The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Glen A Lichtwark - One of the best experts on this subject based on the ideXlab platform.
-
differences in in vivo Muscle Fascicle and tendinous tissue behavior between the ankle plantarflexors during running
Scandinavian Journal of Medicine & Science in Sports, 2018Co-Authors: Adrian K M Lai, Anthony G Schache, Glen A Lichtwark, Marcus G PandyAbstract:The primary human ankle plantarflexors, soleus (SO), medial gastrocnemius (MG), and lateral gastrocnemius (LG) are typically regarded as synergists and play a critical role in running. However, due to differences in Muscle-tendon architecture and joint articulation, the Muscle Fascicles and tendinous tissue of the plantarflexors may exhibit differences in their behavior and interactions during running. We combined in vivo dynamic ultrasound measurements with inverse dynamics analyses to identify and explain differences in Muscle Fascicle, Muscle-tendon unit, and tendinous tissue behavior of the primary ankle plantarflexors across a range of steady-state running speeds. Consistent with their role as a force generator, the Muscle Fascicles of the uniarticular SO shortened less rapidly than the Fascicles of the MG during early stance. Furthermore, the MG and LG exhibited delays in tendon recoil during the stance phase, reflecting their ability to transfer power and work between the knee and ankle via tendon stretch and storage of elastic strain energy. Our findings add to the growing body of evidence surrounding the distinct mechanistic functions of uni- and biarticular Muscles during dynamic movements.
-
Muscle tendon length and force affect human tibialis anterior central aponeurosis stiffness in vivo
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: Brent J Raiteri, Andrew G Cresswell, Glen A LichtwarkAbstract:The factors that drive variable aponeurosis behaviors in active versus passive Muscle may alter the longitudinal stiffness of the aponeurosis during contraction, which may change the Fascicle strains for a given Muscle force. However, it remains unknown whether these factors can drive variable aponeurosis behaviors across different Muscle-tendon unit (MTU) lengths and influence the subsequent Fascicle strains during contraction. Here, we used ultrasound and elastography techniques to examine in vivo Muscle Fascicle behavior and central aponeurosis deformations of human tibialis anterior (TA) during force-matched voluntary isometric dorsiflexion contractions at three MTU lengths. We found that increases in TA MTU length increased both the length and apparent longitudinal stiffness of the central aponeurosis at low and moderate Muscle forces (< 0.01). We also found that increased aponeurosis stiffness was directly related to reduced magnitudes of TA Muscle Fascicle shortening for the same change in force (< 0.01). The increase in slope and shift to longer overall lengths of the active aponeurosis force-length relationship as MTU length increased was likely due to a combination of parallel lengthening of aponeurosis and greater transverse aponeurosis strains. This study provides in vivo evidence that human aponeurosis stiffness is increased from low to moderate forces and that the Fascicle strains for a given Muscle force are MTU length dependent. Further testing is warranted to determine whether MTU length-dependent stiffness is a fundamental property of the aponeurosis in pennate Muscles and evaluate whether this property can enhance Muscle performance.
-
effects of Muscle activation on shear between human soleus and gastrocnemius Muscles
Scandinavian Journal of Medicine & Science in Sports, 2017Co-Authors: Taija Finni, Glen A Lichtwark, Neil J Cronin, Dean L Mayfield, Andrew G CresswellAbstract:Lateral connections between Muscles provide pathways for myofascial force transmission. To elucidate whether these pathways have functional roles in vivo, we examined whether activation could alter the shear between the soleus (SOL) and lateral gastrocnemius (LG) Muscles. We hypothesized that selective activation of LG would decrease the stretch-induced shear between LG and SOL. Eleven volunteers underwent a series of knee joint manipulations where plantar flexion force, LG, and SOL Muscle Fascicle lengths and relative displacement of aponeuroses between the Muscles were obtained. Data during a passive full range of motion were recorded, followed by 20° knee extension stretches in both passive conditions and with selective electrical stimulation of LG. During active stretch, plantar flexion force was 22% greater (P < 0.05) and relative displacement of aponeuroses was smaller than during passive stretch (P < 0.05). Soleus Fascicle length changes did not differ between passive and active stretches but LG Fascicles stretched less in the active than passive condition when the stretch began at angles of 70° and 90° of knee flexion (P < 0.05). The activity-induced decrease in the relative displacement of SOL and LG suggests stronger (stiffer) connectivity between the two Muscles, at least at flexed knee joint angles, which may serve to facilitate myofascial force transmission.
