKandel, E.R., Jessell, T.M., Schwartz, J.H., (1991) Principles of Neural Science, p. 1138. , 3 ed. New York: ElsevierTonet, O., Marinelli, M., Citi, L., Rossini, P.M., Rossini, L., Megali, G., Defining brain-machine interface applications by matching interface performance with device requirements (2008) J Neurosci Methods, 167, pp. 91-104. , http://dx.doi.org/10.1016/j.jneumeth.2007.03.015Kandel, E.R., Jessell, T.M., Schwartz, J.H., (1991) Principles of Neural Science, p. 1137. , 3 ed. New York: ElsevierGraziano, M.S.A., Feedback remapping and the cortical control of movement (2006) Motor Control and Learning, pp. 97-104. , http://dx.doi.org/10.1007/0-387-28287-4_9, In: Latash ML, Lestienne F, New York: SpringerKnikou, M., Conway, B.A., Effects of electrically induced muscle contraction on flexion reflex in human spinal cord injury (2005) Spinal Cord, 43, pp. 640-648. , http://dx.doi.org/10.1038/sj.sc.3101772Pierrot-Deseilligny, E., Burke, D.C., (2005) The Circuitry of the Human Spinal Cord: Its Role in Motor Control and Movement Disorders, p. 642. , http://dx.doi.org/10.1017/CBO9780511545047, Cambridge: Univ PrLoeb, G.E., Learning from the spinal cord (2001) J Physiol, 533, pp. 111-117. , http://dx.doi.org/10.1111/j.1469-7793.2001.0111b.xKern, H., Stramare, R., Martino, L., Gargiulo, P., Carraro, U., Permanent LMN denervation of human skeletal muscle and recovery by hb FES: Management and monitoring (2010) Eur J Translat Myol, 20, pp. 91-104Dietz, V., Harkema, S.J., Locomotor activity in spinal cord-injured persons (2004) J Appl Physiol, 96, pp. 1954-1960. , http://dx.doi.org/10.1152/japplphysiol.00942.2003Thrasher, T.A., Flett, H.M., Popovic, M.R., Gait training regimen for incomplete spinal cord injury using functional electrical stimulation (2006) Spinal Cord, 44, pp. 357-361. , http://dx.doi.org/10.1038/sj.sc.3101864Vanderthommen, M., Duchateau, J., Electrical stimulation as a modality to improve performance of the neuromuscular system (2007) Exerc Sport Sci Rev, 35, pp. 180-185. , http://dx.doi.org/10.1097/jes.0b013e318156e785Higbie, E.J., Cureton, K.J., Warren Iii, G.L., Prior, B.M., Effects of concentric and eccentric training on muscle strength, cross-sectional area, and neural activation (1996) J Appl Physiol, 81, pp. 2173-2181Butler, D.S., (2003) Mobilização Do Sistema Nervoso, p. 270. , Barueri: ManoleRushton, D.N., Functional electrical stimulation and rehabilitation - an hypothesis (2003) Med Eng Phys, 25, pp. 75-78. , http://dx.doi.org/10.1016/S1350-4533(02)00040-1Sheffler, L.R., Chae, J., Neuromuscular electrical stimulation in neurorehabilitation (2007) Muscle Nerve, 35, pp. 562-590. , http://dx.doi.org/10.1002/mus.20758Lippold, O.C.J., Nicholls, J.G., Redfearn, J.W.T., Electrical and mechanical factors in the adaptation of a mammalian muscle spindle (1960) J Physiol, 153, pp. 209-217Lieber, R.L., Kelly, M.J., Torque history of electrically stimulated human quadriceps: Implications for stimulation therapy (1993) J Orthop Res, 11, pp. 131-141. , http://dx.doi.org/10.1002/jor.1100110115Rushton, D.N., Functional electrical stimulation (1997) Physiol Meas, 18, pp. 241-276. , http://dx.doi.org/10.1088/0967-3334/18/4/001Dietz, V., Nakazawa, K., Wirz, M., Erni, T., Level of spinal cord lesion determines locomotor