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Influence of Cervical Muscle Fatigue on Musculo-Tendinous Stiffness of the Head-Neck Segment during Cervical Flexion.

Portero R, Quaine F, Cahouet V, Léouffre M, Servière C, Portero P - PLoS ONE (2015)

Bottom Line: EMG analysis revealed a significant increase of the root mean square for the right SCM (P = 0.0002), the left SCM (P < 0.0001), the right SE (P < 0.0001), and the left SE (P < 0.0001) and a significant decrease of the median power frequency only for the right (P = 0.0006) and the left (P = 0.0003) SCM with muscular fatigue.We did not find significant changes in the head-neck segment musculo-tendinous stiffness with fatigue of cervical muscles.Our findings suggest that with fatigue of cervical flexors, neck muscle activity is modulated in order to maintain the musculo-tendinous stiffness at a steady state.

View Article: PubMed Central - PubMed

Affiliation: Département d'Automatique, GIPSA Lab, UMR CNRS 5216, Université Joseph Fourier, Grenoble, France; Service de Rééducation Neuro-Orthopédique, Hôpital Rothschild (AP-HP), Paris, France.

ABSTRACT

Aim: The aim of this study is to determine if the fatigue of cervical muscles has a significant influence on the head-neck segment musculo-tendinous stiffness.

Methods: Ten men (aged 21.2 ± 1.9 years) performed four quick-release trials of flexion at 30 and 50% MVC before and after the induction of muscular fatigue on cervical flexors. Electromyographic activity was recorded on the sternocleidomastoids (SCM) and spinal erectors (SE), bilaterally. Musculo-tendinous stiffness was calculated through the quick-release method adapted to the head-neck segment.

Results: We noticed a significant linear increase of the head-neck segment musculo-tendinous stiffness with the increase of exertion level both before (P < 0.0001) and after the fatigue procedure (P < 0.0001). However, this linear relationship was not different before and after the fatigue procedure. EMG analysis revealed a significant increase of the root mean square for the right SCM (P = 0.0002), the left SCM (P < 0.0001), the right SE (P < 0.0001), and the left SE (P < 0.0001) and a significant decrease of the median power frequency only for the right (P = 0.0006) and the left (P = 0.0003) SCM with muscular fatigue.

Discussion: We did not find significant changes in the head-neck segment musculo-tendinous stiffness with fatigue of cervical muscles. We found a significant increase in EMG activity in the SCM and the SE after the induction of fatigue of the SCM. Our findings suggest that with fatigue of cervical flexors, neck muscle activity is modulated in order to maintain the musculo-tendinous stiffness at a steady state.

No MeSH data available.


Related in: MedlinePlus

Configuration of head-neck segment rotation.M is a point of the head-neck rigid segment rotating around the resultant center of rotation (CoR) in . Here, XCoR and YCoR represent respectively horizontal and vertical CoR components, LM is the radius of rotation of point M, θ0 is the initial angular position of point M, relative to the horizontal axis (X), and θ(t) is the angular position of point M, function of time (t), and relative to θ0. Anti-clockwise rotation is positive.
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pone.0139333.g002: Configuration of head-neck segment rotation.M is a point of the head-neck rigid segment rotating around the resultant center of rotation (CoR) in . Here, XCoR and YCoR represent respectively horizontal and vertical CoR components, LM is the radius of rotation of point M, θ0 is the initial angular position of point M, relative to the horizontal axis (X), and θ(t) is the angular position of point M, function of time (t), and relative to θ0. Anti-clockwise rotation is positive.

Mentions: where XCoR and YCoR were respectively horizontal and vertical CoR components, LM was the radius of rotation of a point M, θ0 was the initial angular position of point M, relative to the horizontal axis (X), and θ(t) was the angular position of point M, function of time (t), and relative to θ0, as described in Fig 2. The calculation of CoR during QR movement was formulated as an optimization problem with an objective function that evaluated the differences between experimental LEDs displacement measurements (with respect to shoulder position O) and theoretical positions of the corresponding points on rigid head-neck segment. It was mathematically formulated as:


Influence of Cervical Muscle Fatigue on Musculo-Tendinous Stiffness of the Head-Neck Segment during Cervical Flexion.

