Relationship Between Sprint Performance and Muscle Fascicle Length in Female Sprinters.

Anuran jumping is one of the most powerful accelerations in vertebrate locomotion. Several species are hypothesized to use a catapult-like mechanism to store and rapidly release elastic energy, producing power outputs far beyond the capability of muscle. Most evidence for this mechanism comes from measurements of whole-body power output; the decoupling of joint motion and muscle shortening expected in a catapult-like mechanism has not been demonstrated. We used high-speed marker-based biplanar X-ray cinefluoroscopy to quantify plantaris muscle fascicle strain and ankle joint motion in frogs in order to test for two hallmarks of a catapult mechanism: (i) shortening of fascicles prior to joint movement (during tendon stretch), and (ii) rapid joint movement during the jump without rapid muscle-shortening (during tendon recoil). During all jumps, muscle fascicles shortened by an average of 7.8 per cent (54% of total strain) prior to joint movement, stretching the tendon. The subsequent period of initial joint movement and high joint angular acceleration occurred with minimal muscle fascicle length change, consistent with the recoil of the elastic tendon. These data support the plantaris longus tendon as a site of elastic energy storage during frog jumping, and demonstrate that catapult mechanisms may be employed even in sub-maximal jumps.

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Nature of the coupling between neural drive and force-generating capacity in the human quadriceps muscle

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.1908 ◽

2015 ◽

Vol 282 (1819) ◽

pp. 20151908 ◽

Cited By ~ 22

Author(s):

François Hug ◽

Clément Goupille ◽

Daniel Baum ◽

Brent J. Raiteri ◽

Paul W. Hodges ◽

...

Keyword(s):

Muscle Force ◽

Vastus Lateralis ◽

Quadriceps Muscle ◽

Myoelectric Activity ◽

Neural Drive ◽

Fascicle Length ◽

Cross Sectional ◽

Muscle Fascicle ◽

Generating Capacity ◽

The Relationship

The force produced by a muscle depends on both the neural drive it receives and several biomechanical factors. When multiple muscles act on a single joint, the nature of the relationship between the neural drive and force-generating capacity of the synergistic muscles is largely unknown. This study aimed to determine the relationship between the ratio of neural drive and the ratio of muscle force-generating capacity between two synergist muscles (vastus lateralis (VL) and vastus medialis (VM)) in humans. Twenty-one participants performed isometric knee extensions at 20 and 50% of maximal voluntary contractions (MVC). Myoelectric activity (surface electromyography (EMG)) provided an index of neural drive. Physiological cross-sectional area (PCSA) was estimated from measurements of muscle volume (magnetic resonance imaging) and muscle fascicle length (three-dimensional ultrasound imaging) to represent the muscles' force-generating capacities. Neither PCSA nor neural drive was balanced between VL and VM. There was a large ( r = 0.68) and moderate ( r = 0.43) correlation between the ratio of VL/VM EMG amplitude and the ratio of VL/VM PCSA at 20 and 50% of MVC, respectively. This study provides evidence that neural drive is biased by muscle force-generating capacity, the greater the force-generating capacity of VL compared with VM, the stronger bias of drive to the VL.

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Biceps femoris long head muscle fascicle length does not differ between sexes

Journal of Sports Sciences ◽

10.1080/02640414.2019.1641016 ◽

2019 ◽

Vol 37 (21) ◽

pp. 2452-2458

Author(s):

Fearghal P. Behan ◽

Rachael Moody ◽

Tejal Sarika Patel ◽

Edward Lattimore ◽

Thomas M. Maden-Wilkinson ◽

...

