scholarly journals The effects of 12 weeks of static stretch training on the functional, mechanical, and architectural characteristics of the triceps surae muscle–tendon complex

2021 ◽  
Author(s):  
Stefano Longo ◽  
Emiliano Cè ◽  
Angela Valentina Bisconti ◽  
Susanna Rampichini ◽  
Christian Doria ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Maximum Voluntary Contraction ◽  
Muscle Stiffness ◽  
Triceps Surae ◽  
Maximum Force ◽  
Passive Stiffness ◽  
Electromechanical Delay ◽  
Fascicle Length ◽  
Generating Capacity ◽  
Plantarflexor Muscles

Abstract Purpose We investigated the effects of 12 weeks of passive static stretching training (PST) on force-generating capacity, passive stiffness, muscle architecture of plantarflexor muscles. Methods Thirty healthy adults participated in the study. Fifteen participants (STR, 6 women, 9 men) underwent 12-week plantarflexor muscles PST [(5 × 45 s-on/15 s-off) × 2exercises] × 5times/week (duration: 2250 s/week), while 15 participants (CTRL, 6 women, 9 men) served as control (no PST). Range of motion (ROM), maximum passive resistive torque (PRTmax), triceps surae architecture [fascicle length, fascicle angle, and thickness], passive stiffness [muscle–tendon complex (MTC) and muscle stiffness], and plantarflexors maximun force-generating capacity variables (maximum voluntary contraction, maximum muscle activation, rate of torque development, electromechanical delay) were calculated Pre, at the 6th (Wk6), and the 12th week (Wk12) of the protocol in both groups. Results Compared to Pre, STR ROM increased (P < 0.05) at Wk6 (8%) and Wk12 (23%). PRTmax increased at Wk12 (30%, P < 0.05), while MTC stiffness decreased (16%, P < 0.05). Muscle stiffness decreased (P < 0.05) at Wk6 (11%) and Wk12 (16%). No changes in triceps surae architecture and plantarflexors maximum force-generating capacity variables were found in STR (P > 0.05). Percentage changes in ROM correlated with percentage changes in PRTmax (ρ = 0.62, P = 0.01) and MTC stiffness (ρ = − 0.78, P = 0.001). In CTRL, no changes (P > 0.05) occurred in any variables at any time point. Conclusion The expected long-term PST-induced changes in ROM were associated with modifications in the whole passive mechanical properties of the ankle joint, while maximum force-generating capacity characteristics were preserved. 12 weeks of PST do not seem a sufficient stimulus to induce triceps surae architectural changes.

scholarly journals Older Adults Overcome Reduced Triceps Surae Structural Stiffness to Preserve Ankle Joint Quasi-Stiffness During Walking

2020 ◽  
Vol 36 (4) ◽  
pp. 209-216
Author(s):  
Rebecca L. Krupenevich ◽  
William H. Clark ◽  
Gregory S. Sawicki ◽  
Jason R. Franz
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Achilles Tendon ◽  
Ankle Joint ◽  
Muscle Activation ◽  
Muscle Stiffness ◽  
Triceps Surae ◽  
Triceps Surae Muscle ◽  
Age Related ◽  
Lower Ankle Joint

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.

scholarly journals Coordination of hamstrings is individual specific and is related to motor performance

2018 ◽  
Vol 125 (4) ◽  
pp. 1069-1079 ◽  
Author(s):  
Simon Avrillon ◽  
Gaël Guilhem ◽  
Aude Barthelemy ◽  
François Hug
Keyword(s):  
Muscle Activation ◽  
Endurance Performance ◽  
Biceps Femoris ◽  
Significant Negative Correlation ◽  
Hamstring Injury ◽  
Muscle Endurance ◽  
Time To Exhaustion ◽  
Fascicle Length ◽  
Hamstring Muscles ◽  
Generating Capacity