activity in spinal man (1999) Exp Brain Res, 128, pp. 405-409. , http://dx.doi.org/10.1007/s002210050861Donaldson, N., Yu, C.H., A strategy used by paraplegics to stand up using FES (1998) IEEE Trans Rehabil Eng, 6, pp. 162-167. , http://dx.doi.org/10.1109/86.681181Gollee, H., Hunt, K.J., Wood, D.E., New results in feedback control of unsupported standing in paraplegia (2004) IEEE Trans Neural Syst Rehabil Eng, 12, pp. 73-80. , http://dx.doi.org/10.1109/TNSRE.2003.822765Rueterbories, J., Spaich, E.G., Larsen, B., Andersen, O.K., Methods for gait event detection and analysis in ambulatory systems (2010) Med Eng Phys, 32, pp. 545-552. , http://dx.doi.org/10.1016/j.medengphy.2010.03.007Bachschmidt, R.A., Harris, G.F., Simoneau, G.G., Walker-assisted gait in rehabilitation: A study of biomechanics andinstrumentation (2001) IEEE Trans Neural Syst Rehabil Eng, 9, pp. 96-105. , http://dx.doi.org/10.1109/7333.918282Matsunaga, T., Shimada, Y., Sato, K., Muscle fatigue from intermittent stimulation with low and high frequency electrical pulses (1999) Arch Phys Med Rehabil, 80, pp. 48-53. , http://dx.doi.org/10.1016/S0003-9993(99)90306-4McAndrew, D.J., Rosser, N.A.D., Brown, J.M.M., Mechanomyographic measures of muscle contractile properties are influenced by the duration of the stimulatory pulse (2006) J Appl Res, 6, pp. 142-152Krueger, E., Scheeren, E., Chu, G.F.D., Nogueira-Neto, G.N., Button, V., Mechanomyography Analysis With 0.2 S and 1.0 S Time Delay After Onset of Contraction (2010) BIOSTEC 2010: 3rd International Joint Conference on Biomedical Engineering Systems and Technologies, pp. 296-299. , ValênciaZhang, Y., Frank, C.B., Rangayyan, R.M., Bell, G.D., Relationships of the vibromyogram to the surface electromyogram of the human rectus femoris muscle during voluntary isometric contraction (1996) J Rehabil Res Dev, 33, pp. 395-403Nogueira-Neto, G.N., Müller, R.W., Salles, F.A., Nohama, P., Button, V.L.S., (2008) Mechanomyographic Sensor: A Triaxial Accelerometry Approach, pp. 176-179. , International Joint Conference on Biomedical Engineering Systems and Technology, FunchalSeki, K., Ogura, T., Sato, M., Ichie, M., Changes of the evoked mechanomyogram during electrical stimulation (2003) Annual Conference of the International Functional Electrical Stimulation Society, , BrisbaneOrizio, C., Diemont, B., Esposito, F., Alfonsi, E., Parrinello, G., Moglia, A., Surface mechanomyogram reflects the changes in the mechanical properties of muscle at fatigue (1999) Eur J Appl Physiol, 80, pp. 276-284. , http://dx.doi.org/10.1007/s004210050593Krueger-Beck, E., Scheeren, E., Nogueira-Neto, G.N., Button, V., Nohama, P., Mechanomyographic Response during FES in Healthy and Paraplegic Subjects (2010) 32nd Annual International Conference of the IEEE EMBSBuenos Aires, pp. 626-629Krueger-Beck, E., Scheeren, E., Nogueira-Neto, G.N., Button, V., Nohama, P., Optimal FES Parameters Based on Mechanomyographic Efficiency Index (2010) 32nd Annual International Conference of the IEEE EMBS, pp. 1378-1381. , Buenos AiresJezernik, S., Wassink, R.G.V., Keller, T., Sliding mode closed-loop control of FES: Controlling the shank movement (2004) IEEE Trans Biomed Eng, 51, pp. 263-272. , http://dx.doi.org/10.1109/TBME.2003.820393Kurosawa, K., Futami, R., Watanabe, T., Hoshimiya, N., Joint