Effects of Training on Muscle and Tendon in Knee Extensors and Plantar Flexors in Vivo

The purpose of this study was to compare the effects of resistance training on muscle and tendon properties between knee extensors and plantar flexors in vivo. Twenty healthy young men voluntarily participated in this study. The subjects were randomly divided into two training groups: knee extension group (n= 10) and plantar flexion group (n= 10). They performed five sets of exercises with a 1-min rest between sets, which consisted of unilateral knee extension for the knee extension group and plantar flexion for the plantar flexion group at 80% of 1 repetition maximum with 10 repetitions per set (4 days/wk, 12 wk). Before and after training, muscle strength, neural activation level (by interpolated twitch), muscle volume (by magnetic resonance imaging), and tendon stiffness (by ultrasonography) were measured. There were no differences in the training-induced increases in muscle strength, activation level, muscle volume, and tendon stiffness between knee extensors and plantar flexors. These results suggested that if the used protocol of training (i.e., intensity, repetition, etc.) were the same, there were no differences in the training-induced changes in muscle and tendon properties between knee extensors and plantar flexors.

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Comparison of Elasticity of Human Tendon and Aponeurosis in Knee Extensors and Ankle Plantar Flexors in Vivo

Journal of Applied Biomechanics ◽

10.1123/jab.21.2.129 ◽

2005 ◽

Vol 21 (2) ◽

pp. 129-142 ◽

Cited By ~ 15

Author(s):

Keitaro Kubo ◽

Hiroaki Kanehisa ◽

Tetsuo Fukunaga

Keyword(s):

Plantar Flexion ◽

Knee Extension ◽

Knee Extensors ◽

Plantar Flexors ◽

Human Knee ◽

Ultrasonic Apparatus ◽

Muscle Modeling ◽

Human Movements ◽

Maximal Strain

The purposes of this study were to compare the elasticity of tendon and aponeurosis in human knee extensors and ankle plantar flexors in vivo and to examine whether the maximal strain of tendon was correlated to that of aponeurosis. The elongation of tendon and aponeurosis during isometric knee extension (n= 23) and ankle plantar flexion (n= 22), respectively, were determined using a real-time ultrasonic apparatus, while the participants performed ramp isometric contractions up to voluntary maximum. To calculate the strain values from the measured elongation, we measured the respective length of tendon and aponeurosis. For the knee extensors, the maximal strain of aponeurosis (12.1 ± 2.8%) was significantly greater than that of the patella tendon (8.3 ± 2.4%),p< 0.001. On the contrary, the maximal strain of Achilles tendon (5.9 ± 1.4%) was significantly greater than that of aponeurosis in ankle plantar flexors (2.7 ± 1.4%),p< 0.001. Furthermore, for both knee extensors and ankle plantar flexors there was no significant correlation between maximal strain of tendon and aponeurosis. These results would be important for understanding the different roles of tendon and aponeurosis during human movements and for more accurate muscle modeling.

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In vivo Evaluation of Patellar Tendon Stiffness in Individuals with Patellofemoral Pain Syndrome

Applied Bionics and Biomechanics ◽

10.1155/2008/269891 ◽

2008 ◽

Vol 5 (2) ◽

pp. 59-63

Author(s):

Hsin-Yi Liu ◽

Michelle Boling ◽

Darin Padua ◽

R. Alexander Creighton ◽

Paul Weinhold

Keyword(s):

Patellar Tendon ◽

Pain Syndrome ◽

Patellofemoral Pain Syndrome ◽

Knee Extension ◽

Patellofemoral Pain ◽

Knee Extensors ◽

Ultrasonic Technique ◽

In Vivo Evaluation ◽

Tendon Stiffness

The objective of this study was to utilise an ultrasonic technique to assess the effect of patellofemoral pain syndrome (PFPS) on the mechanical properties of the patellar tendon. Seven subjects with PFPS and seven matched control subjects volunteered to participate in this study. Subjects were asked to perform isometric maximal voluntary contractions of the knee extensors while their knee extension torque was monitored and the displacement of the patellar tendon was recorded with an ultrasonic system. Our results showed significantly lower tendon stiffness (by ∼30%) in the PFPS subjects. Although tendon secant modulus was lower by 34% in the PFPS subjects, the difference was not statistically significant. Therefore, we conclude that the ultrasonic technique was able to detect a decrease in the structural stiffness of the patellar tendon associated with PFPS. The decrease in tendon stiffness was moderately correlated with the length of symptoms in these individuals.

