scholarly journals Age-related greater Achilles tendon compliance is not associated with larger plantar flexor muscle fascicle strains in senior women

2014 ◽  
Vol 116 (8) ◽  
pp. 961-969 ◽  
Author(s):  
R. Csapo ◽  
V. Malis ◽  
J. Hodgson ◽  
S. Sinha
Keyword(s):  
Achilles Tendon ◽  
Isometric Contraction ◽  
Sagittal Plane ◽  
Maximum Voluntary Contraction ◽  
Magnetic Resonance Images ◽  
Plantar Flexor ◽  
Flexor Muscle ◽  
Maximum Voluntary Isometric Contraction ◽  
Muscle Fascicle ◽  
Age Related

The aim of the present study was to test the hypothesis that the age-associated decrease of tendon stiffness would necessitate greater muscle fascicle strains to produce similar levels of force during isometric contraction. Greater fascicle strains could force sarcomeres to operate in less advantageous regions of their force-length and force-velocity relationships, thus impairing the capacity to generate strong and explosive contractions. To test this hypothesis, sagittal-plane dynamic velocity-encoded phase-contrast magnetic resonance images of the gastrocnemius medialis (GM) muscle and Achilles tendon (AT) were acquired in six young (YW; 26.1 ± 2.3 yr) and six senior (SW; 76.7 ± 8.3 yr) women during submaximal isometric contraction (35% maximum voluntary isometric contraction) of the plantar flexor muscles. Multiple GM fascicle lengths were continuously determined by automatically tracking regions of interest coinciding with the end points of muscle fascicles evenly distributed along the muscle's proximo-distal length. AT stiffness and Young's modulus were measured as the slopes of the tendon's force-elongation and stress-strain curves, respectively. Despite significantly lower AT stiffness at older age (YW: 120.2 ± 52.3 N/mm vs. SW: 53.9 ± 44.4 N/mm, P = 0.040), contraction-induced changes in GM fascicle lengths were similar in both age groups at equal levels of absolute muscular force (4–5% fascicle shortening in both groups), and even significantly larger in YW (YW: 11–12% vs. SW: 6–8% fascicle shortening) at equal percentage of maximum voluntary contraction. These results suggest that factors other than AT stiffness, such as age-associated changes in muscle composition or fascicle slack, might serve as compensatory adaptations, limiting the degree of fascicle strains upon contraction.

scholarly journals Enthalpy efficiency of the soleus muscle contributes to improvements in running economy

2021 ◽  
Vol 288 (1943) ◽  
pp. 20202784
Author(s):  
Sebastian Bohm ◽  
Falk Mersmann ◽  
Alessandro Santuz ◽  
Adamantios Arampatzis
Keyword(s):  
Soleus Muscle ◽  
Intervention Group ◽  
Running Economy ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Plantar Flexor ◽  
Flexor Muscle ◽  
Shortening Velocity ◽  
Muscle Fascicle ◽  
Flexor Strength

During human running, the soleus, as the main plantar flexor muscle, generates the majority of the mechanical work through active shortening. The fraction of chemical energy that is converted into muscular work (enthalpy efficiency) depends on the muscle shortening velocity. Here, we investigated the soleus muscle fascicle behaviour during running with respect to the enthalpy efficiency as a mechanism that could contribute to improvements in running economy after exercise-induced increases of plantar flexor strength and Achilles tendon (AT) stiffness. Using a controlled longitudinal study design ( n = 23) featuring a specific 14-week muscle–tendon training, increases in muscle strength (10%) and tendon stiffness (31%) and reduced metabolic cost of running (4%) were found only in the intervention group ( n = 13, p < 0.05). Following training, the soleus fascicles operated at higher enthalpy efficiency during the phase of muscle–tendon unit (MTU) lengthening (15%) and in average over stance (7%, p < 0.05). Thus, improvements in energetic cost following increases in plantar flexor strength and AT stiffness seem attributed to increased enthalpy efficiency of the operating soleus muscle. The results further imply that the soleus energy production in the first part of stance, when the MTU is lengthening, may be crucial for the overall metabolic energy cost of running.

scholarly journals Differences in Plantar Flexor Fascicle Length and Pennation Angle between Healthy and Poststroke Individuals and Implications for Poststroke Plantar Flexor Force Contributions

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
John W. Ramsay ◽  
Thomas S. Buchanan ◽  
Jill S. Higginson
Keyword(s):  
Pennation Angle ◽  
Medial Gastrocnemius ◽  
Plantar Flexor ◽  
Flexor Muscle ◽  
Fascicle Length ◽  
Cross Sectional ◽  
Lateral Gastrocnemius ◽  
Relative Contribution ◽  
Muscle Fascicle ◽  
The Individual