angle control by FES using a feedback error learning controller (2005) IEEE Trans Neural Syst Rehabil Eng, 13, pp. 359-371. , http://dx.doi.org/10.1109/TNSRE.2005.847355Abbas, J.J., Triolo, R.J., Experimental evaluation of an adaptive feedforward controller foruse in functional neuromuscular stimulation systems (1997) IEEE Trans Rehabil Eng, 5, pp. 12-22. , http://dx.doi.org/10.1109/86.559345Zhang, D., Zhu, K., Model and control of the locomotion of a biomimic musculoskeletal biped (2006) Artif Life Robotics, 10, pp. 91-95. , http://dx.doi.org/10.1007/s10015-005-0369-1Davoodi, R., Andrews, B.J., Fuzzy logic control of FES rowing exercise in paraplegia (2004) IEEE Trans Biomed Eng, 51, pp. 541-543. , http://dx.doi.org/10.1109/TBME.2003.821043Pai, Y.C., Wening, J.D., Runtz, E.F., Iqbal, K., Pavol, M.J., Role of feedforward control of movement stability in reducing slip-related balance loss and falls among older adults (2003) J Neurophysiol, 90, pp. 755-762. , http://dx.doi.org/10.1152/jn.01118.2002Patil, P.G., Carmena, J.M., Nicolelis, M.A.L., Turner, D.A., Ensemble recordings of human subcortical neurons as a source of motor control signals for a brainmachine interface (2004) Neurosurgery, 55, pp. 27-38Tonet, O., Marinelli, M., Citi, L., Rossini, P.M., Rossini, L., Megali, G., Defining brain-machine interface applications by matching interface performance with device requirements (2008) J Neurosci Method, 167, pp. 91-104. , http://dx.doi.org/10.1016/j.jneumeth.2007.03.015Taylor, P.N., Burridge, J.H., Dunkerley, A.L., Lamb, A., Wood, D.E., Norton, J.A., Patients' perceptions of the Odstock Dropped Foot Stimulator (ODFS) (1999) Clin Rehabil, 13, pp. 439-446. , http://dx.doi.org/10.1191/026921599677086409Fujita, K., Handa, Y., Hoshimiya, N., Ichie, M., Stimulus adjustment protocol for FES-induced standing in paraplegiausing percutaneous intramuscular electrodes (1995) IEEE Trans Rehabil Eng, 3, pp. 360-366. , http://dx.doi.org/10.1109/86.481976Fisekovic, N., Popovic, D.B., New controller for functional electrical stimulation systems (2001) Med Eng Phys, 23, pp. 391-399. , http://dx.doi.org/10.1016/S1350-4533(01)00069-8Langzam, E., Nemirovsky, Y., Isakov, E., Mizrahi, J., Muscle enhancement using closed-loop electrical stimulation: Volitional versus induced torque (2007) J Electromyogr Kinesiol, 17, pp. 275-284. , http://dx.doi.org/10.1016/j.jelekin.2006.03.001Baptista, R.R., Scheeren, E.M., Macintosh, B.R., Vaz, M.A., Low-frequency fatigue at maximal and submaximal muscle contractions (2009) Braz J Med Biol Res, 42, pp. 380-385. , http://dx.doi.org/10.1590/S0100-879X2009000400011Bailey, S.N., Hardin, E.C., Kobetic, R., Boggs, L.M., Pinault, G., Triolo, R.J., Neurotherapeutic and neuroprosthetic effects of implanted functional electrical stimulation for ambulation after incomplete spinal cord injury (2010) J Rehab Res Develop, 47, pp. 7-16. , http://dx.doi.org/10.1682/JRRD.2009.03.0034Kern, H., Carraro, U., Adami, N., Biral, D., Hofer, C., Forstner, C., Home- Based Functional Electrical Stimulation Rescues Permanently Denervated Muscles in Paraplegic Patients With Complete Lower Motor Neuron Lesion (2010) Neurorehabil Neural Repair, , http://dx.doi.org/10.1177/1545968310366129, In Press