Comparison of Lower Limb Muscle Activity during Eccentric and Concentric Exercises in Runners with Achilles Tendinopathy

Ultrasonographic measurements of gastro-soleus fascia thickness in midportion Achilles tendinopathy: A case-control study

BACKGROUND

The Achilles tendon is one of the thickest, largest, and strongest tendons in the human body. Biomechanically, the AT represents the conjoint tendon of the triceps surae muscle, placed in series with the plantar fascia (PF) to ensure force transmission from the triceps surae toward the toes during walking, running, and jumping. Commonly encountered in the diagnostic evaluation of heel pain, Achilles tendinopathy (AT) refers to a combination of pathological changes affecting the tendon itself often resulting from excessive repetitive stress and overuse. Nevertheless, increasing evidence demonstrates that structural alterations due to overuse or abnormal patterns of skeletal muscle activity are not necessarily restricted to the muscles or tendons but can also affect the fascial tissue. At the same time, there has been recent discussion regarding the role of the fascial tissue as a potential contributor to the pathophysiological mechanisms of the development of several musculoskeletal disorders including tendinopathies. To the best of our knowledge, ultrasound (US) imaging studies on the fascial structures related to the triceps surae complex, as well as their possible correlation with Achillodynia have never been presented in the current literature.

METHODS

In the present study, a comparative US imaging evaluation of textural features of the suro-Achilleo-plantar complex was performed in 14 healthy controls and 14 symptomatic subjects complaining of midportion AT. The thickness of the Achilles tendon, paratenon, intermuscular fascia, and PF has been assessed with US. In addition, both groups underwent the Victorian Institute of Sport Assessment-Achilles (VISA-A), a disease-specific questionnaire that measures the severity of symptoms of AT. Correlations between quantitative ultrasound measures and VISA-A scores were determined through Pearson or Spearman's rho correlations.

RESULTS

Our ultrasonographic findings revealed statistically significant differences (p<0.05) in Achilles tendon and paratenon thicknesses between AT patients and controls. No significant differences were observed between groups in PF at the calcaneal insertion as all mean measures were within the expected range of a normal PF on US imaging. In contrast, in tendinopathic subjects, the deep intermuscular fascia between medial gastrocnemius (MG) and soleus (SOL) muscles is significantly (p<0.01) and considerably thickened compared to those of healthy subjects. Moderate correlations exist between tendon and paratenon thicknesses (r= 0.54, p= 0.04) and between MG-SOL fascia and tendon thicknesses (r= 0.58, p= 0.03). Regarding symptom severity and US morphological findings, the Spearman ρ test showed no correlation.

CONCLUSIONS

Our data demonstrate that, in symptomatic subjects, US alterations are not restricted to paratenon and intratendinous areas, but also affect upstream structures along the myofascial chain, resulting in thickening of the fascia interposed between MG and SOL muscles. Moreover, positive correlations were found between MG-SOL fascia thickening and abnormalities in AT, paratenon, and symptom severity. Thus, US alterations in the fascial system should be interpreted within the clinical context of patients with AT as they may in turn represent important predictors of subsequent clinical outcomes and could help healthcare professionals and clinicians to refine non-operative treatment strategies and rehabilitation protocols for this disease.

Can pelvic floor muscle training positions be selected according to the functional status of pelvic floor muscles?

Background

Pelvic floor muscle (PFM) training varies according to the functional status of PFM. It is used to strengthen underactive PFM and relax overactive PFM.

Aim

This study aimed to determine the appropriate PFM training positions according to the functional status of the PFM in women with pelvic floor dysfunction.

Materials and Methods

Seventy-six women diagnosed with pelvic floor dysfunction were included. After the digital palpation, participants were divided into four groups according to the functional status of PFM: normal, overactive, underactive, and nonfunctional. Participants' PFM and abdominal muscle functions were assessed with superficial electromyography in three positions (modified butterfly pose-P1, modified child pose-P2, and modified deep squat with block pose-P3). Friedman's analysis of variance and the Kruskal-Wallis test were used to assess whether the function of the muscles differed according to the functional status of the PFM and training positions.

Results

Normal PFM maximally contracted and relaxed in P1, whereas nonfunctional PFM was in P3 (P > 0.05). Overactive and underactive PFM was most contracted in P2 (P > 0.05) and relaxed in P1 (P < 0.001). In each functional state of the PFM, all abdominal muscles were most relaxed in P1, while their most contracted positions varied (P < 0.05).

Conclusion

This study showed that the positions in which the PFM relaxes and contracts the most may vary according to the functional status of the PFM. Therefore, different PFM training positions may be preferred according to the functional status of the PFM in women with pelvic floor dysfunction. However, more study needs to be done in this subject.

Neuromuscular and structural tendon adaptations after 6 weeks of either concentric or eccentric exercise in individuals with non-insertional Achilles tendinopathy: protocol for a randomised controlled trial

INTRODUCTION

There is limited evidence on the neural strategies employed by the central nervous system to control muscle force in the presence of non-insertional Achilles tendinopathy (NIAT). Additionally, the neuromuscular mechanisms by which exercise may help to resolve tendon pain remain unclear.

