Maximum dorsiflexion increases Achilles tendon force during exercise for midportion Achilles tendinopathy

Effects of sensorimotor training on functional and pain outcomes in achilles tendinopathy: a systematic review

Background

Considering the neuromuscular alterations in Achilles tendinopathy (AT), sensorimotor training (SMT) might be beneficial to restore the neuromuscular capacity of the muscle-tendon complex and thereby improve patients' functions and alleviate symptoms. However, there is still a lack of knowledge concerning the effects of SMT on improving functional (e.g., strength) and pain outcomes in this population. Thus, the purpose of this study was to synthesize current evidence to analyze the efficacy of SMT in people with AT.

Methods

A systematic electronic search was performed in PubMed, Web of Science, and Cochrane Central Register of Controlled Trials from inception to December 2023. Studies applying SMT in people with AT investigating functional or clinical pain outcomes were considered. Protocols had to incorporate balance, stabilization, proprioception, or vibration training. Patients with insertional or mid-portion AT (≥18 years age) diagnosed with clinical or sonographic evaluation were included.

Results

The search yielded 823 records. A total of three randomized controlled trials were considered eligible for the analysis. Each trial used a different SMT protocol: balance training, balance with stabilization training, or whole-body vibration training (WBVT) with other co-interventions. Most functional and pain parameters improved compared to baseline. The first study reported a decrease in pain and an increase in performance (i.e., countermovement jump height) and endurance (i.e., number of heel-raises) by 12-week use of a balance training in addition to isometric, concentric/eccentric, and eccentric exercises. The second study evaluated the four weeks effect of SMT (balance and stabilization training plus eccentric exercises) in addition to passive physiotherapy (deep frictions, ice, ultrasound), resulting in an increased plantarflexion peak torque and reduced pain levels. The third study investigating WBVT reported at 12 weeks an increase in flexibility and a decrease in tendon pain.

Discussion

SMT in addition to other co-interventions (i.e., eccentric, isometric, concentric/eccentric training, physiotherapy) showed improvements in strength, performance, muscle flexibility, and alleviated clinical outcomes of pain. SMT might therefore be useful as part of a multimodal treatment strategy protocol in patients suffering from AT. However, due to the small number of studies included and the diversity of SMT protocols, the current evidence is weak; its additional effectiveness should be evaluated.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=467698, Identifier CRD42023467698.

Effectiveness of Kinesiotherapy in the Treatment of Achilles Tendinopathy-A Narrative Review

This narrative review of kinesiotherapy methods in the treatment of Achilles tendinopathy (AT) encompassed a diverse range of studies, including athletes and untrained people, healthy or injured, undergoing kinesiotherapy treatments. Most experimental studies (86%) reported results related to pain perception, 27% to the range of motion, and 27% to biomechanical assessment. However, the studies showed notable heterogeneity in the outcomes associated with the interventions, and, in this review of kinesiotherapy protocols for AT, a prominent observation emerged regarding their efficacy, suggesting a more favorable impact on pain and tendon stiffness management when comparing the measured parameters between the trained and untrained groups. The importance of tailoring the treatment approach based on the individual's athletic background and conditioning status is underscored. There is a need for personalized rehabilitation strategies in athletic populations. The average duration of kinesiotherapy in the treatment of tendinopathy was 15.3 weeks. This observation underscores the potential of kinesiotherapy interventions as a viable treatment option for individuals with Achilles tendon issues. These findings underscore the urgent need for further research to provide stakeholders with more comprehensive directions for future studies. The results may be helpful for doctors, physiotherapists, trainers, and researchers interested in this topic.

Intratendinous pressure of the Achilles tendon during exercise is related to the degree of tendon torsion

Torsion of the Achilles tendon (AT) enhances tensile strength, but a high degree of torsion might also be a risk factor for Achilles tendinopathy, due to greater internal compression exerted during tensile loading. However, evidence supporting the grounds for this assumption is lacking. Hence, we aimed to investigate the impact of AT torsion type on intratendinous pressure. Eighteen human fresh frozen cadaveric legs were mounted in a testing rig and a miniature pressure catheter was placed through ultrasound-guided insertion in the midportion region of the AT. Intratendinous pressure was measured during a simulated straight-knee calf stretch and eccentric heel drop. The AT was then carefully dissected and classified into Type I (least), Type II (moderate), and Type III (extreme) torsion. Of the ATs examined, nine were found to have Type I torsion (50%), nine Type II (50%), and none Type III. It was found that the intratendinous pressure of the AT increased exponentially with ankle dorsiflexion during both exercises (p < 0.001) and that this increase was greater in ATs with Type II torsion than Type I torsion (p < 0.05). This study provides the first biomechanical data to support the hypothesis that in athletes with a high degree of torsion in the AT, the midportion area will experience more internal compression during exercise, for example, calf stretching and eccentric heel drops. Whether this phenomenon is also associated with an elevated risk for Achilles tendinopathy needs further prospective investigation.