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Morphological and Mechanical Properties of Muscle and Tendon in Highly Trained Sprinters

Journal of Applied Biomechanics ◽

10.1123/jab.27.4.336 ◽

2011 ◽

Vol 27 (4) ◽

pp. 336-344 ◽

Cited By ~ 37

Author(s):

Keitaro Kubo ◽

Toshihiro Ikebukuro ◽

Hideaki Yata ◽

Minoru Tomita ◽

Masaji Okada

Keyword(s):

Mechanical Properties ◽

Muscle Thickness ◽

Knee Extensors ◽

Plantar Flexors ◽

Tendon Stiffness ◽

Running Performance ◽

Medial Side ◽

Official Record ◽

Tendon Properties

The purpose of this study was to investigate muscle and tendon properties in highly trained sprinters and their relations to running performance. Fifteen sprinters and 15 untrained subjects participated in this study. Muscle thickness and tendon stiffness of knee extensors and plantar flexors were measured. Sprinter muscle thickness was significantly greater than that of the untrained subjects for plantar flexors, but not for knee extensors (except for the medial side). Sprinter tendon stiffness was significantly lower than that of the untrained subjects for knee extensors, but not for plantar flexors. The best official record of a 100-m race was significantly correlated to the muscle thickness of the medial side for knee extensors. In conclusion, the tendon structures of highly trained sprinters are more compliant than those of untrained subjects for knee extensors, but not for plantar flexors. Furthermore, a thicker medial side of knee extensors was associated with greater sprinting performance.

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The Effects of Repetitive Drop Jumps on Impact Phase Joint Kinematics and Kinetics

Journal of Applied Biomechanics ◽

10.1123/jab.27.2.108 ◽

2011 ◽

Vol 27 (2) ◽

pp. 108-115 ◽

Cited By ~ 24

Author(s):

Joshua T. Weinhandl ◽

Jeremy D. Smith ◽

Eric L. Dugan

Keyword(s):

Energy Absorption ◽

Plantar Flexion ◽

Knee Extension ◽

Joint Kinematics ◽

Knee Extensors ◽

Initial Contact ◽

Drop Jumps ◽

Impact Phase ◽

The Impact ◽

Kinematics And Kinetics

The purpose of the study was to investigate the effects of fatigue on lower extremity joint kinematics, and kinetics during repetitive drop jumps. Twelve recreationally active males (n= 6) and females (n= 6) (nine used for analysis) performed repetitive drop jumps until they could no longer reach 80% of their initial drop jump height. Kinematic and kinetic variables were assessed during the impact phase (100 ms) of all jumps. Fatigued landings were performed with increased knee extension, and ankle plantar flexion at initial contact, as well as increased ankle range of motion during the impact phase. Fatigue also resulted in increased peak ankle power absorption and increased energy absorption at the ankle. This was accompanied by an approximately equal reduction in energy absorption at the knee. While the knee extensors were the muscle group primarily responsible for absorbing the impact, individuals compensated for increased knee extension when fatigued by an increased use of the ankle plantar flexors to help absorb the forces during impact. Thus, as fatigue set in and individuals landed with more extended lower extremities, they adopted a landing strategy that shifted a greater burden to the ankle for absorbing the kinetic energy of the impact.

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Biomechanics and Exercise

Pediatric Exercise Science ◽

10.1123/pes.2015-0033 ◽

2015 ◽

Vol 27 (1) ◽

pp. 34-38

Author(s):

Thomas D. O’Brien

Keyword(s):

