TY  - JOUR
A1  - Werkhausen, Amelie
A1  - Albracht, Kirsten
A1  - Cronin, Neil J
A1  - Paulsen, Gøran
A1  - Bojsen-Møller, Jens
A1  - Seynnes, Olivier R
T1  - Effect of training-induced changes in achilles tendon stiffness on muscle-tendon behavior during landing
JF  - Frontiers in physiology
N2  - During rapid deceleration of the body, tendons buffer part of the elongation of the muscle-tendon unit (MTU), enabling safe energy dissipation via eccentric muscle contraction. Yet, the influence of changes in tendon stiffness within the physiological range upon these lengthening contractions is unknown. This study aimed to examine the effect of training-induced stiffening of the Achilles tendon on triceps surae muscle-tendon behavior during a landing task. Twenty-one male subjects were assigned to either a 10-week resistance-training program consisting of single-leg isometric plantarflexion (n = 11) or to a non-training control group (n = 10). Before and after the training period, plantarflexion force, peak Achilles tendon strain and stiffness were measured during isometric contractions, using a combination of dynamometry, ultrasound and kinematics data. Additionally, testing included a step-landing task, during which joint mechanics and lengths of gastrocnemius and soleus fascicles, Achilles tendon, and MTU were determined using synchronized ultrasound, kinematics and kinetics data collection. After training, plantarflexion strength and Achilles tendon stiffness increased (15 and 18%, respectively), and tendon strain during landing remained similar. Likewise, lengthening and negative work produced by the gastrocnemius MTU did not change detectably. However, in the training group, gastrocnemius fascicle length was offset (8%) to a longer length at touch down and, surprisingly, fascicle lengthening and velocity were reduced by 27 and 21%, respectively. These changes were not observed for soleus fascicles when accounting for variation in task execution between tests. These results indicate that a training-induced increase in tendon stiffness does not noticeably affect the buffering action of the tendon when the MTU is rapidly stretched. Reductions in gastrocnemius fascicle lengthening and lengthening velocity during landing occurred independently from tendon strain. Future studies are required to provide insight into the mechanisms underpinning these observations and their influence on energy dissipation.
KW  - achilles tendon
KW  - energy absorption
KW  - energy dissipation
KW  - mechanical buffer
KW  - stiffness
Y1  - 2018
U6  - https://doi.org/10.3389/fphys.2018.00794
SN  - 1664-042X
IS  - 9
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  - 
TY  - CHAP
A1  - Yoshinobu, Tatsuo
A1  - Krause, Steffi
A1  - Miyamoto, Ko-ichiro
A1  - Werner, Frederik
A1  - Poghossian, Arshak
A1  - Wagner, Torsten
A1  - Schöning, Michael Josef
T1  - (Bio-)chemical Sensing and Imaging by LAPS and SPIM
T2  - Label-free biosensing: advanced materials, devices and applications
N2  - The light-addressable potentiometric sensor (LAPS) and scanning photo-induced impedance microscopy (SPIM) are two closely related methods to visualise the distributions of chemical species and impedance, respectively, at the interface between the sensing surface and the sample solution. They both have the same field-effect structure based on a semiconductor, which allows spatially resolved and label-free measurement of chemical species and impedance in the form of a photocurrent signal generated by a scanning light beam. In this article, the principles and various operation modes of LAPS and SPIM, functionalisation of the sensing surface for measuring various species, LAPS-based chemical imaging and high-resolution sensors based on silicon-on-sapphire substrates are described and discussed, focusing on their technical details and prospective applications.
KW  - Chemical imaging
KW  - Field-effect device
KW  - Light-addressable potentiometric sensor
KW  - Potentiometry
Y1  - 2018
SN  - 978-3-319-75219-8
SP  - 103
EP  - 132
PB  - Springer
CY  - Cham
ER  -