I know that a large proportion of the muscles in the body are active for a person during her/his gait. But I'm not sure exactly (or approximately) the value of the proportion in percentages with a valid reference.
The proportion of the muscles active during gait not permanent, but many factors affect on the percentage of muscle contribution during gait such as age, walking speed, fitness, injuries, deformities, etc....... However, the following papers maybe help you to answer of this question.
Anders, C., Wagner, H., Puta, C., Grassme, R., & Scholle, H. C. (2009). Healthy humans use sex-specific co-ordination patterns of trunk muscles during gait. European Journal of Applied Physiology, 105(4), 585–594. http://doi.org/10.1007/s00421-008-0938-9
Arnold, A. S., Anderson, F. C., Pandy, M. G., & Delp, S. L. (2005). Muscular contributions to hip and knee extension during the single limb stance phase of normal gait: A framework for investigating the causes of crouch gait. Journal of Biomechanics, 38(11), 2181–2189. http://doi.org/10.1016/j.jbiomech.2004.09.036
Arnold, A. S., Thelen, D. G., Schwartz, M. H., Anderson, F. C., & Delp, S. L. (2007). Muscular coordination of knee motion during the terminal-swing phase of normal gait. Journal of Biomechanics, 40(15), 3314–3324. http://doi.org/10.1016/j.jbiomech.2007.05.006
Arnold, E. M., & Delp, S. L. (2011). Fibre operating lengths of human lower limb muscles during walking. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 366(1570), 1530–9. http://doi.org/10.1098/rstb.2010.0345
Bonnard, M., Camus, M., Coyle, T., & Pailhous, J. (2002). Task-induced modulation of motor evoked potentials in upper-leg muscles during human gait: A TMS study. European Journal of Neuroscience, 16(11), 2225–2230. http://doi.org/10.1046/j.1460-9568.2002.02295.x
Finch, L., Barbeau, H., & Arsenault, B. (1991). Influence of body weight support on normal human gait: development of a gait retraining strategy. Physical Therapy, 71(11), 842–855; discussion 855–856.
Goldberg, S. R., Anderson, F. C., Pandy, M. G., & Delp, S. L. (2004). Muscles that influence knee flexion velocity in double support: Implications for stiff-knee gait. Journal of Biomechanics, 37(8), 1189–1196. http://doi.org/10.1016/j.jbiomech.2003.12.005
Gordon, K. E., Sawicki, G. S., & Ferris, D. P. (2006). Mechanical performance of artificial pneumatic muscles to power an ankle-foot orthosis. Journal of Biomechanics, 39(10), 1832–1841. http://doi.org/10.1016/j.jbiomech.2005.05.018
Hicks, J. L., Schwartz, M. H., Arnold, A. S., & Delp, S. L. (2008). Crouched postures reduce the capacity of muscles to extend the hip and knee during the single-limb stance phase of gait. Journal of Biomechanics, 41(5), 960–967. http://doi.org/10.1016/j.jbiomech.2008.01.002
Ivanenko, Y. P., Cappellini, G., Poppele, R. E., & Lacquaniti, F. (2008). Spatiotemporal organization of ??-motoneuron activity in the human spinal cord during different gaits and gait transitions. European Journal of Neuroscience, 27(12), 3351–3368. http://doi.org/10.1111/j.1460-9568.2008.06289.x
Ivanenko, Y. P., Poppele, R. E., & Lacquaniti, F. (2004). Five basic muscle activation patterns account for muscle activity during human locomotion. The Journal of Physiology, 556(Pt 1), 267–82. http://doi.org/10.1113/jphysiol.2003.057174
Ivanenko, Y. P., Poppele, R. E., & Lacquaniti, F. (2004). Five basic muscle activation patterns account for muscle activity during human locomotion. The Journal of Physiology, 556(Pt 1), 267–282. http://doi.org/10.1113/jphysiol.2003.057174
