Increased Upper Trapezius Muscle Stiffness in Overhead Athletes with Rotator Cuff Tendinopathy

Dependence of Rotator Cuff Muscle Thickness and Stiffness on Low-Level Contractions: Metrology of the Contraction Level Using Shear-Wave Imaging

OBJECTIVE

The study aimed to investigate the effects of the level of contraction during isometric shoulder abduction at different abduction angles on muscle thickness and stiffness of the shoulder girdle in asymptomatic individuals.

DESIGN

Measurement properties study.

SETTING

Biomechanics and motion analysis lab.

PARTICIPANTS

Twenty individuals volunteered to participate in this study.

MAIN OUTCOME MEASURE

The subjects were tested for morphological and mechanical properties, expressed by thickness and stiffness of the supraspinatus tendon and muscle, and upper trapezius muscle. Moreover, acromiohumeral distance was also evaluated using B-mode ultrasound and shear-wave elastography.

INTERVENTION

The thickness and stiffness of the supraspinatus and upper trapezius muscle were assessed at 3 angles of abduction (0°, 60°, and 90°) and 3 levels of contraction (0%, 10%, and 20% of the maximal voluntary isometric contraction) using ultrasonography with shear-wave imaging. Moreover, the acromiohumeral distance was measured to establish the occupation ratio during passive movement.

RESULTS

The supraspinatus and upper trapezius muscle thickness and stiffness were significantly greater at 60° shoulder abduction compared with 0°, and 90° compared with 60°, as well as significantly greater at 20% maximal voluntary isometric contraction compared with 0% and 10% maximal voluntary isometric contraction. Thickness and stiffness were significantly greater in the supraspinatus compared with the upper trapezius muscle at all 3 angles of shoulder abduction for all 3 level of contractions. The acromiohumeral distance decreased significantly from 0° to 60° and from 60° to 90°.

CONCLUSION

Morphological and mechanical properties of the supraspinatus and upper trapezius muscles depended on the relative level of muscle contraction and the angle of shoulder abduction.

Ultrasound elastography of back muscle biomechanical properties: a systematic review and meta-analysis of current methods

OBJECTIVES

To report the current elastography methods used to quantify back muscles' biomechanical characteristics in patients with musculoskeletal disorders (MSKd) and inform on their reliability, validity, and responsiveness.

METHODS

MEDLINE, Embase, CINAHL, Cochrane library and grey literature were consulted. Predefined criteria allowed for study selection and data extraction. The quality of evidence was rated using the COSMIN tool. Data were meta-analyzed in terms of pooled intraclass correlation coefficient (pICC) for reliability and pooled standardized mean difference (pSMD) for validity and responsiveness. Heterogeneity was assessed.

RESULTS

Seventy-nine studies were included in the meta-analysis (total number of participants N = 3178). Three elastography methods were identified: strain imaging (SI; number of cohorts M = 26), shear wave imaging (SWI; M = 50), and vibration sonoelastography (VSE; M = 3). Strain imaging and SWI studies reported good reliability measurement properties (pICC > 0.70) and a medium pSMD (0.58 for SI and 0.60 for SWI; p ≤ 0.020) in discriminating MSKd from controls' condition (validity). Strain imaging studies reported a medium pSMD (0.64; p = 0.005) in detecting within-group changes over time, whereas SWI pSMD was very high (1.24; p = 0.005). Only SWI reported significant but small pSMD (0.30; p = 0.003) in detecting between-group changes over time. The small number of VSE studies could not be meta-analyzed. Heterogeneity was high (I-squared > 90%; p < 0.001).

CONCLUSIONS

Elastography presents good reliability results and a medium pSMD in discriminating MSKd from control conditions. Responsiveness data suggest detectable changes within groups over time using SI and SWI, calling for long-term longitudinal studies. Assessing changes between groups over time using elastography still needs to be proven. Highly significant heterogeneity limits meta-analytic results.

CRITICAL RELEVANCE STATEMENT

While still in its early-stage exploration phase, musculoskeletal ultrasound elastography may reliably quantify back muscles' biomechanics in asymptomatic individuals, moderately discriminate back musculoskeletal disorders and detect biomechanical changes over time in these conditions, calling for long-term longitudinal studies.