-
the mechanical function of the tibialis posterior Muscle and its tendon during locomotion
Journal of Biomechanics, 2016Co-Authors: Jayishni N Maharaj, Andrew G Cresswell, Glen A LichtwarkAbstract:The tibialis posterior (TP) Muscle is believed to provide mediolateral stability of the subtalar joint during the stance phase of walking as it actively lengthens to resist pronation at foot contact and then actively shortens later in stance to contribute to supination. Because of its anatomical structure of short Muscle fibres and long series elastic tissue, we hypothesised that TP would be a strong candidate for energy storage and return. We investigated the potential elastic function of the TP Muscle and tendon through simultaneous measurements of Muscle Fascicle length (ultrasound), Muscle tendon unit length (musculoskeletal modelling) and Muscle activation (intramuscular electromyography). In early stance, TP Fascicles actively shortened as the entire Muscle-tendon unit lengthened, resulting in the absorption of energy through stretch of the series elastic tissue. Energy stored in the tendinous tissue from early stance was maintained during mid-stance, although a small amount of energy may have been absorbed via minimal shortening in the series elastic elements and lengthening of TP Fascicles. A significant amount of shortening occurred in both the Fascicles and Muscle-tendon unit in late stance, as the activation of TP decreased and power was generated. The majority of the shortening was attributable to shortening of the tendinous tissue. We conclude that the tendinous tissue of TP serves two primary functions during walking: 1) to buffer the stretch of its Fascicles during early stance and 2) to enhance the efficiency of the TP through absorption and return of elastic strain energy.
-
ultratrack software for semi automated tracking of Muscle Fascicles in sequences of b mode ultrasound images
Computer Methods and Programs in Biomedicine, 2016Co-Authors: Dominic James Farris, Glen A LichtwarkAbstract:Abstract Background Dynamic measurements of human Muscle Fascicle length from sequences of B-mode ultrasound images have become increasingly prevalent in biomedical research. Manual digitisation of these images is time consuming and algorithms for automating the process have been developed. Here we present a freely available software implementation of a previously validated algorithm for semi-automated tracking of Muscle Fascicle length in dynamic ultrasound image recordings, “UltraTrack”. Methods UltraTrack implements an affine extension to an optic flow algorithm to track movement of the Muscle Fascicle end-points throughout dynamically recorded sequences of images. The underlying algorithm has been previously described and its reliability tested, but here we present the software implementation with features for: tracking multiple Fascicles in multiple Muscles simultaneously; correcting temporal drift in measurements; manually adjusting tracking results; saving and re-loading of tracking results and loading a range of file formats. Results Two example runs of the software are presented detailing the tracking of Fascicles from several lower limb Muscles during a squatting and walking activity. Conclusion We have presented a software implementation of a validated Fascicle-tracking algorithm and made the source code and standalone versions freely available for download.
Andrew G Cresswell - One of the best experts on this subject based on the ideXlab platform.
-
Muscle tendon length and force affect human tibialis anterior central aponeurosis stiffness in vivo
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: Brent J Raiteri, Andrew G Cresswell, Glen A LichtwarkAbstract:The factors that drive variable aponeurosis behaviors in active versus passive Muscle may alter the longitudinal stiffness of the aponeurosis during contraction, which may change the Fascicle strains for a given Muscle force. However, it remains unknown whether these factors can drive variable aponeurosis behaviors across different Muscle-tendon unit (MTU) lengths and influence the subsequent Fascicle strains during contraction. Here, we used ultrasound and elastography techniques to examine in vivo Muscle Fascicle behavior and central aponeurosis deformations of human tibialis anterior (TA) during force-matched voluntary isometric dorsiflexion contractions at three MTU lengths. We found that increases in TA MTU length increased both the length and apparent longitudinal stiffness of the central aponeurosis at low and moderate Muscle forces (< 0.01). We also found that increased aponeurosis stiffness was directly related to reduced magnitudes of TA Muscle Fascicle shortening for the same change in force (< 0.01). The increase in slope and shift to longer overall lengths of the active aponeurosis force-length relationship as MTU length increased was likely due to a combination of parallel lengthening of aponeurosis and greater transverse aponeurosis strains. This study provides in vivo evidence that human aponeurosis stiffness is increased from low to moderate forces and that the Fascicle strains for a given Muscle force are MTU length dependent. Further testing is warranted to determine whether MTU length-dependent stiffness is a fundamental property of the aponeurosis in pennate Muscles and evaluate whether this property can enhance Muscle performance.
