Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer International Publishing  

Background: Patients who have had an Achilles tendon (AT) rupture repaired are potentially at higher risk for re-rupture than those without previous rupture. Little attention has been given to the neuromechanical modulation of muscle–tendon interaction and muscle activation profiles during human dynamic movements after AT rupture repair. Objective: The purpose of this study was to examine muscle–tendon behavior and muscle activation during bilateral hopping. Methods: We enrolled nine subjects who had undergone surgical repair of unilateral AT rupture within the past 1–2 years. Subjects performed bilateral hopping while we took ultrasound, kinematic, and electromyogram recordings and measurements. AT behaviors were also recorded. We then compared responses between values obtained from the ruptured AT leg (LEGATR) and non-ruptured AT leg (LEGNOR). Results: During hopping, the AT stretching amplitudes were greater in the LEGATR than in the LEGNOR, although the peak AT force and stiffness were smaller in the LEGATR than in the LEGNOR. The AT negative mechanical work did not show any significant differences between both legs. However, positive works were significantly lower in the LEGATR than in the LEGNOR. Electromyogram patterns in both soleus and tibialis anterior muscles clearly differed after ground contact for the LEGATR and the LEGNOR. Conclusions: These results suggest that the repaired ruptured AT can be compliant and have insufficient Young’s modulus, which can influence mechanical responses in muscle activities. The modulation of agonist–antagonist muscle activities corresponding to the different levels of stiffness between the LEGATR and the LEGNOR may not be fully functioning during the pre-activation phase.

DOI： 10.1007/s40279-016-0629-3

Scopus

PubMed

Language：Japanese   Publisher：Japan Society of Physical Education, Health and Sport Sciences  

One of the most frequent injuries in Kendo athletes is Achilles tendinopathy in the left leg, for example Achilles tendon rupture. However, preventive approaches for Achilles tendinopathy in Kendo athletes have not been well considered. Therefore, the purpose of the present study was to examine differences in the architectures of the gastrocnemius muscle and Achilles tendon in relation to kendo training experience, and to examine the mechanical properties of the Achilles tendinous tissues (AT) in Kendo athletes in order to clarify why Achilles tendinopathy occurs in the left leg. Sixty-five Kendo male athletes with different periods of kendo training experience and 20 healthy male control subjects participated in this study. The architectural properties of the medial gastrocnemius muscle (MG) and Achilles tendon in both legs were measured using ultrasonography. In addition, 20 expert Kendo male athletes and healthy male controls pair-matched with the kendo athletes for body height and body mass were examined for their AT mechanical properties during passive dorsiflexion of both legs. The differences in the cross&ndash;sectional areas of the Achilles tendon and MG muscle between the left and right legs were greater in Kendo athletes with longer experience. Especially, the expert kendo athletes had lower AT stiffness and Young's modulus in the left leg than did the control subjects. These results suggest that kendo leads to specific Achilles tendon and muscle adaptation. These specific adaptations of the MG fascicles and AT may be one of the risk factors for Achilles tendon rupture in Kendo athletes.<br>

DOI： 10.5432/jjpehss.16012

CiNii Books

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Blackwell Publishing Ltd  

Aim: It has been reported that advancing age causes tendons to become more compliant and fascicles length shorter. This could then lead to enhancement of movement efficiency provided that the elderly adults can activate their muscles in the same way as the younger adults (YOUNG) during dynamic movements. This study was designed to examine the age-specific behaviour of the medial gastrocnemius (MG) fascicles and tendinous tissues together with lower-leg muscle activities when the well-trained elderly runners ran on the treadmill at preferred speeds. Methods: The well-trained 11 elderly subjects (ELD) who have running experiences and 11 YOUNG were recruited as subjects. While ELD were running on the treadmill at their preferred speed, the lengths of the MG fascicles and tendinous tissues (Lfa and LTT respectively) were measured by ultrasonography together with kinematics and lower-leg muscle activities. Results: Although the behaviour of the MG muscle-tendon unit did not show any significant differences between both groups during the contact, our results showed significant differences in fascicle-tendinous tissue behaviour as well as muscle activities. The LTT during the entire contact phase was greater in ELD than in YOUNG (P &lt
0.001). Co-activation of lower-leg muscles from pre-activation to braking phases was higher in ELD than in YOUNG (P &lt
0.01). The changes of the Lfa during contact were less, and the LTT shortening was greater in ELD than in YOUNG (P &lt
0.001). Conclusion: These results imply that ELD cannot activate their muscles similar to YOUNG during running, and those different activities may modify the Lfa to utilize the tendon elasticity effectively.

DOI： 10.1111/apha.12550

Scopus

PubMed

Language：English   Publisher：The Japanese Society of Physical Fitness and Sports Medicine  

The superior success of East-African endurance runners has stimulated a large amount of interest in exploring valid reasons for their performance, especially for neuromuscular mechanics. This review provides a brief overview of classic neuromuscular interaction during running; and, thereafter, describes a specific neuromuscular interaction alternative to the classic stretch-shortening cycle concept for enhancing the running economy of East-African distance runners.

DOI： 10.7600/jpfsm.2.361

CiNii Books

Other Link： https://jlc.jst.go.jp/DN/JALC/10023205641?from=CiNii