Active muscle and tendon stiffness of plantar flexors in sprinters

This study aimed to determine the impact of long-term training on Achilles tendon (AT) and patellar tendon (PT) hypertrophy in sprinters and endurance runners. The cross-sectional area (CSA) of AT and PT in 40 sprinters, 40 endurance runners, and 40 untrained subjects was measured using magnetic resonance imaging. The AT and PT CSAs were calculated at its proximal, middle, and distal portions. Three CSAs of AT and PT were averaged to give an overall absolute CSA for each tendon. To minimize the effect of body size on tendon CSA and obtain relative CSA, overall absolute CSA for each tendon was normalized with body mass. Absolute AT CSA did not differ significantly among all 3 groups. However, we found that relative AT CSA was significantly larger in endurance runners than in sprinters and untrained subjects (P < .001 for both). In contrast, both absolute and relative PT CSAs were significantly larger in sprinters than in endurance runners and untrained subjects (P ≤ .001 for all). These findings indicate that AT hypertrophy is characteristic of endurance runners, whereas PT hypertrophy is characteristic of sprinters. Therefore, we suggest that the AT and PT may undergo specific morphological adaptations in these athletes. K E Y W O R D Scross-sectional area, joint moment, magnetic resonance imaging, tendon stiffness wileyonlinelibrary.com/journal/tsm2Transl Sports Med. 2018;1:104-109.

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Section: Introductionmentioning

confidence: 99%

“…Only 1 study has compared the AT CSA between sprinters and untrained subjects . Kubo et al determined using ultrasonography that AT CSA did not differ between sprinters and untrained subjects. It is well known that magnetic resonance image (MRI) is more appropriate to evaluate tissue size than ultrasonography .…”

Section: Introductionmentioning

confidence: 99%

Specific adaptations of patellar and Achilles tendons in male sprinters and endurance runners

et al. 2018

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“…The probe was manually placed at the same location as the SWE measurement and aligned with the fascicle direction of MG. The short‐range stretch task was performed according to previous studies . Subjects maintained 10%, 30%, 50%, 70%, or 90% MVC torque, with the aid of the visual feedback.…”

Section: Methodsmentioning

confidence: 99%

“…The short-range stretch task was performed according to previous studies. 16,17,24 Subjects maintained 10%, 30%, 50%, 70%, or 90% MVC torque, with the aid of the visual feedback. A dorsiflexion stretch was then applied as fast as possible using the dynamometer from −15 to 15° ankle joint angle (ie, from 15° of plantar flexion to 15° of dorsiflexion).…”

Section: Stretch Task For Ms Us and Ms Alpha Measurementsmentioning

confidence: 99%

“…Furthermore, although the alpha method uses joint angle data to estimate muscle behavior, changes in the joint angle do not correspond to those in muscle fiber length . To try to overcome such limitations of the alpha method, B‐mode ultrasonography has been used to non‐invasively assess active muscle stiffness in more recent years . Kubo measured fascicle length of the medial gastrocnemius (MG) during a short‐range stretch of dorsiflexion and demonstrated that the MG muscle stiffness determined with B‐mode ultrasonography (MS US ) was not related to the muscle stiffness determined with the alpha method (MS Alpha ) at >30% maximal voluntary contraction (MVC) levels .…”

Section: Introductionmentioning

confidence: 99%

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Muscle elasticity under active conditions in humans: A methodological comparison

Miyamoto

Hirata

2019

Transl Sports Med

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Muscle stiffness under active conditions has been evaluated as a measure of muscle elasticity (expressed in N/mm) by the alpha method or B‐mode ultrasonography in humans in vivo. While these are indirect methods, ultrasound shear wave elastography (SWE), which enables direct quantification of tissue shear modulus (a measure of elasticity, expressed in kPa), has recently been used to assess muscle elasticity. We compared muscle shear modulus under active conditions using SWE with active muscle stiffness assessed by the alpha method or B‐mode ultrasonography. Seventeen healthy men participated in this study. Muscle shear modulus of the medial gastrocnemius (MG) was measured during submaximal isometric plantar flexion contractions (10%, 30%, 50%, 70%, and 90% maximal voluntary contraction). Active muscle stiffness of MG during short‐range stretch after submaximal isometric contractions was calculated using the alpha method or based on changes in estimated muscle force and fascicle length. Muscle shear modulus was not correlated with either muscle stiffness determined by the alpha method or B‐mode ultrasonography at any torque levels. These findings indicate the necessity to reconsider the previous findings on muscle elasticity under active conditions in humans, such as the effect of training background and the association with muscular injury risk.

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Relationship between the morphological and mechanical properties of muscle‐tendon units and sprint performance in prepubescent sprinters

2019

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Sprinting is the competitive sport of running short distances; it is enjoyed by both adults and children at all levels of ability. Several previous studies have investigated the characteristics of superior junior sprinters and revealed that their sprinting ability was related to the morphological properties of muscles 1,2 and sprint movement. 3 Recently, the influence of the morphological and mechanical properties of the muscle-tendon units (MTU) on sprinting ability has been examined in adults. Since kinetic and kinematic characteristics of knee and ankle joint are associated with sprint performance, 4 several studies focused on the MTU crossing these joints. In general, a relationship has been reported between the morphological and mechanical properties of MTU of knee extensors or plantar flexors and sprint performance. 5-8 For example, compliant tendon structures of knee extensors 5,6 and increased muscle thickness of both knee extensors and plantar flexors 7,8 have been shown to positively affect sprint performance. On the other hand, it has been reported that the tendon length 6 and muscle stiffness 9 are not correlated with sprint performance. Thus, it is conceivable that the mechanical properties of the tendon structure and the morphological properties of the muscles would be related to sprint performance.Regarding muscle morphology in junior sprinters, only two studies 1,2 have investigated the relationship between the This study aimed to examine the relationship between the morphological and mechanical properties of the muscle-tendon unit and sprint time in prepubescent sprinters. Fifteen prepubescent sprinters participated in this study; the average personal best time in a 100 m race was 14.00 ± 0.68 seconds. The stiffness of the tendon structure was measured using ultrasonography during isometric contraction; the muscle thickness of the vastus lateralis (VL) and the medial gastrocnemius (MG) were also measured. There was a significant negative correlation between tendon structure stiffness of the plantar flexors and 100 m personal best time (r = −0.58, P < 0.05), but not the knee extensors. Unlike for the MG, the muscle thickness of the VL (r = −0.61, P < 0.05) and the 100 m personal best time were significantly negatively correlated. Stepwise regression analysis identified the tendon structure stiffness of the plantar flexors and the muscle thickness of the VL as independent variables, which were significantly associated with the 100 m personal best time (r = 0.77, P < 0.01). These results suggest that in prepubescent sprinters, superior sprint performance is induced by a stiff tendon structure of the plantar flexors and a greater muscle thickness of the VL. K E Y W O R D Smuscle thickness, stiffness, stretch-shortening cycle, ultrasonography

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Active muscle and tendon stiffness of plantar flexors in sprinters

Cited by 20 publications

References 39 publications

Specific adaptations of patellar and Achilles tendons in male sprinters and endurance runners

Specific adaptations of patellar and Achilles tendons in male sprinters and endurance runners

Muscle elasticity under active conditions in humans: A methodological comparison

Relationship between the morphological and mechanical properties of muscle‐tendon units and sprint performance in prepubescent sprinters

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