KEY POINTS

Ultrasound elastography is reviewed for back pain and related musculoskeletal disorder assessments. Growing literature supports good reproducibility, some validity and responsiveness. Back muscle elastography considers assumptions calling for standardized protocols.

Wearable Ultrasound Imaging Device for Dynamic Dual-Direction Shear Wave Elastography of Shoulder Muscle

The shoulder is the most mobile joint in the human body, thus requiring intricate coordination of adjacent muscles. Patients suffered from rotator cuff muscle injuries have several typical symptoms including shoulder pain and difficulty raising the arm, thus reducing work efficiency and compromising the quality of life. Ultrasound has been used widely for shoulder soft tissue imaging as well as ultrasound elastography was introduced in shoulder examination for the dilemma of treating degenerative rotator cuff tears. However, most of the ultrasound examination was performed under a static condition. Providing dynamic information from shoulder muscle is important in clinical applications because the pains sometimes come from various positions of the shoulder during moving. In this study, a customized wearable T-shaped ultrasound transducer (128 + 128 elements) was proposed for shoulder dual-direction shear wave elastography (DDSWE), which provides the SWE for both longitudinal (SW along the muscle fiber) and transverse (SW cross the muscle fiber) directions dynamically. An optical tracking system was synchronized with an ultrasound imaging system to capture shoulder movements in 3-D space with their corresponding ultrasound images. The performance of DDSWE and the accuracy of optical tracking were verified by phantom experiments. Human studies were carried out by volunteers as they are moving their arms. The experimental results show that the bias and precision for the proposed DDSWE in elastic phantom were about 6% and 1.2% for both directions, respectively. A high accuracy of optical tracking was observed using a 3-D motor stage experimental setup. Human experiments show that the shear wave velocities (SWVs) were increased with the angles of shoulder abduction, and the average transverse and longitudinal SWVs were increased from 2.24 to 3.35 m/s and 2.95 to 5.95 m/s with abduction angle from 0° to 60°, respectively, which they are anisotropic-dependent. All the experimental results indicate that the proposed wearable ultrasound DDSWE can quantify the mechanical properties of shoulder muscles dynamically, thereby helping surgeons and physical therapists determine whether the intensity of rehabilitation shoulder be tuned down or escalated in the future.

Changes in gastrocnemius MTU stiffness and their correlation with plantar pressure in patients with knee osteoarthritis

Background

Abnormal, excessive, and repetitive knee load is a critical risk factor for osteoarthritis (OA). The gastrocnemius muscle-tendon unit (MTU) interacts with foot biomechanics and is vital in cushioning the knee load. Abnormal gastrocnemius activation and plantar pressure during walking in patients with knee OA may negatively affect gastrocnemius MTU stiffness, increasing knee load. Few studies investigated the relationship between gastrocnemius MTU stiffness and plantar pressure. This study aimed to evaluate the changes in gastrocnemius MTU stiffness in patients with knee OA and their correlations with plantar pressure and clinical symptoms.

Methods

Thirty women patients with unilateral knee OA and 30 healthy women participants were recruited. Shear wave elastography was used to quantify gastrocnemius MTU stiffness in ankle resting and anatomical 0° positions, defined as natural and neutral positions in this study. A plantar pressure analysis system was used to collect the plantar pressure parameters on the symptomatic side in patients with knee OA. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Visual Analogue Scale (VAS) scores were used to measure the severity of clinical symptoms.

Results

Medial and lateral gastrocnemius (MG and LG) stiffness on both the asymptomatic and symptomatic sides in patients with knee OA was increased compared with that in healthy participants. The MG and LG optimal cutoff stiffness in the natural position was 15.73 kPa and 14.25 kPa, respectively. The optimal cutoff stiffness in the neutral position was 36.32 kPa and 25.43 kPa, respectively, with excellent sensitivity and specificity. The MG and LG stiffness were positively correlated with the percentages of anterior and medial plantar pressure and negatively correlated with the length of pressure center path. The LG and MG were significantly correlated with WOMAC and VAS scores.

Conclusion

Patients with knee OA have increased gastrocnemius muscle stiffness, closely related to plantar pressure and clinical symptoms. Monitoring the gastrocnemius muscle in patients with knee OA can provide an essential basis for its prevention and treatment.

