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Musculotendinous stiffness of triceps surae, maximal rate of force development, and vertical jump performance.

Driss T, Lambertz D, Rouis M, Jaafar H, Vandewalle H - Biomed Res Int (2015)

Bottom Line: The subjects were subdivided in 3 groups in function of CMJ (groups H, M, and L for high, medium, and low performers, resp.).There was a downward curvature of the torque-stiffness relationship at high torques in group H or M and the torque-stiffness regression was linear in group L only.These results suggested that torque-stiffness relationships with a plateau at high torques are more frequent in the best jumpers.

View Article: PubMed Central - PubMed

Affiliation: CeRSM (EA 2931), Equipe de Physiologie, Biomécanique et Imagerie du Mouvement, UFR STAPS, Université Paris Ouest Nanterre La Défense, 200 avenue de la République, 92000 Nanterre, France.

ABSTRACT
The relationships between ankle plantar flexor musculotendinous stiffness (MTS) and performance in a countermovement vertical jump (CMJ) and maximal rate of torque development (MRTD) were studied in 27 active men. MTS was studied by means of quick releases at 20 (S0.2), 40 (S0.4), 60 (S0.6), and 80% (S0.8) of maximal voluntary torque (T(MVC)). CMJ was not correlated with strength indices but was positively correlated with MRTD/BM, S 0.4/BM. The slope α 2 and intercept β 2 of the torque-stiffness relationships from 40 to 80% T(MVC) were correlated negatively (α 2) and positively (β 2) with CMJ. The different stiffness indices were not correlated with MRTD. The prediction of CMJ was improved by the introduction of MRTD in multiple regressions between CMJ and stiffness. CMJ was also negatively correlated with indices of curvature of the torque-stiffness relationship. The subjects were subdivided in 3 groups in function of CMJ (groups H, M, and L for high, medium, and low performers, resp.). There was a downward curvature of the torque-stiffness relationship at high torques in group H or M and the torque-stiffness regression was linear in group L only. These results suggested that torque-stiffness relationships with a plateau at high torques are more frequent in the best jumpers.

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(a) Determination of slopes α1, α2 and intercepts β1, β2 of the torque-stiffness relationship. Torque (T) is expressed as a fraction of the torque produced during a maximal voluntary contraction in isometric mode (TMVC). (b) Determination of the curvature index TC equal to the torque corresponding to half of the difference in stiffness at 0.4 and 0.8 TMVC.
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fig2: (a) Determination of slopes α1, α2 and intercepts β1, β2 of the torque-stiffness relationship. Torque (T) is expressed as a fraction of the torque produced during a maximal voluntary contraction in isometric mode (TMVC). (b) Determination of the curvature index TC equal to the torque corresponding to half of the difference in stiffness at 0.4 and 0.8 TMVC.

Mentions: This slope is an index of stiffness that has the advantage to be independent of the required torque level and to avoid the use of MVC or cross-sectional measurements for normalizing MTS [21, 22]. In contrast to these previous studies mainly performed on nonathletic subjects, a downward inflection of the T-S relationship at high torque has been observed in several subjects in the present study. Different models of curvilinear relationship between T and S (power, logarithmic, exponential…) have been tested but none of them could fit the experimental data in all the subjects. Indeed, the value of S extrapolated for zero torque must be positive but S at zero torque was negative in some subjects. Moreover, a curvilinear model could not accurately fit the experimental data in the subjects whose T-S relationships were linear and the difference between observed and predicted data was high in some subjects. Therefore, the T-S curve was approximated by two linear segments (Figure 2):(3b)S1=α1T+β1 for  T  ranging  from  20  to  60%  MVC,(3c)S2=α2T+β2 for  T  ranging  from  40  to  80%  MVC.


Musculotendinous stiffness of triceps surae, maximal rate of force development, and vertical jump performance.

Driss T, Lambertz D, Rouis M, Jaafar H, Vandewalle H - Biomed Res Int (2015)

(a) Determination of slopes α1, α2 and intercepts β1, β2 of the torque-stiffness relationship. Torque (T) is expressed as a fraction of the torque produced during a maximal voluntary contraction in isometric mode (TMVC). (b) Determination of the curvature index TC equal to the torque corresponding to half of the difference in stiffness at 0.4 and 0.8 TMVC.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4325552&req=5

fig2: (a) Determination of slopes α1, α2 and intercepts β1, β2 of the torque-stiffness relationship. Torque (T) is expressed as a fraction of the torque produced during a maximal voluntary contraction in isometric mode (TMVC). (b) Determination of the curvature index TC equal to the torque corresponding to half of the difference in stiffness at 0.4 and 0.8 TMVC.
Mentions: This slope is an index of stiffness that has the advantage to be independent of the required torque level and to avoid the use of MVC or cross-sectional measurements for normalizing MTS [21, 22]. In contrast to these previous studies mainly performed on nonathletic subjects, a downward inflection of the T-S relationship at high torque has been observed in several subjects in the present study. Different models of curvilinear relationship between T and S (power, logarithmic, exponential…) have been tested but none of them could fit the experimental data in all the subjects. Indeed, the value of S extrapolated for zero torque must be positive but S at zero torque was negative in some subjects. Moreover, a curvilinear model could not accurately fit the experimental data in the subjects whose T-S relationships were linear and the difference between observed and predicted data was high in some subjects. Therefore, the T-S curve was approximated by two linear segments (Figure 2):(3b)S1=α1T+β1 for  T  ranging  from  20  to  60%  MVC,(3c)S2=α2T+β2 for  T  ranging  from  40  to  80%  MVC.

Bottom Line: The subjects were subdivided in 3 groups in function of CMJ (groups H, M, and L for high, medium, and low performers, resp.).There was a downward curvature of the torque-stiffness relationship at high torques in group H or M and the torque-stiffness regression was linear in group L only.These results suggested that torque-stiffness relationships with a plateau at high torques are more frequent in the best jumpers.

View Article: PubMed Central - PubMed

Affiliation: CeRSM (EA 2931), Equipe de Physiologie, Biomécanique et Imagerie du Mouvement, UFR STAPS, Université Paris Ouest Nanterre La Défense, 200 avenue de la République, 92000 Nanterre, France.

ABSTRACT
The relationships between ankle plantar flexor musculotendinous stiffness (MTS) and performance in a countermovement vertical jump (CMJ) and maximal rate of torque development (MRTD) were studied in 27 active men. MTS was studied by means of quick releases at 20 (S0.2), 40 (S0.4), 60 (S0.6), and 80% (S0.8) of maximal voluntary torque (T(MVC)). CMJ was not correlated with strength indices but was positively correlated with MRTD/BM, S 0.4/BM. The slope α 2 and intercept β 2 of the torque-stiffness relationships from 40 to 80% T(MVC) were correlated negatively (α 2) and positively (β 2) with CMJ. The different stiffness indices were not correlated with MRTD. The prediction of CMJ was improved by the introduction of MRTD in multiple regressions between CMJ and stiffness. CMJ was also negatively correlated with indices of curvature of the torque-stiffness relationship. The subjects were subdivided in 3 groups in function of CMJ (groups H, M, and L for high, medium, and low performers, resp.). There was a downward curvature of the torque-stiffness relationship at high torques in group H or M and the torque-stiffness regression was linear in group L only. These results suggested that torque-stiffness relationships with a plateau at high torques are more frequent in the best jumpers.

Show MeSH
Related in: MedlinePlus