TY - JOUR A1 - Schoenrock, Britt A1 - Muckelt, Paul E. A1 - Hastermann, Maria A1 - Albracht, Kirsten A1 - MacGregor, Robert A1 - Martin, David A1 - Gunga, Hans-Christian A1 - Salanova, Michele A1 - Stokes, Maria J. A1 - Warner, Martin B. A1 - Blottner, Dieter T1 - Muscle stiffness indicating mission crew health in space JF - Scientific Reports N2 - Muscle function is compromised by gravitational unloading in space affecting overall musculoskeletal health. Astronauts perform daily exercise programmes to mitigate these effects but knowing which muscles to target would optimise effectiveness. Accurate inflight assessment to inform exercise programmes is critical due to lack of technologies suitable for spaceflight. Changes in mechanical properties indicate muscle health status and can be measured rapidly and non-invasively using novel technology. A hand-held MyotonPRO device enabled monitoring of muscle health for the first time in spaceflight (> 180 days). Greater/maintained stiffness indicated countermeasures were effective. Tissue stiffness was preserved in the majority of muscles (neck, shoulder, back, thigh) but Tibialis Anterior (foot lever muscle) stiffness decreased inflight vs. preflight (p < 0.0001; mean difference 149 N/m) in all 12 crewmembers. The calf muscles showed opposing effects, Gastrocnemius increasing in stiffness Soleus decreasing. Selective stiffness decrements indicate lack of preservation despite daily inflight countermeasures. This calls for more targeted exercises for lower leg muscles with vital roles as ankle joint stabilizers and in gait. Muscle stiffness is a digital biomarker for risk monitoring during future planetary explorations (Moon, Mars), for healthcare management in challenging environments or clinical disorders in people on Earth, to enable effective tailored exercise programmes. KW - Ageing KW - Anatomy KW - Muscle KW - Musculoskeletal system KW - Physiology Y1 - 2024 U6 - http://dx.doi.org/10.1038/s41598-024-54759-6 SN - 2045-2322 N1 - Corresponding author: Dieter Blottner VL - 14 IS - Article number: 4196 PB - Springer Nature CY - London ER - TY - JOUR A1 - Liphardt, Anna-Maria A1 - Fernandez-Gonzalo, Rodrigo A1 - Albracht, Kirsten A1 - Rittweger, Jörn A1 - Vico, Laurence T1 - Musculoskeletal research in human space flight – unmet needs for the success of crewed deep space exploration JF - npj Microgravity N2 - Based on the European Space Agency (ESA) Science in Space Environment (SciSpacE) community White Paper “Human Physiology – Musculoskeletal system”, this perspective highlights unmet needs and suggests new avenues for future studies in musculoskeletal research to enable crewed exploration missions. The musculoskeletal system is essential for sustaining physical function and energy metabolism, and the maintenance of health during exploration missions, and consequently mission success, will be tightly linked to musculoskeletal function. Data collection from current space missions from pre-, during-, and post-flight periods would provide important information to understand and ultimately offset musculoskeletal alterations during long-term spaceflight. In addition, understanding the kinetics of the different components of the musculoskeletal system in parallel with a detailed description of the molecular mechanisms driving these alterations appears to be the best approach to address potential musculoskeletal problems that future exploratory-mission crew will face. These research efforts should be accompanied by technical advances in molecular and phenotypic monitoring tools to provide in-flight real-time feedback. Y1 - 2023 U6 - http://dx.doi.org/10.1038/s41526-023-00258-3 SN - 2373-8065 VL - 9 IS - Article number: 9 SP - 1 EP - 9 PB - Springer Nature ER - TY - JOUR A1 - Heieis, Jule A1 - Böcker, Jonas A1 - D'Angelo, Olfa A1 - Mittag, Uwe A1 - Albracht, Kirsten A1 - Schönau, Eckhard A1 - Meyer, Andreas A1 - Voigtmann, Thomas A1 - Rittweger, Jörn T1 - Curvature of gastrocnemius muscle fascicles as function of muscle–tendon complex length and contraction in humans JF - Physiological Reports N2 - It has been shown that muscle fascicle curvature increases with increasing contraction level and decreasing muscle–tendon complex length. The analyses were done with limited examination windows concerning contraction level, muscle–tendon complex length, and/or intramuscular position of ultrasound imaging. With this study we aimed to investigate the correlation between fascicle arching and contraction, muscle–tendon complex length and their associated architectural parameters in gastrocnemius muscles to