Poststroke plantar flexor muscle weakness has been attributed to muscle atrophy and impaired activation, which cannot collectively explain the limitations in force-generating capability of the entire muscle group. It is of interest whether changes in poststroke plantar flexor muscle fascicle length and pennation angle influence the individual force-generating capability and whether plantar flexor weakness is due to uniform changes in individual muscle force contributions. Fascicle lengths and pennation angles for the soleus, medial, and lateral gastrocnemius were measured using ultrasound and compared between ten hemiparetic poststroke subjects and ten healthy controls. Physiological cross-sectional areas and force contributions to poststroke plantar flexor torque were estimated for each muscle. No statistical differences were observed for any muscle fascicle lengths or for the lateral gastrocnemius and soleus pennation angles between paretic, nonparetic, and healthy limbs. There was a significant decrease (P<0.05) in the paretic medial gastrocnemius pennation angle compared to both nonparetic and healthy limbs. Physiological cross-sectional areas and force contributions were smaller on the paretic side. Additionally, bilateral muscle contributions to plantar flexor torque remained the same. While the architecture of each individual plantar flexor muscle is affected differently after stroke, the relative contribution of each muscle remains the same.

Differences in age-related changes in the plantar flexor muscles and Achilles tendon in men

2006 ◽  
Vol 39 ◽  
pp. S547
Author(s):  
K. Kubo ◽  
M. Morimoto ◽  
T. Komuro ◽  
N. Tsunoda ◽  
H. Kanehisa ◽  
...  
Keyword(s):  
Achilles Tendon ◽  
Plantar Flexor ◽  
Age Related ◽  
Flexor Muscles ◽  
Plantar Flexor Muscles ◽  
Age Related Changes

scholarly journals Biomechanical properties of the plantar flexor muscle-tendon complex 6 months post-rupture of the achilles tendon

2013 ◽  
Vol 31 (9) ◽  
pp. 1469-1474 ◽  
Author(s):  
Peter McNair ◽  
Antoine Nordez ◽  
Margie Olds ◽  
Simon W. Young ◽  
Christophe Cornu
Keyword(s):  
Achilles Tendon ◽  
Biomechanical Properties ◽  
Plantar Flexor ◽  
Flexor Muscle

scholarly journals Passive stiffness of the ankle and plantar flexor muscle performance after Achilles tendon repair: a cross-sectional study

2017 ◽  
Vol 21 (1) ◽  
pp. 51-57 ◽  
Author(s):  
Pollyana R.T. Borges ◽  
Thiago R.T. Santos ◽  
Paula R.S. Procópio ◽  
Jessica H.D. Chelidonopoulos ◽  
Roberto Zambelli ◽  
...  
Keyword(s):  
Achilles Tendon ◽  
Tendon Repair ◽  
Cross Sectional Study ◽  
Muscle Performance ◽  
Plantar Flexor ◽  
Passive Stiffness ◽  
Sectional Study ◽  
Flexor Muscle ◽  
Cross Sectional ◽  
Achilles Tendon Repair

scholarly journals Electromyographic Evidence of Excessive Achilles Tendon Elongation During Isometric Contractions After Achilles Tendon Repair

2019 ◽  
Vol 7 (7_suppl5) ◽  
pp. 2325967119S0032
Author(s):  
Malachy P. McHugh ◽  
Karl F. Orishimo ◽  
Ian J. Kremenic ◽  
Julia Adelman ◽  
Stephen J. Nicholas
Keyword(s):  
Achilles Tendon ◽  
Muscle Fiber ◽  
Fourier Transforms ◽  
Plantar Flexion ◽  
Maximum Voluntary Contraction ◽  
Tendon Repair ◽  
Voluntary Contraction ◽  
Plantar Flexor ◽  
Achilles Tendon Repair ◽  
Tendon Elongation

Objectives: It has been proposed that increased tendon elongation after Achilles tendon repair contributes to selective weakness in end-range plantar flexion (Mullaney et al 2006). Excessive tendon elongation during maximum voluntary contraction (MVC) means greater muscle fiber shortening. Since mean frequency (MF) of the electromyogram (EMG) increases with muscle fiber shortening, it was hypothesized that during isometric plantar flexor MVCs MF would be higher on the involved versus non-involved side. Therefore, the purpose of this study was to examine MF during isometric MVCs in patients with Achilles tendon repairs. Methods: Maximum isometric plantar flexion torque was measured at 20° and 10° dorsiflexion, neutral, and 10° and 20° plantar flexion in 17 patients (mean±SD age, 39±9 years; 15 men, 2 women) 43±24 months after surgery (range, 9 months to 8 years). Surface EMG signals were recorded during strength tests. MF was calculated from Fast Fourier Transforms of medial gastroc (MG) lateral gastroc (LG) and soleus (S) EMG signals. Effect of weakness on MF was assessed using analysis of variance. Based on reported plantar flexor MF values it was estimated that with 17 subjects there would be 80% power to detect a 16% difference in MF between involved and noninvolved legs at P<0.05. Results: Patients had marked weakness in 20° plantar flexion (deficit 28±18%, P<0.01; 14 of 17 deficit >20%) but no significant weakness in 20° dorsiflexion (deficit 8±15%, P=0.20; 4 of 17 deficit >20%). MF increased moving from dorsiflexion to plantar flexion (P<0.001) but overall was not different between involved and noninvolved sides (P=0.22). However, differences in MF between the involved and noninvolved sides were apparent in the patients with marked weakness. At 10° plantar flexion 8 of 17 patients had marked weakness (>20% deficit). MF at 10° plantar flexion was significantly higher on involved versus noninvolved side in patients with weakness but this was not apparent in patients with no weakness (side by group P=0.014; Table 1). MF at 10° plantar flexion average across the 3 muscles was 13% higher on the involved versus noninvolved side in patients with weakness (P=0.012) versus 3% lower in patients with no weakness (P=0.47). Conclusion: Higher MF on the involved versus noninvolved side in patients with significant plantar flexion weakness is consistent with greater muscle fiber shortening. This indicates that weakness was primarily due to excessive lengthening of the repaired Achilles tendon. If weakness were simply due to atrophy, a lower MF would have been be expected and patients would have had weakness throughout the range of motion. Surgical and rehabilitative strategies are needed to prevent excessive tendon elongation and weakness in end-range plantar flexion after Achilles repair. [Table: see text]