Is musculoskeletal pain associated with increased muscle stiffness? Evidence map and critical appraisal of muscle measurements using shear wave elastography

INTRODUCTION AND AIMS

Approximately 21% of the world's population suffers from musculoskeletal conditions, often associated with sensations of stiff muscles. Targeted therapy requires knowing whether typically involved muscles are objectively stiffer compared to asymptomatic individuals. Muscle stiffness is quantified using ultrasound shear wave elastography (SWE). Publications on SWE-based comparisons of muscle stiffness between individuals with and without musculoskeletal pain are increasing rapidly. This work reviewed and mapped the existing evidence regarding objectively measured muscle stiffness in musculoskeletal pain conditions and surveyed current methods of applying SWE to measure muscle stiffness.

METHODS

A systematic search was conducted in PubMed and CINAHL using the keywords "muscle stiffness", "shear wave elastography", "pain", "asymptomatic controls" and synonyms. The search was supplemented by a hand search using Google Scholar. Included articles were critically appraised with the AXIS tool, supplemented by items related to SWE methods. Results were visually mapped and narratively described.

RESULTS

Thirty of 137 identified articles were included. High-quality evidence was missing. The results comprise studies reporting lower stiffness in symptomatic participants, no differences between groups and higher stiffness in symptomatic individuals. Results differed between pain conditions and muscles, and also between studies that examined the same muscle(s) and pathology. The methods of the application of SWE were inconsistent and the reporting was often incomplete.

CONCLUSIONS

Existing evidence regarding the objective stiffness of muscles in musculoskeletal pain conditions is conflicting. Methodological differences may explain most of the inconsistencies between findings. Methodological standards for SWE measurements of muscles are urgently required.

Evaluation of skeletal muscle elasticity using color Doppler shear wave imaging

PURPOSE

This study aimed to (1) assess the precision and reproducibility of color Doppler shear wave imaging (CD SWI) by comparing it with shear wave elastography (SWE) via elasticity phantom measurements, and (2) investigate the potential clinical applications of CD SWI in the upper limb muscles by assessing the reproducibility of skeletal muscle elasticity evaluations.

METHODS

Four elastography phantoms of different stiffness (6.0-7.5 wt%) were used to assess the precision and reproducibility of CD SWI (compared with SWE) at depths. Typical upper limb muscles of 24 men were also assessed for this comparison.

RESULTS

At superficial depths (0-2 cm), the phantom measurements obtained using CD SWI and SWE were similar at all levels of stiffness. Furthermore, both methods were highly reliable, with almost perfect intra- and inter-operator reliabilities. At greater depths (2-4 cm), measurements obtained using both methods were similar at all stiffness levels. Although standard deviations (SDs) of the phantom measurements obtained using both methods at lower stiffness were similar, those at higher stiffness were different. The SD of the CD SWI measurements was < 50% of that of the SWE measurements. However, both methods were highly reliable in the phantom test, with almost perfect intra- and inter-operator reliabilities. The intra- and inter-operator reliabilities of the shear wave velocity measurements for typical muscles of the upper limbs were also substantial in clinical settings.

CONCLUSION

CD SWI is a valid method for measuring elasticity, with precision and reliability as high as those of SWE.

Scapular muscle dynamic stiffness of asymptomatic subjects and subjects with chronic shoulder pain, at rest and isometric contraction conditions

Muscle stiffness had a crucial role in joint stability, particularly, at the shoulder complex. Although changes in upper trapezius muscle stiffness have been described for shoulder pain, contradictory findings have been obtained. Also, existing data regarding scapular muscles are, majorly, about trapezius. Myotonometry is a method used to assess stiffness; however, the reliability values of scapular muscle stiffness through this method have not been assessed in shoulder pain conditions. The present study aims to compare scapular muscles' stiffness (trapezius, serratus anterior, and levator scapulae) between subjects with and without chronic shoulder pain and to evaluate the related test-retest reliability. Twenty-two symptomatic and twenty-two asymptomatic subjects participated in a cross-sectional study. The dynamic muscular stiffness of scapular muscles, at rest and during an isometric contraction, was measured bilaterally with myotonometry, in two moments. The differences in bilateral averaged values between symptomatic and asymptomatic subjects and the effect of the group (group presenting pain in the dominant or non-dominant side, and asymptomatic group) and of the limb (unilateral painful or asymptomatic limb, and bilateral asymptomatic limbs) were investigated. Test-retest intra-rater reliability was determined. An effect of the group was observed at rest, for middle trapezius stiffness, and during contraction, for middle and lower trapezius stiffness. For middle trapezius, increased values were observed in the group presenting pain in non-dominant side comparing to both groups or to group presenting pain in dominant side. The intraclass correlation coefficient, majorly, ranged between 0.775 and 0.989. Participants with pain in the non-dominant side presented an increased middle trapezius' stiffness. Globally, high reliability was observed for scapular muscles dynamic stiffness.

