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van Ark M, Cook JL, Docking SI, Zwerver J, Gaida JE, van den Akker-Scheek I, Rio E. Do isometric and isotonic exercise programs reduce pain in athletes with patellar tendinopathy in-season? A randomised clinical trial. J Sci Med Sport 2016; 19:702-6. [DOI: 10.1016/j.jsams.2015.11.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 11/14/2015] [Accepted: 11/27/2015] [Indexed: 10/22/2022]
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Earp JE, Newton RU, Cormie P, Blazevich AJ. Faster Movement Speed Results in Greater Tendon Strain during the Loaded Squat Exercise. Front Physiol 2016; 7:366. [PMID: 27630574 PMCID: PMC5005367 DOI: 10.3389/fphys.2016.00366] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 08/09/2016] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Tendon dynamics influence movement performance and provide the stimulus for long-term tendon adaptation. As tendon strain increases with load magnitude and decreases with loading rate, changes in movement speed during exercise should influence tendon strain. METHODS Ten resistance-trained men [squat one repetition maximum (1RM) to body mass ratio: 1.65 ± 0.12] performed parallel-depth back squat lifts with 60% of 1RM load at three different speeds: slow fixed-tempo (TS: 2-s eccentric, 1-s pause, 2-s concentric), volitional-speed without a pause (VS) and maximum-speed jump (JS). In each condition joint kinetics, quadriceps tendon length (LT), patellar tendon force (FT), and rate of force development (RFDT) were estimated using integrated ultrasonography, motion-capture, and force platform recordings. RESULTS Peak LT, FT, and RFDT were greater in JS than TS (p < 0.05), however no differences were observed between VS and TS. Thus, moving at faster speeds resulted in both greater tendon stress and strain despite an increased RFDT, as would be predicted of an elastic, but not a viscous, structure. Temporal comparisons showed that LT was greater in TS than JS during the early eccentric phase (10-14% movement duration) where peak RFDT occurred, demonstrating that the tendon's viscous properties predominated during initial eccentric loading. However, during the concentric phase (61-70 and 76-83% movement duration) differing FT and similar RFDT between conditions allowed for the tendon's elastic properties to predominate such that peak tendon strain was greater in JS than TS. CONCLUSIONS Based on our current understanding, there may be an additional mechanical stimulus for tendon adaptation when performing large range-of-motion isoinertial exercises at faster movement speeds.
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Affiliation(s)
- Jacob E Earp
- Human Performance Laboratory, Department of Kinesiology, University of Rhode IslandKingston, RI, USA; Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan UniversityJoondalup, WA, Australia
| | - Robert U Newton
- Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University Joondalup, WA, Australia
| | - Prue Cormie
- Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan UniversityJoondalup, WA, Australia; Institute for Health and Ageing, Australian Catholic UniversityMelbourne, VIC, Australia
| | - Anthony J Blazevich
- Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University Joondalup, WA, Australia
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KAY ANTHONYDAVID, RICHMOND DOMINIC, TALBOT CHRIS, MINA MINAS, BAROSS ANTHONYWILLIAM, BLAZEVICH ANTHONYJOHN. Stretching of Active Muscle Elicits Chronic Changes in Multiple Strain Risk Factors. Med Sci Sports Exerc 2016; 48:1388-96. [DOI: 10.1249/mss.0000000000000887] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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104
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Bogaerts S, Desmet H, Slagmolen P, Peers K. Strain mapping in the Achilles tendon – A systematic review. J Biomech 2016; 49:1411-1419. [DOI: 10.1016/j.jbiomech.2016.02.057] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 09/16/2015] [Accepted: 02/05/2016] [Indexed: 12/22/2022]
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105
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Wiesinger HP, Kösters A, Müller E, Seynnes OR. Effects of Increased Loading on In Vivo Tendon Properties: A Systematic Review. Med Sci Sports Exerc 2016; 47:1885-95. [PMID: 25563908 PMCID: PMC4535734 DOI: 10.1249/mss.0000000000000603] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Supplemental digital content is available in the text. Introduction In vivo measurements have been used in the past two decades to investigate the effects of increased loading on tendon properties, yet the current understanding of tendon macroscopic changes to training is rather fragmented, limited to reports of tendon stiffening, supported by changes in material properties and/or tendon hypertrophy. The main aim of this review was to analyze the existing literature to gain further insights into tendon adaptations by extracting patterns of dose-response and time-course. Methods PubMed/Medline, SPORTDiscus, and Google Scholar databases were searched for studies examining the effect of training on material, mechanical, and morphological properties via longitudinal or cross-sectional designs. Results Thirty-five of 6440 peer-reviewed articles met the inclusion criteria. The key findings were i) the confirmation of a nearly systematic adaptation of tendon tissue to training, ii) the important variability in the observed changes in tendon properties between and within studies, and iii) the absence of a consistent incremental pattern regarding the dose-response or the time-course relation of tendon adaptation within the first months of training. However, long-term (years) training was associated with a larger tendon cross-sectional area, without any evidence of differences in material properties. Our analysis also highlighted several gaps in the existing literature, which may be addressed in future research. Conclusions In line with some cross-species observations about tendon design, tendon cross-sectional area allegedly constitutes the ultimate adjusting parameter to increased loading. We propose here a theoretical model placing tendon hypertrophy and adjustments in material properties as parts of the same adaptive continuum.
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Affiliation(s)
- Hans-Peter Wiesinger
- 1Department of Sport Science and Kinesiology, University of Salzburg, Salzburg, AUSTRIA; and 2Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, NORWAY
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106
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Mersmann F, Bohm S, Schroll A, Boeth H, Duda GN, Arampatzis A. Muscle and tendon adaptation in adolescent athletes: A longitudinal study. Scand J Med Sci Sports 2015; 27:75-82. [PMID: 26644277 DOI: 10.1111/sms.12631] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2015] [Indexed: 12/31/2022]
Abstract
There is evidence that a non-uniform adaptation of muscle and tendon in young athletes results in increased tendon stress during mid-adolescence. The present longitudinal study investigated the development of the morphological and mechanical properties of muscle and tendon of volleyball athletes in a time period of 2 years from mid-adolescence to late adolescence. Eighteen elite volleyball athletes participated in magnetic resonance imaging and ultrasound-dynamometry sessions to determine quadriceps femoris muscle strength, vastus lateralis, medialis and intermedius morphology, and patellar tendon mechanical and morphological properties in mid-adolescence (16 ± 1 years) and late adolescence (18 ± 1 years). Muscle strength, anatomical cross-sectional area (CSA), and volume showed significant (P < 0.05) but moderate increases of 13%, 6%, and 6%, respectively. The increase of patellar tendon CSA (P < 0.05) was substantially greater (27%) and went in line with increased stiffness (P < 0.05; 25%) and reduced stress (P < 0.05; 9%). During late adolescence, a pronounced hypertrophy of the patellar tendon led to a mechanical strengthening of the tendon in relation to the functional and morphological development of the muscle. These adaptive processes may compensate the unfavorable relation of muscle strength and tendon loading capacity in mid-adolescence and might have implications on athletic performance and tendon injury risk.
