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  - 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  -