-
Muscle spindles in human tibialis anterior encode Muscle Fascicle length changes
Journal of Neurophysiology, 2017Co-Authors: James Thomas Day, Leah R Bent, Ingvars Birznieks, Vaughan G Macefield, Andrew G CresswellAbstract:Muscle spindles are exquisitely sensitive to changes in Muscle length, but recordings from human Muscle spindle afferents are usually correlated with joint angle rather than Muscle Fascicle length....
-
Muscle spindles in human tibialis anterior encode Muscle Fascicle length changes
Journal of Neurophysiology, 2017Co-Authors: Leah R Bent, Ingvars Birznieks, Vaughan G Macefield, Andrew G CresswellAbstract:Muscle spindles provide exquisitely sensitive proprioceptive information regarding joint position and movement. Through passively driven length changes in the Muscle-tendon unit (MTU), Muscle spindles detect joint rotations because of their in-parallel mechanical linkage to Muscle Fascicles. In human microneurography studies, Muscle Fascicles are assumed to follow the MTU and, as such, Fascicle length is not measured in such studies. However, under certain mechanical conditions compliant structures can act to decouple the Fascicles, and therefore the spindles, from the MTU. Such decoupling may reduce the fidelity by which Muscle spindles encode joint position and movement. The aim of the present study was to measure, for the first time, both the changes in firing of single Muscle spindle afferents and changes in Muscle Fascicle length in vivo from the tibialis anterior Muscle (TA) during passive rotations about the ankle. Unitary recordings were made from 15 Muscle spindle afferents supplying TA via a microelectrode inserted into the common peroneal nerve. Ultrasonography was used to measure the length of an individual Fascicle of TA. We saw a strong correlation between Fascicle length and firing rate during passive ankle rotations of varying rates (0.1-0.5Hz) and amplitudes (1-9°). In particular, we saw responses observed at relatively small changes in Muscle length that highlight the sensitivity of the TA Muscle to small length changes. This study is the first to measure spindle firing and Fascicle dynamics in vivo and provides an experimental basis for further understanding the link between Fascicle length, MTU length and spindle firing patterns.
-
effects of Muscle activation on shear between human soleus and gastrocnemius Muscles
Scandinavian Journal of Medicine & Science in Sports, 2017Co-Authors: Taija Finni, Glen A Lichtwark, Neil J Cronin, Dean L Mayfield, Andrew G CresswellAbstract:Lateral connections between Muscles provide pathways for myofascial force transmission. To elucidate whether these pathways have functional roles in vivo, we examined whether activation could alter the shear between the soleus (SOL) and lateral gastrocnemius (LG) Muscles. We hypothesized that selective activation of LG would decrease the stretch-induced shear between LG and SOL. Eleven volunteers underwent a series of knee joint manipulations where plantar flexion force, LG, and SOL Muscle Fascicle lengths and relative displacement of aponeuroses between the Muscles were obtained. Data during a passive full range of motion were recorded, followed by 20° knee extension stretches in both passive conditions and with selective electrical stimulation of LG. During active stretch, plantar flexion force was 22% greater (P < 0.05) and relative displacement of aponeuroses was smaller than during passive stretch (P < 0.05). Soleus Fascicle length changes did not differ between passive and active stretches but LG Fascicles stretched less in the active than passive condition when the stretch began at angles of 70° and 90° of knee flexion (P < 0.05). The activity-induced decrease in the relative displacement of SOL and LG suggests stronger (stiffer) connectivity between the two Muscles, at least at flexed knee joint angles, which may serve to facilitate myofascial force transmission.