The torque-sharing strategies between synergistic muscles may have important functional consequences. This study involved two experiments. The first experiment ( n = 22) aimed 1) to determine the relationship between the distribution of activation and the distribution of torque-generating capacity among the heads of the hamstring, and 2) to describe individual torque-sharing strategies and to determine whether these strategies are similar between legs. The second experiment ( n = 35) aimed to determine whether the distribution of activation between the muscle heads affects endurance performance during a sustained submaximal knee flexion task. Surface electromyography (EMG) was recorded from biceps femoris (BF), semimembranosus (SM), and semitendinosus (ST) during submaximal isometric knee flexions. Torque-generating capacity was estimated by measuring muscle volume, fascicle length, pennation angle, and moment arm. The product of the normalized EMG amplitude and the torque-generating capacity was used as an index of muscle torque. The distributions of muscle activation and of torque-generating capacity were not correlated significantly (all P > 0.18). Thus, there was a torque imbalance between the muscle heads (ST torque > BF and SM torque; P < 0.001), the magnitude of which varied greatly between participants. A significant negative correlation was observed between the imbalance of activation across the hamstring muscles and the time to exhaustion ( P < 0.001); i.e., the larger the imbalance of activation across muscles, the lower the muscle endurance performance. Torque-sharing strategies between the heads of the hamstrings are individual specific and related to muscle endurance performance. Whether these individual strategies play a role in hamstring injury remains to be determined. NEW & NOTEWORTHY The distribution of activation among the heads of the hamstring is not related to the distribution of torque-generating capacity. The torque-sharing strategies within hamstring muscles vary greatly between individuals but are similar between legs. Hamstring coordination affects endurance performance; i.e., the larger the imbalance of activation across the muscle heads, the lower the muscle endurance.

Neural Compensation Within the Human Triceps Surae During Prolonged Walking

2011 ◽  
Vol 105 (2) ◽  
pp. 548-553 ◽  
Author(s):  
Neil J. Cronin ◽  
Jussi Peltonen ◽  
Thomas Sinkjaer ◽  
Janne Avela
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Neural Activation ◽  
Fascicle Length ◽  
Muscle Fascicle ◽  
Compound Action Potentials ◽  
Triceps Surae Muscles ◽  
Short Time

During human walking, muscle activation strategies are approximately constant across consecutive steps over a short time, but it is unknown whether they are maintained over a longer duration. Prolonged walking may increase tendinous tissue (TT) compliance, which can influence neural activation, but the neural responses of individual muscles have not been investigated. This study investigated the hypothesis that muscle activity is up- or down-regulated in individual triceps surae muscles during prolonged walking. Thirteen healthy subjects walked on a treadmill for 60 min at 4.5 km/h, while triceps surae muscle activity, maximal muscle compound action potentials, and kinematics were recorded every 5 min, and fascicle lengths were estimated at the beginning and end of the protocol using ultrasound. After 1 h of walking, soleus activity increased by 9.3 ± 0.2% ( P < 0.05) and medial gastrocnemius activity decreased by 9.3 ± 0.3% ( P < 0.01). Gastrocnemius fascicle length at ground contact shortened by 4.45 ± 0.99% ( P < 0.001), whereas soleus fascicle length was unchanged ( P = 0.988). Throughout the stance phase, medial gastrocnemius fascicle lengthening decreased by 44 ± 13% ( P < 0.001), whereas soleus fascicle lengthening amplitude was unchanged ( P = 0.650). The data suggest that a compensatory neural strategy exists between triceps surae muscles and that changes in muscle activation are generally mirrored by changes in muscle fascicle length. These findings also support the notion of muscle-specific changes in TT compliance after prolonged walking and highlight the ability of the CNS to maintain relatively constant movement patterns in spite of neuromechanical changes in individual muscles.

scholarly journals Range of motion, neuromechanical, and architectural adaptations to plantar flexor stretch training in humans

2014 ◽  
Vol 117 (5) ◽  
pp. 452-462 ◽  
Author(s):  
A. J. Blazevich ◽  
D. Cannavan ◽  
C. M. Waugh ◽  
S. C. Miller ◽  
J. B. Thorlund ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Muscle Activation ◽  
Joint Angle ◽  
Maximum Voluntary Contraction ◽  
Muscle Length ◽  
Joint Moment ◽  
Muscle Stiffness ◽  
Control Group ◽  
Plantar Flexor ◽  
Passive Joint