Komura, T., & Nagano, A. (2004). Evaluation of the influence of muscle deactivation on other muscles and joints during gait motion. Journal of Biomechanics, 37(4), 425–436. http://doi.org/10.1016/j.jbiomech.2003.09.022
Kuhtz-Buschbeck, J. P., & Jing, B. (2012). Activity of upper limb muscles during human walking. Journal of Electromyography and Kinesiology, 22(2), 199–206. http://doi.org/10.1016/j.jelekin.2011.08.014
Meyns, P., Bruijn, S. M., & Duysens, J. (2013). The how and why of arm swing during human walking. Gait and Posture. http://doi.org/10.1016/j.gaitpost.2013.02.006
Michel, V., & Do, M. C. (2002). Are stance ankle plantar flexor muscles necessary to generate propulsive force during human gait initiation? Neuroscience Letters, 325(2), 139–143. http://doi.org/10.1016/S0304-3940(02)00255-0
Petersen, T. H., Willerslev-Olsen, M., Conway, B. a, & Nielsen, J. B. (2012). The motor cortex drives the muscles during walking in human subjects. The Journal Of Physiology, 590(Pt 10), 2443–2452. http://doi.org/10.1113/jphysiol.2012.227397
Piazza, S. J., & Delp, S. L. (1996). The influence of muscles on knee flexion during the swing phase of gait. Journal of Biomechanics, 29(6), 723–733. http://doi.org/10.1016/0021-9290(95)00144-1
Pijnappels, M., Van Wezel, B. M. H., Colombo, G., Dietz, V., & Duysens, J. (1998). Cortical facilitation of cutaneous reflexes in leg muscles during human gait. Brain Research, 787(1), 149–153. http://doi.org/10.1016/S0006-8993(97)01557-6
Riley, P. O., & Kerrigan, D. C. (1998). Torque action of two-joint muscles in the swing period of stiff-legged gait: A forward dynamic model analysis. Journal of Biomechanics, 31(9), 835–840. http://doi.org/10.1016/S0021-9290(98)00107-9
Schipplein, O. D., & Andriacchi, T. P. (1991). Interaction between active and passive knee stabilizers during level walking. Journal of Orthopaedic Research, 9(1), 113–119. http://doi.org/10.1002/jor.1100090114
Shelburne, K. B., Torry, M. R., & Pandy, M. G. (2006). Contributions of muscles, ligaments, and the ground-reaction force to tibiofemoral joint loading during normal gait. Journal of Orthopaedic Research, 24(10), 1983–1990. http://doi.org/10.1002/jor.20255
Steele, K. M., Seth, A., Hicks, J. L., Schwartz, M. S., & Delp, S. L. (2010). Muscle contributions to support and progression during single-limb stance in crouch gait. Journal of Biomechanics, 43(11), 2099–2105. http://doi.org/10.1016/j.jbiomech.2010.04.003
Winter, D. A., & Yack, H. J. (1987). EMG profiles during normal human walking: stride-to-stride and inter-subject variability. Electroencephalography and Clinical Neurophysiology, 67(5), 402–411. http://doi.org/10.1016/0013-4694(87)90003-4
Yungher, D. A., Wininger, M. T., Barr, J. B., Craelius, W., & Threlkeld, A. J. (2011). Surface muscle pressure as a measure of active and passive behavior of muscles during gait. Medical Engineering and Physics, 33(4), 464–471. http://doi.org/10.1016/j.medengphy.2010.11.012
This is an very difficult quenstion . You want as an answer the amount of muscle power that we require to walk !
Nor,al walking ask for an muscle strenght of 5 (MRC scale) But walking with less power is posiible even without an cane. OLder people will use often the eccentric way and will walk with no hielstrike and push off because the balance perception and the power of the hipextensor is to low. Or the problems with the balance make that the posture will be more in flexion and that has an negative effect on the power of the hip extensor. Therefore I want always the normal power in the hipextensor and an normal one leg standing than the base to walk is present and can be exercise the other muscvle deficits.