Prevalence, diagnosis and management of musculoskeletal disorders in elite athletes: A mini-review

Musculoskeletal injuries in elite sports are ones of the most impact issue because their remarkable impact on performance caused by drastic absence of training and competition and a progressive deterioration in physical health, emotional and social athletes' dimensions. Also, the prevalence of epidemiologic research found an incidence of musculoskeletal disorders vary within sports and in elite athletes which is even higher as a consequence of higher demand physical performance. This way, the loss of physical performance due to an sport injury impacts not only the individual economic sphere of the professional but also that ofsports entities, reaching, according to some studies, a loss estimated in the range of 74.7 million pounds. Thus, the purpose of this article is to review and to provide an overview of the most common musculoskeletal injuries in elite sports precipitating factors, clinical presentation, evidence-based diagnostic evaluation, and treatment recommendations with a view to preventing medical conditions or musculoskeletal injuries that may alter performance and general health in the elite athletes.

Cluster Analysis of Subjective Shoulder Stiffness and Muscle Hardness: Associations with Central Sensitization-Related Symptoms

Background and Objectives: Understanding the relationships between subjective shoulder stiffness, muscle hardness, and various factors is crucial. Our cross-sectional study identified subgroups of shoulder stiffness based on symptoms and muscle hardness and investigated associated factors. Materials and Methods: measures included subjective stiffness, pain, muscle hardness, and factors like physical and psychological conditions, pressure pain threshold, postural alignment, heart rate variability, and electroencephalography in 40 healthy young individuals. Results: Three clusters were identified: Cluster 1 with high stiffness, pain, and muscle hardness; Cluster 2 with low stiffness and pain but high muscle hardness; and Cluster 3 with low levels of all factors. Cluster 1 had significantly higher central sensitization-related symptoms (CSS) scores than Cluster 2. Subjective stiffness is positively correlated with psychological factors. Conclusions: our results suggest that CSS impacts subjective symptom severity among individuals with similar shoulder muscle hardness.

The application of shear wave elastography with ultrasound for rotator cuff tears: a systematic review

Background

Shear wave elastography (SWE) is an emerging ultrasound-based technology that provides a quantitative assessment of musculoskeletal tissue integrity. This systematic review investigates the use of SWE in the evaluation of rotator cuff tears.

Methods

PubMed, Embase, Web of Science, Google Scholar, and the Cochrane Library databases were searched for relevant studies from 1901 up to June 2022. Articles utilizing SWE in rotator cuff tears were selected based on inclusion and exclusion criteria. The studies included involved the assessment of shear wave velocity, tendon thickness and stiffness after healing, and fatty infiltrates evaluation using SWE. The Newcastle-Ottawa Scale was used to evaluate the risk of bias in included observational studies. Double-sided P value < .05 was considered statistically significant.

Results

Sixteen studies comprising 520 patients were included in the systematic review. SWE demonstrated that shear wave velocities in torn supraspinatus tendons were lower than in healthy supraspinatus tendons. A decrease in tendon SWE modulus elasticity was observed in tendinopathic tendons. Shear wave velocity decreased with increasing fat content and muscle atrophy. The velocity of SWE in muscle in re-tear groups was greater than in the healed group at 1 month after surgery (P < .05).

Conclusion

SWE ultrasound of the supraspinatus tendon can be a useful diagnostic tool for orthopedic surgeons that provide quantitative information on tendinopathic stiffness, velocity, fatty infiltrate, and elasticity characteristics. Decreased tendon velocity of SWE may predict recurrent rotator cuff tears and be useful in postoperative evaluations for muscle healing to plan for future management.

