Training-induced changes in structural and mechanical properties of the patellar tendon are related to muscle hypertrophy but not to strength gains

To obtain a better understanding of the adaptations of human tendon to chronic overloading, we examined the relationships between these adaptations and the changes in muscle structure and function. Fifteen healthy male subjects (20 ± 2 yr) underwent 9 wk of knee extension resistance training. Patellar tendon stiffness and modulus were assessed with ultrasonography, and cross-sectional area (CSA) was determined along the entire length of the tendon by using magnetic resonance imaging. In the quadriceps muscles, architecture and volume measurements were combined to obtain physiological CSA (PCSA), and maximal isometric force was recorded. Following training, muscle force and PCSA increased by 31% ( P < 0.0001) and 7% ( P < 0.01), respectively. Tendon CSA increased regionally at 20–30%, 60%, and 90–100% of tendon length (5–6%; P < 0.05), and tendon stiffness and modulus increased by 24% ( P < 0.001) and 20% ( P < 0.01), respectively. Although none of the tendon adaptations were related to strength gains, we observed a positive correlation between the increase in quadriceps PCSA and the increases in tendon stiffness ( r = 0.68; P < 0.01) and modulus ( r = 0.75; P < 0.01). Unexpectedly, the increase in muscle PCSA was inversely related to the distal and the mean increases in tendon CSA (in both cases, r = −0.64; P < 0.05). These data suggest that, following short-term resistance training, changes in tendon mechanical and material properties are more closely related to the overall loading history and that tendon hypertrophy is driven by other mechanisms than those eliciting tendon stiffening.

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Lower tendon stiffness in very old compared with old individuals is unaffected by short-term resistance training of skeletal muscle

Journal of Applied Physiology ◽

10.1152/japplphysiol.00028.2018 ◽

2018 ◽

Vol 125 (1) ◽

pp. 205-214 ◽

Cited By ~ 1

Author(s):

Christian Skou Eriksen ◽

Cecilie Henkel ◽

Rene B. Svensson ◽

Anne-Sofie Agergaard ◽

Christian Couppé ◽

...

Keyword(s):

Physical Activity ◽

Mechanical Properties ◽

Resistance Training ◽

Patellar Tendon ◽

Cross Sectional ◽

Tendon Stiffness ◽

Very Old ◽

Reduced Physical Activity ◽

Heavy Resistance Training

Aging negatively affects collagen-rich tissue, like tendons, but in vivo tendon mechanical properties and the influence of physical activity after the 8th decade of life remain to be determined. This study aimed to compare in vivo patellar tendon mechanical properties in moderately old (old) and very old adults and the effect of short-term resistance training. Twenty old (9 women, 11 men, >65 yr) and 30 very old (11 women, 19 men, >83 yr) adults were randomly allocated to heavy resistance training (HRT) or no training (CON) and underwent testing of in vivo patellar tendon (PT) mechanical properties and PT dimensions before and after a 3-mo intervention. Previous measurements of muscle properties, blood parameters, and physical activity level were included in the analysis. Data from 9 old HRT, 10 old CON, 14 very old CON, and 12 old HRT adults were analyzed. In addition to lower quadriceps muscle strength and cross-sectional area (CSA), we found lower PT stiffness and Young’s modulus ( P < 0.001) and a trend toward the lower mid-portion PT-CSA ( P = 0.09) in very old compared with old subjects. Daily step count was also lower in very old subjects ( P < 0.001). Resistance training improved muscle strength and cross-sectional area equally in old and very old subjects ( P < 0.05) but did not affect PT mechanical properties or dimension. We conclude that PT material properties are reduced in very old age, and this may likely be explained by reduced physical activity. Three months of resistance training however, could not alter PT mechanical properties in very old individuals. NEW & NOTEWORTHY This research is the first to quantify in vivo tendon mechanical properties in a group of very old adults in their eighties. Patellar tendon stiffness was lower in very old (87 yr on average) compared with moderately old (68 yr on average) individuals. Reduced physical activity with aging may explain some of the loss in tendon stiffness, but regular heavy resistance training for 3 mo was not sufficient to change tendon mechanical properties.

