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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.
Bewegungsanalysesysteme in der Forschung und für niedergelassene Orthopädinnen und Orthopäden
(2023)
Hintergrund
Komplexe biomechanische Bewegungsanalysen können für eine Vielzahl orthopädischer Fragestellungen wichtige Informationen liefern. Bei der Beschaffung von Bewegungsanalysesystemen sind neben den klassischen Messgütekriterien (Validität, Reliabilität, Objektivität) auch räumliche und zeitliche Rahmenbedingungen sowie Anforderungen an die Qualifikation des Messpersonals zu berücksichtigen.
Anwendung
In der komplexen Bewegungsanalyse werden Systeme zur Bestimmung der Kinematik, der Kinetik und der Muskelaktivität (Elektromyographie) eingesetzt. Der vorliegende Artikel gibt einen Überblick über Methoden der komplexen biomechanischen Bewegungsanalyse für den Einsatz in der orthopädischen Forschung oder in der individuellen Patientenversorgung. Neben dem Einsatz zur reinen Bewegungsanalyse wird auch der Einsatz von Bewegungsanalyseverfahren im Bereich des Biofeedbacktrainings diskutiert.
Beschaffung
Für die konkrete Anschaffung von Bewegungsanalysesystemen empfiehlt sich die Kontaktaufnahme mit Fachgesellschaften (z. B. Deutsche Gesellschaft für Biomechanik), Hochschulen und Universitäten mit vorhandenen Bewegungsanalyseeinrichtungen oder Vertriebsfirmen im Bereich der Biomechanik.
Footwear plays a critical role in our daily lives, affecting our performance, health and overall well-being. Well-designed footwear can provide protection, comfort and improved foot functionality, while poorly designed footwear can lead to mobility problems and declines in physical activity. The overall goal of footwear research is to provide a scientific basis for professionals in the field to provide an optimal footwear solution for a given person, for a given task, in a given environment, while using sustainable manufacturing processes. This article suggests potential directions for future research with a focus on athletic footwear biomechanics. Directions include the evidence-based individualisation of footwear, the interaction between design and prolonged use, and improving the sustainability of footwear. The authors also provide a speculative outlook on methodological developments that may provide greater insight into these areas. These developments may include: (1) the use of larger scale, real-world and representative data, (2) the use of 3D printing to create experimental footwear, (3) the advancement of in silico research methods, and (4) furthering multidisciplinary collaboration. If successfully applied in the future, footwear research will contribute to active and healthy lifestyles across the lifespan.
We present a two-dimensional (2D) planar chromatographic separation of estrogenic active compounds on RP-18 W (Merck, 1.14296) phase. A mixture of 8 substances was separated using a solvent mix consisting of hexane, ethyl acetate, acetone (55:15:10, v/v) in the first direction and of acetone and water (15:10, v/v) in the second direction. Separation was performed on an RP-18 W plate over a distance of 70 mm. This 2D-separation method can be used to quantify 17α-ethinylestradiol (EE2) in an effect-directed analysis, using the yeast strain Saccharomyces cerevisiae BJ3505. The test strain (according to McDonnell) contains the estrogen receptor. Its activation by estrogen active compounds is measured by inducing the reporter gene lacZ which encodes the enzyme β-galactosidase. This enzyme activity is determined on plate by using the fluorescent substrate MUG (4-methylumbelliferyl-β-d-galactopyranoside).