-
the mechanical function of the tibialis posterior Muscle and its tendon during locomotion
Journal of Biomechanics, 2016Co-Authors: Jayishni N Maharaj, Andrew G Cresswell, Glen A LichtwarkAbstract:The tibialis posterior (TP) Muscle is believed to provide mediolateral stability of the subtalar joint during the stance phase of walking as it actively lengthens to resist pronation at foot contact and then actively shortens later in stance to contribute to supination. Because of its anatomical structure of short Muscle fibres and long series elastic tissue, we hypothesised that TP would be a strong candidate for energy storage and return. We investigated the potential elastic function of the TP Muscle and tendon through simultaneous measurements of Muscle Fascicle length (ultrasound), Muscle tendon unit length (musculoskeletal modelling) and Muscle activation (intramuscular electromyography). In early stance, TP Fascicles actively shortened as the entire Muscle-tendon unit lengthened, resulting in the absorption of energy through stretch of the series elastic tissue. Energy stored in the tendinous tissue from early stance was maintained during mid-stance, although a small amount of energy may have been absorbed via minimal shortening in the series elastic elements and lengthening of TP Fascicles. A significant amount of shortening occurred in both the Fascicles and Muscle-tendon unit in late stance, as the activation of TP decreased and power was generated. The majority of the shortening was attributable to shortening of the tendinous tissue. We conclude that the tendinous tissue of TP serves two primary functions during walking: 1) to buffer the stretch of its Fascicles during early stance and 2) to enhance the efficiency of the TP through absorption and return of elastic strain energy.
Yasuo Kawakami - One of the best experts on this subject based on the ideXlab platform.
-
in vivo behavior of Muscle Fascicles and tendinous tissues in human tibialis anterior Muscle during twitch contraction
Journal of Biomechanics, 2007Co-Authors: Ryutaro Himeno, Toshihiko Nagayoshi, Toshiyuki Kurihara, Kentaro Chino, Tetsuo Fukunaga, Hiroaki Kanehisa, Yasuo KawakamiAbstract:Abstract In this study we investigated the time course of length and velocity of Muscle Fascicles and tendinous tissues (TT) during isometric twitch contraction, and examined how their interaction relates to the time course of external torque and Muscle Fascicle force generation. From seven males, supra-maximal twitch contractions (singlet) of the tibialis anterior Muscle were induced at 30°, 10° and −10° plantar flexed positions. The length and velocity of Fascicles and TT were determined from a series of their transverse ultrasound images. The maximal external torque appeared when the shortening velocity of Fascicles was zero. The Fascicle and TT length, and external torque showed a 10–30 ms delay of each onset, with a significant difference in half relaxation times at −10°. The time course of TT elongation, and Fascicle and tendinous velocities did not differ between joint angles. Curvilinear length–force properties, whose slope of quasi-linear part was ranged from −15.0 to −5.9 N/mm for Fascicles and 5.4 to 14.3 N/mm for TT, and a loop-like pattern of velocity–force properties, in which the mean power was ranged from 0.14 to 0.80 W for Fascicles, and 0.14 to 0.81 W for TT were also observed. These results were attributed to the Muscle–tendon interaction, depending on the slack and non-linearity of length–force relationship of compliant TT. We conclude that the mechanical interaction between Fascicles and TT, are significant determinants of twitch force and time characteristics.
-
in vivo behavior of Muscle Fascicles and tendinous tissues in human tibialis anterior Muscle during twitch contraction
Journal of Biomechanics, 2007Co-Authors: Toshiaki Oda, Toshihiko Nagayoshi, Toshiyuki Kurihara, Kentaro Chino, Ryutaro Himeno, Tetsuo Fukunaga, Hiroaki Kanehisa, Dean C Hay, Yasuo KawakamiAbstract:In this study we investigated the time course of length and velocity of Muscle Fascicles and tendinous tissues (TT) during isometric twitch contraction, and examined how their interaction relates to the time course of external torque and Muscle Fascicle force generation. From seven males, supra-maximal twitch contractions (singlet) of the tibialis anterior Muscle were induced at 30 degrees , 10 degrees and -10 degrees plantar flexed positions. The length and velocity of Fascicles and TT were determined from a series of their transverse ultrasound images. The maximal external torque appeared when the shortening velocity of Fascicles was zero. The Fascicle and TT length, and external torque showed a 10-30 ms delay of each onset, with a significant difference in half relaxation times at -10 degrees . The time course of TT elongation, and Fascicle and tendinous velocities did not differ between joint angles. Curvilinear length-force properties, whose slope of quasi-linear part was ranged from -15.0 to -5.9 N/mm for Fascicles and 5.4 to 14.3N/mm for TT, and a loop-like pattern of velocity-force properties, in which the mean power was ranged from 0.14 to 0.80 W for Fascicles, and 0.14 to 0.81 W for TT were also observed. These results were attributed to the Muscle-tendon interaction, depending on the slack and non-linearity of length-force relationship of compliant TT. We conclude that the mechanical interaction between Fascicles and TT, are significant determinants of twitch force and time characteristics.