The neuromuscular adaptations in response to muscle stretch training have not been clearly described. In the present study, changes in muscle (at fascicular and whole muscle levels) and tendon mechanics, muscle activity, and spinal motoneuron excitability were examined during standardized plantar flexor stretches after 3 wk of twice daily stretch training (4 × 30 s). No changes were observed in a nonexercising control group ( n = 9), however stretch training elicited a 19.9% increase in dorsiflexion range of motion (ROM) and a 28% increase in passive joint moment at end ROM ( n = 12). Only a trend toward a decrease in passive plantar flexor moment during stretch (−9.9%; P = 0.15) was observed, and no changes in electromyographic amplitudes during ROM or at end ROM were detected. Decreases in Hmax:Mmax(tibial nerve stimulation) were observed at plantar flexed (gastrocnemius medialis and soleus) and neutral (soleus only) joint angles, but not with the ankle dorsiflexed. Muscle and fascicle strain increased (12 vs. 23%) along with a decrease in muscle stiffness (−18%) during stretch to a constant target joint angle. Muscle length at end ROM increased (13%) without a change in fascicle length, fascicle rotation, tendon elongation, or tendon stiffness following training. A lack of change in maximum voluntary contraction moment and rate of force development at any joint angle was taken to indicate a lack of change in series compliance of the muscle-tendon unit. Thus, increases in end ROM were underpinned by increases in maximum tolerable passive joint moment (stretch tolerance) and both muscle and fascicle elongation rather than changes in volitional muscle activation or motoneuron pool excitability.

scholarly journals Changes in stretch reflexes and muscle stiffness with age in prepubescent children

2007 ◽  
Vol 102 (6) ◽  
pp. 2352-2360 ◽  
Author(s):  
Jean-Francois Grosset ◽  
Isabelle Mora ◽  
Daniel Lambertz ◽  
Chantal Pérot
Keyword(s):  
Stretch Reflex ◽  
Motor Response ◽  
Muscle Stiffness ◽  
Triceps Surae ◽  
Reflex Response ◽  
Passive Stiffness ◽  
Hoffmann Reflex ◽  
Stretch Reflexes ◽  
T Reflex ◽  
Tendon Jerk

Musculo-articular stiffness of the triceps surae (TS) increases with age in prepubescent children, under both passive and active conditions. This study investigates whether these changes in muscle stiffness influence the amplitude of the reflex response to muscle stretch. TS stiffness and reflex activities were measured in 46 children (7–11 yr old) and in 9 adults. The TS Hoffmann reflex (H reflex) and T reflex (tendon jerk) in response to taping the Achilles tendon were evaluated at rest and normalized to the maximal motor response (Mmax). Sinusoidal perturbations of passive or activated muscles were used to evoke stretch reflexes and to measure passive and active musculoarticular stiffness. The children's Hmax-to-Mmax ratio did not change with age and did not differ from adult values. The T-to-Mmax ratio increased with age but remained significantly lower than in adults. Passive stiffness also increased with age and was correlated with the T-to-Mmax ratio. Similarly, the children's stretch reflex and active musculoarticular stiffness were significantly correlated and increased with age. We conclude that prepubescent children have smaller T reflexes and stretch reflexes than adults, and the lower musculoarticular stiffness is mainly responsible for these smaller reflexes, as indicated by the parallel increases in reflex and stiffness.

Effects of ballistic stretching training on the properties of human muscle and tendon structures

2014 ◽  
Vol 117 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Andreas Konrad ◽  
Markus Tilp
Keyword(s):  
Structural Changes ◽  
Maximum Voluntary Contraction ◽  
Intervention Group ◽  
Voluntary Contraction ◽  
Pennation Angle ◽  
Muscle Stiffness ◽  
Fascicle Length ◽  
Mechanical Adaptation ◽  
Resistive Torque ◽  
Length Changes