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Changes in the human muscle force-velocity relationship in response to resistance training and subsequent detraining

Journal of Applied Physiology ◽

10.1152/japplphysiol.00091.2005 ◽

2005 ◽

Vol 99 (1) ◽

pp. 87-94 ◽

Cited By ~ 83

Author(s):

Lars L. Andersen ◽

Jesper L. Andersen ◽

S. Peter Magnusson ◽

Charlotte Suetta ◽

Jørgen L. Madsen ◽

...

Keyword(s):

Resistance Training ◽

Knee Extension ◽

Limb Movement ◽

Cross Sectional Area ◽

Contractile Properties ◽

Type I ◽

Maximal Velocity ◽

Sectional Area ◽

Cross Sectional ◽

Muscle Cross Sectional Area

Previous studies show that cessation of resistance training, commonly known as “detraining,” is associated with strength loss, decreased neural drive, and muscular atrophy. Detraining may also increase the expression of fast muscle myosin heavy chain (MHC) isoforms. The present study examined the effect of detraining subsequent to resistance training on contractile performance during slow-to-medium velocity isokinetic muscle contraction vs. performance of maximal velocity “unloaded” limb movement (i.e., no external loading of the limb). Maximal knee extensor strength was measured in an isokinetic dynamometer at 30 and 240°/s, and performance of maximal velocity limb movement was measured with a goniometer during maximal unloaded knee extension. Muscle cross-sectional area was determined with MRI. Electromyographic signals were measured in the quadriceps and hamstring muscles. Twitch contractions were evoked in the passive vastus lateralis muscle. MHC isoform composition was determined with SDS-PAGE. Isokinetic muscle strength increased 18% ( P < 0.01) and 10% ( P < 0.05) at slow and medium velocities, respectively, along with gains in muscle cross-sectional area and increased electromyogram in response to 3 mo of resistance training. After 3 mo of detraining these gains were lost, whereas in contrast maximal unloaded knee extension velocity and power increased 14% ( P < 0.05) and 44% ( P < 0.05), respectively. Additionally, faster muscle twitch contractile properties along with an increased and decreased amount of MHC type II and MHC type I isoforms, respectively, were observed. In conclusion, detraining subsequent to resistance training increases maximal unloaded movement speed and power in previously untrained subjects. A phenotypic shift toward faster muscle MHC isoforms (I → IIA → IIX) and faster electrically evoked muscle contractile properties in response to detraining may explain the present results.

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Physiological Adaptations following Resistance Training in Youth Athletes—A Narrative Review

Pediatric Exercise Science ◽

10.1123/pes.2016-0023 ◽

2016 ◽

Vol 28 (4) ◽

pp. 501-520 ◽

Cited By ~ 26

Author(s):

Kirsten Legerlotz ◽

Robert Marzilger ◽

Sebastian Bohm ◽

Adamantios Arampatzis

Keyword(s):

Resistance Training ◽

Injury Risk ◽

Structural Changes ◽

Neuromuscular Control ◽

Physiological Adaptation ◽

Cross Sectional ◽

Youth Athletes ◽

Stimulus Response ◽

Physiological Adaptations ◽

Induced Changes

Purpose:To understand the mechanisms for the effects of resistance training on functional parameters, and to assess the injury risk of the involved tissues, it is necessary to examine the underlying morphological and structural changes of the respective tissues.Methods:The presented information on physiological adaptations have been deduced from cross-sectional studies comparing youth athletes with controls and children with adults as well as from longitudinal studies examining the effects of resistance training in untrained children and adolescents and in youth athletes.Results:The evidence indicates, that training induced changes in motor performance rely partly on enhanced neuromuscular control, and partly on morphological adaptation of muscles and tendons, such as changes in muscle, muscle fiber and tendon cross-sectional area, muscle composition, and tendon material properties, with the bone also adapting by increasing bone mineral content and cortical area.Conclusion:Although the training induced adaptations of the investigated tissues follows similar principles in children as in adults, the magnitude of the adaptive response appears to be more subtle. As studies investigating physiological adaptation in youth athletes are sparse, more research in this area is warranted to elucidate the specific physiological stimulus-response relationship necessary for effective training programs and injury prevention.

