Study on the Application of the Bio-Electrical Impedance Method for the Estimation of Tendon Elongation

Fukuoka

et al. 2011

J Physiol Anthropol

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The purpose of this study was to highlight the issues related to thickness-based muscle size evaluation that is commonly done in field studies. The cross-sectional area, thickness (the vertical distance from the upper end of the elbow flexors to that of the humerus) and width (the horizontal distance from the left to the right end of the elbow flexors) of the elbow flexors at levels from the reference site (60% of the upper arm length from the acromial process of the scapula to the lateral epicondyle of the humerus) to 5 cm distal to it were determined in 11 young men using magnetic resonance imaging, both at rest and during isometric elbow flexion at 30% of maximal voluntary contraction. During 30% of maximal voluntary contraction, the thickness increased but the width decreased at each measurement site compared with those at rest. This was possibly due to difference in muscle slackness between both conditions. The correlation coefficients between the thickness and cross-sectional area for the elbow flexors were significantly lower at rest (rϭ0.551-0.856) than during 30% of maximal voluntary contraction (rϭ0.711-0.922). The present findings indicate that the thickness-based muscle size measurement at rest includes errors owing to the slackness of the resting muscles.

Section: Discussionmentioning

confidence: 99%

Methodological Issues Related to Thickness-Based Muscle Size Evaluation

Akagi

Fukuoka

et al. 2011

J Physiol Anthropol

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“…The contraction-induced increase in elbow flexor thickness is apparently associated with the corresponding elongation of the tendon and disappearance of muscle slackness with contractions (Akagi et al, 2008). The amount of tendon elongation is positively related to the contraction intensity (Ito et al, 1998;Ohta et al, 2005) and the extent to which the muscle slackness disappears is expectedly influenced by the contraction intensity, suggesting that the elbow flexor MAs might be dependent on the contraction intensity. Moreover, since elbow flexor MAs at rest change depending on the elbow joint angle (Amis et al, 1979;Gonzalez et al, 1996;Koo et al, 2002), the effect of the contraction intensity on MAs of elbow flexors might vary across different elbow joint angles.…”

mentioning

confidence: 95%

In Vivo Measurements of Moment Arm Lengths of Three Elbow Flexors at Rest and During Isometric Contractions

Akagi¹,

Journal of Applied Biomechanics

Hashizume

et al. 2012

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The purpose of this study was to determine in vivo moment arm lengths (MAs) of three elbow flexors at rest and during low- and relatively high-intensity contractions, and to examine the contraction intensity dependence of MAs at different joint positions. At 50°, 80° and 110° of elbow flexion, MAs of the biceps brachii, brachialis and brachioradialis were measured in 10 young men using sagittal images of the right arm obtained by magnetic resonance imaging, at rest and during 20% and 60% of isometric maximal voluntary elbow flexion. In most conditions, MAs increased with isometric contractions, which is presumably due to the contraction-induced thickening of the muscles. This phenomenon was especially evident in the flexed elbow positions. The influence of the contraction intensities on the increases in MAs varied across the muscles. These results suggest that in vivo measurements of each elbow flexor MA during contractions are essential to properly examine the effects on the interrelationships between elbow flexion torque and individual muscle forces.

“…In addition, the individual differences in muscle CSA at each site during isometric contractions were generally larger than those at rest as shown in Figure 3. In the previous study cited above (16), the elongation of the distal tendon of the biceps brachii was shown to be highly individual during isometric contractions (the CVs for 14 young men were approximately 34-47% during 10-80%MVC). This may be a reason for the large differences in muscle CSA at each site under the contracted condition because the elongation of the distal tendon of the biceps brachii is a factor in the contraction-induced change in the CSA distribution pattern along the upper arm length as described above.…”

Section: Discussionmentioning

confidence: 95%

“…Consequently, the elongation of the tendon induced by isometric contractions affects the above CSA distribution pattern. It has been shown that, compared with at rest, the contraction-induced increase in the length of the distal tendon of the biceps brachii is 2.0, 3.3, 6.0, 7.5, and 8.5 mm during 10%MVC, 20%MVC, 40%MVC, 60%MVC and 80% MVC, respectively (16). Thus, the tendon elongation appears prominently during low-intensity contraction and comes close to its peak above a relatively high contractile level, likely contributing to the present results on the contraction-induced change in muscle CSA.…”

Section: Discussionmentioning

confidence: 98%

“…It is therefore unrealistic to measure muscle CSA during MVC with MRI. However, the contraction-induced elongation of a tendon, which is considered to be a factor affecting the corresponding increase in the CSA of elbow flexors (4), is remarkable in a low-intensity contraction (11,16). Additionally, muscle architecture has also been shown to change significantly with low-intensity contraction using MRI (8,18).…”

Section: Introductionmentioning

confidence: 97%

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Determination of Contraction-Induced Changes in Elbow Flexor Cross-Sectional Area for Evaluating Muscle Size-Strength Relationship During Contraction

Akagi

Journal of Strength and Conditioning Research

Hashizume

et al. 2015

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The aims of this study were to determine contraction-induced changes in the elbow flexor cross-sectional area (CSA) and to examine whether the maximal CSA during a high-intensity contraction is more closely related to the strength than that at rest in the elbow flexors. Fourteen young male subjects participated in this study. The elbow flexor CSAs were measured at sites from 1 cm proximal to 6 cm distal to the reference site (60% of the upper arm length from the acromial process of the scapula to the lateral epicondyle of the humerus) (every 1 cm; 8 sampling sites) using magnetic resonance imaging, at rest and during 10, 20, 40, 60, and 80% of maximal voluntary contraction (MVC) of isometric elbow flexion. The elbow flexor CSA changed greatly during low-intensity contractions, and this contraction-induced change was small over 60%MVC. Compared with at rest, greater CSA around the muscle belly and smaller CSA in the distal portion of the elbow flexors were found in contracted conditions. The MVC strength was significantly correlated with the maximal CSAs at rest and each contraction level, but stepwise multiple regression analysis selected only that during 80%MVC as a significant contributor for estimating the MVC strength. These results suggest that, in the elbow flexors, the contraction-induced change in the CSA reaches its peak under high contractile level and that the maximal CSA during 80%MVC is more closely related to the MVC strength than that at rest.