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Affiliation(s)
- F Mersmann
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin School of Movement Science, Berlin, Germany
| | - S Bohm
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin School of Movement Science, Berlin, Germany
| | - A Schroll
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin School of Movement Science, Berlin, Germany
| | - H Boeth
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - G N Duda
- Berlin School of Movement Science, Berlin, Germany.,Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - A Arampatzis
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin School of Movement Science, Berlin, Germany
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107
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Johansson FR, Skillgate E, Adolfsson A, Jenner G, DeBri E, Swärdh L, Cools AM. Asymptomatic Elite Adolescent Tennis Players' Signs of Tendinosis in Their Dominant Shoulder Compared With Their Nondominant Shoulder. J Athl Train 2015; 50:1299-305. [PMID: 26651279 PMCID: PMC4741256 DOI: 10.4085/1062-6050-51.1.07] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
CONTEXT Tennis is an asymmetric overhead sport with specific muscle-activation patterns, especially eccentrically in the rotator cuff. Magnetic resonance imaging (MRI) findings in asymptomatic adolescent elite tennis players have not previously been reported. OBJECTIVE The first aim of the study was to describe MRI findings regarding adaptations or abnormalities, as well as muscle cross-sectional area (CSA), of the rotator cuff. The second aim of the study was to investigate the rotator cuff based on the interpretation of the MRI scans as normal versus abnormal, with the subdivision based on the grade of tendinosis, and its association with eccentric rotator cuff strength in the dominant arm (DA) of the asymptomatic elite adolescent tennis player. SETTING Testing environment at the radiology department of Medicinsk Röntgen AB. PATIENTS OR OTHER PARTICIPANTS Thirty-five asymptomatic elite tennis players (age = 17.4 ± 2.7 years) were selected based on ranking and exposure time. INTERVENTION(S) We assessed MRI scans and measured the CSA of the rotator cuff muscle. The non-DA (NDA) was used as a control. In addition, eccentric testing of the external rotators of the DA was performed with a handheld dynamometer. RESULTS The DA and NDA displayed different frequencies of infraspinatus tendinosis (grade 1 changes) (P < .05). Rotator cuff measurements revealed larger infraspinatus and teres minor CSA (P < .05) in the DA than in the NDA. Mean eccentric external-rotation strength in the DA stratified by normal tendon and tendinosis was not different between groups (P = .723). CONCLUSIONS Asymptomatic adolescent elite tennis players demonstrated infraspinatus tendinosis more frequently in the DA than in the NDA. Clinicians must recognize these tendon changes in order to modify conditioning and performance programs appropriately.
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Affiliation(s)
- Fredrik R. Johansson
- Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Belgium
| | - Eva Skillgate
- Institute of Environmental Medicine, Stockholm, Sweden
| | | | - Göran Jenner
- Medicinsk Röntgen AB Hötorget, Stockholm, Sweden
| | | | - Leif Swärdh
- OrthoCenter/IFK kliniken, Gothenburg, Sweden
| | - Ann M. Cools
- Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Belgium
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108
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Lionello G, Fognani R, Baleani M, Sudanese A, Toni A. Suturing the myotendinous junction in total hip arthroplasty: A biomechanical comparison of different stitching techniques. Clin Biomech (Bristol, Avon) 2015; 30:1077-82. [PMID: 26392227 DOI: 10.1016/j.clinbiomech.2015.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 08/31/2015] [Accepted: 09/01/2015] [Indexed: 02/07/2023]
Abstract
BACKGROUND The repair of the myotendinous junction following total hip arthroplasty is challenging as this region is the weakest part of the muscle structure. This study investigated the mechanical behaviour and the mode of failure of different suturing techniques of the myotendinous junction. A new asymmetrical stitch was compared to two widely used techniques, i.e. the simple stitch (two loops in parallel) and the figure-of-eight stitch. METHODS The ovine triceps brachii myotendinous junction was selected as the experimental model. Each technique was sewn in muscle belly on one side and in a polyester belt (no-tendon configuration) or in thin tendon (full configuration) on the other side. The former was chosen to determine the grasping power of the stitch on the muscle despite the tendon quality, the latter to simulate a very thin gluteus medius tendon. FINDINGS The new stitch showed a higher ultimate strength (+40%) compared to the two controls in the no-tendon configuration. In the full configuration, no significant increase was observed, although failure of the new stitch always occurred at the tendon side. Furthermore, the new stitch does not alter the stiffness of repair. INTERPRETATION The new stitch has a higher grasping power on muscle belly than the single passing-through stitches thanks to the multiple fixation points, which better distribute the load in the tissue. However, such performance can be fully exploited only in the presence of good quality tendons.
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Affiliation(s)
- Giacomo Lionello
- Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Roberta Fognani
- Laboratorio Prometeo, Istituto Ortopedico Rizzoli, Bologna, Italy
| | | | - Alessandra Sudanese
- Ortopedia-Traumatologia e Chirurgia protesica e dei reimpianti d'anca e di ginocchio, Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Aldo Toni
- Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Bologna, Italy; Ortopedia-Traumatologia e Chirurgia protesica e dei reimpianti d'anca e di ginocchio, Istituto Ortopedico Rizzoli, Bologna, Italy
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109
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Abstract
The majority of muscles have distinct tendinous attachments to bones; however, only a few tendons develop painful conditions. That simple observation prompts us to ask a few questions. Are there commonalities in morphology and pathology among the painful tendons? What contributes to the propensity for pathology in some, but not all, tendons? And, consequently, should all tendinopathies be managed equally? Two common tendinopathies are those affecting the Achilles and supraspinatus, which are presented in this special issue and serve as excellent models to discuss similarities and contrasts. J Orthop Sports Phys Ther 2015;45(11):829-832. doi:10.2519/jospt.2015.0114.
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110
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Abstract
Synopsis Tendinopathy is a very common disorder in both recreational and elite athletes. Many individuals have recurrent symptoms that lead to chronic conditions and termination of sports activity. Exercise has become a popular and somewhat efficacious treatment regime, and isolated eccentric exercise has been particularly promoted. In this clinical commentary, we review the relevant evidence for different exercise regimes in tendinopathy rehabilitation, with particular focus on the applied loads that are experienced by the tendon and how the exercise regime may affect these applied loads. There is no convincing clinical evidence to demonstrate that isolated eccentric loading exercise improves clinical outcomes more than other loading therapies. However, the great variation and sometimes insufficient reporting of the details of treatment protocols may hamper the interpretation of what may be the optimal exercise regime with respect to parameters such as load magnitude, speed of movement, and recovery period between exercise sessions. Future studies should control for these loading parameters, evaluate various exercise dosages, and think beyond isolated eccentric exercises to arrive at firm recommendations regarding rehabilitation of individuals with tendinopathies. J Orthop Sports Phys Ther 2015;45(11):853-863. Epub 14 Oct 2015. doi:10.2519/jospt.2015.5910.
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111
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Franz JR, Thelen DG. Depth-dependent variations in Achilles tendon deformations with age are associated with reduced plantarflexor performance during walking. J Appl Physiol (1985) 2015; 119:242-9. [PMID: 26023223 PMCID: PMC4526706 DOI: 10.1152/japplphysiol.00114.2015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 05/26/2015] [Indexed: 01/05/2023] Open
Abstract
The anatomical arrangement of the Achilles tendon (AT), with distinct fascicle bundles arising from the gastrocnemius and soleus muscles, may facilitate relatively independent behavior of the triceps surae muscles. A reduced capacity for sliding between adjacent tendon fascicles with age may couple gastrocnemius and soleus muscle behavior, thereby potentially contributing to diminished plantarflexor performance commonly observed in old adults. Nine healthy young (mean age, 23.9 yr) and eight healthy old (69.9 yr) adults walked at three speeds (0.75, 1.00, and 1.25 m/s) on a force-sensing treadmill. We coupled dynamic ultrasound imaging of the free AT with motion capture and inverse dynamic analyses to compute, in part: 1) depth-dependent variations in AT tissue displacements and elongations and 2) net ankle joint kinetics during push-off. The difference in displacements between superficial and deep AT regions, and in their corresponding elongations, did not differ between old and young adults at the slower two walking speeds (P > 0.61). However, old adults walked with 41% smaller depth-dependent variations in free AT displacements and elongations at 1.25 m/s (P = 0.02). These more uniform tendon deformations in old adults most strongly correlated with reduced peak ankle moment (R(2) = 0.40), but also significantly correlated with reduced peak power generation (R(2) = 0.15) and positive ankle work during push-off (R(2) = 0.19) (P > 0.01). Our findings: 1) demonstrate a potential role for nonuniform AT deformations in governing gastrocnemius and soleus muscle-tendon function and 2) allude to altered tendon behavior that may contribute to the age-related reduction in plantarflexor performance during walking.