The purpose of this study was to investigate the influence of a 6-wk ballistic stretching training program on various parameters of the human gastrocnemius medialis muscle and the Achilles tendon. It is known that ballistic stretching is an appropriate means of increasing the range of motion (RoM), but information in the literature about the mechanical adaptation of the muscle-tendon unit (MTU) is scarce. Therefore, in this study, a total of 48 volunteers were randomly assigned into ballistic stretching and control groups. Before and following the stretching intervention, we determined the maximum dorsiflexion RoM with the corresponding fascicle length and pennation angle. Passive resistive torque (PRT) and maximum voluntary contraction (MVC) were measured with a dynamometer. Muscle-tendon junction (MTJ) displacement allowed us to determine the length changes in tendon and muscle, and hence to calculate stiffness. Mean RoM increased significantly from 33.8 ± 6.3° to 37.8 ± 7.2° only in the intervention group, but other functional (PRT, MVC) and structural (fascicle length, pennation angle, muscle stiffness, tendon stiffness) parameters were unaltered. Thus the increased RoM could not be explained by structural changes in the MTU and was likely due to increased stretch tolerance.

Long-term use of high-heeled shoes alters the neuromechanics of human walking

2012 ◽  
Vol 112 (6) ◽  
pp. 1054-1058 ◽  
Author(s):  
Neil J. Cronin ◽  
Rod S. Barrett ◽  
Christopher P. Carty
Keyword(s):  
Lower Limb ◽  
Muscle Activation ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Lower Limb Muscle ◽  
Limb Muscle ◽  
Fascicle Length ◽  
High Heel ◽  
Muscle Fascicle

Human movement requires an ongoing, finely tuned interaction between muscular and tendinous tissues, so changes in the properties of either tissue could have important functional consequences. One condition that alters the functional demands placed on lower limb muscle-tendon units is the use of high-heeled shoes (HH), which force the foot into a plantarflexed position. Long-term HH use has been found to shorten medial gastrocnemius muscle fascicles and increase Achilles tendon stiffness, but the consequences of these changes for locomotor muscle-tendon function are unknown. This study examined the effects of habitual HH use on the neuromechanical behavior of triceps surae muscles during walking. The study population consisted of 9 habitual high heel wearers who had worn shoes with a minimum heel height of 5 cm at least 40 h/wk for a minimum of 2 yr, and 10 control participants who habitually wore heels for less than 10 h/wk. Participants walked at a self-selected speed over level ground while ground reaction forces, ankle and knee joint kinematics, lower limb muscle activity, and gastrocnemius fascicle length data were acquired. In long-term HH wearers, walking in HH resulted in substantial increases in muscle fascicle strains and muscle activation during the stance phase compared with barefoot walking. The results suggest that long-term high heel use may compromise muscle efficiency in walking and are consistent with reports that HH wearers often experience discomfort and muscle fatigue. Long-term HH use may also increase the risk of strain injuries.

scholarly journals The Influence of Growth, Maturation and Resistance Training on Muscle-Tendon and Neuromuscular Adaptations: A Narrative Review

Sports ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 59
Author(s):  
Nakul Tumkur Anil Kumar ◽  
Jon L. Oliver ◽  
Rhodri S. Lloyd ◽  
Jason S. Pedley ◽  
John M. Radnor
Keyword(s):  
Resistance Training ◽  
Muscle Activation ◽  
Muscle Thickness ◽  
Electromechanical Delay ◽  
Fascicle Length ◽  
Cross Sectional ◽  
Subsequent Effect ◽  
Motor Unit Activation ◽  
The Impact ◽  
And Training

The purpose of this article is to provide an overview of the growth, maturation and resistance training-related changes in muscle-tendon and neuromuscular mechanisms in youth, and the subsequent effect on performance. Sprinting, jumping, kicking, and throwing are common movements in sport that have been shown to develop naturally with age, with improvements in performance being attributed to growth and maturity-related changes in neuromuscular mechanisms. These changes include moderate to very large increases in muscle physiological cross-sectional area (CSA), muscle volume and thickness, tendon CSA and stiffness, fascicle length, muscle activation, pre-activation, stretch reflex control accompanied by large reductions in electro-mechanical delay and co-contraction. Furthermore, a limited number of training studies examining neuromuscular changes following four to 20 weeks of resistance training have reported trivial to moderate differences in tendon stiffness, muscle CSA, muscle thickness, and motor unit activation accompanied by reductions in electromechanical delay (EMD) in pre-pubertal children. However, the interaction of maturity- and training-related neuromuscular adaptions remains unclear. An understanding of how different neuromuscular mechanisms adapt in response to growth, maturation and training is important in order to optimise training responsiveness in youth populations. Additionally, the impact that these muscle-tendon and neuromuscular changes have on force producing capabilities underpinning performance is unclear.