develop hypotheses concerning the fundamental mechanism of fascicle curving. Twelve participants were tested in five different positions (90°/105°*, 90°/90°*, 135°/90°*, 170°/90°*, and 170°/75°*; *knee/ankle angle). They performed isometric contractions at four different contraction levels (5%, 25%, 50%, and 75% of maximum voluntary contraction) in each position. Panoramic ultrasound images of gastrocnemius muscles were collected at rest and during constant contraction. Aponeuroses and fascicles were tracked in all ultrasound images and the parameters fascicle curvature, muscle–tendon complex strain, contraction level, pennation angle, fascicle length, fascicle strain, intramuscular position, sex and age group were analyzed by linear mixed effect models. Mean fascicle curvature of the medial gastrocnemius increased with contraction level (+5 m−1 from 0% to 100%; p = 0.006). Muscle–tendon complex length had no significant impact on mean fascicle curvature. Mean pennation angle (2.2 m−1 per 10°; p < 0.001), inverse mean fascicle length (20 m−1 per cm−1; p = 0.003), and mean fascicle strain (−0.07 m−1 per +10%; p = 0.004) correlated with mean fascicle curvature. Evidence has also been found for intermuscular, intramuscular, and sex-specific intramuscular differences of fascicle curving. Pennation angle and the inverse fascicle length show the highest predictive capacities for fascicle curving. Due to the strong correlations between pennation angle and fascicle curvature and the intramuscular pattern of curving we suggest for future studies to examine correlations between fascicle curvature and intramuscular fluid pressure. KW - biomechanics KW - connective tissue KW - physiology KW - ultrasound Y1 - 2023 U6 - http://dx.doi.org/10.14814/phy2.15739 SN - 2051-817X VL - 11 IS - 11 SP - e15739, Seite 1-11 PB - Wiley ER - TY - JOUR A1 - Waldvogel, Janice A1 - Freyler, Kathrin A1 - Helm, Michael A1 - Monti, Elena A1 - Stäudle, Benjamin A1 - Gollhofer, Albert A1 - Narici, Marco V. A1 - Ritzmann, Ramona A1 - Albracht, Kirsten T1 - Changes in gravity affect neuromuscular control, biomechanics, and muscle-tendon mechanics in energy storage and dissipation tasks JF - Journal of Applied Physiology N2 - This study evaluates neuromechanical control and muscle-tendon interaction during energy storage and dissipation tasks in hypergravity. During parabolic flights, while 17 subjects performed drop jumps (DJs) and drop landings (DLs), electromyography (EMG) of the lower limb muscles was combined with in vivo fascicle dynamics of the gastrocnemius medialis, two-dimensional (2D) kinematics, and kinetics to measure and analyze changes in energy management. Comparisons were made between movement modalities executed in hypergravity (1.8 G) and gravity on ground (1 G). In 1.8 G, ankle dorsiflexion, knee joint flexion, and vertical center of mass (COM) displacement are lower in DJs than in DLs; within each movement modality, joint flexion amplitudes and COM displacement demonstrate higher values in 1.8 G than in 1 G. Concomitantly, negative peak ankle joint power, vertical ground reaction forces, and leg stiffness are similar between both movement modalities (1.8 G). In DJs, EMG activity in 1.8 G is lower during the COM deceleration phase than in 1 G, thus impairing quasi-isometric fascicle behavior. In DLs, EMG activity before and during the COM deceleration phase is higher, and fascicles are stretched less in 1.8 G than in 1 G. Compared with the situation in 1 G, highly task-specific neuromuscular activity is diminished in 1.8 G, resulting in fascicle lengthening in both movement modalities. Specifically, in DJs, a high magnitude of neuromuscular activity is impaired, resulting in altered energy storage. In contrast, in DLs, linear stiffening of the system due to higher neuromuscular activity combined with lower fascicle stretch enhances the buffering function of the tendon, and thus the capacity to safely dissipate energy. KW - electromyography KW - locomotion KW - overload KW - stretch-shortening cycle KW - ultrasound Y1 - 2023 U6 - http://dx.doi.org/10.1152/japplphysiol.00279.2022 SN - 1522-1601 (Onlineausgabe) SN - 8750-7587 (Druckausgabe) VL - 134 IS - 1 SP - 190 EP - 202 PB - American Physiological Society CY - Bethesda, Md. ER - TY - JOUR A1 - Stäudle, Benjamin A1 - Seynnes, Olivier A1 - Laps, Guido A1 - Brüggemann, Gert-Peter A1 - Albracht, Kirsten T1 - Altered gastrocnemius contractile behavior in former achilles tendon rupture patients during walking JF - Frontiers in Physiology N2 - Achilles tendon rupture (ATR) remains associated with functional