-
Muscle fiber and tendon length changes in the human vastus lateralis during slow pedaling
Journal of Applied Physiology, 2001Co-Authors: Tetsuro Muraoka, Yasuo Kawakami, Masanobu Tachi, T FukunagaAbstract:Muscle Fascicle lengths of vastus lateralis (VL) Muscle were measured in five healthy men during slow pedaling to investigate the interaction between Muscle fibers and tendon. Subjects cycled at a pedaling rate of 40 rpm (98 W). During exercise, Fascicle lengths changed from 91 ± 7 (SE) to 127 ± 5 mm. It was suggested that Fascicles were on the descending limb of their force-length relationship. The average shortening velocity of Fascicle was greater than that of Muscle-tendon complex in the first half of the knee extension phase and was less in the second half. The maximum shortening velocity of Fascicle in the knee extension phase was less than that of Muscle-tendon complex by 22 ± 9%. These discrepancies in velocities were mainly caused by the elongation of the tendinous tissue. It was suggested that the elasticity of VL tendinous tissue enabled VL Fascicles to develop force at closer length to their optimal length and kept the maximum shortening velocity of VL Fascicles low during slow pedaling.
Robert D. Herbert - One of the best experts on this subject based on the ideXlab platform.
-
effect of transducer orientation on errors in ultrasound image based measurements of human medial gastrocnemius Muscle Fascicle length and pennation
PLOS ONE, 2016Co-Authors: Robert D. Herbert, Simon C Gandevia, Bart BolsterleeAbstract:Ultrasound imaging is often used to measure Muscle Fascicle lengths and pennation angles in human Muscles in vivo. Theoretically the most accurate measurements are made when the transducer is oriented so that the image plane aligns with Muscle Fascicles and, for measurements of pennation, when the image plane also intersects the aponeuroses perpendicularly. However this orientation is difficult to achieve and usually there is some degree of misalignment. Here, we used simulated ultrasound images based on three-dimensional models of the human medial gastrocnemius, derived from magnetic resonance and diffusion tensor images, to describe the relationship between transducer orientation and measurement errors. With the transducer oriented perpendicular to the surface of the leg, the error in measurement of Fascicle lengths was about 0.4 mm per degree of misalignment of the ultrasound image with the Muscle Fascicles. If the transducer is then tipped by 20°, the error increases to 1.1 mm per degree of misalignment. For a given degree of misalignment of Muscle Fascicles with the image plane, the smallest absolute error in Fascicle length measurements occurs when the transducer is held perpendicular to the surface of the leg. Misalignment of the transducer with the Fascicles may cause Fascicle length measurements to be underestimated or overestimated. Contrary to widely held beliefs, it is shown that pennation angles are always overestimated if the image is not perpendicular to the aponeurosis, even when the image is perfectly aligned with the Fascicles. An analytical explanation is provided for this finding.
