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Neil J. Cronin - One of the best experts on this subject based on the ideXlab platform.
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repeatability and sensitivity of passive mechanical stiffness measurements in the Triceps Surae Muscle tendon complex
Scandinavian Journal of Medicine & Science in Sports, 2021Co-Authors: Josh Walker, Neil J. Cronin, Athanassios Bissas, Barney Wainwright, Brian HanleyAbstract:Measurements of Muscle-tendon unit passive mechanical properties are often used to illustrate acute and chronic responses to a training stimulus. The purpose of this study was to quantify the inter-session repeatability of Triceps Surae passive stiffness measurements in athletic and non-athletic populations, with the view to discussing its usefulness both as a Muscle-tendon profiling tool and a control measure for studies with multiple data collection sessions. The study also aimed to observe the effects of quiet standing on passive stiffness parameters. Twenty-nine men (10 cyclists, nine triathletes, 10 controls) visited the laboratory on three separate occasions, where passive stiffness tests were carried out using an isokinetic dynamometer and B-mode ultrasound. Participants were fully rested on two of the sessions and subjected to 20 min of quiet standing in the other. The passive stiffness assessment generally showed only moderate inter-session repeatability but was still able to detect inter-group differences, with triathletes showing higher passive stiffness than cyclists (p < 0.05). Furthermore, quiet standing impacted passive stiffness by causing a reduction in ankle joint range of motion, although mechanical resistance to stretch in the Muscle-tendon unit at a given joint angle was relatively unaffected. These findings show that passive stiffness assessment is appropriate for detecting inter-group differences in the Triceps Surae and even the effects of a low-intensity task such as quiet standing, despite showing some inter-session variation. However, the inter-session variation suggests that passive stiffness testing might not be suitable as a control measure when testing participants on multiple sessions.
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conditioning hops increase Triceps Surae Muscle force and achilles tendon strain energy in the stretch shortening cycle
Scandinavian Journal of Medicine & Science in Sports, 2018Co-Authors: Jakob Kummel, Neil J. Cronin, Andreas Kramer, Janne Avela, Markus GruberAbstract:Postactivation potentiation can improve athletic performance, but the underlying mechanisms are poorly understood. This study investigated the effect of conditioning hops on Triceps Surae Muscle force and tendon strain and its contribution to potentiated stretch-shortening cycle (SSC) performance. Thirty-two subjects participated in two experiments. In both experiments, subjects performed three drop jumps (DJs) after prior conditioning with 10 maximal hops, three unconditioned DJs served as control. Ground reaction forces, kinematics, and Triceps Surae electromyographic activity were recorded. Ultrasound imaging was used to determine fascicle lengths (FASC) of the gastrocnemius (GM) and soleus Muscles (experiment 1) and the length of the Achilles tendon (experiment 2) during the DJs. DJ height after the conditioning hops was significantly higher compared to control DJs (experiment 1: +12% and experiment 2: +19%). A significantly shorter GM FASC during the DJs performed after the conditioning hops coincided with an increased force acting on the Triceps Surae Muscle. Moreover, the Triceps Surae Muscle-tendon unit (MTU) showed increased energy absorption during the eccentric phase of the DJs and increased energy release during the concentric phase. The second experiment revealed a higher Achilles tendon strain in DJs performed after the conditioning hops compared to control DJs. No significant differences in Muscle activities were observed. The shorter FASC in GM and the larger Achilles tendon strain facilitated MTU energy transfer from the eccentric to the concentric phase during the DJ. Thereby, conditioning hops improved SSC efficacy and DJ performance.
