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

Bampouras, TM and Reeves, ND and Baltzopoulos, V and Maganaris, CN (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 1439-6327

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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: Article
Additional Information: The final publication is available at Springer via http://dx.doi.org/10.1007/s00421-017-3693-y
Uncontrolled Keywords: 1106 Human Movement And Sports Science
Subjects: R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Sport & Exercise Sciences
Publisher: Springer Verlag
Related URLs:
Date Deposited: 25 Sep 2017 09:35
Last Modified: 25 Sep 2017 09:35
DOI or Identification number: 10.1007/s00421-017-3693-y
URI: http://researchonline.ljmu.ac.uk/id/eprint/7174

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