TY - JOUR
T1 - A phenomenological model that predicts forces generated when electrical stimulation is superimposed on submaximal volitional contractions
AU - Perumal, Rámu
AU - Wexler, Anthony S.
AU - Kesar, Trisha M.
AU - Jancosko, Angela
AU - Laufer, Yocheved
AU - Binder-Macleod, Stuart A.
PY - 2010/6
Y1 - 2010/6
N2 - Superimposition of electrical stimulation during voluntary contractions is used to produce functional movements in individuals with central nervous system impairment, to evaluate the ability to activate a muscle, to characterize the nature of fatigue, and to improve muscle strength during postsurgical rehabilitation. Currently, the manner in which voluntary contractions and electrically elicited forces summate is not well understood. The objective of the present study is to develop a model that predicts the forces obtained when electrical stimulation is superimposed on a volitional contraction. Quadriceps femoris muscles of 12 able-bodied subjects were tested. Our results showed that the total force produced when electrical stimulation was superimposed during a volitional contraction could be modeled by the equation T = V + S[(MaxForce - VJ/MaxForce]N, where T is the total force produced, V is the force in response to volitional contraction alone, S is the force response to the electrical stimulation alone, MaxForce is the maximum force-generating ability of the muscle, and N is a parameter that we posit depends on the differences in the motor unit recruitment order and firing rates between volitional and electrically elicited contractions. In addition, our results showed that the model predicted accurately (intraclass correlation coefficient ≥ 0.97) the total force in response to a wide range of stimulation intensities and frequencies superimposed on a wide range of volitional contraction levels. Thus the model will be helpful to clinicians and scientists to predict the amount of stimulation needed to produce the targeted, force levels in individuals with partial paralysis.
AB - Superimposition of electrical stimulation during voluntary contractions is used to produce functional movements in individuals with central nervous system impairment, to evaluate the ability to activate a muscle, to characterize the nature of fatigue, and to improve muscle strength during postsurgical rehabilitation. Currently, the manner in which voluntary contractions and electrically elicited forces summate is not well understood. The objective of the present study is to develop a model that predicts the forces obtained when electrical stimulation is superimposed on a volitional contraction. Quadriceps femoris muscles of 12 able-bodied subjects were tested. Our results showed that the total force produced when electrical stimulation was superimposed during a volitional contraction could be modeled by the equation T = V + S[(MaxForce - VJ/MaxForce]N, where T is the total force produced, V is the force in response to volitional contraction alone, S is the force response to the electrical stimulation alone, MaxForce is the maximum force-generating ability of the muscle, and N is a parameter that we posit depends on the differences in the motor unit recruitment order and firing rates between volitional and electrically elicited contractions. In addition, our results showed that the model predicted accurately (intraclass correlation coefficient ≥ 0.97) the total force in response to a wide range of stimulation intensities and frequencies superimposed on a wide range of volitional contraction levels. Thus the model will be helpful to clinicians and scientists to predict the amount of stimulation needed to produce the targeted, force levels in individuals with partial paralysis.
KW - Force summation
KW - Functional electrical stimulation
KW - Rate coding
KW - Recruitment order
UR - http://www.scopus.com/inward/record.url?scp=77953150240&partnerID=8YFLogxK
U2 - 10.1152/japplphysiol.01231.2009
DO - 10.1152/japplphysiol.01231.2009
M3 - Article
C2 - 20299613
AN - SCOPUS:77953150240
SN - 8750-7587
VL - 108
SP - 1595
EP - 1604
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 6
ER -