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Quantification of functional knee flexor to extensor moment ratio using isokinetics and electromyography.
J Athl Train. 2007 Oct-Dec; 42(4):477-85.JA

Abstract

CONTEXT

Evaluating moment balance around the knee helps athletic trainers set appropriate targets for injury prevention and rehabilitation programs.

OBJECTIVE

To examine the knee flexor (KF) to knee extensor (KE) moment ratios using the moments when each muscle group acts as an agonist and using the moments when the KE acts as an agonist and the KF acts as an antagonist.

DESIGN

Cross-sectional.

SETTING

University research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Seventeen pubertal males (age = 13.7 +/- 0.2 years, height = 1.61 +/- 0.04 m, mass = 51.3 +/- 2.7 kg).

INTERVENTION(S)

The subjects performed maximal isokinetic concentric KE (KE(CON)) and eccentric KF (KF(ECC)) efforts and performed eccentric KE (KE(ECC)) and concentric KF efforts at 60 degrees /s and 180 degrees /s while we recorded the bipolar surface electromyographic (EMG) signal of the involved muscles. The KF antagonist moment was estimated from EMG-moment relationships determined during calibration KF efforts. Maximal moments were used to estimate the KF:KE ratios, and EMG-based moments were used to estimate the antagonist to agonist ratios.

MAIN OUTCOME MEASURE(S)

We calculated KF:KE ratios for various angular positions, velocities, and movement directions.

RESULTS

The KF(ECC):KE(CON) ratio significantly increased as the knee extended (P < .05) at increased angular velocity (P < .05), reaching a value of 3.14 +/- 1.95 at full extension. The estimated knee flexor antagonist to knee extensor agonist ratio also increased near full extension (0.32 +/- 0.21).

CONCLUSIONS

Although the KFs have a higher capacity to produce maximal moment near knee extension and at increased angular velocities, knee joint movement is achieved through a balanced coactivation of the 2 antagonistic muscle groups to maintain joint stability and movement efficiency. The combined use of moment and EMG data can provide additional useful information regarding muscle balance around the knee.

Authors+Show Affiliations

Aristotle University of Thessaloniki, Serres, Greece. ekellis@phed-sr.auth.grNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

18174936

Citation

Kellis, Eleftherios, and Athanasios Katis. "Quantification of Functional Knee Flexor to Extensor Moment Ratio Using Isokinetics and Electromyography." Journal of Athletic Training, vol. 42, no. 4, 2007, pp. 477-85.
Kellis E, Katis A. Quantification of functional knee flexor to extensor moment ratio using isokinetics and electromyography. J Athl Train. 2007;42(4):477-85.
Kellis, E., & Katis, A. (2007). Quantification of functional knee flexor to extensor moment ratio using isokinetics and electromyography. Journal of Athletic Training, 42(4), 477-85.
Kellis E, Katis A. Quantification of Functional Knee Flexor to Extensor Moment Ratio Using Isokinetics and Electromyography. J Athl Train. 2007 Oct-Dec;42(4):477-85. PubMed PMID: 18174936.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Quantification of functional knee flexor to extensor moment ratio using isokinetics and electromyography. AU - Kellis,Eleftherios, AU - Katis,Athanasios, PY - 2008/1/5/pubmed PY - 2008/2/22/medline PY - 2008/1/5/entrez KW - coactivation KW - injury index KW - muscle balance KW - rehabilitation KW - strength SP - 477 EP - 85 JF - Journal of athletic training JO - J Athl Train VL - 42 IS - 4 N2 - CONTEXT: Evaluating moment balance around the knee helps athletic trainers set appropriate targets for injury prevention and rehabilitation programs. OBJECTIVE: To examine the knee flexor (KF) to knee extensor (KE) moment ratios using the moments when each muscle group acts as an agonist and using the moments when the KE acts as an agonist and the KF acts as an antagonist. DESIGN: Cross-sectional. SETTING: University research laboratory. PATIENTS OR OTHER PARTICIPANTS: Seventeen pubertal males (age = 13.7 +/- 0.2 years, height = 1.61 +/- 0.04 m, mass = 51.3 +/- 2.7 kg). INTERVENTION(S): The subjects performed maximal isokinetic concentric KE (KE(CON)) and eccentric KF (KF(ECC)) efforts and performed eccentric KE (KE(ECC)) and concentric KF efforts at 60 degrees /s and 180 degrees /s while we recorded the bipolar surface electromyographic (EMG) signal of the involved muscles. The KF antagonist moment was estimated from EMG-moment relationships determined during calibration KF efforts. Maximal moments were used to estimate the KF:KE ratios, and EMG-based moments were used to estimate the antagonist to agonist ratios. MAIN OUTCOME MEASURE(S): We calculated KF:KE ratios for various angular positions, velocities, and movement directions. RESULTS: The KF(ECC):KE(CON) ratio significantly increased as the knee extended (P < .05) at increased angular velocity (P < .05), reaching a value of 3.14 +/- 1.95 at full extension. The estimated knee flexor antagonist to knee extensor agonist ratio also increased near full extension (0.32 +/- 0.21). CONCLUSIONS: Although the KFs have a higher capacity to produce maximal moment near knee extension and at increased angular velocities, knee joint movement is achieved through a balanced coactivation of the 2 antagonistic muscle groups to maintain joint stability and movement efficiency. The combined use of moment and EMG data can provide additional useful information regarding muscle balance around the knee. SN - 1938-162X UR - https://www.unboundmedicine.com/medline/citation/18174936/Quantification_of_functional_knee_flexor_to_extensor_moment_ratio_using_isokinetics_and_electromyography_ L2 - https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/18174936/ DB - PRIME DP - Unbound Medicine ER -