Keyword(s):

Biceps Femoris ◽

Fascicle Length ◽

Muscle Fascicle ◽

Long Head ◽

Biceps Femoris Long Head

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Pressure based MRI-compatible muscle fascicle length and joint angle estimation

Journal of NeuroEngineering and Rehabilitation ◽

10.1186/s12984-020-00745-8 ◽

2020 ◽

Vol 17 (1) ◽

Author(s):

Hyungeun Song ◽

Erica Israel ◽

Shriya Srinivasan ◽

Hugh Herr

Keyword(s):

Joint Angle ◽

Fascicle Length ◽

Angle Estimation ◽

Muscle Fascicle

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Change in Muscle Fascicle Length Influences the Recruitment and Discharge Rate of Motor Units During Isometric Contractions

Journal of Neurophysiology ◽

10.1152/jn.00537.2005 ◽

2005 ◽

Vol 94 (5) ◽

pp. 3126-3133 ◽

Cited By ~ 37

Author(s):

Benjamin Pasquet ◽

Alain Carpentier ◽

Jacques Duchateau

Keyword(s):

Motor Unit ◽

Ankle Joint ◽

Discharge Rate ◽

Motor Units ◽

Motor Unit Recruitment ◽

Isometric Contractions ◽

Neutral Position ◽

Proprioceptive Information ◽

Fascicle Length ◽

Muscle Fascicle

This study examines the effect of fascicle length change on motor-unit recruitment and discharge rate in the human tibialis anterior (TA) during isometric contractions of various intensities. The torque produced during dorsiflexion and the surface and intramuscular electromyograms (EMGs) from the TA were recorded in eight subjects. The behavior of the same motor unit ( n = 59) was compared at two ankle joint angles (+10 and −10° around the ankle neutral position). Muscle fascicle length of the TA was measured noninvasively using ultrasonography recordings. When the ankle angle was moved from 10° plantarflexion to 10° dorsiflexion, the torque produced during maximal voluntary contraction (MVC) was significantly reduced [35.2 ± 3.3 vs. 44.3 ± 4.2 (SD) Nm; P < 0.001] and the average surface EMG increased (0.47 ± 0.08 vs. 0.43 ± 0.06 mV; P < 0.05). At reduced ankle joint angle, muscle fascicle length declined by 12.7% ( P < 0.01) at rest and by 18.9% ( P < 0.001) during MVC. Motor units were activated at a lower recruitment threshold for short compared with long muscle fascicle length, either when expressed in absolute values (2.1 ± 2.5 vs. 3.6 ± 3.7 Nm; P < 0.001) or relative to their respective MVC (5.2 ± 6.1 vs. 8.8 ± 9.0%). Higher discharge rate and additional motor-unit recruitment were observed at a given absolute or relative torque when muscle fascicles were shortened. However, the data indicate that increased rate coding was mainly present at low torque level (<10% MVC), when the muscle-tendon complex was compliant, whereas recruitment of additional motor units played a dominant role at higher torque level and decreased compliance (10–35% MVC). Taken together, the results suggest that the central command is modulated by the afferent proprioceptive information during submaximal contractions performed at different muscle fascicle lengths.

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Plantar Flexor Muscle Architecture Changes as a Result of Eccentric Exercise in Patients With Achilles Tendinosis

Foot & Ankle Specialist ◽

10.1177/1938640014539812 ◽

2014 ◽

Vol 7 (6) ◽

pp. 460-465 ◽

Cited By ~ 1

Author(s):

Matthew T. Crill ◽

Gregory Berlet ◽

Christopher Hyer

Keyword(s):