Achilles Tendon ◽

Young’S Modulus ◽

Young's Modulus ◽

Plantar Flexion ◽

Tendon Injury ◽

Time Curve ◽

Tendon Stiffness ◽

Prepubertal Children ◽

Experimental Group ◽

Tendon Properties

Children develop lower levels of muscle force, and at slower rates, than adults. While strength training in children is expected to reduce this differential, a synchronous adaptation in the tendon must be achieved to ensure forces continue to be transmitted to the skeleton with efficiency while minimizing the risk of strainrelated tendon injury. We hypothesized that resistance training (RT) would alter tendon mechanical properties in children concomitantly with changes in force production characteristics. Twenty prepubertal children (8.9 ± 0.3 years) were equally divided into control (nontraining) and experimental (training) groups. The training group completed a 10-week RT intervention consisting of 2-3 sets of 8-15 plantar flexion contractions performed twice weekly on a recumbent calf raise machine. Achilles tendon properties (cross-sectional area, elongation, stress, strain, stiffness and Young’s modulus), electromechanical delay (EMD; time between the onset of muscle activity and force), rate of force development (RFD; slope of the force-time curve) and rate of EMG increase (REI; slope of the EMG-time curve) were measured before and after RT. Tendon stiffness and Young’s modulus increased significantly after RT in the experimental group only (~29% and ~25%, respectively); all other tendon properties were not significantly altered, although there were mean decreases in both peak tendon strain and strain at a given force level (14% and 24%, respectively, n.s) which may have implications for tendon injury risk and muscle fiber mechanics. A ~13% decrease in EMD was found after RT for the experimental group which paralleled the increase in tendon stiffness (r = −0.59), however RFD and REI were unchanged. The present data show that the Achilles tendon adapts to RT in prepubertal children and is paralleled by a change in EMD, although the magnitude of this change did not appear to be sufficient to influence RFD. These findings are of potential importance within the context of the efficiency and execution of movement.

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Training-induced alterations of the in vivo force-velocity relationship of human muscle

Journal of Applied Physiology ◽

10.1152/jappl.1981.51.3.750 ◽

1981 ◽

Vol 51 (3) ◽

pp. 750-754 ◽

Cited By ~ 135

Author(s):

V. J. Caiozzo ◽

J. J. Perrine ◽

V. R. Edgerton

Keyword(s):

Training Group ◽

Knee Extension ◽

Knee Extensors ◽

Velocity Relationship ◽

Slow Velocity ◽

Group A ◽

Force Velocity ◽

Group B ◽

Relationship Of

Seventeen male and female subjects (ages 20–38 yr) were tested pre- and posttraining for maximal knee extension torque at seven specific velocities (0, 0.84, 1.68, 2.51, 3.35, 4.19, and 5.03 rad . s-1) with an isokinetic dynamometer. Maximal knee extension torques were recorded at a specific joint angle (0.52 rad below the horizontal plane) for all test speeds. Subjects were randomly assigned to one of three experimental groups: group A, control, n = 7; group B, training at 1.68 rad . s-1, n = 5; or group C, training at 4.19 rad . s-1, n = 5. Subjects trained the knee extensors by performing two sets of 10 single maximal voluntary efforts three times a week for 4 wk. Before training, each training group exhibited a leveling-off of muscular tension in the slow velocity-high force region of the in vivo force-velocity relationship. Training at 1.68 rad . s-1 resulted in significant (P less than 0.05) improvements at all velocities except for 5.03 rad . s-1 and markedly affected the leveling-off in the slow velocity-high force region. Training at 4.19 rad . s-1 did not affect the leveling-off phenomenon but brought about significant improvements (P less than 0.05) at velocities of 2.51, 3.35, and 4.19 rad . s-1. The changes seen in the leveling-off phenomenon suggest that training at 1.68 rad . s-1 might have brought about an enhancement of motoneuron activation.

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Effects of long-term athletic training on muscle morphology and tendon stiffness in preadolescence: association with jump performance

European Journal of Applied Physiology ◽

10.1007/s00421-020-04490-7 ◽

2020 ◽

Vol 120 (12) ◽

pp. 2715-2727

Author(s):

Nikolaos Pentidis ◽

Falk Mersmann ◽

Sebastian Bohm ◽

Erasmia Giannakou ◽

Nickos Aggelousis ◽

...

Keyword(s):

