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

2020 ◽  
Author(s):  
Sebastian Bohm ◽  
Falk Mersmann ◽  
Alessandro Santuz ◽  
Adamantios Arampatzis
Keyword(s):  
Achilles Tendon ◽  
Soleus Muscle ◽  
Intervention Group ◽  
Running Economy ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Plantar Flexor ◽  
Tendon Stiffness ◽  
Flexor Strength ◽  
Human Running

AbstractDuring 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 (i.e. the enthalpy efficiency) depends on the muscle shortening velocity. Here, we investigated the soleus muscle fascicle behavior during running with respect to the enthalpy efficiency as a mechanism that could explain previously reported improvements in running economy after exercise-induced increases of plantar flexor strength and Achilles tendon stiffness. Healthy amateur runners were randomly assigned to a control (n=10) or intervention group (n=13), which performed a specific 14-week muscle-tendon training. Significant increases in plantar flexor maximum strength (10%) and Achilles tendon stiffness (31%) yet reduced metabolic cost of running (4%) was found only in the intervention group (p<0.05). Following training, the soleus fascicle velocity profile throughout stance was altered, with the fascicles operating at a higher enthalpy efficiency during the phase of muscle-tendon unit lengthening (15%) and in average over stance (7%, p<0.05). These findings show that the improvements in energetic cost following increases in plantar flexor strength and Achilles tendon stiffness can be attributed to increased enthalpy efficiency of the operating soleus. This provides the first experimental evidence that the soleus enthalpy efficiency is a determinant of human running economy. Furthermore, the current results imply that the soleus energy production in the first part of the stance phase were the muscle-tendon unit is lengthening is crucial for the overall metabolic energy cost of running.

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 Reduced Achilles Tendon Stiffness Disrupts Calf Muscle Neuromechanics in Elderly Gait

Gerontology ◽  
2021 ◽  
pp. 1-11
Author(s):  
Rebecca L. Krupenevich ◽  
Owen N. Beck ◽  
Gregory S. Sawicki ◽  
Jason R. Franz
Keyword(s):  
Older Adults ◽  
Achilles Tendon ◽  
Metabolic Cost ◽  
Calf Muscle ◽  
Metabolic Energy ◽  
Joint Work ◽  
Tendon Stiffness ◽  
Age Related ◽  
Ankle Muscle ◽  
Metabolic Energy Expenditure

Older adults walk slower and with a higher metabolic energy expenditure than younger adults. In this review, we explore the hypothesis that age-related declines in Achilles tendon stiffness increase the metabolic cost of walking due to less economical calf muscle contractions and increased proximal joint work. This viewpoint may motivate interventions to restore ankle muscle-tendon stiffness, improve walking mechanics, and reduce metabolic cost in older adults.

scholarly journals Elastic energy savings and active energy cost in a simple model of running

2021 ◽  
Vol 17 (11) ◽  
pp. e1009608
Author(s):  
Ryan T. Schroeder ◽  
Arthur D. Kuo
Keyword(s):  
Elastic Energy ◽  
Energy Cost ◽  
Energy Savings ◽  
Mechanical Energy ◽  
Metabolic Cost ◽  
The Body ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Mass Model ◽  
Human Running

The energetic economy of running benefits from tendon and other tissues that store and return elastic energy, thus saving muscles from costly mechanical work. The classic “Spring-mass” computational model successfully explains the forces, displacements and mechanical power of running, as the outcome of dynamical interactions between the body center of mass and a purely elastic spring for the leg. However, the Spring-mass model does not include active muscles and cannot explain the metabolic energy cost of running, whether on level ground or on a slope. Here we add explicit actuation and dissipation to the Spring-mass model, and show how they explain substantial active (and thus costly) work during human running, and much of the associated energetic cost. Dissipation is modeled as modest energy losses (5% of total mechanical energy for running at 3 m s-1) from hysteresis and foot-ground collisions, that must be restored by active work each step. Even with substantial elastic energy return (59% of positive work, comparable to empirical observations), the active work could account for most of the metabolic cost of human running (about 68%, assuming human-like muscle efficiency). We also introduce a previously unappreciated energetic cost for rapid production of force, that helps explain the relatively smooth ground reaction forces of running, and why muscles might also actively perform negative work. With both work and rapid force costs, the model reproduces the energetics of human running at a range of speeds on level ground and on slopes. Although elastic return is key to energy savings, there are still losses that require restorative muscle work, which can cost substantial energy during running.