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Affiliation(s)
- Jason R Franz
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, Wisconsin;
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112
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Zhang ZJ, Ng GYF, Fu SN. Effects of habitual loading on patellar tendon mechanical and morphological properties in basketball and volleyball players. Eur J Appl Physiol 2015; 115:2263-9. [DOI: 10.1007/s00421-015-3209-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 06/25/2015] [Indexed: 01/08/2023]
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113
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Bohm S, Mersmann F, Arampatzis A. Human tendon adaptation in response to mechanical loading: a systematic review and meta-analysis of exercise intervention studies on healthy adults. SPORTS MEDICINE-OPEN 2015; 1:7. [PMID: 27747846 PMCID: PMC4532714 DOI: 10.1186/s40798-015-0009-9] [Citation(s) in RCA: 224] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 01/29/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND The present article systematically reviews recent literature on the in vivo adaptation of asymptomatic human tendons following increased chronic mechanical loading, and meta-analyzes the loading conditions, intervention outcomes, as well as methodological aspects. METHODS The search was performed in the databases PubMed, Web of Knowledge, and Scopus as well as in the reference lists of the eligible articles. A study was included if it conducted (a) a longitudinal exercise intervention (≥8 weeks) on (b) healthy humans (18 to 50 years), (c) investigating the effects on mechanical (i.e., stiffness), material (i.e., Young's modulus) and/or morphological properties (i.e., cross-sectional area (CSA)) of tendons in vivo, and was reported (d) in English language. Weighted average effect sizes (SMD, random-effects) and heterogeneity (Q and I 2 statistics) of the intervention-induced changes of tendon stiffness, Young's modulus, and CSA were calculated. A subgroup analysis was conducted regarding the applied loading intensity, muscle contraction type, and intervention duration. Further, the methodological study quality and the risk of bias were assessed. RESULTS The review process yielded 27 studies with 37 separate interventions on either the Achilles or patellar tendon (264 participants). SMD was 0.70 (confidence interval: 0.51, 0.88) for tendon stiffness (N=37), 0.69 (0.36, 1.03) for Young's modulus (N=17), and 0.24 (0.07, 0.42) for CSA (N=33), with significant overall intervention effects (p<0.05). The heterogeneity analysis (stiffness: I 2 =30%; Young's modulus: I 2 =57%; CSA: I 2 =21%) indicated that differences in the loading conditions may affect the adaptive responses. The subgroup analysis confirmed that stiffness adaptation significantly (p<0.05) depends on loading intensity (I 2 =0%), but not on muscle contraction type. Although not significantly different, SMD was higher for interventions with longer duration (≥12 weeks). The average score of 71±9% in methodological quality assessment indicated an appropriate quality of most studies. CONCLUSIONS The present meta-analysis provides elaborate statistical evidence that tendons are highly responsive to diverse loading regimens. However, the data strongly suggests that loading magnitude in particular plays a key role for tendon adaptation in contrast to muscle contraction type. Furthermore, intervention-induced changes in tendon stiffness seem to be more attributed to adaptations of the material rather than morphological properties.
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Affiliation(s)
- Sebastian Bohm
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Philippstr. 13, Haus 11, 10115, Berlin, Germany
| | - Falk Mersmann
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Philippstr. 13, Haus 11, 10115, Berlin, Germany
| | - Adamantios Arampatzis
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Philippstr. 13, Haus 11, 10115, Berlin, Germany.
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114
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Hoffrén-Mikkola M, Ishikawa M, Rantalainen T, Avela J, Komi PV. Neuromuscular mechanics and hopping training in elderly. Eur J Appl Physiol 2014; 115:863-77. [DOI: 10.1007/s00421-014-3065-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 11/25/2014] [Indexed: 11/25/2022]
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115
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Milgrom Y, Milgrom C, Altaras T, Globus O, Zeltzer E, Finestone AS. Achilles tendons hypertrophy in response to high loading training. Foot Ankle Int 2014; 35:1303-8. [PMID: 25212862 DOI: 10.1177/1071100714550651] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Whether the human Achilles tendon undergoes hypertrophic changes as measured by an increase in cross-sectional area, in response to endurance training exercise remains in question. We investigated the hypothesis that transition from civilian life through 6 months of elite infantry training would induce adaptive Achilles tendon hypertrophy. METHODS Seventy-two new elite infantry recruits had the cross-sectional area of their Achilles tendons measured at a point 2.5 cm proximal to the Achilles insertion by ultrasound before beginning elite infantry training. Measurements were repeated by the same ultrasonographer for those recruits who were still in the training program at 6 months. Prior to beginning the study the intraobserver reliability of the ultrasonographer's Achilles tendon measurements was calculated (intraclass correlation coefficient = .96). Fifty-five recruits completed 6 months of training. RESULTS The mean cross-sectional area of their right Achilles tendon increased from 47.0 ± 11.2 to 50.2 ± 9.6 mm(2) (P = .037) and the left Achilles tendon from 47.2 ± 8.9 to 51.1 ± 8.3 mm(2) (P = .013). The change in cross-sectional area did not correlate with subject height, weight, prior sport history, or jumping and running abilities. CONCLUSIONS An abrupt stimulus of 6 months of elite infantry training was adequate to induce hypertrophic changes in the Achilles tendon. This is the first human prospective study showing an increase in the Achilles tendon cross-sectional area in response to rigorous endurance type training. The finding supports the hypothesis that the Achilles tendon in response to sufficiently high and sustained loading can remodel its morphological properties and thereby strengthen itself. LEVEL OF EVIDENCE Level II, etiology study.
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Affiliation(s)
- Yael Milgrom
- Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | | | - Talya Altaras
- Israel Defense Forces Medical Corps, Tel Hashomer, Israel Institute for Warrior Health Research, Tel Hashomer, Israel
| | - Opher Globus
- Israel Defense Forces Medical Corps, Tel Hashomer, Israel
| | - Ehud Zeltzer
- Israel Defense Forces Medical Corps, Tel Hashomer, Israel Institute for Warrior Health Research, Tel Hashomer, Israel
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116
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Koff MF, Pownder SL, Shah PH, Yang LW, Potter HG. Ultrashort echo imaging of cyclically loaded rabbit patellar tendon. J Biomech 2014; 47:3428-32. [DOI: 10.1016/j.jbiomech.2014.08.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 08/07/2014] [Accepted: 08/19/2014] [Indexed: 11/27/2022]
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117
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Bohm S, Mersmann F, Tettke M, Kraft M, Arampatzis A. Human Achilles tendon plasticity in response to cyclic strain: effect of rate and duration. ACTA ACUST UNITED AC 2014; 217:4010-7. [PMID: 25267851 DOI: 10.1242/jeb.112268] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
High strain magnitude and low strain frequency are important stimuli for tendon adaptation. Increasing the rate and duration of the applied strain may enhance the adaptive responses. Therefore, our purpose was to investigate the effect of strain rate and duration on Achilles tendon adaptation. The study included two experimental groups (N=14 and N=12) and a control group (N=13). The participants of the experimental groups exercised according to a reference protocol (14 weeks, four times a week), featuring a high strain magnitude (~6.5%) and a low strain frequency (0.17 Hz, 3 s loading/3 s relaxation) on one leg and with either a higher strain rate (one-legged jumps) or a longer strain duration (12 s loading) on the other leg. The strain magnitude and loading volume were similar in all protocols. Before and after the interventions, the tendon stiffness, Young's modulus and cross-sectional area were examined using magnetic resonance imaging, ultrasound and dynamometry. The reference and long strain duration protocols induced significantly increased (P<0.05) tendon stiffness (57% and 25%), cross-sectional area (4.2% and 5.3%) and Young's modulus (51% and 17%). The increases in tendon stiffness and Young's modulus were higher in the reference protocol. Although region-specific tendon hypertrophy was also detected after the high strain rate training, there was only a tendency of increased stiffness (P=0.08) and cross-sectional area (P=0.09). The control group did not show any changes (P=0.86). The results provide evidence that a high strain magnitude, an appropriate strain duration and repetitive loading are essential components for an efficient adaptive stimulus for tendons.