Muscle Strength ◽

Achilles Tendon ◽

Muscle Hypertrophy ◽

Muscle Thickness ◽

Pennation Angle ◽

Triceps Surae ◽

Plantar Flexors ◽

Tendon Stiffness ◽

Jumping Performance

Abstract Purpose Evidence on training-induced muscle hypertrophy during preadolescence is limited and inconsistent. Possible associations of muscle strength and tendon stiffness with jumping performance are also not investigated. We investigated the thickness and pennation angle of the gastrocnemius medialis muscle (GM), as indicators for potential muscle hypertrophy in preadolescent athletes. Further, we examined the association of triceps surae muscle–tendon properties with jumping performance. Methods Eleven untrained children (9 years) and 21 similar-aged artistic gymnastic athletes participated in the study. Muscle thickness and pennation angle of the GM were measured at rest and muscle strength of the plantar flexors and Achilles tendon stiffness during maximum isometric contractions. Jumping height in squat (SJ) and countermovement jumps (CMJ) was examined using a force plate. We evaluated the influence of normalised muscle strength and tendon stiffness on jumping performance with a linear regression model. Results Muscle thickness and pennation angle did not differ significantly between athletes and non-athletes. In athletes, muscle strength was greater by 25% and jumping heights by 36% (SJ) and 43% (CMJ), but Achilles tendon stiffness did not differ between the two groups. The significant predictor for both jump heights was tendon stiffness in athletes and normalised muscle strength for the CMJ height in non-athletes. Conclusion Long-term artistic gymnastics training during preadolescence seems to be associated with increased muscle strength and jumping performance but not with training-induced muscle hypertrophy or altered tendon stiffness in the plantar flexors. Athletes benefit more from tendon stiffness and non-athletes more from muscle strength for increased jumping performance.

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Proprioceptive Neuromuscular Facilitation Improves Balance and Knee Extensors Strength of Older Fallers

ISRN Rehabilitation ◽

10.5402/2012/402612 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 5

Author(s):

Marcelo Pinto Pereira ◽

Mauro Gonçalves

Keyword(s):

Exercise Program ◽

Knee Extensor ◽

Training Group ◽

Knee Extension ◽

Knee Extensors ◽

Control Group ◽

Extension Rate ◽

Neuromuscular Activation ◽

Activation Level ◽

Proprioceptive Neuromuscular Facilitation

Falls are one of the major problems for elderly people and proprioceptive exercises have been suggested as an alternative in rehabilitation and preventive programs. The purpose of this study was to investigate the influence of a proprioceptive neuromuscular facilitation (PNF) exercise program on balance, knee extension and flexion isometric torque, and knee extension rate of force development (RFD). Fourteen older faller subjects (>60 years) were equally assigned into two groups: a control group (CG: n=7) and a training group (TG: n=7). The PNF training program was performed for 10 weeks on TG, with a frequency of three times per week. Patients were assessed before and after the PNF program, with respect to balance (Berg Balance Scale score—BBS), knee maximal isometric extension and flexion torque, knee extensor RFD, and knee extensors and flexors neuromuscular activation level and coactivation level around the knee. After 10 weeks, balance (P<0.001) and knee extension torque (P=0.05) were improved in TG while no differences were found for CG. These improvements were mainly attributed to central nervous system adaptations, since no differences were found for neuromuscular activation level and coactivation.

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Neuromuscular factors contributing to in vivo eccentric moment generation

Journal of Applied Physiology ◽

10.1152/jappl.1997.83.1.40 ◽

1997 ◽

Vol 83 (1) ◽

pp. 40-45 ◽

Cited By ~ 52

Author(s):

Sandra Webber ◽

Dean Kriellaars

Keyword(s):

Linear Relationship ◽

Knee Extensor ◽

Motor Units ◽

Voluntary Contraction ◽

Contractile Element ◽

Knee Extensors ◽

Activation Level ◽

In Series

Webber, Sandra, and Dean Kriellaars. Neuromuscular factors contributing to in vivo eccentric moment generation. J. Appl. Physiol. 83(1): 40–45, 1997.—Muscle series elasticity and its contribution to eccentric moment generation was examined in humans. While subjects [male, n = 30; age 26.3 ± 4.8 (SD) yr; body mass 78.8 ± 13.1 kg] performed an isometric contraction of the knee extensors at 60° of knee flexion, a quick stretch was imposed with a 12°-step displacement at 100°/s. The test was performed at 10 isometric activation levels ranging from 1.7 to 95.2% of maximal voluntary contraction (MVC). A strong linear relationship was observed between the peak imposed eccentric moment derived from quick stretch and the isometric activation level ( y = 1.44 x + 7.08; r = 0.99). This increase in the eccentric moment is consistent with an actomyosin-dependent elasticity located in series with the contractile element of muscle. By extrapolating the linear relationship to 100% MVC, the predicted maximum eccentric moment was found to be 151% MVC, consistent with in vitro data. A maximal voluntary, knee extensor strength test was also performed (5–95°, 3 repetitions, ±50, 100, 150, 200, and 250°/s). The predicted maximum eccentric moment was 206% of the angle- and velocity-matched, maximal voluntary eccentric moments. This was attributed to a potent neural regulatory mechanism that limits the recruitment and/or discharge of motor units during maximal voluntary eccentric contractions.

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