Comparison of single and multiple joint muscle functions and neural drive of trained athletes and untrained individuals

2021 ◽  
pp. 1-11
Author(s):  
Kale Mehmet
Keyword(s):  
Muscle Activation ◽  
Time Windows ◽  
Knee Extension ◽  
Electromechanical Delay ◽  
Neural Drive ◽  
Lower Limb Muscles ◽  
Explosive Force ◽  
Biarticular Muscle ◽  
Voluntary Contractions ◽  
Maximum Voluntary Force

BACKGROUND: There is insufficient knowledge about the rate of force development (RFD) characteristics over both single and multiple joint movements and the electromechanical delay (EMD) values obtained in athletes and untrained individuals. OBJECTIVE: To compare single and multiple joint functions and the neural drive of trained athletes and untrained individuals. METHODS: Eight trained athletes and 10 untrained individuals voluntarily participated to the study. The neuromuscular performance was assessed during explosive and maximum voluntary isometric contractions during leg press and knee extension related to single and multiple joint. Explosive force and surface electromyography of eight superficial lower limb muscles were measured in five 50-ms time windows from their onset, and normalized to peak force and electromyography activity at maximum voluntary force, respectively. The EMD was determined from explosive voluntary contractions (EVC’s). RESULTS: The results showed that there were significant differences in absolute forces during knee extension maximum voluntary force and EVC’s (p< 0.01) while trained athletes achieved greater relative forces than untrained individuals of EVC at all five time points (p< 0.05). CONCLUSIONS: The differences in explosive performance between trained athletes and untrained individuals in both movements may be explained by different levels of muscle activation within groups, attributed to variation in biarticular muscle function over both activities.

Moderate-duration static stretch reduces active and passive plantar flexor moment but not Achilles tendon stiffness or active muscle length

2009 ◽  
Vol 106 (4) ◽  
pp. 1249-1256 ◽  
Author(s):  
Anthony D. Kay ◽  
Anthony J. Blazevich
Keyword(s):  
Mechanical Properties ◽  
Achilles Tendon ◽  
Muscle Stiffness ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Static Stretch ◽  
Tendon Stiffness ◽  
Neuromuscular Activity ◽  
Time Motion ◽  
The Impact

The effects of static stretch on muscle and tendon mechanical properties and muscle activation were studied in fifteen healthy human volunteers. Peak active and passive moment data were recorded during plantar flexion trials on an isokinetic dynamometer. Electromyography (EMG) monitoring of the triceps surae muscles, real-time motion analysis of the lower leg, and ultrasound imaging of the Achilles-medial gastrocnemius muscle-tendon junction were simultaneously conducted. Subjects performed three 60-s static stretches before being retested 2 min and 30 min poststretch. There were three main findings in the present study. First, peak concentric moment was significantly reduced after stretch; 60% of the deficit recovered 30 min poststretch. This was accompanied by, and correlated with ( r = 0.81 ; P < 0.01) reductions in peak triceps surae EMG amplitude, which was fully recovered at 30 min poststretch. Second, Achilles tendon length was significantly shorter during the concentric contraction after stretch and at 30 min poststretch; however, no change in tendon stiffness was detected. Third, passive joint moment was significantly reduced after stretch, and this was accompanied by significant reductions in medial gastrocnemius passive muscle stiffness; both measures fully recovered by 30 min poststretch. These data indicate that the stretching protocol used in this study induced losses in concentric moment that were accompanied by, and related to, reductions in neuromuscular activity, but they were not associated with alterations in tendon stiffness or shorter muscle operating length. Reductions in passive moment were associated with reductions in muscle stiffness, whereas tendon mechanics were unaffected by the stretch. Importantly, the impact on mechanical properties and neuromuscular activity was minimal at 30 min poststretch.

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