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Triceps Surae Muscle tendon properties in older endurance and sprint trained athletes
Journal of Applied Physiology, 2016Co-Authors: Lauri Stenroth, Jussi Peltonen, Neil J. Cronin, Sarianna Sipilä, Marko Korhonen, Taija FinniAbstract:Previous studies have shown that aging is associated with alterations in Muscle architecture and tendon properties (Morse CI, Thom JM, Birch KM, Narici MV. Acta Physiol Scand 183: 291-298, 2005; Narici MV, Maganaris CN, Reeves ND, Capodaglio P. J Appl Physiol 95: 2229-2234, 2003; Stenroth L, Peltonen J, Cronin NJ, Sipila S, Finni T. J Appl Physiol 113: 1537-1544, 2012). However, the possible influence of different types of regular exercise loading on Muscle architecture and tendon properties in older adults is poorly understood. To address this, Triceps Surae Muscle-tendon properties were examined in older male endurance (OE, n = 10, age = 74.0 ± 2.8 yr) and sprint runners (OS, n = 10, age = 74.4 ± 2.8 yr), with an average of 42 yr of regular training experience, and compared with age-matched [older control (OC), n = 33, age = 74.8 ± 3.6 yr] and young untrained controls (YC, n = 18, age = 23.7 ± 2.0 yr). Compared with YC, Achilles tendon cross-sectional area (CSA) was 22% (P = 0.022), 45% (P = 0.001), and 71% (P < 0.001) larger in OC, OE, and OS, respectively. Among older groups, OS had significantly larger tendon CSA compared with OC (P = 0.033). No significant between-group differences were observed in Achilles tendon stiffness. In older groups, Young's modulus was 31-44%, and maximal tendon stress 44-55% lower, than in YC (P ≤ 0.001). OE showed shorter soleus fascicle length than both OC (P < 0.05) and YC (P < 0.05). These data suggest that long-term running does not counteract the previously reported age-related increase in tendon CSA, but, instead, may have an additive effect. The greatest Achilles tendon CSA was observed in OS followed by OE and OC, suggesting that adaptation to running exercise is loading intensity dependent. Achilles tendon stiffness was maintained in older groups, even though all older groups displayed larger tendon CSA and lower tendon Young's modulus. Shorter soleus Muscle fascicles in OE runners may be an adaptation to life-long endurance running.
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Age-related differences in Achilles tendon properties and Triceps Surae Muscle architecture in vivo.
Journal of applied physiology (Bethesda Md. : 1985), 2012Co-Authors: Lauri Stenroth, Jussi Peltonen, Neil J. Cronin, Sarianna Sipilä, Taija FinniAbstract:This study examined the concurrent age-related differences in Muscle and tendon structure and properties. Achilles tendon morphology and mechanical properties and Triceps Surae Muscle architecture ...
Jason R Franz - One of the best experts on this subject based on the ideXlab platform.
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age related changes to Triceps Surae Muscle subtendon interaction dynamics during walking
Scientific Reports, 2021Co-Authors: William H Clark, Jason R FranzAbstract:Push-off intensity is largely governed by the forces generated by the Triceps Surae (TS) Muscles (gastrocnemius-GAS, soleus-SOL). During walking, the TS Muscles undergo different fascicle kinematics and contribute differently to biomechanical subtasks. These differences may be facilitated by the Achilles tendon (AT), which is comprised of subtendons that originate from the TS Muscles. We and others have revealed non-uniform displacement patterns within the AT-evidence for sliding between subtendons that may facilitate independent Muscle actuation. However, in older adults, we have observed more uniform AT tissue displacements that correlate with reduced push-off intensity. Here, we employed dual-probe ultrasound imaging to investigate TS Muscle length change heterogeneity (GAS-SOL) as a determinant of reduced push-off intensity in older adults. Compared to young, older adults walked with more uniform AT tissue displacements and reduced TS Muscle length change heterogeneity. These Muscle-level differences appeared to negatively impact push-off intensity-evidenced by between-group differences in the extent to which TS Muscle length change heterogeneity correlates with mechanical output across walking tasks. Our findings suggest that the capacity for sliding between subtendons may facilitate independent TS Muscle actuation in young adults but may restrict that actuation in older adults, likely contributing to reduced push-off intensity.