The proportion of the muscles active during gait not permanent, but many factors affect on the percentage of muscle contribution during gait such as age, walking speed, fitness, injuries, deformities, etc....... However, the following papers maybe help you to answer of this question.
Anders, C., Wagner, H., Puta, C., Grassme, R., & Scholle, H. C. (2009). Healthy humans use sex-specific co-ordination patterns of trunk muscles during gait. European Journal of Applied Physiology, 105(4), 585–594. http://doi.org/10.1007/s00421-008-0938-9
Arnold, A. S., Anderson, F. C., Pandy, M. G., & Delp, S. L. (2005). Muscular contributions to hip and knee extension during the single limb stance phase of normal gait: A framework for investigating the causes of crouch gait. Journal of Biomechanics, 38(11), 2181–2189. http://doi.org/10.1016/j.jbiomech.2004.09.036
Arnold, A. S., Thelen, D. G., Schwartz, M. H., Anderson, F. C., & Delp, S. L. (2007). Muscular coordination of knee motion during the terminal-swing phase of normal gait. Journal of Biomechanics, 40(15), 3314–3324. http://doi.org/10.1016/j.jbiomech.2007.05.006
Arnold, E. M., & Delp, S. L. (2011). Fibre operating lengths of human lower limb muscles during walking. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 366(1570), 1530–9. http://doi.org/10.1098/rstb.2010.0345
Bonnard, M., Camus, M., Coyle, T., & Pailhous, J. (2002). Task-induced modulation of motor evoked potentials in upper-leg muscles during human gait: A TMS study. European Journal of Neuroscience, 16(11), 2225–2230. http://doi.org/10.1046/j.1460-9568.2002.02295.x
Finch, L., Barbeau, H., & Arsenault, B. (1991). Influence of body weight support on normal human gait: development of a gait retraining strategy. Physical Therapy, 71(11), 842–855; discussion 855–856.
Goldberg, S. R., Anderson, F. C., Pandy, M. G., & Delp, S. L. (2004). Muscles that influence knee flexion velocity in double support: Implications for stiff-knee gait. Journal of Biomechanics, 37(8), 1189–1196. http://doi.org/10.1016/j.jbiomech.2003.12.005
Gordon, K. E., Sawicki, G. S., & Ferris, D. P. (2006). Mechanical performance of artificial pneumatic muscles to power an ankle-foot orthosis. Journal of Biomechanics, 39(10), 1832–1841. http://doi.org/10.1016/j.jbiomech.2005.05.018
Hicks, J. L., Schwartz, M. H., Arnold, A. S., & Delp, S. L. (2008). Crouched postures reduce the capacity of muscles to extend the hip and knee during the single-limb stance phase of gait. Journal of Biomechanics, 41(5), 960–967. http://doi.org/10.1016/j.jbiomech.2008.01.002
Ivanenko, Y. P., Cappellini, G., Poppele, R. E., & Lacquaniti, F. (2008). Spatiotemporal organization of ??-motoneuron activity in the human spinal cord during different gaits and gait transitions. European Journal of Neuroscience, 27(12), 3351–3368. http://doi.org/10.1111/j.1460-9568.2008.06289.x
Ivanenko, Y. P., Poppele, R. E., & Lacquaniti, F. (2004). Five basic muscle activation patterns account for muscle activity during human locomotion. The Journal of Physiology, 556(Pt 1), 267–82. http://doi.org/10.1113/jphysiol.2003.057174
Ivanenko, Y. P., Poppele, R. E., & Lacquaniti, F. (2004). Five basic muscle activation patterns account for muscle activity during human locomotion. The Journal of Physiology, 556(Pt 1), 267–282. http://doi.org/10.1113/jphysiol.2003.057174