Skeletal Muscle Assessment Using Quantitative Ultrasound: A Narrative Review

Ultrasound (US) is an important imaging tool for skeletal muscle analysis. The advantages of US include point-of-care access, real-time imaging, cost-effectiveness, and absence of ionizing radiation. However, US can be highly dependent on the operator and/or US system, and a portion of the potentially useful information carried by raw sonographic data is discarded in image formation for routine qualitative US. Quantitative ultrasound (QUS) methods provide analysis of the raw or post-processed data, revealing additional information about normal tissue structure and disease status. There are four QUS categories that can be used on muscle and are important to review. First, quantitative data derived from B-mode images can help determine the macrostructural anatomy and microstructural morphology of muscle tissues. Second, US elastography can provide information about muscle elasticity or stiffness through strain elastography or shear wave elastography (SWE). Strain elastography measures the induced tissue strain caused either by internal or external compression by tracking tissue displacement with detectable speckle in B-mode images of the examined tissue. SWE measures the speed of induced shear waves traveling through the tissue to estimate the tissue elasticity. These shear waves may be produced using external mechanical vibrations or internal "push pulse" ultrasound stimuli. Third, raw radiofrequency signal analyses provide estimates of fundamental tissue parameters, such as the speed of sound, attenuation coefficient, and backscatter coefficient, which correspond to information about muscle tissue microstructure and composition. Lastly, envelope statistical analyses apply various probability distributions to estimate the number density of scatterers and quantify coherent to incoherent signals, thus providing information about microstructural properties of muscle tissue. This review will examine these QUS techniques, published results on QUS evaluation of skeletal muscles, and the strengths and limitations of QUS in skeletal muscle analysis.

Scapulohumeral kinematics and neuromuscular control during scaption are associated with passive stiffness and strength of periscapular muscles in competitive adolescent swimmers

The passive stiffness and strength of periscapular muscles may affect scapulohumeral control, especially in overhead athletes due to sports-specific training. This study tried to assess the relationship between the passive stiffness and strength of periscapular muscles, scapulohumeral kinematics and neuromuscular control during scaption in swimmers. Ten male adolescent competitive front-crawl swimmers were recruited. The passive stiffness and strength of periscapular muscles were measured in standard postures by a hand-held myotonometer and dynamometer, respectively. Surface electromyography and electromagnetic tracking systems were synchronized to record the muscle activities and scapulohumeral kinematics during scaption. Correlations between the passive stiffness or strength of periscapular muscles and the kinematics or muscle activity were examined by Spearman's rank correlation coefficient. The maximal strength of periscapular muscles correlated positively with the ranges of upward and external rotation of the scapula and negatively with muscle activity during scaption. Passive stiffness of periscapular muscles was associated with the downward rotation of the scapula and triggered an increase in muscle activity. Increased passive stiffness or decreased strength in the periscapular muscles may affect their role in controlling the scapular rotation and contribute to compensation from adjacent muscles. Our findings suggest that when attempting to evaluate scapular behavior, it may be beneficial to examine muscle strength and passive stiffness of periscapular muscles.

Stiffness and thickness of the upper trapezius muscle increase after repeated climbing bouts in male climbers

Background

Indoor climbing involves overloading the shoulder girdle, including the rotator cuff and upper trapezius muscles. This on the field study aimed to investigate the effects of repeated climbing bouts on morphological and mechanical measures of the upper trapezius muscle.

Materials and Methods

Fifteen experienced male climbers participated in the study. Rate of perceived exertion (RPE), blood lactate concentration ([La^-]_b), and stiffness and thickness over four points of the upper trapezius were assessed before and after a repeated climbing exercise. The procedure for the climbing exercise consisted of five climbs for a total time of 5-minutes per climb, followed by a 5-minute rest.

Results

The analysis showed an increase from baseline to after the 3rd climb (p ≤ 0.01) for RPE and after the 5th climb for [La^-]_b (p ≤ 0.001). Muscle stiffness and thickness increased at all points (1-2-3-4) after the 5th climb (p ≤ 0.01). We found spatial heterogeneity in muscle stiffness and thickness; muscle stiffness was the highest at Point 4 (p ≤ 0.01), while muscle thickness reached the highest values at points 1-2 (both p ≤ 0.01). Moreover, the analysis between the dominant and non-dominant shoulder showed greater stiffness after the 1^st climb at Point 1 (p = 0.004) and after the 5^th climb at Point 4 (p ≤ 0.001).