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Affiliation(s)
- Sebastian Bohm
- Humboldt-Universität zu Berlin, Department of Training and Movement Sciences, 10115 Berlin, Germany
| | - Falk Mersmann
- Humboldt-Universität zu Berlin, Department of Training and Movement Sciences, 10115 Berlin, Germany
| | - Martin Tettke
- Technische Universität Berlin, Department of Medical Technology, 10587 Berlin, Germany
| | - Marc Kraft
- Technische Universität Berlin, Department of Medical Technology, 10587 Berlin, Germany
| | - Adamantios Arampatzis
- Humboldt-Universität zu Berlin, Department of Training and Movement Sciences, 10115 Berlin, Germany
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118
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Altered tendon characteristics and mechanical properties associated with insertional achilles tendinopathy. J Orthop Sports Phys Ther 2014; 44:680-9. [PMID: 25103130 DOI: 10.2519/jospt.2014.5369] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
STUDY DESIGN Case-control laboratory study. OBJECTIVES To compare tendon characteristics (shape, composition) and mechanical properties (strain, stiffness) on the involved side of participants with insertional Achilles tendinopathy (IAT) to the uninvolved side and to controls, and to examine if severity of tendon pathology is associated with severity of symptoms during function. BACKGROUND Despite the severity and chronicity of IAT, the quality of theoretical evidence available to guide the development of exercise interventions is low. While tendon pathology of midportion Achilles tendinopathy has been described, there are few studies specific to IAT. METHODS Twenty individuals with unilateral IAT and 20 age- and sex-matched controls volunteered to participate. Ultrasound imaging was used to quantify changes in tendon shape (diameter) and composition (echogenicity). A combination of ultrasound and dynamometry was used to measure tendon mechanical properties (strain and stiffness) during passive ankle rotation toward dorsiflexion. Generalized estimating equations were used to examine the association between IAT, alterations in tendon properties, and participant demographics. Pearson correlation was used to examine the association between severity of tendon pathology and severity of symptoms (Victorian Institute of Sport Assessment-Achilles). RESULTS The side with IAT had a larger tendon diameter (P<.001), lower echogenicity (P<.001), higher strain (P = .011), and lower stiffness (P = .007) compared to the side without IAT and the controls. On the involved side of participants with IAT, a lower echogenicity correlated with higher severity of symptoms (r = 0.603, P = .010). CONCLUSION Ultrasound imaging combined with dynamometry can discriminate alterations in tendon shape, composition, and mechanics in participants with IAT. Future clinical trials for IAT may consider strategies to alter tendon characteristics and restore tendon mechanics.
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Sharifnezhad A, Marzilger R, Arampatzis A. Effects of load magnitude, muscle length and velocity during eccentric chronic loading on the longitudinal growth of the vastus lateralis muscle. ACTA ACUST UNITED AC 2014; 217:2726-33. [PMID: 24803466 DOI: 10.1242/jeb.100370] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The present study investigated the longitudinal growth of the vastus lateralis muscle using four eccentric exercise protocols with different mechanical stimuli by modifying the load magnitude, lengthening velocity and muscle length at which the load was applied. Thirty-one participants voluntarily participated in this study in two experimental and one control group. The first experimental group (N=10) exercised the knee extensors of one leg at 65% (low load magnitude) of the maximum isometric voluntary contraction (MVC) and the second leg at 100% MVC (high load magnitude) with 90 deg s(-1) angular velocity, from 25 to 100 deg knee angle. The second experimental group (N=10) exercised one leg at 100% MVC, 90 deg s(-1), from 25 to 65 deg knee angle (short muscle length). The other leg was exercised at 100% MVC, 240 deg s(-1) angular velocity (high muscle lengthening velocity) from 25 to 100 deg. In the pre- and post-intervention measurements, we examined the fascicle length of the vastus lateralis at rest and the moment-angle relationship of the knee extensors. After 10 weeks of intervention, we found a significant increase (~14%) of vastus lateralis fascicle length compared with the control group, yet only in the leg that was exercised with high lengthening velocity. The findings provide evidence that not every eccentric loading causes an increase in fascicle length and that the lengthening velocity of the fascicles during the eccentric loading, particularly in the phase where the knee joint moment decreases (i.e. deactivation of the muscle), seems to be an important factor for longitudinal muscle growth.
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Affiliation(s)
- Ali Sharifnezhad
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
| | - Robert Marzilger
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
| | - Adamantios Arampatzis
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
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Bohm S, Mersmann F, Marzilger R, Schroll A, Arampatzis A. Asymmetry of Achilles tendon mechanical and morphological properties between both legs. Scand J Med Sci Sports 2014; 25:e124-32. [DOI: 10.1111/sms.12242] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2014] [Indexed: 12/19/2022]
Affiliation(s)
- S. Bohm
- Department of Training and Movement Sciences; Humboldt-Universität zu Berlin; Berlin Germany
| | - F. Mersmann
- Department of Training and Movement Sciences; Humboldt-Universität zu Berlin; Berlin Germany
| | - R. Marzilger
- Department of Training and Movement Sciences; Humboldt-Universität zu Berlin; Berlin Germany
| | - A. Schroll
- Department of Training and Movement Sciences; Humboldt-Universität zu Berlin; Berlin Germany
| | - A. Arampatzis
- Department of Training and Movement Sciences; Humboldt-Universität zu Berlin; Berlin Germany
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121
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Rosengarten SD, Cook JL, Bryant AL, Cordy JT, Daffy J, Docking SI. Australian football players’ Achilles tendons respond to game loads within 2 days: an ultrasound tissue characterisation (UTC) study. Br J Sports Med 2014; 49:183-7. [DOI: 10.1136/bjsports-2013-092713] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Jeong S, Lee DY, Choi DS, Lee HD. Acute effect of heel-drop exercise with varying ranges of motion on the gastrocnemius aponeurosis-tendon's mechanical properties. J Electromyogr Kinesiol 2014; 24:375-9. [PMID: 24717405 DOI: 10.1016/j.jelekin.2014.03.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 02/11/2014] [Accepted: 03/10/2014] [Indexed: 11/28/2022] Open
Abstract
The objectives of this study was to investigate the acute effects of various magnitudes of tendon strain on the mechanical properties of the human medial gastrocnemius (MG) in vivo during controlled heel-drop exercises. Seven male and seven female volunteers performed two different exercises executed one month apart: one was a heel-drop exercise on a block (HDB), and the other was a heel-drop exercise on level floor (HDL). In each regimen, the subjects completed a session of 150 heel-drop exercises (15 repetitions×10 sets; with a 30 s rest following each set). Before and immediately after the heel-drop exercise, the ankle plantar flexor torque and elongation of the MG were measured using a combined measurement system of dynamometry and ultrasonography and then the MG tendon strain and stiffness were evaluated in each subject. The tendon stiffness measured prior to the exercises was not significantly different between the two groups 23.7±10.6N/mm and 24.1±10.0N/mm for the HDB and HDL, respectively (p>.05). During the heel-drop exercise, it was found that the tendon strain during the heel-drop exercise on a block (8.4±3.7%) was significantly higher than the strain measured on the level floor (5.4±3.8%) (p<.05). In addition, the tendon stiffness following the heel-drop exercise on a block (32.3±12.2N/mm) was significantly greater than the tendon stiffness measured following the heel-drop exercise on the level floor (25.4±11.4N/mm) (p<.05). The results of this study suggest that tendon stiffness immediately following a heel-drop exercise depends on the magnitude of tendon strain.
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Affiliation(s)
- Siwoo Jeong
- Department of Physical Education, College of Sciences in Education, Yonsei University, Seoul, Republic of Korea
| | - Dae-Yeon Lee
- Department of Silver Industrial Engineering, College of Future Human Resource Development, Kangnam University, Yongin, Republic of Korea
| | - Dong-Sung Choi
- Department of Physical Education, College of Sciences in Education, Yonsei University, Seoul, Republic of Korea
| | - Hae-Dong Lee
- Department of Physical Education, College of Sciences in Education, Yonsei University, Seoul, Republic of Korea.