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the effects of Triceps Surae Muscle stimulation on localized achilles subtendon tissue displacements
The Journal of Experimental Biology, 2021Co-Authors: Nathan L Lehr, William H Clark, Michael D Lewek, Jason R FranzAbstract:The Triceps Surae Muscle tendon unit is comprised of the lateral and medial gastrocnemius (MG) and soleus (SOL) Muscles and three in series elastic "subtendons" that form the Achilles tendon. Comparative literature and our own in vivo evidence suggests that sliding between adjacent subtendons may facilitate independent Muscle actuation. We aim to more clearly define the relation between individual Muscle activation and subtendon tissue displacements. Here, during fixed-end contractions, electrical Muscle stimulation controlled the magnitude of force transmitted via individual Triceps Surae Muscles while ultrasound imaging recorded resultant subtendon tissue displacements. We hypothesized that MG and SOL stimulation would elicit larger displacements in their associated subtendon. 10 young adults completed 4 experimental activations at 3 ankle angles (-20°, 0°, 20°) with knee flexed to approximately 20°: MG stimulation (STIMMG), SOL stimulation (STIMSOL), combined stimulation, and volitional contraction. At 20° plantarflexion, STIMSOL elicited 49% larger tendon non-uniformity (SOL - MG subtendon tissue displacement) than that of STIMMG (p=0.004). For STIMSOL, a one-way post-hoc ANOVA revealed a significant main effect of ankle angle (p=0.009) on Achilles tendon non-uniformity. However, peak tendon non-uniformity decreased by an average of 61% from plantarflexion to dorsiflexion, likely due to an increase in passive tension. Our results suggest that localized tissue displacements within the Achilles tendon respond in anatomically consistent ways to differential patterns of Triceps Surae Muscle activation, but these relations are highly susceptible to ankle angle. This in vivo evidence points to at least some mechanical independence in actuation between the human Triceps Surae Muscle-subtendon units.
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older adults overcome reduced Triceps Surae structural stiffness to preserve ankle joint quasi stiffness during walking
Journal of Applied Biomechanics, 2020Co-Authors: Rebecca L Krupenevich, William Clark, Gregory S Sawicki, Jason R FranzAbstract:Ankle joint quasi-stiffness is an aggregate measure of the interaction between Triceps Surae Muscle stiffness and Achilles tendon stiffness. This interaction may be altered due to age-related changes in the structural properties and functional behavior of the Achilles tendon and Triceps Surae Muscles. The authors hypothesized that, due to a more compliant of Achilles' tendon, older adults would exhibit lower ankle joint quasi-stiffness than young adults during walking and during isolated contractions at matched Triceps Surae Muscle activations. The authors also hypothesized that, independent of age, Triceps Surae Muscle stiffness and ankle joint quasi-stiffness would increase with Triceps Surae Muscle activation. The authors used conventional gait analysis in one experiment and, in another, electromyographic biofeedback and in vivo ultrasound imaging applied during isolated contractions. The authors found no difference in ankle joint quasi-stiffness between young and older adults during walking. Conversely, this study found that (1) young and older adults modulated ankle joint quasi-stiffness via activation-dependent changes in Triceps Surae Muscle length-tension behavior and (2) at matched activation, older adults exhibited lower ankle joint quasi-stiffness than young adults. Despite age-related reductions during isolated contractions, ankle joint quasi-stiffness was maintained in older adults during walking, which may be governed via activation-mediated increases in Muscle stiffness.