OBJECTIVE

This study aims to first establish changes in the gastrocnemius-soleus motor unit firing properties after applying a training protocol of 6 weeks based on either controlled eccentric or concentric contractions in individuals with NIAT. Second, we want to determine changes in the level of pain and function and mechanical and structural properties of the Achilles tendon after applying the same training protocol. Additionally, we want to compare these variables at baseline between individuals with NIAT and asymptomatic controls.

METHODS AND ANALYSIS

A total of 26 individuals with chronic (>3 months) NIAT and 13 healthy controls will participate in the study. Individuals with NIAT will be randomised to perform eccentric or concentric training for 6 weeks. Motor unit firing properties of the medial gastrocnemius, lateral gastrocnemius and soleus muscles will be assessed using high-density surface electromyography, as well as Achilles tendon length, cross-sectional area, thickness and stiffness using B-mode ultrasonography and shear wave elastography. Moreover, participants will complete a battery of questionnaires to document their level of pain and function.

ETHICS AND DISSEMINATION

Ethical approval (ERN-20-0604A) for the study was obtained from the Science, Technology, Engineering and Mathematics Ethical Review Committee of the University of Birmingham. The results of the study will be published in peer-review journals.

TRIAL REGISTRATION NUMBER

ISRCTN46462385.

Are Plantarflexor Muscle Impairments Present Among Individuals with Achilles Tendinopathy and Do They Change with Exercise? A Systematic Review with Meta-analysis

Background

Understanding plantarflexor muscle impairments among individuals with Achilles tendinopathy (AT) may help to guide future research and inform clinical management of AT. Therefore, the aim of this review is to evaluate plantarflexor muscle impairments among individuals with AT and whether plantarflexor muscle function changes following resistance training interventions.

Methods

We searched relevant databases including Cochrane Central Register of Controlled Trials, Ovid (MEDLINE, EMBASE, AMED) and EBSCO (CINAHL Plus and SPORTDiscus) up to September 2020. Studies investigating plantarflexor muscle function were included if they met the following criteria: (1) any study design enabled comparison of plantarflexor muscle function between individuals with and without AT, or the affected and unaffected side of individuals with unilateral AT, and (2) any studies enabled investigation of change in plantarflexion muscle function over time with use of resistance training intervention. We included studies that recruited adults with either insertional or mid-portion AT of any duration. Study selection, quality assessment and data extraction were undertaken independently by two reviewers. Discrepancies were resolved via discussion, or by consulting a third reviewer where necessary. The Joanna Briggs Institute (JBI) critical appraisal tools specific to each study design were used to assess the methodological quality of included studies. Grading the strength of evidence for each outcome was determined according to the quality and number of studies.

Results

A total of 25 studies (545 participants) met inclusion. Participants’ mean age was 40 ± 7 years old. Six studies were high quality for all domains, while the remaining were susceptible to the risk of bias (e.g. selection criteria, reporting findings). This review identified moderate evidence that individuals with AT have impairment in maximal plantarflexor torque (seven studies including one with a mixed population) on their affected side, compared with the unaffected side. Impairments were modest (9% and 13% [pooled effect divided by mean of the unaffected side scores]) and of uncertain clinical importance. The remaining evidence, primarily among individuals with mid-portion AT, showed conflicting impairments for plantarflexor function (i.e. explosive strength and endurance) between sides. There was limited to very limited evidence for improvement in plantarflexor endurance (7% and 23%) but not power or strength (five studies including one with a mixed population for strength) over time, despite individuals undertaking several weeks of resistance training.

Conclusions

Plantarflexor impairments appear more common between sides than compared with control groups but given limitations in the literature further exploration of these relationships is needed.

Registration

PROSPERO Database; number CRD42019100747.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40798-021-00308-8.

A novel murine muscle loading model to investigate Achilles musculotendinous adaptation

Achilles tendinopathy is a debilitating condition affecting the entire spectrum of society and a condition that increases the risk of tendon rupture. Effective therapies remain elusive, as anti-inflammatory drugs and surgical interventions show poor long-term outcomes. Eccentric loading of the Achilles muscle-tendon unit is an effective physical therapy for treatment of symptomatic human tendinopathy. Here, we introduce a novel mouse model of hindlimb muscle loading designed to achieve a tissue-targeted therapeutic exercise. This model includes the application of tissue (muscle and tendon)-loading "doses," coupled with ankle dorsiflexion and plantarflexion, inspired by human clinical protocols. Under computer control, the foot was rotated through the entire ankle joint range of motion while the plantar flexors simultaneously contracted to simulate body mass loading, consistent with human therapeutic exercises. This approach achieved two key components of the heel drop and raise movement: ankle range of motion coupled with body mass loading. Model development entailed the tuning of parameters such as footplate speed, number of repetitions, number of sets of repetitions, treatment frequency, treatment duration, and treatment timing. Initial model development was carried out on uninjured mice to define a protocol that was well tolerated and nondeleterious to tendon biomechanical function. When applied to a murine Achilles tendinopathy model, muscle loading led to a significant improvement in biomechanical outcome measures, with a decrease in cross-sectional area and an increase in material properties, compared with untreated animals. Our model facilitates the future investigation of mechanisms whereby rehabilitative muscle loading promotes healing of Achilles tendon injuries.NEW & NOTEWORTHY We introduce a novel mouse model of hindlimb muscle loading designed to achieve a tissue-targeted therapeutic exercise. This innovative model allows for application of muscle loading "doses," coupled with ankle dorsiflexion and plantarflexion, inspired by human loading clinical treatment. Our model facilitates future investigation of mechanisms whereby rehabilitative muscle loading promotes healing of Achilles tendon injuries.