-
ultrasound imaging of the human medial gastrocnemius Muscle how to orient the transducer so that Muscle Fascicles lie in the image plane
Journal of Biomechanics, 2016Co-Authors: Bart Bolsterlee, Simon C Gandevia, Robert D. HerbertAbstract:The length and pennation of Muscle Fascicles are frequently measured using ultrasonography. Conventional ultrasonography imaging methods only provide two-dimensional images of Muscles, but Muscles have complex three-dimensional arrangements. The most accurate measurements will be obtained when the ultrasound transducer is oriented so that endpoints of a Fascicle lie on the ultrasound image plane and the image plane is oriented perpendicular to the aponeurosis, but little is known about how to find this optimal transducer orientation in the frequently-studied medial gastrocnemius Muscle. In the current study, we determined the optimal transducer orientation at 9 sites in the medial gastrocnemius Muscle of 8 human subjects by calculating the angle of misalignment between three-dimensional Muscle Fascicles, reconstructed from diffusion tensor images, and the plane of a virtual ultrasound image. The misalignment angle was calculated for a range of tilts and rotations of the ultrasound transducer relative to a reference orientation that was perpendicular to the skin and parallel to the tibia. With the transducer in the reference orientation, the misalignment was substantial (mean across sites and subjects of 6.5°, range 1.4 to 20.2°). However for all sites and subjects a near-optimal alignment (on average 2.6°, range 0.5° to 6.0°) could be achieved by maintaining 0° tilt and applying a small rotation (typically less than 10°). On the basis of these data we recommend that ultrasonographic measurements of medial gastrocnemius Muscle Fascicle architecture be obtained, at least for relaxed Muscles under static conditions, with the transducer oriented perpendicular to the skin and nearly parallel to the tibia.
-
reliability and validity of ultrasound measurements of Muscle Fascicle length and pennation in humans a systematic review
Journal of Applied Physiology, 2013Co-Authors: Li Khim Kwah, Rafael Z Pinto, Joanna Diong, Robert D. HerbertAbstract:Ultrasound imaging is widely used to measure architectural features of human skeletal Muscles in vivo. We systematically reviewed studies of the reliability and validity of two-dimensional ultrasound measurement of Muscle Fascicle lengths or pennation angles in human skeletal Muscles. A comprehensive search was conducted in June 2011. Thirty-six reliability studies and six validity studies met the inclusion criteria. Data from these studies indicate that ultrasound measurements of Muscle Fascicle lengths are reliable across a broad range of experimental conditions [intraclass correlation coefficient (ICC) and r values were always > 0.6, and coefficient of variation values were always 0.5 and coefficient of variation values were always 0.7) under certain conditions, such as when large limb Muscles are imaged in a relaxed state and the limb or joint remains stationary. Future studies on validity should consider ways to test for the validity of two-dimensional ultrasound imaging in contracted or moving Muscles and the best method of probe alignment.
-
passive mechanical properties of human gastrocnemius Muscle tendon units Muscle Fascicles and tendons in vivo
The Journal of Experimental Biology, 2007Co-Authors: Phu Hoang, Robert D. Herbert, Gabrielle Todd, Robert B Gorman, Simon C GandeviaAbstract:SUMMARY This study provides the first in vivo measures of the passive length–tension properties of relaxed human Muscle Fascicles and their tendons. A new method was used to derive passive length–tension properties of human gastrocnemius Muscle–tendon units from measures of ankle stiffness obtained at a range of knee angles. Passive length–tension curves of the Muscle–tendon unit were then combined with ultrasonographic measures of Muscle Fascicle length and pennation to determine passive length–tension curves of the Muscle Fascicles and tendons. Mean slack lengths of the Fascicles, tendons and whole Muscle–tendon units were 3.3±0.5 cm, 39.5±1.6 cm and 42.3±1.5 cm, respectively (means ± s.d., N =6). On average, the Muscle–tendon units were slack (i.e. their passive tension was zero) over the shortest 2.3±1.2 cm of their range. With combined changes of knee and ankle angles, the maximal increase in length of the gastrocnemius Muscle–tendon unit above slack length was 6.7±1.9 cm, of which 52.4±11.7% was due to elongation of the tendon. Muscle Fascicles and tendons underwent strains of 86.4±26.8% and 9.2±4.1%, respectively, across the physiological range of lengths. We conclude that the relaxed human gastrocnemius Muscle–tendon unit falls slack over about one-quarter of its in vivo length and that Muscle Fascicle strains are much greater than tendon strains. Nonetheless, because the tendons are much longer than the Muscle Fascicles, tendons contribute more than half of the total compliance of the Muscle–tendon unit.
Marcus G Pandy - One of the best experts on this subject based on the ideXlab platform.