Case Series ◽

Muscle Architecture ◽

Medial Gastrocnemius ◽

Eccentric Training ◽

Plantar Flexors ◽

Flexor Muscle ◽

Fascicle Length ◽

Achilles Tendinosis ◽

Muscle Fascicle ◽

Maximal Load

Eccentric training for Achilles tendinosis (AT) has been reported to significantly improve patient symptoms. There has been no biomechanical explanation on the mechanism for specific rehabilitation technique. The purpose of this study was to determine changes in muscle architecture that occurred as a result of Achilles tendinosis injury and a subsequent eccentric rehabilitation program. Twenty-five patients (age, 53.3 ± 17.5 years) diagnosed with AT participated in 6 weeks of rehabilitation. Specific exercises for the ankle plantar flexors consisted of maximal load eccentric muscle action using 3 sets of 15 repetitions. Patients also completed a protocol for AT, which consisting of traditional rehabilitation. Medial gastrocnemius (GM) and lateral gastrocnemius (GL) muscle fascicle length and thickness were measured with ultrasound at 2-week intervals from initial treatment day to the end of 6 weeks of rehabilitation. Medial gastrocnemius fascicle length increased (45.1 ± 10.5 mm to 51.4 ± 10.5 mm; P = .22) between the initial day of rehabilitation and after 6 weeks of rehabilitation. But, GM thickness (16.3 ± 3.5 mm to 16.8 ± 2.0 mm), GL fascicle length (47.2 ± 10.0 mm to 47.1 ± 7.4 mm), and GL thickness (14.9 ± 5.2 mm to 14.4 ± 2.7 mm) did not change as a result of rehabilitation. A 6-week eccentric-biased exercise increased the GM muscle fascicle length by 12%, but GM thickness, GL fascicle length, and GL thickness did not change as a result of rehabilitation. Eccentric training for the treatment of AT is well recognized, but the mechanism of action has not been previously reported. A 6-week eccentric training protocol increased the GM muscle fascicle length by 12%, and this correlated with improvement in a validated patient outcome scoring system. Further study is warranted to determine a predictive relationship between improvement of GM fascicle length and outcome scores. Levels of Evidence: Therapeutic, Level IV: Case series

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Ultrasound Structural Changes in Triceps Surae After a 1-Year Daily Self-stretch Program: A Prospective Randomized Controlled Trial in Chronic Hemiparesis

Neurorehabilitation and Neural Repair ◽

10.1177/1545968319829455 ◽

2019 ◽

Vol 33 (4) ◽

pp. 245-259 ◽

Cited By ~ 6

Author(s):

Maud Pradines ◽

Mouna Ghedira ◽

Raphaël Portero ◽

Ingrid Masson ◽

Christina Marciniak ◽

...

Keyword(s):

Structural Changes ◽

Controlled Trial ◽

Triceps Surae ◽

Medial Gastrocnemius ◽

Plantar Flexors ◽

Fascicle Length ◽

Rehabilitation Programs ◽

Lower Limb Muscles ◽

Muscle Fascicle ◽

Prospective Randomized Controlled Trial

Introduction. The effects of long-term stretching (>6 months) in hemiparesis are unknown. This prospective, randomized, single-blind controlled trial compared changes in architectural and clinical parameters in plantar flexors of individuals with chronic hemiparesis following a 1-year guided self-stretch program, compared with conventional rehabilitation alone. Methods. Adults with chronic stroke-induced hemiparesis (time since lesion >1 year) were randomized into 1 of 2, 1-year rehabilitation programs: conventional therapy (CONV) supplemented with the Guided Self-rehabilitation Contract (GSC) program, or CONV alone. In the GSC group, specific lower limb muscles, including plantar flexors, were identified for a diary-based treatment utilizing daily, high-load, home self-stretching. Blinded assessments included (1) ultrasonographic measurements of soleus and medial gastrocnemius (MG) fascicle length and thickness, with change in soleus fascicle length as primary outcome; (2) maximum passive muscle extensibility (XV1, Tardieu Scale); (3) 10-m maximal barefoot ambulation speed. Results. In all, 23 individuals (10 women; mean age [SD], 56 [±12] years; time since lesion, 9 [±8] years) were randomized into either the CONV (n = 11) or GSC (n = 12) group. After 1 year, all significant between-group differences favored the GSC group: soleus fascicle length, +18.1mm [9.3; 29.9]; MG fascicle length, +6.3mm [3.5; 9.1]; soleus thickness, +4.8mm [3.0; 7.7]; XV1 soleus, +4.1° [3.1; 7.2]; XV1 gastrocnemius, +7.0° [2.1; 11.9]; and ambulation speed, +0.07m/s [+0.02; +0.16]. Conclusions. In chronic hemiparesis, daily self-stretch of the soleus and gastrocnemius over 1 year using GSC combined with conventional rehabilitation increased muscle fascicle length, extensibility, and ambulation speed more than conventional rehabilitation alone.

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