Portero R, Quaine F, Cahouet V, Léouffre M, Servière C, Portero P - PLoS ONE (2015)

Configuration of head-neck segment rotation.M is a point of the head-neck rigid segment rotating around the resultant center of rotation (CoR) in . Here, XCoR and YCoR represent respectively horizontal and vertical CoR components, LM is the radius of rotation of point M, θ0 is the initial angular position of point M, relative to the horizontal axis (X), and θ(t) is the angular position of point M, function of time (t), and relative to θ0. Anti-clockwise rotation is positive.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4587888&req=5

pone.0139333.g002: Configuration of head-neck segment rotation.M is a point of the head-neck rigid segment rotating around the resultant center of rotation (CoR) in . Here, XCoR and YCoR represent respectively horizontal and vertical CoR components, LM is the radius of rotation of point M, θ0 is the initial angular position of point M, relative to the horizontal axis (X), and θ(t) is the angular position of point M, function of time (t), and relative to θ0. Anti-clockwise rotation is positive.
Mentions: where XCoR and YCoR were respectively horizontal and vertical CoR components, LM was the radius of rotation of a point M, θ0 was the initial angular position of point M, relative to the horizontal axis (X), and θ(t) was the angular position of point M, function of time (t), and relative to θ0, as described in Fig 2. The calculation of CoR during QR movement was formulated as an optimization problem with an objective function that evaluated the differences between experimental LEDs displacement measurements (with respect to shoulder position O) and theoretical positions of the corresponding points on rigid head-neck segment. It was mathematically formulated as:

Bottom Line: EMG analysis revealed a significant increase of the root mean square for the right SCM (P = 0.0002), the left SCM (P < 0.0001), the right SE (P < 0.0001), and the left SE (P < 0.0001) and a significant decrease of the median power frequency only for the right (P = 0.0006) and the left (P = 0.0003) SCM with muscular fatigue.We did not find significant changes in the head-neck segment musculo-tendinous stiffness with fatigue of cervical muscles.Our findings suggest that with fatigue of cervical flexors, neck muscle activity is modulated in order to maintain the musculo-tendinous stiffness at a steady state.

View Article: PubMed Central - PubMed

Affiliation: Département d'Automatique, GIPSA Lab, UMR CNRS 5216, Université Joseph Fourier, Grenoble, France; Service de Rééducation Neuro-Orthopédique, Hôpital Rothschild (AP-HP), Paris, France.

ABSTRACT

Aim: The aim of this study is to determine if the fatigue of cervical muscles has a significant influence on the head-neck segment musculo-tendinous stiffness.

Methods: Ten men (aged 21.2 ± 1.9 years) performed four quick-release trials of flexion at 30 and 50% MVC before and after the induction of muscular fatigue on cervical flexors. Electromyographic activity was recorded on the sternocleidomastoids (SCM) and spinal erectors (SE), bilaterally. Musculo-tendinous stiffness was calculated through the quick-release method adapted to the head-neck segment.

Results: We noticed a significant linear increase of the head-neck segment musculo-tendinous stiffness with the increase of exertion level both before (P < 0.0001) and after the fatigue procedure (P < 0.0001). However, this linear relationship was not different before and after the fatigue procedure. EMG analysis revealed a significant increase of the root mean square for the right SCM (P = 0.0002), the left SCM (P < 0.0001), the right SE (P < 0.0001), and the left SE (P < 0.0001) and a significant decrease of the median power frequency only for the right (P = 0.0006) and the left (P = 0.0003) SCM with muscular fatigue.

Discussion: We did not find significant changes in the head-neck segment musculo-tendinous stiffness with fatigue of cervical muscles. We found a significant increase in EMG activity in the SCM and the SE after the induction of fatigue of the SCM. Our findings suggest that with fatigue of cervical flexors, neck muscle activity is modulated in order to maintain the musculo-tendinous stiffness at a steady state.

No MeSH data available.


Related in: MedlinePlus