TY  - JOUR
A1  - Quittmann, Oliver J.
A1  - Abel, Thomas
A1  - Albracht, Kirsten
A1  - Strüder, Heiko K.
T1  - Biomechanics of all-out handcycling exercise: kinetics, kinematics and muscular activity of a 15-s sprint test in able-bodied participants
JF  - Sports Biomechanics
N2  - This study aims to quantify the kinematics, kinetics and muscular activity of all-out handcycling exercise and examine their alterations during the course of a 15-s sprint test. Twelve able-bodied competitive triathletes performed a 15-s all-out sprint test in a recumbent racing handcycle that was attached to an ergometer. During the sprint test, tangential crank kinetics, 3D joint kinematics and muscular activity of 10 muscles of the upper extremity and trunk were examined using a power metre, motion capturing and surface electromyography (sEMG), respectively. Parameters were compared between revolution one (R1), revolution two (R2), the average of revolution 3 to 13 (R3) and the average of the remaining revolutions (R4). Shoulder abduction and internal-rotation increased, whereas maximal shoulder retroversion decreased during the sprint. Except for the wrist angles, angular velocity increased for every joint of the upper extremity. Several muscles demonstrated an increase in muscular activation, an earlier onset of muscular activation in crank cycle and an increased range of activation. During the course of a 15-s all-out sprint test in handcycling, the shoulder muscles and the muscles associated to the push phase demonstrate indications for short-duration fatigue. These findings are helpful to prevent injuries and improve performance in all-out handcycling.
KW  - Handbike
KW  - sEMG
KW  - Paralympic sport
KW  - performance testing
KW  - high-intensity exercise
Y1  - 2022
U6  - https://doi.org/10.1080/14763141.2020.1745266
SN  - 1752-6116 (Onlineausgabe)
SN  - 1476-3141 (Druckausgabe)
VL  - 21
IS  - 10
SP  - 1200
EP  - 1223
PB  - Taylor & Francis
CY  - London
ER  - 
TY  - JOUR
A1  - Kleefeld, Andreas
A1  - Zimmermann, M.
ED  - Constanda, Christian
ED  - Bodmann, Bardo E.J.
ED  - Harris, Paul J.
T1  - Computing Elastic Interior Transmission Eigenvalues
JF  - Integral Methods in Science and Engineering
N2  - An alternative method is presented to numerically compute interior elastic transmission eigenvalues for various domains in two dimensions. This is achieved by discretizing the resulting system of boundary integral equations in combination with a nonlinear eigenvalue solver. Numerical results are given to show that this new approach can provide better results than the finite element method when dealing with general domains.
Y1  - 2022
SN  - 978-3-031-07171-3
U6  - https://doi.org/10.1007/978-3-031-07171-3_10
N1  - Corresponding author: Andreas Kleefeld
SP  - 139
EP  - 155
PB  - Birkhäuser
CY  - Cham
ER  - 
TY  - JOUR
A1  - Harris, Isaac
A1  - Kleefeld, Andreas
T1  - Analysis and computation of the transmission eigenvalues with a conductive boundary condition
JF  - Applicable Analysis
N2  - We provide a new analytical and computational study of the transmission eigenvalues with a conductive boundary condition. These eigenvalues are derived from the scalar inverse scattering problem for an inhomogeneous material with a conductive boundary condition. The goal is to study how these eigenvalues depend on the material parameters in order to estimate the refractive index. The analytical questions we study are: deriving Faber–Krahn type lower bounds, the discreteness and limiting behavior of the transmission eigenvalues as the conductivity tends to infinity for a sign changing contrast. We also provide a numerical study of a new boundary integral equation for computing the eigenvalues. Lastly, using the limiting behavior we will numerically estimate the refractive index from the eigenvalues provided the conductivity is sufficiently large but unknown.
KW  - Boundary integral equations
KW  - Inverse spectral problem
KW  - Conductive boundary condition
KW  - Transmission eigenvalues
Y1  - 2020
U6  - https://doi.org/10.1080/00036811.2020.1789598
SN  - 1563-504X
VL  - 101
IS  - 6
SP  - 1880
EP  - 1895
PB  - Taylor & Francis
CY  - London
ER  -