Conclusions

For muscle thickness, the analysis showed significant changes in time and location between the dominant and the non-dominant shoulder. Bilateral increases in upper trapezius muscle stiffness and thickness, with simultaneous increases in RPE and blood lactate in response to consecutive climbs eliciting fatigue.

Scapular Dynamic Muscular Stiffness Assessed through Myotonometry: A Narrative Review

Several tools have been used to assess muscular stiffness. Myotonometry stands out as an accessible, handheld, and easy to use tool. The purpose of this review was to summarize the psychometric properties and methodological considerations of myotonometry and its applicability in assessing scapular muscles. Myotonometry seems to be a reliable method to assess several muscles stiffness, as trapezius. This method has been demonstrated fair to moderate correlation with passive stiffness measured by shear wave elastography for several muscles, as well as with level of muscle contraction, pinch and muscle strength, Action Research Arm Test score and muscle or subcutaneous thickness. Myotonometry can detect scapular muscles stiffness differences between pre- and post-intervention in painful conditions and, sometimes, between symptomatic and asymptomatic subjects.

Effect of Rounded and Hunched Shoulder Postures on Myotonometric Measurements of Upper Body Muscles in Sedentary Workers

Background: Shoulder pain is prominent among sedentary employees who make motions of the upper limbs on a regular basis. Rounded shoulder posture (RSP) and hunched shoulder posture (HSP) are the most common clinical postural misalignments. These causes the spine to bend and raise tension on the nerve roots, which has a negative impact on upper-extremity muscular strength and function. Therefore, this study was carried out to investigate the effect of RSP and HSP on the mechanical parameters of the upper body muscles in clinically asymptomatic sedentary workers. Methods: Twenty office workers with RSP, 20 with HSP, and 20 with normal shoulder posture (NSP) were matched for age, BMI, and type of job. Volunteers were split into groups based on photometric shoulder angle measurements. Mechanical properties such as muscle tone, stiffness, and elasticity of the upper trapezius, middle trapezius, posterior deltoid, and pectoralis major were assessed in sedentary postures. Results: The study revealed a significant decrease in muscle tone for the pectoralis major and a significant increase in muscle stiffness for the poster deltoid in both RSP and HSP as compared to NSP. Specifically, muscle tone decreased from 20.1 ± 4.0 to 12.4 ± 3.1 Hz (38.3%), (p ≤ 0.001) in RSP and from 20.1 ± 4.0 to 14.0 ± 4.8 Hz (30.3%), (p ≤ 0.001) in HSP. Muscle stiffness increased from 309.9 ± 70.7 to 348.15 ± 68.7 N/m (11%), (p ≤ 0.001) in RSP and from 309.9 ± 70.7 to 441.7 ± 45.9 N/m (29.8%), (p ≤ 0.001) in HSP. Conclusions: RSP and HSP have an impact on the tone, stiffness, and elasticity of upper body muscles in healthy asymptomatic sedentary workers. These postures, on a regular basis, may affect physical health and decrease workers’ productivity. In addition, it is recommended for sedentary workers to take regular breaks and attend training that could help improve their physical health.

Effects of alternating heat and cold stimulation using a wearable thermo-device on subjective and objective shoulder stiffness

BACKGROUND

Technological innovations have allowed the use of miniature apparatus that can easily control and program heat and cold stimulations using Peltier elements. The wearable thermo-device has a potential to be applied to conventional contrast bath therapy. This study aimed to examine the effects of alternating heat and cold stimulation (HC) using a wearable thermo-device on subjective and objective improvement of shoulder stiffness.

METHODS

Twenty healthy young male individuals (20.3 ± 0.6 years) participated in this study. The interventions were randomly conducted under four conditions, including HC, heat stimulation, cold stimulation, and no stimulation on their bilateral trapezius muscle, after a 30-min typing task. Each intervention was administered at least 1 week apart. The analyzed limb was the dominant arm. Muscle hardness was assessed using a portable muscle hardness meter, as well as the skin temperature over the stimulated area. After each condition, the participants were asked for feedback regarding subjective improvement in refreshed feelings, muscle stiffness, and muscle fatigue using an 11-point numerical rating scale.

