Structural and pathological changes in the enthesis are influenced by the muscle contraction type during exercise

2021 ◽  
Author(s):  
Kaichi Ozone ◽  
Takanori Kokubun ◽  
Kei Takahata ◽  
Haruna Takahashi ◽  
Moe Yoneno ◽  
...  
Keyword(s):  
Muscle Contraction ◽  
Pathological Changes ◽  
Contraction Type

scholarly journals When Antagonist Muscles at the Ankle Interfere with Maximal Voluntary Contraction under Isometric and Anisometric Conditions

2021 ◽  
Author(s):  
Maxime Billot ◽  
Julien Duclay ◽  
Philippe Rigoard ◽  
Romain David ◽  
Alain Martin
Keyword(s):  
Muscle Contraction ◽  
Maximal Voluntary Contraction ◽  
Voluntary Contraction ◽  
Triceps Surae ◽  
Emg Activity ◽  
Muscular Performance ◽  
Rehabilitation Programs ◽  
Antagonist Muscles ◽  
Contraction Type ◽  
The Difference

Purpose: While resultant maximal voluntary contraction (MVC) is commonly used to assess muscular performance, the simultaneous activation of antagonist muscles could dramatically underestimate the strength of the agonist muscles. While quantification of antagonist torque has been performed in plantar- (PF) and dorsi-flexion (DF) joint in isometric conditions, it has yet to be determined in anisometric (concentric and eccentric) conditions. Methods: The experiment was performed in 9 participants through 2 sessions (reliability). The MVCs in DF and PF were measured in isometric, concentric and eccentric conditions (10°.s-1). Electromyographic (EMG) activities from the soleus, gastrocnemius medialis and lateralis, and tibialis anterior muscles were simultaneously recorded. The EMG biofeedback method was used to quantify antagonist torque, where participants were asked to maintain a level of EMG activity, corresponding to antagonist EMG activity and related to the muscle contraction type, according to a visual EMG bio-feedback displayed on a screen. Results: Resultant torque significantly underestimated agonist torque in DF MVC (30-65%) and to a lesser extent in PF MVC (3%). Triceps surae antagonist torque was significantly modified with muscle contraction type, showing higher antagonist torque in isometric (29 Nm) than eccentric (23 Nm, p < 0.001) and concentric (14 Nm, p < 0.001) conditions and resulting in modification of the DF MVC torque-velocity shape. The difference between DF eccentric and concentric MVC was attenuated when considered agonist torque (12%) rather than resultant torque (45%). Conclusion: Estimation of the antagonist torque in isometric or anisometric condition brings new insights to assessment of muscular performance and could result in costly misinterpretation in strength training and/or rehabilitation programs.

scholarly journals The Effect of Muscle Contraction Type on Neuromuscular Complexity in Trained Individuals

2019 ◽  
Vol 51 (Supplement) ◽  
pp. 340
Author(s):  
Luis Hernandez ◽  
Peter Chomentowski ◽  
Clayton L. Camic
Keyword(s):  
Muscle Contraction ◽  
Contraction Type

Effects of Bracing on Isokinetic Torque for the Chronically Unstable Ankle

1999 ◽  
Vol 8 (2) ◽  
pp. 83-98 ◽  
Author(s):  
Heather D. Hartsell ◽  
Sandi J. Spaulding
Keyword(s):  
Muscle Contraction ◽  
Repeated Measures ◽  
Peak Torque ◽  
Joint Motion ◽  
Repeated Measures Design ◽  
Isokinetic Torque ◽  
Contraction Type

Because the effects of bracing on dynamic torque production are unknown, the purpose of this study was to determine the effects of flexible and semirigid braces on isokinetic torque production at varying velocities produced by the invertor and evertor muscles for the chronically unstable ankle. Ten healthy and 14 chronically unstable ankles were tested, with a repeated-measures design including joint motion (inversion, eversion), muscle contraction type (concentric, eccentric), brace condition (unbraced, flexible, semirigid), and velocity (60, 120, 180, 240°/s). Multiple ANOVAs with repeated-measures and Bonferroni-adjusted comparisons were performed. Results showed that the chronically unstable ankle was significantly weaker than the healthy ankle, regardless of muscle contraction type or joint motion, and that bracing did not deter the muscles' ability to produce peak torque either concentrically or eccentrically. The chronically unstable ankle requires enhanced strengthening, particularly eccentrically and at higher, more functional velocities. Bracing can reduce or prevent injury to the ankle without deterring torque production.

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