Conditioning of the Achilles tendon via ankle exercise improves correlations between sonographic measures of tendon thickness and body anthropometry

The Influence of Different Modes of Exercise on Healthy and Injured Tendons

Tendons are essential components of the musculoskeletal system that links the skeletal muscle to the skeleton. This dense connective tissue exhibits great plasticity. Therefore, research on the influence of types of exercise, including acute and long-term training, on the structural and mechanical properties of tendons in athletic and sedentary populations is of critical importance in the design of scientific-based exercise plans and effective tendinopathy treatment. Here, we review recent studies on the relationship between exercise and tendon health and tendinopathy repair to provide a general understanding of how exercise may reshape tendons.

Combined extracorporeal shockwave therapy and exercise for the treatment of tendinopathy: A narrative review

Tendinopathy is a chronic degenerative musculoskeletal disorder that is common in both athletes and the general population. Exercise and extracorporeal shockwave therapy (ESWT) is among the most common treatments used to mediate tendon healing and regeneration. The review presents the current understanding of mechanisms of action of ESWT and exercise in isolation and briefly synthesises evidence of their effectiveness for various tendinopathies. The central purpose of the review is to synthesize research findings investigating the combination of ESWT and exercise for five common tendinopathies (plantar heel pain, rotator cuff, lateral elbow, Achilles, and patellar tendinopathy) and provide recommendations on clinical applicability. Collectively, the available evidence indicates that ESWT combined with exercise in the form of eccentric training, tissue-specific stretching, or heavy slow resistance training are effective for specific tendinopathies and can therefore be recommended in treatment. Whilst there are at present a limited number of studies investigating combined EWST and exercise approaches, there is evidence to suggest that the combination improves outcomes in the treatment of plantar heel pain, Achilles, lateral elbow, and rotator cuff tendinopathy. However, despite overall positive outcomes in patellar tendinopathy, the combined treatment has not been shown at present to offer additional benefit over eccentric exercise alone.

Acute Effects of Resistance Training with Blood Flow Restriction on Achilles Tendon Thickness

The Achilles tendon is one of the strongest and thickest tendons of the human body. Several studies have reported an immediate decrease in Achilles tendon thickness after a single bout of resistance training. However, the effects of blood flow restriction training on Achilles tendon thickness have not been investigated. The purpose of this study was to investigate the acute effects of different regimens of resistance training on Achilles tendon thickness. Fiftytwo participants (27.3 ± 7 years; 177.6 ± 11 cm; 72.2 ± 13.7 kg) were randomly allocated into one of the three groups: low-intensity exercise without (LI, n = 13) and with blood flow restriction (LI-BFR, n = 24), and high-intensity exercise (HI, n = 15). Participants from LI and LI-BFR groups performed four sets (1 x 30 + 3 x 15 reps) at 30% 1RM, while the HI group performed four sets (1 x 30 with 30% 1RM + 3 x 10 reps with 75% 1RM). All groups performed a plantar flexion exercise. For the LI-BFR group, a blood pressure cuff was placed on the dominant calf and inflated at 30% of the individual´s occlusion pressure (47.6 ± 19.8 mmHg). Sonographic images of Achilles tendon thickness were taken at pre, immediately after, 60 min and 24 h following acute bouts of exercise. Achilles tendon thickness was significantly reduced immediately after, 60 min and 24 h post-LI-BFR exercise (pre: 4.4 ± 0.4 mm vs. IA: 3.8 ± 0.4 mm vs. 60 min: 3.7 ± 0.3 mm vs. 24 h: 4.1 ± 0.3 mm; p < 0.001), whereas Achilles tendon thickness was unchanged for HI and LI groups (p > 0.05). These results suggest that blood flow restriction training may be an effective strategy to stimulate a positive response in Achilles tendon thickness.

Proposing a Minimal Data Set of Musculoskeletal Ultrasound Imaging Biomarkers to Inform Clinical Practice: An Analysis Founded on the Achilles Tendon

Tendon integrity can be described using a wide range of biomarkers via specialized analysis software for images recorded by musculoskeletal ultrasonography. This study proposes a minimal biomarker data set to characterize Achilles tendon ultrasound images and to differentiate between symptomatic and asymptomatic Achilles tendon images. Forty-one individuals with unilateral Achilles tendinopathy and 35 healthy controls had their Achilles tendon images recorded bilaterally by ultrasonography in the longitudinal and transverse planes. A set of 22 biomarkers, organized around three dimensions (geometric, composition and texture), were computed in each plane. A symmetry index, reflecting relative side differences, was compared between groups and analyzed through principal component analysis to isolate biomarkers that best explained data variance. A specific minimal data set was identified by linear regression in the longitudinal (mean thickness, echogenicity, variance and homogeneity at 90°) and transverse (mean thickness, echogenicity and mean homogeneity) planes to characterize and differentiate Achilles tendon integrity.

Does Magnetic Resonance Imaging Provide Superior Reliability for Achilles and Patellar Tendon Cross-Sectional Area Measurements Compared with Ultrasound Imaging?