limitations years after injury. Architectural remodeling of the gastrocnemius medialis (GM) muscle is typically observed in the affected leg and may compensate force deficits caused by a longer tendon. Yet patients seem to retain functional limitations during—low-force—walking gait. To explore the potential limits imposed by the remodeled GM muscle-tendon unit (MTU) on walking gait, we examined the contractile behavior of muscle fascicles during the stance phase. In a cross-sectional design, we studied nine former patients (males; age: 45 ± 9 years; height: 180 ± 7 cm; weight: 83 ± 6 kg) with a history of complete unilateral ATR, approximately 4 years post-surgery. Using ultrasonography, GM tendon morphology, muscle architecture at rest, and fascicular behavior were assessed during walking at 1.5 m⋅s–1 on a treadmill. Walking patterns were recorded with a motion capture system. The unaffected leg served as control. Lower limbs kinematics were largely similar between legs during walking. Typical features of ATR-related MTU remodeling were observed during the stance sub-phases corresponding to series elastic element (SEE) lengthening (energy storage) and SEE shortening (energy release), with shorter GM fascicles (36 and 36%, respectively) and greater pennation angles (8° and 12°, respectively). However, relative to the optimal fascicle length for force production, fascicles operated at comparable length in both legs. Similarly, when expressed relative to optimal fascicle length, fascicle contraction velocity was not different between sides, except at the time-point of peak series elastic element (SEE) length, where it was 39 ± 49% lower in the affected leg. Concomitantly, fascicles rotation during contraction was greater in the affected leg during the whole stance-phase, and architectural gear ratios (AGR) was larger during SEE lengthening. Under the present testing conditions, former ATR patients had recovered a relatively symmetrical walking gait pattern. Differences in seen AGR seem to accommodate the profound changes in MTU architecture, limiting the required fascicle shortening velocity. Overall, the contractile behavior of the GM fascicles does not restrict length- or velocity-dependent force potentials during this locomotor task. KW - tendon rupture KW - muscle fascicle behavior KW - walking gait KW - force generation KW - ultrasound imaging Y1 - 2022 U6 - http://dx.doi.org/10.3389/fphys.2022.792576 SN - 1664-042X VL - 13 PB - Frontiers Research Foundation CY - Lausanne ER - 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 - http://dx.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 - Herssens, Nolan A1 - Cowburn, James A1 - Albracht, Kirsten A1 - Braunstein, Bjoern A1 - Cazzola, Dario A1 - Colyer, Steffi A1 - Minetti, Alberto E. A1 - Pavei, Gaspare A1 - Rittweger, Jörn A1 - Weber, Tobias A1 - Green, David A. ED - Cattaneo, Luigi T1 - Movement in low gravity environments (MoLo) programme – the MoLo-L.O.O.P. study protocol JF - PLOS ONE / Public Library of Science N2 - Exposure to prolonged periods in microgravity is associated with deconditioning of the musculoskeletal system due to chronic changes in mechanical stimulation. Given astronauts will operate on the Lunar surface for extended periods of time, it is critical to quantify both external (e.g., ground reaction forces) and internal (e.g., joint reaction forces) loads of relevant movements performed during Lunar missions. Such knowledge is key to predict musculoskeletal deconditioning and determine appropriate exercise countermeasures associated with extended exposure to hypogravity. Y1 - 2022 U6 - http://dx.doi.org/10.1371/journal.pone.0278051 SN - 1932-6203 VL - 17 IS - 11 PB - Plos CY - San Francisco ER - TY - JOUR A1 - Heinke, Lars N. A1 - Knicker, Axel J. A1 - Albracht, Kirsten T1 - Test-retest reliability of the internal shoulder rotator muscles' stretch reflex in healthy men JF - Journal of Electromyography and Kinesiology N2 - Until now the reproducibility of the short latency stretch reflex of the internal rotator muscles of the glenohumeral joint has not been identified. Twenty-three healthy male participants performed three sets of external shoulder rotation stretches with various pre-activation levels on two different dates of measurement to assess test-retest reliability. All stretches were applied with a dynamometer acceleration of 104°/s2 and a velocity of 150°/s. Electromyographical response was measured via surface EMG. Reflex latencies showed a pre-activation effect (ƞ2 = 0,355). ICC ranged from 0,735 to 0,909 indicating an overall “good” relative