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Triceps Surae Muscle subtendon interaction differs between young and older adults
Connective Tissue Research, 2020Co-Authors: William H Clark, Jason R FranzAbstract:Background: Mechanical power generated via Triceps Surae Muscle-tendon interaction during walking is important for walking performance. This interaction is made complex by distinct "subtendons" arising from the lateral and medial gastrocnemius (GAS) and soleus (SOL) Muscles. Comparative data and our own in vivo evidence allude to a reduced capacity for sliding between adjacent subtendons compromising the Achilles tendon in old age. However, its unclear if and how these changes affect Muscle contractile behavior.Objective: We investigated aging effects on Triceps Surae Muscle-subtendon interaction using dual-probe ultrasound imaging during isolated Muscle contractions. We hypothesized that, compared to young adults, older adults would have more uniform subtendon tissue displacements that are accompanied by anatomically consistent differences in GAS versus SOL Muscle length change behavior.Materials and Methods: 9 younger subjects (age: 25.1 ± 5.6 years) and 10 older adult subjects (age: 74.3 ± 3.4 years) completed a series of ramped maximum isometric voluntary contractions at ankle angles spanning 0° (neutral) to 30° plantarflexion. Two linear array ultrasound transducers simultaneously recorded GAS and SOL fascicle kinematics and tissue displacements in their associated tendinous structures.Results: We revealed that older adults have more uniform subtendon tissue displacements that extend to anatomically consistent and potentially unfavorable changes in Muscle contractile behavior - evidenced by smaller differences between gastrocnemius and soleus peak shortening during isometric force generation.Conclusions: These findings provide an important biomechanical basis for previously reported correlations between more uniform Achilles subtendon behavior and reduced ankle moment generation during waking in older adults.
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ankle rotation and Muscle loading effects on the calcaneal tendon moment arm an in vivo imaging and modeling study
Annals of Biomedical Engineering, 2019Co-Authors: Jason R Franz, Ashish Khanchandani, Hannah Mckenny, William ClarkAbstract:In this combined in vivo and computational modeling study, we tested the central hypothesis that ankle joint rotation and Triceps Surae Muscle loading have independent and combinatory effects on the calcaneal (i.e., Achilles) tendon moment arm (CTma) that are not fully captured in contemporary musculoskeletal models of human movement. We used motion capture guided ultrasound imaging to estimate instantaneous variations in the CTma during a series of isometric and isotonic contractions compared to predictions from scaled, lower extremity computational models. As hypothesized, we found that Muscle loading: (i) independently increased the CTma by up to 8% and (ii) attenuated the effects of ankle joint rotation, the latter likely through changes in tendon slack and tendon curvature. Neglecting the effects of Triceps Surae Muscle loading in lower extremity models led to an underestimation of the CTma, on average, particularly in plantarflexion when those effects were most prominent. We also found little agreement between in vivo estimates and model predictions on an individual subject by subject basis, alluding to unaccounted for variation in anatomical morphology and thus fundamental limitations in model scaling. Together, these findings contribute to improving our understanding of the physiology of ankle moment and power generation and novel opportunities for model development.
Taija Finni - One of the best experts on this subject based on the ideXlab platform.
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Effects of Muscle Action Type on Corticospinal Excitability and Triceps Surae Muscle-Tendon Mechanics
Journal of Neurophysiology, 2017Co-Authors: Pedro Frederico Valadão, Taija Finni, Sadao Kurokawa, Janne AvelaAbstract:The present study provides new insight into the motor control of eccentric Muscle actions. It was demonstrated that task-dependent corticospinal excitability modulation does not seem to depend on s...