This study investigated the reliability of Achilles and patellar tendon cross-sectional area (CSA) measurement using ultrasound imaging (USI) and magnetic resonance imaging (MRI). Fifteen healthy adults were imaged twice on two occasions, interrupted by a tendon loading protocol. Tendon CSA segmentations were conducted by an experienced and an inexperienced rater blinded to information regarding subject, session and loading status. USI provided good test-retest reliability (intra-class correlation coefficient [ICC] 2,1 > 0.85, standard error of measurement [SEM] 5%-6%), while with MRI it was excellent (ICC 2,1 > 0.92, SEM 4%) for the experienced rater. This study suggests that MRI provides superior reliability for tendon CSA measurements compared with USI. However, the difference in reliability between the methods was small, and the results were inconclusive regarding objectivity and sensitivity to change when assessed based on the effect of loading. We concluded that both methods can be used for reliable CSA measurements of the Achilles and patellar tendons when using a highly standardized measurement protocol and when conducted by an experienced rater.

Quantitative ultrasound imaging of Achilles tendon integrity in symptomatic and asymptomatic individuals: reliability and minimal detectable change

Background

Quantifying the integrity of the Achilles tendon (AT) is a rehabilitation challenge. Adopting quantitative ultrasound measurements (QUS measurements) of the AT could fill this gap by 1) evaluating the test-retest reliability and accuracy of QUS measurements of the AT; 2) determining the best protocol for collecting QUS measurements in clinical practice.

Methods

A total of 23 ATs with symptoms of Achilles tendinopathy and 63 asymptomatic ATs were evaluated. Eight images were recorded for each AT (2 visits × 2 evaluators × 2 images). Multiple sets of QUS measurements were taken: geometric (thickness, width, area), first-order statistics (computed from a grayscale histogram distribution: echogenicity, variance, skewness, kurtosis, entropy) and texture features (computed from co-occurrence matrices: contrast, energy, homogeneity). A generalizability study quantified the reliability and standard error of measurement (accuracy) of each QUS measurement, and a decision study identified the best measurement taking protocols.

Results

Geometric QUS measurements demonstrated excellent accuracy and reliability. QUS measurements computed from the grayscale histogram distribution revealed poor accuracy and reliability. QUS measurements derived from co-occurrence matrices showed variable accuracy and moderate to excellent reliability. In clinical practice, using an average of the results of three images collected by a single evaluator during a single visit is recommended.

Conclusions

The use of geometric QUS measurements enables quantification of AT integrity in clinical practice and research settings. More studies on QUS measurements derived from co-occurrence matrices are warranted.

The Accuracy of the VISA-P Questionnaire, Single-Leg Decline Squat, and Tendon Pain History to Identify Patellar Tendon Abnormalities in Adult Athletes

Study Design Cross-sectional clinical assessment. Background Patellar tendinopathy is not always accompanied by patellar tendon abnormalities (PTAs). Thus, clinical screening tools to help identify patients with patellar tendon pain who have PTAs could enhance clinical decision making and patient prognosis. Objectives To test the diagnostic accuracy of the Victorian Institute of Sport Assessment-Patella (VISA-P) questionnaire, a single-leg decline squat (SLDS), tendon pain history, age, and years of sports participation to identify athletes with symptomatic patellar tendons who have PTAs confirmed on imaging. Methods Data provided by ultrasound examination, the VISA-P questionnaire, the SLDS, tendon pain history, age, and years of sport participation were collected in 43 athletes. A classification and regression tree (CART) model was developed to verify variables associated with PTA occurrence. Likelihood ratios (LRs) were computed for positive and negative tests. Results The SLDS, VISA-P questionnaire, and tendon pain history were associated with PTA occurrence. Athletes with negative results on all 3 tests (CART model) had a lower likelihood of having PTAs (negative LR = 0.3; 95% confidence interval [CI]: 0.2, 0.5). The isolated use of the SLDS or tendon pain history (positive LR = 4.2; 95% CI: 2.3, 7.14 and 4.5; 95% CI: 1.8, 11.1, respectively) had similar influence on probability of PTA presence compared to the CART model (positive LR = 4.1; 95% CI: 2.5, 6.3). Conclusion Although the objective was to investigate a clinical test to identify PTAs, the combined use of the tests had greater accuracy to identify individuals without PTAs. Level of Evidence Diagnosis, level 3b. J Orthop Sports Phys Ther 2016;46(8):673-680. Epub 3 Jul 2016. doi:10.2519/jospt.2016.6192.

TENDINOPATHY AND OBESITY

Introduction

Tendinopathies and tendon tears account for over 30% of all musculoskeletal consultations. Obesity, which is becoming one of the world´s most prevalent public health issues, may be associated with this condition.

Objective

To review the literature about tendinopathies and obesity association.

Methods

This is a descriptive exploratory study using the portal Medline. Literature in English language from 2006 to 2014 were reviewed.

Results

The pathogenesis of tendinopathies includes inflammatory, regenerative and degenerative processes that happen simultaneously from early to late phases of the disease. Mechanical stress upon tendons seems to be one of the most important factors to initiate the inflammatory response, but it´s not the only one that can deflagrate it: there are other extrinsic, genetic and metabolic factors that may be involved. Therefore, tendinopathies in obese patients can be due to tendon overload because of the excess of weight, but also because of increased production of pro-inflammatory mediators related to fat tissue such as adipokines. This pro-inflammatory state that obese people can suffer is known as adiposopathy, or sick fat syndrome. Weight loss is associated with decrease in adipokines and improvement of musculoskeletal symptoms.