Effects of eccentric training on mechanical properties of the plantar flexor muscle-tendon complex

2013 ◽  
Vol 114 (5) ◽  
pp. 523-537 ◽  
Author(s):  
Alexandre Fouré ◽  
Antoine Nordez ◽  
Christophe Cornu
Keyword(s):  
Mechanical Properties ◽  
Achilles Tendon ◽  
Plantar Flexion ◽  
Triceps Surae ◽  
Elastic Component ◽  
Plantar Flexor ◽  
Eccentric Training ◽  
Tendon Stiffness ◽  
Series Elastic Component ◽  
Series Elastic

Eccentric training is a mechanical loading classically used in clinical environment to rehabilitate patients with tendinopathies. In this context, eccentric training is supposed to alter tendon mechanical properties but interaction with the other components of the muscle-tendon complex remains unclear. The aim of this study was to determine the specific effects of 14 wk of eccentric training on muscle and tendon mechanical properties assessed in active and passive conditions in vivo. Twenty-four subjects were randomly divided into a trained group ( n = 11) and a control group ( n = 13). Stiffness of the active and passive parts of the series elastic component of plantar flexors were determined using a fast stretch during submaximal isometric contraction, Achilles tendon stiffness and dissipative properties were assessed during isometric plantar flexion, and passive stiffness of gastrocnemii muscles and Achilles tendon were determined using ultrasonography while ankle joint was passively moved. A significant decrease in the active part of the series elastic component stiffness was found ( P < 0.05). In contrast, a significant increase in Achilles tendon stiffness determined under passive conditions was observed ( P < 0.05). No significant change in triceps surae muscles and Achilles tendon geometrical parameters was shown ( P > 0.05). Specific changes in muscle and tendon involved in plantar flexion are mainly due to changes in intrinsic mechanical properties of muscle and tendon tissues. Specific assessment of both Achilles tendon and plantar flexor muscles allowed a better understanding of the functional behavior of the muscle-tendon complex and its adaptation to eccentric training.

Concentric muscle contractions before static stretching minimize, but do not remove, stretch-induced force deficits

2010 ◽  
Vol 108 (3) ◽  
pp. 637-645 ◽  
Author(s):  
Anthony D. Kay ◽  
Anthony J. Blazevich
Keyword(s):  
Achilles Tendon ◽  
Range Of Motion ◽  
Muscle Activity ◽  
Joint Moment ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Plantar Flexor ◽  
Tendon Stiffness ◽  
Concentric Contractions ◽  
Time Motion

The effects of concentric contractions and passive stretching on musculotendinous stiffness and muscle activity were studied in 18 healthy human volunteers. Passive and concentric plantar flexor joint moment data were recorded on an isokinetic dynamometer with simultaneous electromyogram (EMG) monitoring of the triceps surae, real-time motion analysis of the lower leg, and ultrasound imaging of the Achilles-medial gastrocnemius muscle-tendon junction. The subjects then performed six 8-s ramped maximal voluntary concentric contractions before repeating both the passive and concentric trials. Concentric moment was significantly reduced (6.6%; P < 0.01), which was accompanied by, and correlated with ( r = 0.60–0.94; P < 0.05), significant reductions in peak triceps surae EMG amplitude (10.2%; P < 0.01). Achilles tendon stiffness was significantly reduced (11.7%; P < 0.01), but no change in gastrocnemius medialis muscle operating length was detected. The subjects then performed three 60-s static plantar flexor stretches before being retested 2 and 30 min poststretch. A further reduction in concentric joint moment (5.8%; P < 0.01) was detected poststretch at 90% of range of motion, with no decrease in muscle activity or Achilles tendon stiffness, but a significant increase in muscle operating length and decrease in tendon length was apparent at this range of motion ( P < 0.05). Thirty minutes after stretching, muscle activity significantly recovered to pre-maximal voluntary concentric contractions levels, whereas concentric moment and Achilles tendon stiffness remained depressed. These data show that the performance of maximal concentric contractions can substantially reduce neuromuscular activity and muscle force, but this does not prevent a further stretch-induced loss in active plantar flexor joint moment. Importantly, the different temporal changes in EMG and concentric joint moment indicate that a muscle-based mechanism was likely responsible for the force losses poststretch.

scholarly journals Plantar Flexor Strength after Surgical Repair of the Achilles Tendon Rupture.