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Obst SJ, Barrett RS, Newsham-West R. Immediate effect of exercise on achilles tendon properties: systematic review. Med Sci Sports Exerc 2014; 45:1534-44. [PMID: 23439426 DOI: 10.1249/mss.0b013e318289d821] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
INTRODUCTION Understanding the mechanical and morphological adaptation of the Achilles tendon (AT) in response to acute exercise could have important implications for athletic performance, injury prevention, and rehabilitation. The purpose of this study was to conduct a systematic review and critical evaluation of the literature to determine the immediate effect of a single bout of exercise on the mechanical and morphological properties of the AT in vivo. METHODS Five electronic research databases were systematically searched for intervention-based studies reporting mechanical and morphological properties of the AT after a single bout of exercise. RESULTS Searches revealed 3292 possible articles; 21 met the inclusion criteria. There is evidence that maximal isometric contractions and prolonged static stretching (>5 min) of the triceps surae complex cause an immediate decrease in AT stiffness, whereas prolonged running and hopping have minimal effect. Limited but consistent evidence exists, indicating that AT hysteresis is reduced after prolonged static stretching. Consistent evidence supports a reduction in free AT diameter (anterior-posterior) after dynamic ankle exercise, and this change appears most pronounced in the healthy tendon and after eccentric exercise. CONCLUSIONS The mechanical and morphological properties of the AT in vivo are affected by acute exercise in a mode- and dose-dependent manner. Transient changes in AT stiffness, hysteresis, and diameter after unaccustomed exercise modes and doses may expose the tendon to increased risk of strain injury and impact on the mechanical function of the triceps surae muscle-tendon unit.
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Affiliation(s)
- Steven J Obst
- School of Rehabilitation Sciences and Center for Musculoskeletal Research, Griffith Health Institute, Griffith University, Queensland, Australia.
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Obst SJ, Renault JB, Newsham-West R, Barrett RS. Three-dimensional deformation and transverse rotation of the human free Achilles tendon in vivo during isometric plantarflexion contraction. J Appl Physiol (1985) 2014; 116:376-84. [DOI: 10.1152/japplphysiol.01249.2013] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Freehand three-dimensional ultrasound (3DUS) was used to investigate longitudinal and biaxial transverse deformation and rotation of the free Achilles tendon in vivo during a voluntary submaximal isometric muscle contraction. Participants ( n = 8) were scanned at rest and during a 70% maximal voluntary isometric contraction (MVIC) of the plantarflexors. Ultrasound images were manually digitized to render a 3D reconstruction of the free Achilles tendon for the computation of tendon length, volume, cross-sectional area (CSA), mediolateral diameter (MLD), anteroposterior diameter (APD), and transverse rotation. Tendon longitudinal and transverse (CSA, APD, and MLD) deformation and strain at 70% MVIC were calculated relative to the resting condition. There was a significant main effect of contraction on tendon length and mean CSA, MLD, and APD ( P < 0.05), but no effect on tendon volume ( P = 0.70). Group mean transverse strains for CSA, MLD, and APD averaged over the length of the tendon were −5.5%, −8.7% and 8.7%, respectively. Peak CSA, MLD, and APD transverse strains all occurred between 40% and 60% of tendon length. Transverse rotation of the free tendon was negligible at rest but increased under load, becoming externally rotated relative to the calcaneal insertion. The relationship between longitudinal and transverse strains of the free Achilles tendon during muscle-induced elongation may be indicative of interfascicle reorganization. The finding that transverse rotation and strain peaked in midportion of the free Achilles tendon may have important implications for tendon injury mechanisms and estimation of tendon stress in vivo.
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Affiliation(s)
- Steven J. Obst
- School of Rehabilitation Sciences and Centre for Musculoskeletal Research, Griffith Health Institute, Griffith University, Queensland, Australia
| | | | - Richard Newsham-West
- School of Rehabilitation Sciences and Centre for Musculoskeletal Research, Griffith Health Institute, Griffith University, Queensland, Australia
| | - Rod S. Barrett
- School of Rehabilitation Sciences and Centre for Musculoskeletal Research, Griffith Health Institute, Griffith University, Queensland, Australia
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Grigg NL, Wearing SC, O’Toole JM, Smeathers JE. The effect of exercise repetition on the frequency characteristics of motor output force: Implications for Achilles tendinopathy rehabilitation. J Sci Med Sport 2014; 17:13-7. [DOI: 10.1016/j.jsams.2013.03.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 03/18/2013] [Accepted: 03/28/2013] [Indexed: 11/30/2022]
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Mersmann F, Bohm S, Schroll A, Boeth H, Duda G, Arampatzis A. Evidence of imbalanced adaptation between muscle and tendon in adolescent athletes. Scand J Med Sci Sports 2013; 24:e283-9. [PMID: 24372566 DOI: 10.1111/sms.12166] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2013] [Indexed: 11/29/2022]
Abstract
Adolescence may be regarded as a critical phase of tissue plasticity in young growing athletes, as the adaptation process of muscle-tendon unit is affected by both environmental mechanical stimuli and maturation. The present study investigated potential imbalances of knee extensor muscle strength and patellar tendon properties in adolescent compared with middle-aged athletes featuring long-term musculotendinous adaptations. Nineteen adolescent elite volleyball athletes [(A), 15.9 ± 0.6 years] and 18 middle-aged competitively active former elite volleyball athletes [(MA), 46.9 ± 0.6 years] participated in magnetic resonance imaging and ultrasound-dynamometry sessions to determine quadriceps femoris muscle strength, vastus lateralis morphology and patellar tendon mechanical and morphological properties. There was no significant age effect on the physiological cross-sectional area of the vastus lateralis and maximum knee extension moment (P > 0.05) during voluntary isometric contractions. However, the patellar tendon cross-sectional area was significantly smaller (A: 107.4 ± 27.5 mm(2) ; MA: 121.7 ± 39.8 mm(2) ) and the tendon stress during the maximal contractions was significantly higher in adolescent compared with the middle-aged athletes (A: 50.0 ± 10.1 MPa; MA: 40.0 ± 9.5 MPa). These findings provide evidence of an imbalanced development of muscle strength and tendon mechanical and morphological properties in adolescent athletes, which may have implications for the risk of tendon overuse injuries.