Conclusion

The relation of obesity and tendinopathies is supported by evidences of recent studies, exemplified in this review of literature.

Three-dimensional morphology and strain of the Achilles free tendon immediately following eccentric heel drop exercise

Our understanding of the immediate effects of exercise on Achilles free tendon transverse morphology is limited to single site measurements acquired at rest using 2D ultrasound. The purpose of this study was to provide a detailed 3D description of changes in Achilles free tendon morphology immediately following a single clinical dose of exercise. Freehand 3D ultrasound was used to measure Achilles free tendon length, and regional cross-sectional area (CSA), medio-lateral (ML) diameter and antero-posterior (AP) diameter in healthy young adults (n=14) at rest and during isometric muscle contraction, immediately before and after 3×15 eccentric heel drops. Post-exercise reductions in transverse strain were limited to CSA and AP diameter in the mid-proximal region of the Achilles free tendon during muscle contraction. The change in CSA strain during muscle contraction was significantly correlated to the change in longitudinal strain (r=−0.72); and the change in AP diameter strain (r=0.64). Overall findings suggest the Achilles free tendon experiences a complex change in 3D morphology following eccentric heel drop exercise that manifests under contractile, but not rest conditions, is most pronounced in the mid-proximal tendon, and primarily driven by changes in AP diameter strain and not ML diameter strain.

Immediate effect of exercise on achilles tendon properties: systematic review

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.

The time course of in vivo recovery of transverse strain in high-stress tendons following exercise

OBJECTIVE

To evaluate the time course of the recovery of transverse strain in the Achilles and patellar tendon following a bout of resistance exercise.

METHODS

Seventeen healthy adults underwent sonographic examination of the right patellar (n=9) and Achilles (n=8) tendons immediately prior to and following 90 repetitions of weight-bearing quadriceps and gastrocnemius-resistance exercise performed against an effective resistance of 175% and 250% body weight, respectively. Sagittal tendon thickness was determined 20 mm from the enthesis and transverse strain, as defined by the stretch ratio, was repeatedly monitored over a 24 h recovery period.

RESULTS

Resistance exercise resulted in an immediate decrease in Achilles (t7=10.6, p<0.01) and patellar (t8=8.9, p<0.01) tendon thickness, resulting in an average transverse stretch ratio of 0.86±0.04 and 0.82±0.05, which was not significantly different between tendons. The magnitude of the immediate transverse strain response, however, was reduced with advancing age (r=0.63, p<0.01). Recovery in transverse strain was prolonged compared with the duration of loading and exponential in nature. The average primary recovery time was not significantly different between the Achilles (6.5±3.2 h) and patellar (7.1±3.2 h) tendons. Body weight accounted for 62% and 64% of the variation in recovery time, respectively.

CONCLUSIONS

Despite structural and biochemical differences between the Achilles and patellar tendon, the mechanisms underlying transverse creep recovery in vivo appear similar and are highly time dependent. These novel findings have important implications concerning the time required for the mechanical recovery of high-stress tendons following an acute bout of exercise.

Impact of age, sex, obesity, and steroid use on quinolone-associated tendon disorders

BACKGROUND

Quinolone antibiotics are associated with increased risk of tendinopathy. Identifying at-risk individuals has important clinical implications. We examined whether age, sex, glucocorticoid use, obesity, diabetes, and renal failure/dialysis predispose individuals to the adverse effects of quinolones.

METHODS

Among 6.4 million patients in The Health Improvement Network (THIN) database, 28,907 cases of Achilles tendonitis and 7685 cases of tendon rupture were identified in a case-crossover study. For each participant, we ascertained whether there was a prescription of a quinolone and comparison antibiotic within 30 days before the diagnosis of tendon disorder (case period) and a prescription of the same medications within 30 days 1 year before disease diagnosis (control period).

RESULTS

Use of quinolones was strongly associated with an increased risk of Achilles tendonitis (odds ratio [OR], 4.3; 95% confidence interval [CI], 3.2-5.7) and tendon rupture (OR, 2.0; 95% CI, 1.2-3.3). No association was found between the use of other antibiotics and either outcome. The association with Achilles tendonitis was stronger among participants who were aged more than 60 years (OR, 8.3 vs 1.6), who were nonobese (OR, 7.7 vs 2.4), and who used oral glucocorticoids (OR, 9.1 vs 3.2). The association was nonsignificantly stronger in women (OR, 5.0 vs 3.6), diabetic persons (OR, 7.0 vs 4.1), and those in renal failure or receiving dialysis (OR, 20.0 vs 3.9). The effect for tendon rupture was stronger in women, with borderline significance in glucocorticoid users and nonobese persons.

CONCLUSION

Quinolone-associated tendinopathy is more pronounced among elderly persons, nonobese persons, and individuals with concurrent use of glucocorticoids.