RESULTS

With regard to muscle hardness, only the HC condition significantly decreased from 1.43 N to 1.37 N (d = 0.44, p < 0.05). Additionally, reduced muscle hardness in HC condition was associated with the degree of skin cooling during the intervention (cold max: r = 0.634, p < 0.01; cold change: r = -0.548, p < 0.05). Subjective improvement in refreshed feelings, muscle stiffness, and muscle fatigue was determined in the HC and heat stimulation conditions compared with the no stimulation condition (p < 0.01 and p < 0.05, respectively). Moreover, the HC condition showed significantly greater improvements in muscle stiffness and fatigue compared to the cold stimulation condition (p < 0.05).

CONCLUSIONS

The current study demonstrated that HC promoted not only better subjective symptoms, such as muscle stiffness and fatigue, but also lesser muscle hardness. Furthermore, an association was observed between the degree of skin temperature cooling and reduced muscle hardness during HC. Further investigations on the ratio and intensity of cooling should be conducted in the future to establish the optimal HC protocol for muscle stiffness or fatigue.

TRIAL REGISTRATION

UMIN000040620 . Registered 1 June 2020.

Effects of dry needling on mechanical and contractile properties of the upper trapezius with latent myofascial trigger points: A randomized controlled trial

BACKGROUND

Latent trigger point (LTrP) can cause motor dysfunction and disturb normal patterns of motor recruitment.

OBJECTIVE

To analyze the effects of DN in the upper trapezius (UT) LTrP on pain and the mechanical and contractile properties of the muscle.

DESIGN

A randomized, double-blinded, parallel-group-trial.

METHODS

Fifty healthy volunteers with LTrPs in the UT were randomly divided into a DN-group (n = 26) and a Sham-DN-group (n = 24) and received one session of DN or placebo treatment. Mechanical and contractile properties of the muscle and pressure pain perception (PPP) were evaluated before treatment and in a 30min, 24 h and 72 h follow-up after treatment.

RESULTS

In the mechanical properties, the DN-group showed lower values than the Sham-DN-group for dynamic stiffness at 72 h (p = 0.04). The DN-group showed lower values for dynamic stiffness at 72 h from baseline (278.74 ± 38.40 to 261.54 ± 33.64 N/m; p = 0.01) and for tone at 72 h from 30min (16.62 ± 1.27 to 15.88 ± 1.31 Hz; p = 0.01). In the contractile properties, the DN-group showed higher values for maximal radial displacement (Dm) of the muscle belly at 72 h from baseline (5.38 ± 1.67 to 6.13 ± 1.70 mm; p = 0.04), higher values for contraction time at 30min (28.53 ± 8.80 s; p = 0.03) and lower ones at 72 h (24.74 ± 4.36 s; p = 0.04) from baseline (26.97 ± 6.63 s). The DN-group showed a decrease of PPP from baseline to 72 h after treatment (5.16 ± 1.33 to 4.02 ± 0.97 mm; p < 0.01).

CONCLUSION

The application of DN in healthy volunteers over LTrPs in the UT decreased dynamic stiffness, tone and contraction time and increased Dm at 72 h after treatment. Additionally, the PPP showed a decrease at 72 h after needling. CLINICALTRIALS.GOV: NCT04466813.

Neck Disability Index Is Better in Classification of Recovery after Whiplash Injury in Comparison with Ultrasound Shear Wave Elastography of Trapezius Muscle

A prospective observational study comparing shear wave elastography (SWE) of trapezius muscle with Neck Disability Index (NDI) in a prediction model of health status six months after a whiplash injury. Both SWE values, measured by two radiologists, and NDI scores were obtained at baseline and after physical therapy (PT) (6-month period). Those values were compared with a 3-point Likert scale (no, partial or full recovery). Twenty-two subjects completed the study. A decrease in trapezius stiffness was detected by both radiologists, statistically significant for one (Δ10.1 kPa; p = 0.04) but not for the second radiologist (Δ8.63 kPa; p = 0.07). The measurements showed excellent intra-observer (ICC 0.75–0.94) and inter-observer (ICC 0.78–0.88) reliability. After six months, fully recovered patients showed lower NDI scores than partially recovered patients (Δ22.98; p < 0.001). SWE values did not differ with the recovery status (55.6 ± 9.7 vs. 57 ± 15.8, Δ1.45; p = 0.82). The single most accurate variable in classifying health status six months after whiplash injury was the relative change of NDI, and it showed the highest accuracy (73.9%) and low Akaike information criterion (AIC = 39.2). Overall, the most accurate classification was obtained when combining NDI and SWE after physical therapy with an accuracy of 77.3% and a decrease in AIC (32.8).