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Triceps Surae Muscle tendon properties in older endurance and sprint trained athletes
Journal of Applied Physiology, 2016Co-Authors: Lauri Stenroth, Jussi Peltonen, Neil J. Cronin, Sarianna Sipilä, Marko Korhonen, Taija FinniAbstract:Previous studies have shown that aging is associated with alterations in Muscle architecture and tendon properties (Morse CI, Thom JM, Birch KM, Narici MV. Acta Physiol Scand 183: 291-298, 2005; Narici MV, Maganaris CN, Reeves ND, Capodaglio P. J Appl Physiol 95: 2229-2234, 2003; Stenroth L, Peltonen J, Cronin NJ, Sipila S, Finni T. J Appl Physiol 113: 1537-1544, 2012). However, the possible influence of different types of regular exercise loading on Muscle architecture and tendon properties in older adults is poorly understood. To address this, Triceps Surae Muscle-tendon properties were examined in older male endurance (OE, n = 10, age = 74.0 ± 2.8 yr) and sprint runners (OS, n = 10, age = 74.4 ± 2.8 yr), with an average of 42 yr of regular training experience, and compared with age-matched [older control (OC), n = 33, age = 74.8 ± 3.6 yr] and young untrained controls (YC, n = 18, age = 23.7 ± 2.0 yr). Compared with YC, Achilles tendon cross-sectional area (CSA) was 22% (P = 0.022), 45% (P = 0.001), and 71% (P < 0.001) larger in OC, OE, and OS, respectively. Among older groups, OS had significantly larger tendon CSA compared with OC (P = 0.033). No significant between-group differences were observed in Achilles tendon stiffness. In older groups, Young's modulus was 31-44%, and maximal tendon stress 44-55% lower, than in YC (P ≤ 0.001). OE showed shorter soleus fascicle length than both OC (P < 0.05) and YC (P < 0.05). These data suggest that long-term running does not counteract the previously reported age-related increase in tendon CSA, but, instead, may have an additive effect. The greatest Achilles tendon CSA was observed in OS followed by OE and OC, suggesting that adaptation to running exercise is loading intensity dependent. Achilles tendon stiffness was maintained in older groups, even though all older groups displayed larger tendon CSA and lower tendon Young's modulus. Shorter soleus Muscle fascicles in OE runners may be an adaptation to life-long endurance running.
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Age-related differences in Achilles tendon properties and Triceps Surae Muscle architecture in vivo.
Journal of applied physiology (Bethesda Md. : 1985), 2012Co-Authors: Lauri Stenroth, Jussi Peltonen, Neil J. Cronin, Sarianna Sipilä, Taija FinniAbstract:This study examined the concurrent age-related differences in Muscle and tendon structure and properties. Achilles tendon morphology and mechanical properties and Triceps Surae Muscle architecture ...
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Muscle synergism during isometric plantarflexion in achilles tendon rupture patients and in normal subjects revealed by velocity encoded cine phase contrast mri
Clinical Biomechanics, 2006Co-Authors: Taija Finni, John A Hodgson, Reggie V Edgerton, S K SinhaAbstract:Abstract Background The Triceps Surae Muscle is often considered to be the sole contributor to the plantarflexion torque although the deeper plantarflexor Muscles may also be activated in the plantarflexion task. Methods We measured coordinative strategies and Muscle synergism during isometric plantarflexion task from 11 volunteers. Velocities from the distal end of the medial gastrocnemius, soleus, and flexor hallucis longus Muscles were encoded in the superior–inferior direction using cine phase-contrast magnetic resonance imaging. Eight of the subjects were healthy and served as controls for subject to subject variability. Three of the subjects had experienced an Achilles tendon rupture followed by surgical repair and they were measured up to 8 weeks of rehabilitation. Results There were marked individual differences in the use of the different Muscles during plantarflexion task in control subjects. Soleus to flexor hallucis longus displacement ratio during contraction varied from 0.4 to 9.6 while the moment arm ratio between Achilles tendon and flexor hallucis longus tendons was 1.9 (standard deviation 0.2). In Achilles tendon rupture patients the relative contribution of flexor hallucis longus was very high both in their injured and uninjured leg. This coordinative strategy remained throughout rehabilitation. Interpretation The findings suggest that early recovery of plantarflexion torque after Achilles tendon rupture may be due to compensation by flexor hallucis longus as well as to normalization of the Triceps Surae Muscle function. Also, this study suggests that the individual differences in coordinative strategies in addition to moment arms and Muscle–tendon properties can influence the calculation of forces produced by individual Muscles.
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neuromuscular behaviour of the Triceps Surae Muscle tendon complex during running and jumping
International Journal of Sports Medicine, 2003Co-Authors: Heikki Kyrolainen, Taija Finni, Janne Avela, Paavo V KomiAbstract:The present study examined the behaviour of the Achilles tendon (AT) - Triceps Surae (TS) Muscle complex during running and long jump take-off. High AT forces were measured in the push-off phase in running even with very low EMG activity. In the long jump, high rate of stiffness development was a characteristic of the braking phase of the jump. The results suggest that high and well-coordinated activation patterns of the leg extensor Muscles during the preactivation and eccentric phases together with high stretching velocities of Muscle-tendon complex provide basis for appropriate tendomuscular stiffness. This together with high force at the end of the eccentric phase enables an effective push-off (concentric) phase.
