TY - JOUR
T1 - Joint-afferent-mediated muscle activations yield a near-maximum torque response of the quadriceps
AU - Dhaher, Yasin Y.
N1 - Funding Information:
The author gratefully acknowledges the Dr. Ralph and Marian C. Falk Medical Research Trust, the National Institute of Health (AR46422-03; 5P60AR30692) and the Whitaker Foundation for their support of this research. The author would also like to thank Drs. W.Z. Rymer, Madeleine Lowery and Jessica Langston for their comments on earlier drafts of this manuscript.
PY - 2004/3/15
Y1 - 2004/3/15
N2 - Previous work from our laboratory has shown that reflex activity is systematically evoked in a number of major knee muscles by large (>5°) (non-physiological) abduction angular perturbations of the human knee. This reflex action was shown to originate from periarticular tissue afferents. Furthermore, it was demonstrated that specific muscle activation patterns exist in knee muscles with preferential activation in medial muscles in response to the lateral perturbations. This study examines the hypothesis that in response to the mechanical stimulus, the sensory information mediated by these afferents results in activation patterns that provide the largest resisting moment by the knee muscles. It is further hypothesized that this near maximum resistance cannot be achieved by the selective activation of medial muscles alone. To examine this, the previously reported mechanically induced reflex EMG activation patterns, a stochastic 3D musculoskeletal patello-femoral joint model, and new data from selective electrical stimulation experiments were used. Using the model, the knee adduction-abduction moment in response to an applied abduction load at the knee joint for every possible random set of quadriceps activity was computed. These adduction moments were then compared to the adduction moment computed by the model when the mechanically induced muscle activation patterns were used. The data presented here illustrated that selective activation of a medial muscle alone would result in an abduction moment, regardless of the knee flexion angle. Furthermore, the findings of this study revealed that the recorded combinations of muscle activity provide a near maximum capability of the quadriceps muscles to resist externally applied abducting stimuli. It was concluded that stabilization in the abduction direction could only be achieved by a control strategy that involves activation of both medial and lateral muscles at the knee. It was also concluded that this control strategy was near optimal when mediated by joint afferents.
AB - Previous work from our laboratory has shown that reflex activity is systematically evoked in a number of major knee muscles by large (>5°) (non-physiological) abduction angular perturbations of the human knee. This reflex action was shown to originate from periarticular tissue afferents. Furthermore, it was demonstrated that specific muscle activation patterns exist in knee muscles with preferential activation in medial muscles in response to the lateral perturbations. This study examines the hypothesis that in response to the mechanical stimulus, the sensory information mediated by these afferents results in activation patterns that provide the largest resisting moment by the knee muscles. It is further hypothesized that this near maximum resistance cannot be achieved by the selective activation of medial muscles alone. To examine this, the previously reported mechanically induced reflex EMG activation patterns, a stochastic 3D musculoskeletal patello-femoral joint model, and new data from selective electrical stimulation experiments were used. Using the model, the knee adduction-abduction moment in response to an applied abduction load at the knee joint for every possible random set of quadriceps activity was computed. These adduction moments were then compared to the adduction moment computed by the model when the mechanically induced muscle activation patterns were used. The data presented here illustrated that selective activation of a medial muscle alone would result in an abduction moment, regardless of the knee flexion angle. Furthermore, the findings of this study revealed that the recorded combinations of muscle activity provide a near maximum capability of the quadriceps muscles to resist externally applied abducting stimuli. It was concluded that stabilization in the abduction direction could only be achieved by a control strategy that involves activation of both medial and lateral muscles at the knee. It was also concluded that this control strategy was near optimal when mediated by joint afferents.
KW - Knee abduction moment
KW - Monte Carlo simulation
KW - Periarticular tissue reflex
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U2 - 10.1016/j.jneumeth.2003.09.014
DO - 10.1016/j.jneumeth.2003.09.014
M3 - Article
C2 - 14757339
AN - SCOPUS:0742289543
SN - 0165-0270
VL - 133
SP - 1
EP - 17
JO - Journal of Neuroscience Methods
JF - Journal of Neuroscience Methods
IS - 1-2
ER -