Therapeutic effects following extracorporeal shock wave therapy for insertional and non-insertional Achilles tendinopathy

Background

The treatment for Achilles tendinopathy varies widely, and there is no consensus regarding the optimal treatment for both non-insertional and insertional Achilles tendinopathy. The purpose of this study was to evaluate the clinical efficacy of extracorporeal shock wave therapy (ESWT) in the treatment of insertional and non-insertional Achilles tendinopathy (AT).

Methods

Sixty patients with AT were invited to participate in this study. Patients were allocated to one of two groups according to the site of the AT, including an insertional AT (IAT) group and a non-insertional AT (NIAT) group. ESWT was performed once a week for five weeks for both groups. The Victorian Institute of Sport Assessment-Achilles questionnaire (VISA-A) score and the visual analog scale (VAS) were used five times to evaluate the clinical outcomes, including before treatment, immediately after treatment, as well as one month, three months, and five years after treatment.

Results

At three months after treatment, the IAT group exhibited a significantly higher VISA-A score (82 ± 6 vs. 76 ± 11; p = 0.01) and a significantly lower VAS score (1 ± 1 vs. 2 ± 1; p < 0.001) when compared with the NIAT group. At the five-year assessment, the IAT group (1 ± 1) had a significantly lower VAS score than the NIAT group (2 ± 1) (p = 0.02), while no significant difference for the VISA-A score was observed between the groups (84 ± 8 vs. 84 ± 10; p = 0.98).

Conclusions

Extracorporeal shock wave treatment can improve the symptoms of both insertional and non-insertional AT. The IAT patients experienced better clinical outcomes compared with the NIAT patients.

Effects of exercise treatment on functional outcome parameters in mid-portion achilles tendinopathy: a systematic review

Exercise interventions are evident in the treatment of mid-portion Achilles tendinopathy (AT). However, there is still a lack of knowledge concerning the effect of different exercise treatments on improving a specific function (e.g., strength) in this population. Thus, this study aimed to systematically review the effect of exercise treatments on different functional outcomes in mid-portion AT. An electronic database of Pubmed, Web of Science, and Cochrane Central Register of Controlled Trials were searched from inception to 21 February 2023. Studies that investigated changes in plantar flexor function with exercise treatments were considered in mid-portion AT. Only randomized controlled trials (RCTs) and clinical controlled trials (CCTs) were included. Functional outcomes were classified by kinetic (e.g., strength), kinematic [e.g., ankle range of motion (ROM)], and sensorimotor (e.g., balance index) parameters. The types of exercise treatments were classified into eccentric, concentric, and combined (eccentric plus concentric) training modes. Quality assessment was appraised using the Physiotherapy Evidence Database scale for RCTs, and the Joanna Briggs Institute scale for CCTs. The search yielded 2,260 records, and a total of ten studies were included. Due to the heterogeneity of the included studies, a qualitative synthesis was performed. Eccentric training led to improvements in power outcomes (e.g., height of countermovement jump), and in strength outcomes (e.g., peak torque). Concentric training regimens showed moderate enhanced power outcomes. Moreover, one high-quality study showed an improvement in the balance index by eccentric training, whereas the application of concentric training did not. Combined training modalities did not lead to improvements in strength and power outcomes. Plantarflexion and dorsiflexion ROM measures did not show relevant changes by the exercise treatments. In conclusion, eccentric training is evident in improving strength outcomes in AT patients. Moreover, it shows moderate evidence improvements in power and the sensorimotor parameter "balance index". Concentric training presents moderate evidence in the power outcomes and can therefore be considered as an alternative to improve this function. Kinematic analysis of plantarflexion and dorsiflexion ROM might not be useful in AT people. This study expands the knowledge what types of exercise regimes should be considered to improve the functional outcomes in AT.

The load borne by the Achilles tendon during exercise: A systematic review of normative values

The Achilles tendon (AT) can be exposed to considerable stress during athletic activities and is often subject to pathologies such as tendinopathies. When designing a prevention or rehabilitation protocol, mechanical loading is a key factor to consider. This implies being able to accurately determine the load applied to the AT when performing exercises that stress this tendon. A systematic review was performed to synthesize the load borne by the AT during exercises/activities. Three databases (Pubmed, Embase and Cochrane) were searched for articles up to May 2021, and only the studies assessing the AT load in newtons relative to body-weight (BW) on humans during activities or exercises were included. Most of the 11 included studies assessed AT load when running or walking (N = 10), and only three tested exercises were usually performed during rehabilitation. The load on the tendon ranged from 2.7 to 3.95 BW when walking, from 4.15 to 7.71 BW when running, and from 0.41 to 7.3 BW according to the strengthening exercise performed. From the collected data, a progression of exercises progressively loading the Achilles tendon, as well as the possible connections with walking and running activities, could be defined. However, the trends highlighted in the relationship between tendon loading and walking or running speeds present some inconsistencies. Further research is still needed to clarify them, but also to complete the data set in healthy and injured people.

