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The role of agonist and antagonist muscles in explaining isometric knee extension torque variation with hip joint angle

Bampouras, Theodoros M. and Reeves, Neil D. and Baltzopoulos, Vasilios and Maganaris, Constantinos N. (2017) The role of agonist and antagonist muscles in explaining isometric knee extension torque variation with hip joint angle. European Journal of Applied Physiology, 117 (10). pp. 2039-2045. ISSN 1439-6319

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    Abstract

    Purpose The biarticular rectus femoris (RF), operating on the ascending limb of the force–length curve, produces more force at longer lengths. However, experimental studies consistently report higher knee extension torque when supine (longer RF length) compared to seated (shorter RF length). Incomplete activation in the supine position has been proposed as the reason for this discrepancy, but differences in antagonistic co-activation could also be responsible due to altered hamstrings length. We examined the role of agonist and antagonist muscles in explaining the isometric knee extension torque variation with changes in hip joint angle. Method Maximum voluntary isometric knee extension torque (joint MVC) was recorded in seated and supine positions from nine healthy males (30.2 ± 7.7 years). Antagonistic torque was estimated using EMG and added to the respective joint MVC (corrected MVC). Submaximal tetanic stimulation quadriceps torque was also recorded. Result Joint MVC was not different between supine (245 ± 71.8 Nm) and seated (241 ± 69.8 Nm) positions and neither was corrected MVC (257 ± 77.7 and 267 ± 87.0 Nm, respectively). Antagonistic torque was higher when seated (26 ± 20.4 Nm) than when supine (12 ± 7.4 Nm). Tetanic torque was higher when supine (111 ± 31.9 Nm) than when seated (99 ± 27.5 Nm). Conclusion Antagonistic co-activation differences between hip positions do not account for the reduced MVC in the supine position. Rather, reduced voluntary knee extensor muscle activation in that position is the major reason for the lower MVC torque when RF is lengthened (hip extended). These findings can assist standardising muscle function assessment and improving musculoskeletal modelling applications.

    Item Type: Journal Article
    Journal or Publication Title: European Journal of Applied Physiology
    Additional Information: The final publication is available at Springer via http://dx.doi.org/10.1007/s00421-017-3693-y
    Subjects: ?? ELECTRICAL MUSCLE STIMULATIONMUSCLE ACTIVATION CAPACITYQUADRICEPS FUNCTIONSEATED TORQUESUPINE TORQUE ??
    Departments: Faculty of Health and Medicine > Medicine
    ID Code: 127557
    Deposited By: ep_importer_pure
    Deposited On: 09 Oct 2018 14:12
    Refereed?: Yes
    Published?: Published
    Last Modified: 30 Apr 2019 02:57
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/127557

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