Komura, T., & Nagano, A. (2004). Evaluation of the influence of muscle deactivation on other muscles and joints during gait motion. Journal of Biomechanics, 37(4), 425–436. http://doi.org/10.1016/j.jbiomech.2003.09.022
Kuhtz-Buschbeck, J. P., & Jing, B. (2012). Activity of upper limb muscles during human walking. Journal of Electromyography and Kinesiology, 22(2), 199–206. http://doi.org/10.1016/j.jelekin.2011.08.014
Meyns, P., Bruijn, S. M., & Duysens, J. (2013). The how and why of arm swing during human walking. Gait and Posture. http://doi.org/10.1016/j.gaitpost.2013.02.006
Michel, V., & Do, M. C. (2002). Are stance ankle plantar flexor muscles necessary to generate propulsive force during human gait initiation? Neuroscience Letters, 325(2), 139–143. http://doi.org/10.1016/S0304-3940(02)00255-0
Petersen, T. H., Willerslev-Olsen, M., Conway, B. a, & Nielsen, J. B. (2012). The motor cortex drives the muscles during walking in human subjects. The Journal Of Physiology, 590(Pt 10), 2443–2452. http://doi.org/10.1113/jphysiol.2012.227397
Piazza, S. J., & Delp, S. L. (1996). The influence of muscles on knee flexion during the swing phase of gait. Journal of Biomechanics, 29(6), 723–733. http://doi.org/10.1016/0021-9290(95)00144-1
Pijnappels, M., Van Wezel, B. M. H., Colombo, G., Dietz, V., & Duysens, J. (1998). Cortical facilitation of cutaneous reflexes in leg muscles during human gait. Brain Research, 787(1), 149–153. http://doi.org/10.1016/S0006-8993(97)01557-6
Riley, P. O., & Kerrigan, D. C. (1998). Torque action of two-joint muscles in the swing period of stiff-legged gait: A forward dynamic model analysis. Journal of Biomechanics, 31(9), 835–840. http://doi.org/10.1016/S0021-9290(98)00107-9
Schipplein, O. D., & Andriacchi, T. P. (1991). Interaction between active and passive knee stabilizers during level walking. Journal of Orthopaedic Research, 9(1), 113–119. http://doi.org/10.1002/jor.1100090114
Shelburne, K. B., Torry, M. R., & Pandy, M. G. (2006). Contributions of muscles, ligaments, and the ground-reaction force to tibiofemoral joint loading during normal gait. Journal of Orthopaedic Research, 24(10), 1983–1990. http://doi.org/10.1002/jor.20255
Steele, K. M., Seth, A., Hicks, J. L., Schwartz, M. S., & Delp, S. L. (2010). Muscle contributions to support and progression during single-limb stance in crouch gait. Journal of Biomechanics, 43(11), 2099–2105. http://doi.org/10.1016/j.jbiomech.2010.04.003
Winter, D. A., & Yack, H. J. (1987). EMG profiles during normal human walking: stride-to-stride and inter-subject variability. Electroencephalography and Clinical Neurophysiology, 67(5), 402–411. http://doi.org/10.1016/0013-4694(87)90003-4
Yungher, D. A., Wininger, M. T., Barr, J. B., Craelius, W., & Threlkeld, A. J. (2011). Surface muscle pressure as a measure of active and passive behavior of muscles during gait. Medical Engineering and Physics, 33(4), 464–471. http://doi.org/10.1016/j.medengphy.2010.11.012
Gait Analysis: Normal and Pathological Function by Jacquelin Perry and Judith Burnfield is a very useful text book -- that shows the timing of lower limb muscle activity per gait cycle.
If you are talking about natural gait, so you have the following: In a ideal condition, less than 5% of the inferior motor neurons are active. It is not about how many muscles, but how!? You know what I mean? Along the evolution, human CNS had to make some adaptations by intending to improve efficiency and reduce metabolic costs(and here I am talking about gait).