Biomechanics and lower limb function are altered in athletes and runners with achilles tendinopathy compared with healthy controls: A systematic review

Achilles tendinopathy (AT) is a debilitating injury in athletes, especially for those engaged in repetitive stretch-shortening cycle activities. Clinical risk factors are numerous, but it has been suggested that altered biomechanics might be associated with AT. No systematic review has been conducted investigating these biomechanical alterations in specifically athletic populations. Therefore, the aim of this systematic review was to compare the lower-limb biomechanics of athletes with AT to athletically matched asymptomatic controls. Databases were searched for relevant studies investigating biomechanics during gait activities and other motor tasks such as hopping, isolated strength tasks, and reflex responses. Inclusion criteria for studies were an AT diagnosis in at least one group, cross-sectional or prospective data, at least one outcome comparing biomechanical data between an AT and healthy group, and athletic populations. Studies were excluded if patients had Achilles tendon rupture/surgery, participants reported injuries other than AT, and when only within-subject data was available.. Effect sizes (Cohen's d) with 95% confidence intervals were calculated for relevant outcomes. The initial search yielded 4,442 studies. After screening, twenty studies (775 total participants) were synthesised, reporting on a wide range of biomechanical outcomes. Females were under-represented and patients in the AT group were three years older on average. Biomechanical alterations were identified in some studies during running, hopping, jumping, strength tasks and reflex activity. Equally, several biomechanical variables studied were not associated with AT in included studies, indicating a conflicting picture. Kinematics in AT patients appeared to be altered in the lower limb, potentially indicating a pattern of "medial collapse". Muscular activity of the calf and hips was different between groups, whereby AT patients exhibited greater calf electromyographic amplitudes despite lower plantar flexor strength. Overall, dynamic maximal strength of the plantar flexors, and isometric strength of the hips might be reduced in the AT group. This systematic review reports on several biomechanical alterations in athletes with AT. With further research, these factors could potentially form treatment targets for clinicians, although clinical approaches should take other contributing health factors into account. The studies included were of low quality, and currently no solid conclusions can be drawn.

Foundational Principles and Adaptation of the Healthy and Pathological Achilles Tendon in Response to Resistance Exercise: A Narrative Review and Clinical Implications

Therapeutic exercise is widely considered a first line fundamental treatment option for managing tendinopathies. As the Achilles tendon is critical for locomotion, chronic Achilles tendinopathy can have a substantial impact on an individual's ability to work and on their participation in physical activity or sport and overall quality of life. The recalcitrant nature of Achilles tendinopathy coupled with substantial variation in clinician-prescribed therapeutic exercises may contribute to suboptimal outcomes. Further, loading the Achilles tendon with sufficiently high loads to elicit positive tendon adaptation (and therefore promote symptom alleviation) is challenging, and few works have explored tissue loading optimization for individuals with tendinopathy. The mechanism of therapeutic benefit that exercise therapy exerts on Achilles tendinopathy is also a subject of ongoing debate. Resultingly, many factors that may contribute to an optimal therapeutic exercise protocol for Achilles tendinopathy are not well described. The aim of this narrative review is to explore the principles of tendon remodeling under resistance-based exercise in both healthy and pathologic tissues, and to review the biomechanical principles of Achilles tendon loading mechanics which may impact an optimized therapeutic exercise prescription for Achilles tendinopathy.

Modelling and in vivo evaluation of tendon forces and strain in dynamic rehabilitation exercises: a scoping review

OBJECTIVES

Although exercise is considered the preferred approach for tendinopathies, the actual load that acts on the tendon in loading programmes is usually unknown. The objective of this study was to review the techniques that have been applied in vivo to estimate the forces and strain that act on the human tendon in dynamic exercises used during rehabilitation.

DESIGN

Scoping review.

DATA SOURCES

Embase, PubMed, Web of Science and Google Scholar were searched from database inception to February 2021.

ELIGIBILITY CRITERIA

Cross-sectional studies available in English or Spanish language were included if they focused on evaluating the forces or strain of human tendons in vivo during dynamic exercises. Studies were excluded if they did not evaluate tendon forces or strain; if they evaluated running, walking, jumping, landing or no dynamic exercise at all; and if they were conference proceedings or book chapters.

DATA EXTRACTION AND SYNTHESIS

Data extracted included year of publication, study setting, study population characteristics, technique used and exercises evaluated. The studies were grouped by the types of techniques and the tendon location.

RESULTS

Twenty-one studies were included. Fourteen studies used an indirect methodology based on inverse dynamics, nine of them in the Achilles and five in the patellar tendon. Six studies implemented force transducers for measuring tendon forces in open carpal tunnel release surgery patients. One study applied an optic fibre technique to detect forces in the patellar tendon. Four studies measured strain using ultrasound-based techniques.

CONCLUSIONS

There is a predominant use of inverse dynamics, but force transducers, optic fibre and estimations from strain data are also used. Although these tools may be used to make general estimates of tendon forces and strains, the invasiveness of some methods and the loss of immediacy of others make it difficult to provide immediate feedback to the individuals.