TY  - JOUR
A1  - Werkhausen, Amelie
A1  - Willwacher, Steffen
A1  - Albracht, Kirsten
T1  - Medial gastrocnemius muscle fascicles shorten throughout stance during sprint acceleration
JF  - Scandinavian Journal of Medicine & Science in Sports
N2  - The compliant nature of distal limb muscle-tendon units is traditionally considered suboptimal in explosive movements when positive joint work is required. However, during accelerative running, ankle joint net mechanical work is positive. Therefore, this study aims to investigate how plantar flexor muscle-tendon behavior is modulated during fast accelerations. Eleven female sprinters performed maximum sprint accelerations from starting blocks, while gastrocnemius muscle fascicle lengths were estimated using ultrasonography. We combined motion analysis and ground reaction force measurements to assess lower limb joint kinematics and kinetics, and to estimate gastrocnemius muscle-tendon unit length during the first two acceleration steps. Outcome variables were resampled to the stance phase and averaged across three to five trials. Relevant scalars were extracted and analyzed using one-sample and two-sample t-tests, and vector trajectories were compared using statistical parametric mapping. We found that an uncoupling of muscle fascicle behavior from muscle-tendon unit behavior is effectively used to produce net positive mechanical work at the joint during maximum sprint acceleration. Muscle fascicles shortened throughout the first and second steps, while shortening occurred earlier during the first step, where negative joint work was lower compared with the second step. Elastic strain energy may be stored during dorsiflexion after touchdown since fascicles did not lengthen at the same time to dissipate energy. Thus, net positive work generation is accommodated by the reuse of elastic strain energy along with positive gastrocnemius fascicle work. Our results show a mechanism of how muscles with high in-series compliance can contribute to net positive joint work.
KW  - locomotion
KW  - muscle mechanics
KW  - running
KW  - sprint start
KW  - ultrasonography
Y1  - 2021
U6  - https://doi.org/10.1111/sms.13956
SN  - 0905-7188 (Druckausgabe)
SN  - 1600-0838 (Onlineausgabe)
VL  - 31
IS  - 7
SP  - 1471
EP  - 1480
PB  - Wiley-Blackwell
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Wert, Stefan
A1  - Iken, Heiko
A1  - Schöning, Michael Josef
A1  - Matysik, Frank-Michael
T1  - Development of a temperature‐pulse enhanced electrochemical glucose biosensor and characterization of its stability via scanning electrochemical microscopy
JF  - Electroanalysis
N2  - Glucose oxidase (GOx) is an enzyme frequently used in glucose biosensors. As increased temperatures can enhance the performance of electrochemical sensors, we investigated the impact of temperature pulses on GOx that was drop-coated on flattened Pt microwires. The wires were heated by an alternating current. The sensitivity towards glucose and the temperature stability of GOx was investigated by amperometry. An up to 22-fold increase of sensitivity was observed. Spatially resolved enzyme activity changes were investigated via scanning electrochemical microscopy. The application of short (<100 ms) heat pulses was associated with less thermal inactivation of the immobilized GOx than long-term heating.
Y1  - 2021
U6  - https://doi.org/10.1002/elan.202100089
SN  - 1521-4109
IS  - Early View
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Yoshinobu, Tatsuo
A1  - Schöning, Michael Josef
T1  - Light-addressable potentiometric sensors (LAPS) for cell monitoring and biosensing
JF  - Current Opinion in Electrochemistry
Y1  - 2021
U6  - https://doi.org/10.1016/j.coelec.2021.100727
SN  - 2451-9103
IS  - In Press, Journal Pre-proof
PB  - Elsevier
CY  - Amsterdam
ER  -