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Effect of androgenic-anabolic steroids and heavy strength training on patellar tendon morphological and mechanical properties

Journal of Applied Physiology ◽

10.1152/japplphysiol.01417.2012 ◽

2013 ◽

Vol 115 (1) ◽

pp. 84-89 ◽

Cited By ~ 39

Author(s):

Olivier R. Seynnes ◽

Sigitas Kamandulis ◽

Ramutis Kairaitis ◽

Christian Helland ◽

Emma-Louise Campbell ◽

...

Keyword(s):

Resistance Training ◽

Patellar Tendon ◽

Anabolic Steroids ◽

Tendon Injury ◽

Limit Strain ◽

Cross Sectional ◽

Collagen Remodeling ◽

History Of ◽

Androgenic Anabolic Steroids

Combined androgenic-anabolic steroids (AAS) and overloading affects tendon collagen metabolism and ultrastructure and is often associated with a higher risk of injury. The aim of this prospective study was to investigate whether such effects would be reflected in the patellar tendon properties of individuals with a history of long-term resistance training and AAS abuse (RTS group), compared with trained (RT) and untrained (CTRL) nonsteroids users. Tendon cross-sectional area (CSA), stiffness, Young's modulus, and toe limit strain were measured in vivo, from synchronized ultrasonography and dynamometry data. The patellar tendon of RT and RTS subjects was much stiffer and larger than in the CTRL group. However, stiffness and modulus were higher in the RTS group (26%, P < 0.05 and 30%, P < 0.01, respectively) than in the RT group. Conversely, tendon CSA was 15% ( P < 0.05) larger in the RT group than in RTS, although differences disappeared when this variable was normalized to quadriceps maximal isometric torque. Yet maximal tendon stress was higher in RTS than in RT (15%, P < 0.05), without any statistical difference in maximal strain and toe limit strain between groups. The present lack of difference in toe limit strain does not substantiate the hypothesis of changes in collagen crimp pattern associated with AAS abuse. However, these findings indicate that tendon adaptations from years of heavy resistance training are different in AAS users, suggesting differences in collagen remodeling. Some of these adaptations (e.g., higher stress) could be linked to a higher risk of tendon injury.

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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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Circulatory microRNAs are not effective biomarkers of muscle size and function in middle-aged men

AJP Cell Physiology ◽

10.1152/ajpcell.00395.2018 ◽

2019 ◽

Vol 316 (2) ◽

pp. C293-C298 ◽

Cited By ~ 2

Author(s):

Randall F. D’Souza ◽

Nina Zeng ◽

Sally D. Poppitt ◽

David Cameron-Smith ◽

Cameron J. Mitchell

Keyword(s):

Lean Mass ◽

Knee Extension ◽

Muscle Size ◽

Whole Body ◽

Regulatory Function ◽

Middle Aged ◽

Cross Sectional ◽

Total Body ◽

And Function ◽

Body Lean Mass

Loss of muscle size and strength with aging is a major cause of morbidity. Although muscle size and strength are measured by imaging or fiber cross-sectional staining and exercise testing, respectively, the development of circulatory biomarkers for these phenotypes would greatly simplify identification of muscle function deficits. MicroRNAs (miRNAs) are short noncoding RNAs that regulate gene translation and, thereby, contribute to muscle phenotype. To assess circulatory miRNAs (c-miRNAs) applicability as potential biomarkers of muscular phenotypes, fasting plasma and muscle samples were obtained from 50 middle-aged healthy men [mean (SD); age: 48.8 yr (SD 4.5); BMI: 26.6 kg/m2 (SD 3.3)]. RT-PCR of 38 miRNAs with known regulatory function within skeletal muscle identified four c-miRNAs (miR-221, miR-451a, miR-361, and miR-146a) related to either total body lean mass, leg lean mass, and 50% thigh cross-sectional area (CSA), but not strength. There was no relationship with the expression of these miRNAs in muscle. Six miRNAs within muscle were correlated with whole body lean mass, leg lean mass, and isometric knee extension torque (miR-133a and miR-146a), and 50% thigh CSA (miR-486, miR-208b, miR-133b, and miR-208a). Only miR-23b demonstrated a relationship between tissue and circulatory expression; however, only 10% of the variance was explained. miR-146a in both plasma and muscle was related to phenotype; however, no relationship between plasma and muscle expression was evident. A different subset of miRNAs correlated to muscle phenotype in muscle compared with plasma samples, suggesting that c-miRNA biomarkers of muscle phenotype are likely unrelated to muscle expression in healthy individuals.