Jens Bojsenmoller - One of the best experts on this subject based on the ideXlab platform.
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altered Triceps Surae Muscle tendon unit properties after 6 months of static stretching
Medicine and Science in Sports and Exercise, 2021Co-Authors: Marie M Moltubakk, M M Magulas, Fabienne O Villars, Olivier R Seynnes, S P Magnusson, Jens BojsenmollerAbstract:Introduction This study examined the effects of 24 wk of daily static stretching of the plantarflexors (unilateral 4 × 60-s stretching, whereas the contralateral leg served as a control; n = 26) on joint range of motion (ROM), Muscle-tendon unit morphological and mechanical properties, neural activation, and contractile function. Methods Torque-angle/velocity was obtained in passive and active conditions using isokinetic dynamometry, whereas Muscle-tendon morphology and mechanical properties were examined using ultrasonography. Results After the intervention, ROM increased (stretching, +11° ± 7°; control, 4° ± 8°), and passive torque (stretching, -10 ± 11 N·m; control, -7 ± 10 N·m) and normalized EMG amplitude (stretching, -3% ± 6%; control, -3% ± 4%) at a standardized dorsiflexion angle decreased. Increases were seen in passive tendon elongation at a standardized force (stretching, +1.3 ± 1.6 mm; control, +1.4 ± 2.1 mm) and in maximal passive Muscle and tendon elongation. Angle of peak torque shifted toward dorsiflexion. No changes were seen in tendon stiffness, resting tendon length, or gastrocnemius medialis fascicle length. Conformable changes in ROM, passive dorsiflexion variables, tendon elongation, and angle of peak torque were observed in the nonstretched leg. Conclusions The present findings indicate that habitual stretching increases ROM and decreases passive torque, altering Muscle-tendon behavior with the potential to modify contractile function.
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specialized properties of the Triceps Surae Muscle tendon unit in professional ballet dancers
Scandinavian Journal of Medicine & Science in Sports, 2018Co-Authors: Marie M Moltubakk, M M Magulas, Fabienne O Villars, Olivier R Seynnes, Jens BojsenmollerAbstract:This study compared professional ballet dancers (n = 10) to nonstretching controls (n = 10) with the purpose of comparing Muscle and tendon morphology, mechanical, neural, and functional properties of the Triceps Surae and their role for ankle joint flexibility. Torque-angle and torque-velocity data were obtained during passive and active conditions by use of isokinetic dynamometry, while tissue morphology and mechanical properties were evaluated by ultrasonography. Dancers displayed longer gastrocnemius medialis fascicles (55 ± 5 vs 47 ± 6 mm) and a longer (207 ± 33 vs 167 ± 10 mm) and more compliant (230 ± 87 vs 364 ± 106 N/mm) Achilles tendon compared to controls. Greater passive ankle dorsiflexion range of motion (40 ± 7 vs 17 ± 9°) was seen in dancers, resulting from greater fascicle strain and greater elongation of the Muscle. Peak electromyographic (EMG) activity recorded during passive stretching was lower in dancers, and at common joint angles, dancers displayed lower EMG amplitude and lower passive joint stiffness. No differences between groups were seen in maximal isometric plantar flexor torque, isokinetic peak torque, angle of peak torque, or work. In conclusion, the greater ankle joint flexibility of professional dancers seems attributed to multiple differences in morphological and mechanical properties of Muscle and tendinous tissues, and to factors related to neural activation.
Kiros Karamanidis - One of the best experts on this subject based on the ideXlab platform.