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Affiliation(s)
- F Mersmann
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.,Center for Sports Science and Sports Medicine, Berlin, Germany
| | - S Bohm
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.,Center for Sports Science and Sports Medicine, Berlin, Germany
| | - A Schroll
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.,Center for Sports Science and Sports Medicine, Berlin, Germany
| | - H Boeth
- Center for Sports Science and Sports Medicine, Berlin, Germany.,Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - G Duda
- Center for Sports Science and Sports Medicine, Berlin, Germany.,Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - A Arampatzis
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.,Center for Sports Science and Sports Medicine, Berlin, Germany
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127
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Malliaras P, Barton CJ, Reeves ND, Langberg H. Achilles and patellar tendinopathy loading programmes : a systematic review comparing clinical outcomes and identifying potential mechanisms for effectiveness. Sports Med 2013; 43:267-86. [PMID: 23494258 DOI: 10.1007/s40279-013-0019-z] [Citation(s) in RCA: 232] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
INTRODUCTION Achilles and patellar tendinopathy are overuse injuries that are common among athletes. Isolated eccentric muscle training has become the dominant conservative management strategy for Achilles and patellar tendinopathy but, in some cases, up to 45 % of patients may not respond. Eccentric-concentric progressing to eccentric (Silbernagel combined) and eccentric-concentric isotonic (heavy-slow resistance; HSR) loading have also been investigated. In order for clinicians to make informed decisions, they need to be aware of the loading options and comparative evidence. The mechanisms of loading also need to be elucidated in order to focus treatment to patient deficits and refine loading programmes in future studies. OBJECTIVES The objectives of this review are to evaluate the evidence in studies that compare two or more loading programmes in Achilles and patellar tendinopathy, and to review the non-clinical outcomes (potential mechanisms), such as improved imaging outcomes, associated with clinical outcomes. METHODS Comprehensive searching (MEDLINE, EMBASE, CINAHL, Current Contents and SPORTDiscus(™)) identified 403 studies. Two authors independently reviewed studies for inclusion and quality. The final yield included 32 studies; ten compared loading programmes and 28 investigated at least one potential mechanism (six studies compared loading programmes and investigated potential mechanisms). RESULTS This review has identified limited (Achilles) and conflicting (patellar) evidence that clinical outcomes are superior with eccentric loading compared with other loading programmes, questioning the currently entrenched clinical approach to these injuries. There is equivalent evidence for Silbernagel combined (Achilles) and greater evidence for HSR loading (patellar). The only potential mechanism that was consistently associated with improved clinical outcomes in both Achilles and patellar tendon rehabilitation was improved neuromuscular performance (e.g. torque, work, endurance), and Silbernagel-combined (Achilles) HSR loading (patellar) had an equivalent or higher level of evidence than isolated eccentric loading. In the Achilles tendon, a majority of studies did not find an association between improved imaging (e.g. reduced anteroposterior diameter, proportion of tendons with Doppler signal) and clinical outcomes, including all high-quality studies. In contrast, HSR loading in the patellar tendon was associated with reduced Doppler area and anteroposterior diameter, as well as greater evidence of collagen turnover, and this was not seen following eccentric loading. HSR seems more likely to lead to tendon adaptation and warrants further investigation. Improved jump performance was associated with Achilles but not patellar tendon clinical outcomes. The mechanisms associated with clinical benefit may vary between loading interventions and tendons. CONCLUSION There is little clinical or mechanistic evidence for isolating the eccentric component, although it should be made clear that there is a paucity of good quality evidence and several potential mechanisms have not been investigated, such as neural adaptation and central nervous system changes (e.g. cortical reorganization). Clinicians should consider eccentric-concentric loading alongside or instead of eccentric loading in Achilles and patellar tendinopathy. Good-quality studies comparing loading programmes and evaluating clinical and mechanistic outcomes are needed in both Achilles and patellar tendinopathy rehabilitation.
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Affiliation(s)
- Peter Malliaras
- Centre for Sports and Exercise Medicine, Mile End Hospital, Queen Mary, University of London, London, UK.
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Boivin GP, Platt KM, Corbett J, Reeves J, Hardy AL, Elenes EY, Charnigo RJ, Hunter SA, Pearson KJ. The effects of high-fat diet, branched-chainamino acids and exercise on female C57BL/6 mouse Achilles tendon biomechanical properties. Bone Joint Res 2013; 2:186-92. [PMID: 24021530 PMCID: PMC3774102 DOI: 10.1302/2046-3758.29.2000196] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Objectives The goals of this study were: 1) to determine if high-fat diet
(HFD) feeding in female mice would negatively impact biomechanical
and histologic consequences on the Achilles tendon and quadriceps
muscle; and 2) to investigate whether exercise and branched-chain
amino acid (BCAA) supplementation would affect these parameters
or attenuate any negative consequences resulting from HFD consumption. Methods We examined the effects of 16 weeks of 60% HFD feeding, voluntary
exercise (free choice wheel running) and BCAA administration in
female C57BL/6 mice. The Achilles tendons and quadriceps muscles
were removed at the end of the experiment and assessed histologically
and biomechanically. Results HFD feeding significantly decreased the Achilles tendon modulus
without histological alterations. BCAA administration significantly
decreased the stiffness of Achilles tendons in the exercised normal
diet mice. Exercise partially ameliorated both the weight gain and
glucose levels in the HFD-fed mice, led to a significant decrease
in the maximum load of the Achilles tendon, and an increase in the
average fibril diameter of the quadriceps femoris muscle. There
were significant correlations between body weight and several biomechanical
properties, demonstrating the importance of controlling obesity
for maintaining healthy tendon properties. Conclusions In summary, this study showed a significant impact of obesity
and body weight on tendon biomechanical properties with limited
effects of exercise and BCAAs. Cite this article: Bone Joint Res 2013;2:186–92.
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Affiliation(s)
- G P Boivin
- Wright State University Boonshoft Schoolof Medicine, 3640 Col. Glenn Highway, Dayton, Ohio45435, USA
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129
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Galloway MT, Lalley AL, Shearn JT. The role of mechanical loading in tendon development, maintenance, injury, and repair. J Bone Joint Surg Am 2013; 95:1620-8. [PMID: 24005204 PMCID: PMC3748997 DOI: 10.2106/jbjs.l.01004] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Tendon injuries often result from excessive or insufficient mechanical loading, impairing the ability of the local tendon cell population to maintain normal tendon function. The resident cell population composing tendon tissue is mechanosensitive, given that the cells are able to alter the extracellular matrix in response to modifications of the local loading environment. Natural tendon healing is insufficient, characterized by improper collagen fibril diameter formation, collagen fibril distribution, and overall fibril misalignment. Current tendon repair rehabilitation protocols focus on implementing early, well-controlled eccentric loading exercises to improve repair outcome. Tissue engineers look toward incorporating mechanical loading regimens to precondition cell populations for the creation of improved biological augmentations for tendon repair.
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Affiliation(s)
- Marc T. Galloway
- Cincinnati Sports Medicine and Orthopaedic Center, 7423 Mason Montgomery Road, Cincinnati, OH 45249
| | - Andrea L. Lalley
- Engineering Research Center, University of Cincinnati, 2901 Woodside Drive, ERC Room 701, Cincinnati, OH 45221. E-mail address for A.L. Lalley:
| | - Jason T. Shearn
- Engineering Research Center, University of Cincinnati, 2901 Woodside Drive, ERC Room 701, Cincinnati, OH 45221. E-mail address for A.L. Lalley:
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Ekizos A, Papatzika F, Charcharis G, Bohm S, Mersmann F, Arampatzis A. Ultrasound does not provide reliable results for the measurement of the patellar tendon cross sectional area. J Electromyogr Kinesiol 2013; 23:1278-82. [PMID: 24021864 DOI: 10.1016/j.jelekin.2013.08.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Revised: 08/07/2013] [Accepted: 08/08/2013] [Indexed: 11/28/2022] Open
Abstract
PURPOSE This study examined the reliability of patellar tendon cross sectional area (CSA) measurement using brightness mode ultrasonography. METHODS The patellar tendon CSA of fourteen participants was examined on two different days and at three different positions (proximal, median and distal). Five trials per day were conducted in each position, replacing the ultrasound probe on every trial. The images were examined by three different and equally experienced observers. We compared the mean of the five trials in each position to examine the day, observer and position effect. Further, Bland and Altman plots, root mean square (RMS) differences and intraclass correlation coefficients (ICC) were calculated. RESULTS There was a significant (p < 0.05) day, observer and position effect on the CSA, while the average ICC was 0.592. The Bland and Altman plots showed that differences between conditions or groups, should be in average lower than 37% or higher than 55% of the patellar tendon CSA to be important for clinical or intervention studies. CONCLUSION Our findings show low reliability of the method, which resulted from the low clarity and unclear visibility of tissue boundaries in the ultrasound images. Therefore, the measurement of the CSA of the patellar tendon using ultrasound does not provide accurate and reliable results.