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Determining the Force-Length-Velocity Relations of the Quadriceps Muscles: II. Maximum Muscle Stress

Journal of Applied Biomechanics ◽

10.1123/jab.15.2.191 ◽

1999 ◽

Vol 15 (2) ◽

pp. 191-199 ◽

Cited By ~ 11

Author(s):

John W. Chow ◽

Warren G. Darling ◽

James C. Ehrhardt

Keyword(s):

Knee Flexion ◽

Isometric Force ◽

Muscle Length ◽

Gravitational Effect ◽

Knee Extension ◽

Cross Sectional ◽

Average Value ◽

Isometric Knee Extension ◽

Maximum Effort ◽

Muscle Stress

The purpose of this study was to determine the maximum muscle stress (σ), defined as the maximum isometric force divided by the physiological cross-sectional area, of the quadriceps muscles for a pilot study involving musculoskeletal modeling. One female subject performed maximum effort isometric knee extension exercises on an isokinetic dynamometer at different attachment arm angles. The gravitational effect was taken into consideration when determining the isometric resultant knee torques at different knee flexion angles. The anatomical and geometric parameters of the quadriceps muscles were obtained from radiography and magnetic resonance imaging taken from the subject. The σ value was computed using me measured knee torques, musculoskeletal parameters data, and information reported in the literature. The computation procedures used in this study represented the first attempt to incorporate the concept of optimal muscle length in the determination of maximum muscle stress. The σ values obtained from the data for nine different knee flexion angles ranged from 21.4 to 30.5 N/cm2. The average value of 25.6 ± 2.6 N/cm2 is notably smaller than the human σ values reported in the literature, but is comparable to the σ values obtained from isolated muscles.

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An 8-week resistance training protocol is effective in adapting quadriceps but not patellar tendon shear modulus measured by Supersonic Shearwave Imaging

10.1101/434423 ◽

2018 ◽

Author(s):

P. Mannarino ◽

T. T. Matta ◽

F. O. Oliveira

Keyword(s):

Mechanical Properties ◽

Resistance Training ◽

Shear Modulus ◽

Patellar Tendon ◽

Vastus Lateralis ◽

Knee Extensor ◽

Muscle Thickness ◽

Knee Extension ◽

Post Intervention ◽

Training Protocol

ABSTRACTHabitual loading and resistance training (RT) can determine changes in muscle and tendon morphology but also in its mechanical properties. Conventional ultrasound (US) evaluation of these mechanical properties present limitations that can now be overcome with the advent of Supersonic Shearwave Imaging (SSI). The objective of this study was to analyze the Vastus Lateralis (VL) and patellar tendon (PT) mechanical properties adaptations to an 8-week RT protocol using SSI. We submitted 15 untrained health young men to an 8-week RT directed knee extensor mechanism. VL and PT shear modulus (μ) was assessed pre and post intervention with SSI. VL muscle thickness (VL MT) and knee extension torque (KT) was also measure pre and post intervention to ensure the RT efficiency. Significant increases were observed in VL MT and KT (pre= 2.40 ± 0.40 cm and post= 2.63 ± 0.35 cm, p = 0.0111, and pre= 294.66 ± 73.98 Nm and post= 338.93 ± 76.39 Nm, p = 0.005, respectively). The 8-week RT was also effective in promoting VL μ adaptations (pre= 4.87 ± 1.38 kPa and post= 9.08.12 ± 1.86 kPa, p = 0.0105), but not in significantly affecting PT μ (pre= 78.85 ± 7.37 kPa and post= 66.41 ± 7.25 kPa, p = 0.1287). The present study showed that an 8-week resistance training protocol was effective in adapting VL μ but not PT μ. Further investigation should be conducted with special attention to longer interventions, to possible PT differential individual responsiviness and to the muscle-tendon resting state tension environment.

