The role of agonist and antagonist muscles in explaining isometric knee extension torque variation with hip joint angle
| Autor: | Vasilios Baltzopoulos, Constantinos N. Maganaris, Theodoros M. Bampouras, Neil D. Reeves |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
Adult
Male medicine.medical_specialty Supine position Knee Joint Physiology Electrical muscle stimulation medicine.medical_treatment Isometric exercise Knee extension RC1200 03 medical and health sciences 0302 clinical medicine Physical medicine and rehabilitation Isometric Contraction Physiology (medical) Z728 Humans Medicine Torque Knee Orthopedics and Sports Medicine Muscle Skeletal Z723 Z722 business.industry Public Health Environmental and Occupational Health 030229 sport sciences General Medicine Anatomy musculoskeletal system Joint angle business Tetanic stimulation human activities 030217 neurology & neurosurgery |
| ISSN: | 1439-6327 |
| Popis: | 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. \ud \ud 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. \ud \ud 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 Nm 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). \ud \ud Conclusion: Antagonistic co-activation differences between hip position do not account for the reduced MVC in the supine position. Rather, a 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. |
| Databáze: | OpenAIRE |
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