-
differences in in vivo Muscle Fascicle and tendinous tissue behavior between the ankle plantarflexors during running
Scandinavian Journal of Medicine & Science in Sports, 2018Co-Authors: Adrian K M Lai, Anthony G Schache, Glen A Lichtwark, Marcus G PandyAbstract:The primary human ankle plantarflexors, soleus (SO), medial gastrocnemius (MG), and lateral gastrocnemius (LG) are typically regarded as synergists and play a critical role in running. However, due to differences in Muscle-tendon architecture and joint articulation, the Muscle Fascicles and tendinous tissue of the plantarflexors may exhibit differences in their behavior and interactions during running. We combined in vivo dynamic ultrasound measurements with inverse dynamics analyses to identify and explain differences in Muscle Fascicle, Muscle-tendon unit, and tendinous tissue behavior of the primary ankle plantarflexors across a range of steady-state running speeds. Consistent with their role as a force generator, the Muscle Fascicles of the uniarticular SO shortened less rapidly than the Fascicles of the MG during early stance. Furthermore, the MG and LG exhibited delays in tendon recoil during the stance phase, reflecting their ability to transfer power and work between the knee and ankle via tendon stretch and storage of elastic strain energy. Our findings add to the growing body of evidence surrounding the distinct mechanistic functions of uni- and biarticular Muscles during dynamic movements.
-
human ankle plantar flexor Muscle tendon mechanics and energetics during maximum acceleration sprinting
Journal of the Royal Society Interface, 2016Co-Authors: Anthony G Schache, Nicholas A.t. Brown, Marcus G PandyAbstract:Tendon elastic strain energy is the dominant contributor to Muscle–tendon work during steady-state running. Does this behaviour also occur for sprint accelerations? We used experimental data and computational modelling to quantify Muscle Fascicle work and tendon elastic strain energy for the human ankle plantar flexors (specifically soleus and medial gastrocnemius) for multiple foot contacts of a maximal sprint as well as for running at a steady-state speed. Positive work done by the soleus and medial gastrocnemius Muscle Fascicles decreased incrementally throughout the maximal sprint and both Muscles performed more work for the first foot contact of the maximal sprint (FC1) compared with steady-state running at 5 m s−1 (SS5). However, the differences in tendon strain energy for both Muscles were negligible throughout the maximal sprint and when comparing FC1 to SS5. Consequently, the contribution of Muscle Fascicle work to stored tendon elastic strain energy was greater for FC1 compared with subsequent foot contacts of the maximal sprint and compared with SS5. We conclude that tendon elastic strain energy in the ankle plantar flexors is just as vital at the start of a maximal sprint as it is at the end, and as it is for running at a constant speed.
-
in vivo behavior of the human soleus Muscle with increasing walking and running speeds
Journal of Applied Physiology, 2015Co-Authors: Nicholas A.t. Brown, Anthony G Schache, Glen A Lichtwark, Adrian K M Lai, Yichung Lin, Marcus G PandyAbstract:The interaction between the Muscle Fascicle and tendon components of the human soleus (SO) Muscle influences the capacity of the Muscle to generate force and mechanical work during walking and running. In the present study, ultrasound-based measurements of in vivo SO Muscle Fascicle behavior were combined with an inverse dynamics analysis to investigate the interaction between the Muscle Fascicle and tendon components over a broad range of steady-state walking and running speeds: slow-paced walking (0.7 m/s) through to moderate-paced running (5.0 m/s). Irrespective of a change in locomotion mode (i.e., walking vs. running) or an increase in steady-state speed, SO Muscle Fascicles were found to exhibit minimal shortening compared with the Muscle-tendon unit (MTU) throughout stance. During walking and running, the Muscle Fascicles contributed only 35 and 20% of the overall MTU length change and shortening velocity, respectively. Greater levels of Muscle activity resulted in increasingly shorter SO Muscle Fascicles as locomotion speed increased, both of which facilitated greater tendon stretch and recoil. Thus the elastic tendon contributed the majority of the MTU length change during walking and running. When transitioning from walking to running near the preferred transition speed (2.0 m/s), greater, more economical ankle torque development is likely explained by the SO Muscle Fascicles shortening more slowly and operating on a more favorable portion (i.e., closer to the plateau) of the force-length curve.