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Effects of Concentric and Eccentric Training on the Stiffness and Blood Circulation of the Patellar Tendon

Sports Medicine International Open ◽

10.1055/s-0042-121000 ◽

2017 ◽

Vol 01 (02) ◽

pp. E43-E49 ◽

Cited By ~ 6

Author(s):

Keitaro Kubo ◽

Hideaki Yata

Keyword(s):

Oxygen Saturation ◽

Blood Volume ◽

Patellar Tendon ◽

Blood Circulation ◽

Training Group ◽

Knee Extensors ◽

Control Group ◽

Cross Sectional ◽

Tendon Stiffness ◽

Before And After

AbstractThe aim of the present study was to investigate the effects of concentric (CON) and eccentric (ECC) training on stiffness and blood circulation of the tendon, and clarify whether relative changes in tendon stiffness are related to those in tendon blood circulation. 17 subjects were assigned to training (n=9) and control (n=8) groups. Training group completed 12 weeks of unilateral training program for knee extensors. They performed 5 sets of CON or ECC at 80% of 1RM with 10 repetitions. Before and after training, cross-sectional area, stiffness, hysteresis, blood volume, and oxygen saturation of the patellar tendon were measured. Oxygen saturation significantly increased with CON and ECC. Stiffness significantly increased with CON but not with ECC. Other measured variables did not change after training. Furthermore, the relative change in tendon stiffness did not correlate with that in blood volume or oxygen saturation. In control group, measured variables did not change after training. These results suggest that tendon stiffness increased after CON but not after ECC; however no significant differences in the changes observed in size and blood circulation of the tendon were found between 2 protocols. Furthermore, changes in tendon stiffness were not related to those in tendon blood circulation.

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Analysis of Pharyngeal Airway Using Lateral Cephalogram vs CBCT Images: A Cross-sectional Retrospective Study

The Open Dentistry Journal ◽

10.2174/1874210601509010263 ◽

2015 ◽

Vol 9 (1) ◽

pp. 263-266 ◽

Cited By ~ 6

Author(s):

Pegah Bronoosh ◽

Leila Khojastepour

Keyword(s):

Region Of Interest ◽

Initial Examination ◽

Lateral Cephalogram ◽

Cross Sectional ◽

3 Dimensional ◽

Form And Function ◽

Pharyngeal Airway ◽

Volume Measurements ◽

Orthodontic Patients ◽

And Function

Background : As the basic biological relationship of form and function, changes in the normal pattern of nasopharyngeal space can profoundly affect the development of the craniofacial growth. The lateral cephalogram, part of the patient’s normal records for orthodontic treatment, may show some of these changes either at the initial examination or later during treatment. The validity of the information the lateral cephalogram may present, have been questioned previously. The aim of this study was to assess correlation between the area and the volume measurements of pharyngeal airway size in a lateral cephalogram and a 3-dimensional (3D) cone-beam computed tomography (CBCT) scan in adolescent subjects. Materials and Methods : CBCT scan and a lateral cephalogram of 35 subjects which were taken within 1 week were included in this study. Airway area of the region of interest from the lateral cephalogram and airway volume over the same of region of interest from the CBCT scan were assessed for all patients. The correlation between the area and the volume measurements were evaluated statistically by Pearson’s correlation coefficient test. Mann Whitney U Test was used for comparing the area and the volume measurements in different sex. Results : Strong correlation was found between lateral cephalogram and CBCT measurements of pharyngeal airway. (r=0.831). Conclusion : Pharyngeal airway area on a lateral cephalogram is correlated strongly with volumetric data on CBCT images. Henceforth the use of CBCT images for volume measurements in orthodontic patients can aid in the better evaluation of airways and acted as a diagnostic instrument in this area.

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