reliability. SRD 95% lay between ±7,0 to ±12,3 ms.. The reflex gain showed overall poor test-retest reproducibility. The chosen methodological approach presented a suitable test protocol for shoulder muscles stretch reflex latency evaluation. A proof-of-concept study to validate the presented methodical approach in shoulder involvement including subjects with clinically relevant conditions is recommended. KW - stretch reflex KW - shoulder KW - test-retest reliability KW - intraclass correlation coefficient KW - standard error of measurement Y1 - 2021 U6 - http://dx.doi.org/10.1016/j.jelekin.2021.102611 SN - 1050-6411 VL - 62 IS - Article 102611 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Waldvogel, Janice A1 - Ritzmann, Ramona A1 - Freyler, Kathrin A1 - Helm, Michael A1 - Monti, Elena A1 - Albracht, Kirsten A1 - Stäudle, Benjamin A1 - Gollhofer, Albert A1 - Narici, Marco T1 - The Anticipation of Gravity in Human Ballistic Movement JF - Frontiers in Physiology N2 - Stretch-shortening type actions are characterized by lengthening of the pre-activated muscle-tendon unit (MTU) in the eccentric phase immediately followed by muscle shortening. Under 1 g, pre-activity before and muscle activity after ground contact, scale muscle stiffness, which is crucial for the recoil properties of the MTU in the subsequent push-off. This study aimed to examine the neuro-mechanical coupling of the stretch-shortening cycle in response to gravity levels ranging from 0.1 to 2 g. During parabolic flights, 17 subjects performed drop jumps while electromyography (EMG) of the lower limb muscles was combined with ultrasound images of the gastrocnemius medialis, 2D kinematics and kinetics to depict changes in energy management and performance. Neuro-mechanical coupling in 1 g was characterized by high magnitudes of pre-activity and eccentric muscle activity allowing an isometric muscle behavior during ground contact. EMG during pre-activity and the concentric phase systematically increased from 0.1 to 1 g. Below 1 g the EMG in the eccentric phase was diminished, leading to muscle lengthening and reduced MTU stretches. Kinetic energy at take-off and performance were decreased compared to 1 g. Above 1 g, reduced EMG in the eccentric phase was accompanied by large MTU and muscle stretch, increased joint flexion amplitudes, energy loss and reduced performance. The energy outcome function established by linear mixed model reveals that the central nervous system regulates the extensor muscles phase- and load-specifically. In conclusion, neuro-mechanical coupling appears to be optimized in 1 g. Below 1 g, the energy outcome is compromised by reduced muscle stiffness. Above 1 g, loading progressively induces muscle lengthening, thus facilitating energy dissipation. Y1 - 2021 U6 - http://dx.doi.org/10.3389/fphys.2021.614060 SN - 1664-042X PB - Frontiers CY - Lausanne ER - TY - JOUR A1 - Richter, Charlotte A1 - Braunstein, Bjoern A1 - Staeudle, Benjamin A1 - Attias, Julia A1 - Suess, Alexander A1 - Weber, Tobias A1 - Mileva, Katya N. A1 - Rittweger, Joern A1 - Green, David A. A1 - Albracht, Kirsten T1 - Contractile behavior of the gastrocnemius medialis muscle during running in simulated hypogravity JF - npj Microgravity N2 - Vigorous exercise countermeasures in microgravity can largely attenuate muscular degeneration, albeit the extent of applied loading is key for the extent of muscle wasting. Running on the International Space Station is usually performed with maximum loads of 70% body weight (0.7 g). However, it has not been investigated how the reduced musculoskeletal loading affects muscle and series elastic element dynamics, and thereby force and power generation. Therefore, this study examined the effects of running on the vertical treadmill facility, a ground-based analog, at simulated 0.7 g on gastrocnemius medialis contractile behavior. The results reveal that fascicle−series elastic element behavior differs between simulated hypogravity and 1 g running. Whilst shorter peak series elastic element lengths at simulated 0.7 g appear to be the result of lower muscular and gravitational forces acting on it, increased fascicle lengths and decreased velocities could not be anticipated, but may inform the development of optimized running training in hypogravity. However, whether the alterations in contractile behavior precipitate musculoskeletal degeneration warrants further study. Y1 - 2021 U6 - http://dx.doi.org/10.1038/s41526-021-00155-7 SN - 2373-8065 N1 - Corresponding author: Charlotte Richter VL - 7 IS - Article number: 32 PB - Springer Nature CY - New York ER -