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simplified Triceps Surae Muscle volume assessment in older adults
Frontiers in Physiology, 2019Co-Authors: Kiros Karamanidis, Gaspar Epro, Matthias König, Falk Mersmann, Adamantios ArampatzisAbstract:Triceps Surae (TS) Muscle volume can be estimated in young adults by only considering the maximal anatomical cross-sectional area (ACSAmax) and the length of the Muscle due to the presence of a constant Muscle-specific shape factor. This study aimed to investigate if this simplified Muscle volume assessment is also applicable in older adults or if Muscle-specific shape changes with aging. MRI sequences were taken from the dominant leg of 21 older female adults. The boundaries of all three TS Muscles (SOL, soleus; GM, gastrocnemius medialis; GL, gastrocnemius lateralis) were manually outlined in transverse image sequences, and Muscle volume for each Muscle was calculated as the integral of the obtained cross-sectional areas of the contours along the whole length of the Muscle (measured volume) and, in addition, by using the average Muscle-specific shape factors of each Muscle obtained from the ratio of the measured volume and the product of ACSAmax and the Muscle length (estimated volume). There were no differences in the measured and estimated Muscle volumes (SOL: 357.7 ± 61.8 vs. 358.8 ± 65.3 cm3; GM: 179.5 ± 32.8 vs. 179.8 ± 33.3 cm3; GL: 90.2 ± 15.9 vs. 90.4 ± 14.8 cm3). However, when using the reported shape factors of younger adults instead, we found a significant (p < 0.05) overestimation of Muscle volume for SOL and GM with average RMS differences of 6.1 and 7.6%, respectively. These results indicate that corrections of Muscle-specific shape factors are needed when using the previously proposed simplified Muscle volume assessment as aging may not only be accompanied with Muscle atrophy but also changes in the shape of skeletal Muscle.
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Table_1_Evidence of a Uniform Muscle-Tendon Unit Adaptation in Healthy Elite Track and Field Jumpers: A Cross Sectional Investigation.DOCX
2019Co-Authors: Gaspar Epro, Steve Hunter, Matthias König, Falk Schade, Kiros KaramanidisAbstract:Different adaptive responses to mechanical loading between Muscle and tendon can lead to non-uniform biomechanical properties within the Muscle-tendon unit. The current study aimed to analyze the mechanical properties of the Triceps Surae Muscle-tendon unit in healthy male and female elite track and field jumpers in order to detect possible inter-limb differences and intra-limb non-uniformities in Muscle and tendon adaptation. The Triceps Surae Muscle strength and tendon stiffness were analyzed in both limbs during maximal voluntary isometric plantar flexion contractions using synchronous dynamometry and ultrasonography in sixty-seven healthy young male (n = 35) and female (n = 32) elite international level track and field jumpers (high jump, long jump, triple jump, pole vault). Triceps Surae Muscle-tendon unit intra-limb uniformity was assessed using between limb symmetry indexes in the Muscle strength and tendon stiffness. Independent from sex and jumping discipline the take-off leg showed a significantly higher (p < 0.05) Triceps Surae Muscle strength and tendon stiffness, suggesting different habitual mechanical loading between legs. However, despite these inter-limb discrepancies no differences were detected in the symmetry indexes of Muscle strength (5.9 ± 9.4%) and tendon stiffness (8.1 ± 11.5%). This was accompanied by a significant correlation between the symmetry indexes of Muscle strength and tendon stiffness (r = 0.44; p < 0.01; n = 67). Thus, the current findings give evidence for a uniform Muscle-tendon unit adaptation in healthy elite track and field jumpers, which can be reflected as a protective mechanism to maintain its integrity to meet the functional demand.
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effects of Triceps Surae Muscle strength and tendon stiffness on the reactive dynamic stability and adaptability of older female adults during perturbed walking
Journal of Applied Physiology, 2018Co-Authors: Gaspar Epro, Christopher Mccrum, Andreas Mierau, Michael Leyendecker, Gertpeter Bruggemann, Kiros KaramanidisAbstract:Triceps Surae Muscle weakness and a more compliant Achilles tendon partly limit older adults’ ability to effectively enlarge the base of support and recover dynamic stability after an unexpected pe...