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Affiliation(s)
- Antonis Ekizos
- Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Germany
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131
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Malliaras P, Kamal B, Nowell A, Farley T, Dhamu H, Simpson V, Morrissey D, Langberg H, Maffulli N, Reeves ND. Patellar tendon adaptation in relation to load-intensity and contraction type. J Biomech 2013; 46:1893-9. [PMID: 23773532 DOI: 10.1016/j.jbiomech.2013.04.022] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Revised: 04/20/2013] [Accepted: 04/23/2013] [Indexed: 11/26/2022]
Abstract
BACKGROUND Loading leads to tendon adaptation but the influence of load-intensity and contraction type is unclear. Clinicians need to be aware of the type and intensity of loading required for tendon adaptation when prescribing exercise. The aim of this study was to investigate the influence of contraction type and load-intensity on patellar tendon mechanical properties. METHOD Load intensity was determined using the 1 repetition maximum (RM) on a resistance exercise device at baseline and fortnightly intervals in four randomly allocated groups of healthy, young males: (1) control (no training); (2) concentric (80% of concentric-eccentric 1RM, 4×7-8); (3) standard load eccentric only (80% of concentric-eccentric 1RM, 4×12-15 repetitions) and (4) high load eccentric (80% of eccentric 1RM, 4×7-8 repetitions). Participants exercised three times a week for 12 weeks on a leg extension machine. Knee extension maximum torque, patellar tendon CSA and length were measured with dynamometry and ultrasound imaging. Patellar tendon force, stress and strain were calculated at 25%, 50%, 75% and 100% of maximum torque during isometric knee extension contractions, and stiffness and modulus at torque intervals of 50-75% and 75-100%. Within group and between group differences in CSA, force, elongation, stress, strain, stiffness and modulus were investigated. The same day reliability of patellar tendon measures was established with a subset of eight participants. RESULTS Patellar tendon modulus increased in all exercise groups compared with the control group (p<0.05) at 50-75% of maximal voluntary isometric contraction (MVIC), but only in the high eccentric group compared with the control group at 75-100% of MVIC (p<0.05). The only other group difference in tendon properties was a significantly greater increase in maximum force in the high eccentric compared with the control group (p<0.05). Five repetition maximum increased in all groups but the increase was significantly greater in the high load eccentric compared with the other exercise groups (p<0.05). CONCLUSION Load at different intensity levels and contraction types increased patellar tendon modulus whereas muscle strength seems to respond more to load-intensity. High load eccentric was, however, the only group to have significantly greater increase in force, stiffness and modulus (at the highest torque levels) compared with the control group. The effects and clinical applicability of high load interventions needs to be investigated further.
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Affiliation(s)
- Peter Malliaras
- Centre for Sports and Exercise Medicine, Queen Mary, University of London, UK.
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WEARING SCOTTC, HOOPER SUEL, PURDAM CRAIG, COOK JILL, GRIGG NICOLE, LOCKE SIMON, SMEATHERS JAMESE. The Acute Transverse Strain Response of the Patellar Tendon to Quadriceps Exercise. Med Sci Sports Exerc 2013; 45:772-7. [DOI: 10.1249/mss.0b013e318279a81a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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133
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Lower limb mechanical properties: determining factors and implications for performance. Sports Med 2013; 42:929-40. [PMID: 23009192 DOI: 10.1007/bf03262304] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Limb stiffness or musculotendinous stiffness (MTS) has previously been examined in relation to performance and characterized using a number of different methods. However, the fact that MTS shows only low to moderate correlations to performances may indicate a lack of understanding of this parameter. In addition to this, variation is seen between studies examining the same factors. To date, our understanding of MTS and its components are not complete and thus it is unclear which characteristic value represents the ideal index of stiffness as it relates to performance. Moreover, it is uncertain how MTS stiffness as a functional measure relates to performance, and also if there is an optimal amount of MTS stiffness for specific functions or tasks. The knowledge of the interplay of MTU stiffness as it relates to performance and injury risk is also poorly understood in that there is likely a disparity between levels of stiffness required to optimize performance and those required to minimize injury risk. The aim of this article is to review the literature as it describes the components of MTS and to discuss these in terms of their relationship to functional performance; consider adaptations of the MTU with training along with associated performance changes; highlight and discuss how stiffness may affect loading of the soft and bony tissues in terms of the MTU components and gender, with respect to risk of injury; discuss the apparent differences in the literature regarding associations of the various forms of stiffness index to function; suggest recommendations for training in light of adaptation of the muscle and tendon and injury risk in context of gender; and, finally, to highlight potential limitations of current methodologies and suggest further work to gain insight into the mechanisms of stiffness. It is hoped that by suggesting future work, a more detailed and comprehensive understanding of MTS will be gained, thus enabling appropriate interventions to optimally modify this parameter for specific requirements.
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Blazevich AJ, Cannavan D, Waugh CM, Fath F, Miller SC, Kay AD. Neuromuscular factors influencing the maximum stretch limit of the human plantar flexors. J Appl Physiol (1985) 2012; 113:1446-55. [PMID: 22923509 DOI: 10.1152/japplphysiol.00882.2012] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Maximum joint range of motion is an important parameter influencing functional performance and musculoskeletal injury risk. Nonetheless, a complete description of the muscle architectural and tendon changes that occur during stretch and the factors influencing maximum range of motion is lacking. We measured muscle-tendon elongation and fascicle lengthening and rotation sonographically during maximal plantar flexor stretches in 21 healthy men. Electromyogram (EMG) recordings were obtained synchronously with ultrasound and joint moment data, and H-reflex measurements were made with the ankle at neutral (0°) and dorsiflexed (50% maximal passive joint moment) positions; the maximum H amplitude (normalized to maximum M-wave amplitude; M(max)) and H-amplitude elicited at a stimulation intensity that evoked 10% M(max) were obtained. Maximal stretch was accomplished through significant muscle (14.9%; 30 mm) and tendon lengthening (8.4%; 22 mm). There were similar relative changes in fascicle length and angle, but planimetric modeling indicated that the contribution of fascicle rotation to muscle lengthening was small (<4 mm). Subjects with a greater range of motion showed less resistance to stretch and a greater passive joint moment at stretch termination than less flexible subjects (i.e., greater stretch tolerance). Also, greater fascicle rotation accompanied muscle elongation (9.7 vs. 5.9%) and there was a greater tendon length at stretch termination in more flexible subjects. Finally, a moderate correlation between the angle of EMG onset and maximum range of motion was obtained (r = 0.60, P < 0.05), despite there being no difference in H-reflex magnitudes between the groups. Thus clear differences in the neuromuscular responses to stretch were observed between "flexible" and "inflexible" subjects.
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Affiliation(s)
- A J Blazevich
- Centre for Exercise and Sports Science Research, School of Exercise and Health Sciences, Edith Cowan University, Joondalup, Australia.
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136
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Schleip R, Müller DG. Training principles for fascial connective tissues: scientific foundation and suggested practical applications. J Bodyw Mov Ther 2012; 17:103-15. [PMID: 23294691 DOI: 10.1016/j.jbmt.2012.06.007] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 06/16/2012] [Accepted: 06/18/2012] [Indexed: 02/07/2023]
Abstract
Conventional sports training emphasizes adequate training of muscle fibres, of cardiovascular conditioning and/or neuromuscular coordination. Most sports-associated overload injuries however occur within elements of the body wide fascial net, which are then loaded beyond their prepared capacity. This tensional network of fibrous tissues includes dense sheets such as muscle envelopes, aponeuroses, as well as specific local adaptations, such as ligaments or tendons. Fibroblasts continually but slowly adapt the morphology of these tissues to repeatedly applied challenging loading stimulations. Principles of a fascia oriented training approach are introduced. These include utilization of elastic recoil, preparatory counter movement, slow and dynamic stretching, as well as rehydration practices and proprioceptive refinement. Such training should be practiced once or twice a week in order to yield in a more resilient fascial body suit within a time frame of 6-24 months. Some practical examples of fascia oriented exercises are presented.