Achilles Pain, Stiffness, and Muscle Power Deficits: Midportion Achilles Tendinopathy Revision 2018

The Orthopaedic Section of the American Physical Therapy Association (APTA) has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability, and Health (ICF). The purpose of these revised clinical practice guidelines is to review recent peer-reviewed literature and make recommendations related to midportion Achilles tendinopathy. J Orthop Sports Phys Ther 2018;48(5):A1-A38. doi:10.2519/jospt.2018.0302.

Effectiveness of Eccentric Exercise and a Vibration or Cryotherapy Program in Enhancing Rectus Abdominis Muscle Thickness and Inter-Rectus Distance in Patients with Chronic Mid-Portion Achilles Tendinopathy: A Randomized Clinical Trial

Purpose: Abdominal muscles are key in maintaining body stability and balance and an improvement in the functioning of these muscles could influence the rehabilitation process in lower limb pathologies such as Achilles Tendinopathy (AT). The aim was to explore whether calf eccentric exercise (EE) with vibration training was more effective at causing adaptation to the rectus anterior (RA) thickness and inter-rectus distance (IRD) than calf EE with cryotherapy. Methods: The investigation was a single-blinded, randomized, controlled clinical trial (NCT03515148). Sixty-one individuals diagnosed with mid-portion AT were recruited and divided in two groups: group A (n = 30) followed an EE with vibration program and group B (n = 31) an EE program with cryotherapy, for 12-weeks. RA muscle thickness and IRD were measured in maximal isometric contraction and at rest as an indication of superficial abdominal muscle activation. Results: IRD measures showed a significant (P < 0.05) decrease at baseline, 4 and at 12-weeks in both groups, but no significant differences were observed between the intervention groups. RA thickness was significantly increased (P < 0.05) in measures at baseline, 4 and 12-weeks showed a significant increase in maximal isometric contraction and at rest in favor of the EE vibration program group. Conclusions: The present study showed a RA thickness increase in both groups in favor of the EE vibration program with respect to cryotherapy added to EE in short and mid term in maximal isometric contraction and at rest in subjects with chronic mid-portion AT. IRD was decreased in both groups without between-groups differences.

Recovery levels after eccentric and concentric loading in maximal force

[Purpose] The aim of this study was to compare the differences in recovery periods after maximal concentric and eccentric exercises. [Subjects and Methods] Twenty-two participants voluntarily participated and were divided into two groups: the athlete and sedentary groups. An incremental treadmill running test was performed until exhaustion. During the subsequent passive recovery session, heart rate and venous blood lactate level were determined every 3 minutes until the venous blood lactate level reached 2 mmol/l. The same test protocol was implemented 15 days later. [Results] Both groups showed significantly shorter running durations in concentric exercise, while significant differences were found between the athlete and sedentary groups in terms of venous blood lactate level responses. In addition, there were significant differences between the athlete and sedentary groups in terms of running duration and heart rate in concentric and eccentric exercises. [Conclusion] The present study revealed no difference between the athlete and sedentary groups in terms of recovery durations after eccentric and concentric loadings, although the athletes demonstrated faster recovery in terms of HR compared with the sedentary group. It was thought that concentric exercises cause greater physiological responses.

Reliability of electromyography parameters during stair deambulation in patellofemoral pain syndrome

Reliability is essential to all aspects of the measure, as it shows the quality of the information and allows rational conclusions with regard to the data. There has been controversial results regarding the reliability of electromyographic parameters assessed during stair ascent and descent in individuals with patellofemoral pain syndrome (PFPS). Therefore, this study aims to determine the reliability of time and frequency domain electromyographic parameters on both gestures in women with PFPS. Thirty-one women with PFPS were selected to participate in this study. Data from vastus lateralis and medialis were collected during stair deambulation. The selected parameters were: automatic onset, median frequency bands of low, medium and high frequency. Reliability was determined by intraclass correlation coefficient and the standard error of measurement. The frequency domain variables have shown good reliability, with the stair ascent presenting the best rates. On the other hand, onset has proved to be inconsistent in all measures. Our findings suggest that stair ascent is more reliable than stair descent to evaluate subjects with PFPS in the most cases.