1992 ◽  
Vol 7 (2) ◽  
pp. 97-102
Author(s):  
Yositaka SHIBA ◽  
Akihiro WATANABE ◽  
Yumiko ISHIMORI ◽  
Shuichi OBUCHI
Keyword(s):  
Achilles Tendon ◽  
Tendon Rupture ◽  
Surgical Repair ◽  
Achilles Tendon Rupture ◽  
Plantar Flexor ◽  
Flexor Strength

Comparison of Plantar Flexor Musculotendinous Stiffness, Geometry, and Architecture in Male Runners With and Without a History of Tibial Stress Fracture

2015 ◽  
Vol 31 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Derek N. Pamukoff ◽  
J. Troy Blackburn
Keyword(s):  
Achilles Tendon ◽  
Stress Fracture ◽  
Joint Stiffness ◽  
Medial Gastrocnemius ◽  
Plantar Flexor ◽  
Fascicle Length ◽  
Tendon Stiffness ◽  
Tibial Stress Fracture ◽  
History Of ◽  
Musculotendinous Stiffness

Greater lower extremity joint stiffness may be related to the development of tibial stress fractures in runners. Musculotendinous stiffness is the largest contributor to joint stiffness, but it is unclear what factors contribute to musculotendinous stiffness. The purpose of this study was to compare plantar flexor musculotendinous stiffness, architecture, geometry, and Achilles tendon stiffness between male runners with and without a history of tibial stress fracture. Nineteen healthy runners (age = 21 ± 2.7 years; mass = 68.2 ± 9.3 kg; height = 177.3 ± 6.0 cm) and 19 runners with a history of tibial stress fracture (age = 21 ± 2.9 years; mass = 65.3 ± 6.0 kg; height = 177.2 ± 5.2 cm) were recruited from community running groups and the university’s varsity and club cross-country teams. Plantar flexor musculotendinous stiffness was estimated from the damped frequency of oscillatory motion about the ankle follow perturbation. Ultrasound imaging was used to measure architecture and geometry of the medial gastrocnemius. Dependent variables were compared between groups via one-way ANOVAs. Previously injured runners had greater plantar flexor musculotendinous stiffness (P< .001), greater Achilles tendon stiffness (P= .004), and lesser Achilles tendon elongation (P= .003) during maximal isometric contraction compared with healthy runners. No differences were found in muscle thickness, pennation angle, or fascicle length.

Isometric contractions reduce plantar flexor moment, Achilles tendon stiffness, and neuromuscular activity but remove the subsequent effects of stretch

2009 ◽  
Vol 107 (4) ◽  
pp. 1181-1189 ◽  
Author(s):  
Anthony D. Kay ◽  
Anthony J. Blazevich
Keyword(s):  
Achilles Tendon ◽  
Muscle Activity ◽  
Joint Moment ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Isometric Contractions ◽  
Plantar Flexor ◽  
Tendon Stiffness ◽  
Neuromuscular Activity ◽  
Passive Joint

The effects of isometric contractions and passive stretching on muscle-tendon mechanics and muscle activity were studied in 16 healthy human volunteers. First, peak concentric and passive ankle joint moment data were recorded on an isokinetic dynamometer with electromyographic monitoring of the triceps surae; real-time motion analysis of the lower leg and ultrasound imaging of the Achilles-medial gastrocnemius muscle-tendon junction were simultaneously conducted. Second, the subjects performed six 8-s maximal voluntary isometric contractions (MVICs) before repeating the passive and active trials. Although there was no decrease in isometric joint moment after MVICs, peak concentric moment was significantly reduced (11.5%, P < 0.01). This was accompanied by, and correlated with ( r = 0.90, P < 0.01), significant reductions in peak triceps surae electromyographic amplitude (21.0%, P < 0.01). Achilles tendon stiffness (10.9%, P < 0.01) and passive joint moment (4.9%, P < 0.01) were also significantly reduced. Third, the subjects performed three 60-s static plantar flexor stretches before being retested 2 and 30 min after stretch. The stretch protocol caused no significant change in any measure. At 30 min after stretching, significant recovery in concentric moment and muscle activity was detected at dorsiflexed joint angles, while Achilles tendon stiffness and passive joint moment remained significantly reduced. These data show that the performance of MVICs interrupts the normal stretch-induced losses in active and passive plantar flexor joint moment and neuromuscular activity, largely because concentric strength and tendon properties were already affected. Importantly, the decrease in Achilles tendon stiffness remained 30 min later, which may be an important etiological factor for muscle-tendon strain injury risk.