The Effect of Functional Home-Based Strength Training Programs on the Mechano-Morphological Properties of the Plantar Flexor Muscle-Tendon Unit in Children With Spastic Cerebral Palsy

2019 ◽  
Vol 31 (1) ◽  
pp. 67-76 ◽  
Author(s):  
Annika Kruse ◽  
Christian Schranz ◽  
Martin Svehlik ◽  
Markus Tilp
Keyword(s):  
Cerebral Palsy ◽  
Strength Training ◽  
Achilles Tendon ◽  
Vastus Lateralis ◽  
Morphological Properties ◽  
Spastic Cerebral Palsy ◽  
Plantar Flexor ◽  
Flexor Muscle ◽  
Gastrocnemius Medialis ◽  
Home Based

Purpose: The purpose of this study was to investigate the effects of functional progressive resistance training (PRT) and high-intensity circuit training (HICT) on the mechano-morphological properties of the plantar flexor muscle-tendon unit in children with spastic cerebral palsy. Methods: Twenty-two children (12.8 [2.6] y old, Gross Motor Function Classification System levels I/II = 19/3) were randomly assigned to either a PRT group or an HICT group. The interventions consisted of functional lower limb exercises, which were performed at home 3 times per week for 8 weeks. Measurements at baseline, preintervention, postintervention, and follow-up were taken to assess ankle joint range of motion and the properties of the gastrocnemius medialis, vastus lateralis, rectus femoris, and Achilles tendon (eg, thickness, strength, stiffness). Results: Despite a nonsignificant increase in active torque in the HICT group, neither gastrocnemius medialis morphology nor Achilles tendon properties were significantly altered after the interventions. Vastus lateralis thickness increased following PRT only. Conclusions: Functional home-based strength training did not lead to significant changes at the muscular level in children with cerebral palsy. We therefore assume that a more specific stimulus of higher intensity combined with a longer training duration might be necessary to evoke changes in muscles and tendons in individuals with cerebral palsy.

scholarly journals Foot strike pattern during running alters muscle-tendon dynamics of the gastrocnemius and the soleus

2019 ◽  
Author(s):  
Jennifer R. Yong ◽  
Christopher L. Dembia ◽  
Amy Silder ◽  
Rachel W. Jackson ◽  
Michael Fredericson ◽  
...  
Keyword(s):  
Energy Storage ◽  
Achilles Tendon ◽  
Muscle Mechanics ◽  
Plantar Flexor ◽  
Flexor Muscle ◽  
Tendon Mechanics ◽  
Foot Strike ◽  
Efficient Gait ◽  
Musculoskeletal Simulations ◽  
Plantar Flexor Muscles

ABSTRACTRunning is thought to be an efficient gait due, in part, to the behavior of the plantar flexor muscles and the elastic energy storage in the Achilles tendon. Although plantar flexor muscle mechanics and Achilles tendon energy storage have been explored during rearfoot striking, they have not been fully characterized during forefoot striking. This study examines how plantar flexor muscle-tendon mechanics during running differ between rearfoot and forefoot striking. We used musculoskeletal simulations, driven by joint angles and electromyography recorded from runners using both rearfoot and forefoot striking running patterns, to characterize plantar flexor muscle-tendon mechanics. The simulations revealed that foot strike pattern affected the soleus and gastrocnemius differently. For the soleus, forefoot striking resulted in decreased tendon energy storage and decreased positive fiber work compared to rearfoot striking. For the gastrocnemius, forefoot striking resulted in greater activation and increased negative fiber work compared to rearfoot striking. The increased activation and negative fiber work in the gastrocnemius during forefoot striking suggest that runners planning to convert to forefoot striking would benefit from a progressive eccentric gastrocnemius strengthening program to avoid injury.

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