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Affiliation(s)
- Robert Schleip
- Fascia Research Group, Division of Neurophysiology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
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137
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Heinemeier KM, Skovgaard D, Bayer ML, Qvortrup K, Kjaer A, Kjaer M, Magnusson SP, Kongsgaard M. Uphill running improves rat Achilles tendon tissue mechanical properties and alters gene expression without inducing pathological changes. J Appl Physiol (1985) 2012; 113:827-36. [PMID: 22797314 DOI: 10.1152/japplphysiol.00401.2012] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Overuse Achilles tendinopathy is a common and challenging problem in sports medicine. Little is known about the etiology of this disorder, and the development of a good animal model for overuse tendinopathy is essential for advancing insight into the disease mechanisms. Our aim was to test a previously proposed rat model for Achilles tendon overuse. Ten adult male Sprague-Dawley rats ran on a treadmill with 10° incline, 1 h/day, 5 days/wk (17-20 m/min) for 12 wk and were compared with 12 control rats. Histological, mechanical, and gene-expression changes were measured on the Achilles tendons after the intervention, and local tendon glucose-uptake was measured before and after the intervention with positron emission tomography. No differences were detected between runners and controls in tissue histology or in glucose uptake, indicating that tendon pathology was not induced. Greater tendon tissue modulus (P < 0.005) and failure stress/body weight (P < 0.02) in runners compared with controls further supported that tendons successfully adapted to uphill running. Several genes of interest were regulated after 12 wk of running. Expression of collagen III and insulin-like growth factor I was increased, while collagen I was unchanged, and decreases were seen in noncollagen matrix components (fibromodulin and biglycan), matrix degrading enzymes, transforming growth factor-β1, and connective tissue growth factor. In conclusion, the tested model could not be validated as a model for Achilles tendinopathy, as the rats were able to adapt to 12 wk of uphill running without any signs of tendinopathy. Improved mechanical properties were observed, as well as changes in gene-expression that were distinctly different from what is seen in tendinopathy and in response to short-term tendon loading.
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Affiliation(s)
- K M Heinemeier
- Institute of Sports Medicine, Department of Orthopedic Surgery M81, Bispebjerg Hospital and Centre of Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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Cronin NJ, Barrett RS, Carty CP. Long-term use of high-heeled shoes alters the neuromechanics of human walking. J Appl Physiol (1985) 2012; 112:1054-8. [PMID: 22241055 DOI: 10.1152/japplphysiol.01402.2011] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
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.
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Affiliation(s)
- Neil J. Cronin
- Neuromuscular Research Centre, Department of Biology of Physical Activity, University of Jyväskylä, Finland; and
| | - Rod S. Barrett
- Musculoskeletal Research Program, Griffith Health Institute, Griffith University, Queensland, Australia
| | - Christopher P. Carty
- Musculoskeletal Research Program, Griffith Health Institute, Griffith University, Queensland, Australia
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Schulze F, Mersmann F, Bohm S, Arampatzis A. A wide number of trials is required to achieve acceptable reliability for measurement patellar tendon elongation in vivo. Gait Posture 2012; 35:334-8. [PMID: 22178032 DOI: 10.1016/j.gaitpost.2011.09.107] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 07/11/2011] [Accepted: 09/13/2011] [Indexed: 02/02/2023]
Abstract
The purpose of the current study was to examine the reproducibility of patellar tendon elongation measurements using brightness-mode ultrasonography (BMU) during isometric knee extension contractions. We hypothesized that the measurement of the patellar tendon elongation during only one maximal voluntary isometric knee extension contractions would not provide reliable results and that a wide number of trials is required to achieve acceptable reliability. Ten participants (eight male and two female) performed 10 isometric knee extension contractions on two separate days (5 trials on each day). Using a modified knee brace, the ultrasound probe was firmly adjusted in the sagittal plane overlying the patellar tendon. The registered ultrasound images were analyzed by three different but equally trained observers. The reproducibility was examined by the calculation of the within-day, between-day and overall coefficient of multiple correlations (wCMC, bCMC and oCMC). The Spearman-Brown prophecy formula was use to estimate the required trials to achieve the desired reliability. The wCMC, bCMC and oCMC were in average 0.824, 0.798 and 0.770, respectively, suggesting a rather moderate reproducibility of patellar tendon elongation measurements. For a high reliability (≥0.95) of tendon elongation measurements 5-6 trials are required. Finally, the results revealed an independence of the measurements from days and observers.
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Affiliation(s)
- Felix Schulze
- Humboldt-University Berlin, Department of Training and Movement Sciences, Berlin, Germany
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140
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Measurement of in vivo tendon function. J Shoulder Elbow Surg 2012; 21:149-57. [PMID: 22244057 DOI: 10.1016/j.jse.2011.10.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Revised: 10/29/2011] [Accepted: 10/31/2011] [Indexed: 02/01/2023]
Abstract
Chronic tendon pathologies (eg, rotator cuff tears, Achilles tendon ruptures) are common, painful, debilitating, and a significant source of medical expense. Treatment strategies for managing tendon pathologies vary widely in invasiveness and cost, with little scientific basis on which to base treatment selection. Conventional techniques for assessing the outcomes of physical therapy or surgical repair typically rely on patient-based assessments of pain and function, physical measures (eg, strength, range of motion, or stability), and qualitative assessments using magnetic resonance imaging or ultrasound. Unfortunately, these conventional techniques provide only an indirect assessment of tendon function. The inability to make a direct quantitative assessment of the tendon's mechanical capabilities may help to explain the relatively high rate of failed tendon repairs and has led to an interest in the development of tools for directly assessing in vivo tendon function. The purpose of this article is to review methods for assessing tendon function (ie, mechanical properties and capabilities) during in vivo activities. This review will describe the general principles behind the experimental techniques and provide examples of previous applications of these techniques. In addition, this review will characterize the advantages and limitations of each technique, along with its potential clinical utility. Future efforts should focus on developing broadly translatable technologies for quantitatively assessing in vivo tendon function. The ability to accurately characterize the in vivo mechanical properties of tendons would improve patient care by allowing for the systematic development and assessment of new techniques for treating tendon pathologies.
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141
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Fouré A, Cornu C, Nordez A. Is tendon stiffness correlated to the dissipation coefficient? Physiol Meas 2011; 33:N1-9. [DOI: 10.1088/0967-3334/33/1/n1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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142
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Kongsgaard M, Nielsen CH, Hegnsvad S, Aagaard P, Magnusson SP. Mechanical properties of the human Achilles tendon, in vivo. Clin Biomech (Bristol, Avon) 2011; 26:772-7. [PMID: 21392868 DOI: 10.1016/j.clinbiomech.2011.02.011] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 01/29/2011] [Accepted: 02/17/2011] [Indexed: 02/07/2023]
Abstract
BACKGROUND Ultrasonography has been widely applied for in vivo measurements of tendon mechanical properties. Assessments of human Achilles tendon mechanical properties have received great interest. Achilles tendon injuries predominantly occur in the tendon region between the Achilles-soleus myotendinous junction and Achilles-calcaneus osteotendinous junction i.e. in the free Achilles tendon. However, there has been no adequate ultrasound based method for quantifying the mechanical properties of the free human Achilles tendon. This study aimed to: 1) examine the mechanical properties of the free human Achilles tendon in vivo by the use of ultrasonography and 2) assess the between-day reproducibility of these measurements. METHODS Ten male subjects had the Achilles tendon moment arm length, Achilles tendon cross sectional area and free Achilles tendon length determined. All subjects performed isometric plantarflexion ramp contractions to assess between-day reproducibility on two separate days. Simultaneous ultrasonography based measurements of Achilles-soleus myotendinous junction and Achilles-calcaneus osteotendinous junction displacement together with Achilles tendon force estimates yielded free Achilles tendon mechanical properties. FINDINGS Free Achilles tendon maximal force, deformation and stiffness were 1924 (SD 229) N, 2.2 (SD 0.6) mm and 2622 (SD 534) N/mm on day 1. For between-day reproducibility there were no significant differences between days for free Achilles tendon mechanical properties. The between-day correlation coefficient and typical error percent were 0.81 and 5.3% for maximal Achilles tendon force, 0.85 and 11.8% for maximal Achilles tendon deformation and 0.84 and 8.8% for Achilles tendon stiffness respectively. Last, osteotendinous junction proximal displacement on average contributed with 71 (SD 12) % of proximal myotendinous junction displacement. INTERPRETATION This study, for the first time, presents an ultrasonography based in vivo method for measurement of free AT mechanical properties. The method is applicable for evaluation of free human Achilles tendon mechanical properties in relation to training, injury and rehabilitation.
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Affiliation(s)
- M Kongsgaard
- Institute of Sports Medicine, Dept. Othopedic Surgery M, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Denmark.
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