scholarly journals The force–length–velocity potential of the human soleus muscle is related to the energetic cost of running

2019 ◽  
Vol 286 (1917) ◽  
pp. 20192560 ◽  
Author(s):  
Sebastian Bohm ◽  
Falk Mersmann ◽  
Alessandro Santuz ◽  
Adamantios Arampatzis
Keyword(s):  
Soleus Muscle ◽  
Velocity Potential ◽  
Running Economy ◽  
Energetic Cost ◽  
Shortening Velocity ◽  
Optimal Length ◽  
Muscle Belly ◽  
Work Production ◽  
Force Velocity ◽  
Force Potential

According to the force–length–velocity relationships, the muscle force potential is determined by the operating length and velocity, which affects the energetic cost of contraction. During running, the human soleus muscle produces mechanical work through active shortening and provides the majority of propulsion. The trade-off between work production and alterations of the force–length and force–velocity potentials (i.e. fraction of maximum force according to the force–length–velocity curves) might mediate the energetic cost of running. By mapping the operating length and velocity of the soleus fascicles onto the experimentally assessed force–length and force–velocity curves, we investigated the association between the energetic cost and the force–length–velocity potentials during running. The fascicles operated close to optimal length (0.90 ± 0.10 L 0 ) with moderate velocity (0.118 ± 0.039 V max [maximum shortening velocity]) and, thus, with a force–length potential of 0.92 ± 0.07 and a force–velocity potential of 0.63 ± 0.09. The overall force–length–velocity potential was inversely related ( r = −0.52, p = 0.02) to the energetic cost, mainly determined by a reduced shortening velocity. Lower shortening velocity was largely explained ( p < 0.001, R 2 = 0.928) by greater tendon gearing, shorter Achilles tendon lever arm, greater muscle belly gearing and smaller ankle angle velocity. Here, we provide the first experimental evidence that lower shortening velocities of the soleus muscle improve running economy.

Does Foot Anthropometry Predict Metabolic Cost During Running?

2017 ◽  
Vol 33 (5) ◽  
pp. 317-322 ◽  
Author(s):  
Herman van Werkhoven ◽  
Stephen J. Piazza
Keyword(s):  
Oxygen Consumption ◽  
Achilles Tendon ◽  
Body Height ◽  
Force Plate ◽  
Metabolic Cost ◽  
Running Economy ◽  
Metabolic Energy ◽  
Flexor Muscle ◽  
Reaction Forces ◽  
Tendon Force

Several recent investigations have linked running economy to heel length, with shorter heels being associated with less metabolic energy consumption. It has been hypothesized that shorter heels require larger plantar flexor muscle forces, thus increasing tendon energy storage and reducing metabolic cost. The goal of this study was to investigate this possible mechanism for metabolic cost reduction. Fifteen male subjects ran at 16 km⋅h−1 on a treadmill and subsequently on a force-plate instrumented runway. Measurements of oxygen consumption, kinematics, and ground reaction forces were collected. Correlational analyses were performed between oxygen consumption and anthropometric and kinetic variables associated with the ankle and foot. Correlations were also computed between kinetic variables (peak joint moment and peak tendon force) and heel length. Estimated peak Achilles tendon force normalized to body weight was found to be strongly correlated with heel length normalized to body height (r = −.751, p = .003). Neither heel length nor any other measured or calculated variable were correlated with oxygen consumption, however. Subjects with shorter heels experienced larger Achilles tendon forces, but these forces were not associated with reduced metabolic cost. No other anthropometric and kinetic variables considered explained the variance in metabolic cost across individuals.

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