Are muscle weakness and stiffness risk factors of the development of rotator cuff tendinopathy in overhead athletes: a systematic review

Background:

Underlying muscle weakness and stiffness may increase the risk of developing rotator cuff tendinopathy. This systematic review aims to assess existing prospective studies to summarize whether muscle weakness and stiffness are risk factors for the development of rotator cuff tendinopathy in overhead athletes.

Methods:

A systematic search was performed using PRISMA guidelines. Prospective studies measuring muscle strength or stiffness and the incidence of rotator cuff tendinopathy were included. Quality assessment was performed with the Newcastle-Ottawa quality assessment scale.

Results:

The search yielded six studies, with a total of 523 trained overhead athletes followed up for one season. External rotation (ER) and internal rotation (IR) strength were described as protective factors against the development of rotator cuff tendinopathy. Athletes who did not sustain shoulder injuries had statistically stronger eccentric IR (p < 0.01) and ER (p < 0.05) strength in the pre-season assessment. Muscle stiffness indicated by limited range of motion of <106° for shoulder ER was described as a risk factor with an odds ratio of 1.12 (p < 0.001). Imbalance between ER and IR strength was reported as risk factors for shoulder injuries in two studies, with a relative risk of 2.57 (p < 0.05) reported in one study. Supraspinatus weakness was also reported as a risk factor for shoulder injuries in one study.

Conclusion:

Limited evidence support ER, IR weakness, limited ER range of motion, and very limited evidence support imbalance in ER/IR strength, and supraspinatus weakness as risk factors for rotator cuff tendinopathy in overhead athletes. No existing studies investigated the general population on this topic. Future cohort studies may improve on existing evidence with investigations on the general public, a longer follow-up time, clearly documented injury history, and a stringent diagnosis to rotator cuff tendinopathy.

Reliability of Trapezius Muscle Hardness Measurement: A Comparison between Portable Muscle Hardness Meter and Ultrasound Strain Elastography

Prolonged computer work and smartphone use can cause stiffness of the neck and shoulder muscles, including the trapezius muscle. Hence, muscle hardness quantification is clinically beneficial. The present study aimed to examine the reliability of trapezius muscle hardness measurement using a portable muscle hardness meter and ultrasound strain elastography. Overall, 20 healthy young men participated in this study. Prior to measurement, the participant’s subjective symptoms, particularly shoulder muscle stiffness, were rated using an 11-point verbal scale. Furthermore, hardness of the right and left upper trapezius muscles was assessed. In the strain elastography assessment, muscle hardness was evaluated using strain ratio. Results showed that, in quantifying upper trapezius muscle hardness, both portable muscle hardness meter and strain elastography had an excellent intra-tester reliability (>0.9). However, the correlation coefficients between muscle hardness values assessed using a muscle hardness meter and those evaluated with strain elastography did not significantly differ, and the scores for subjective shoulder stiffness did not correspond to muscle hardness values. Therefore, the hardness of the trapezius muscle does not directly reflect the subjective shoulder stiffness. Future studies should thoroughly examine the location of the shoulder stiffness, and check whether it is accompanied by local pain or tenderness.

Interrater and Intrarater Reliability of a Handheld Myotonometer in Measuring Mechanical Properties of the Neck and Orofacial Muscles

OBJECTIVE

The purpose this study was to investigate the reliability of a handheld myotonometer in measuring the mechanical properties of the neck and orofacial muscles in asymptomatic individuals.

METHODS

The study included 16 healthy participants. The mechanical properties (frequency, decrement, stiffness, relaxation time, and creep) of the selected muscles were measured with a MyotonPRO myotonometer (Mumeetria Ltd, Tallinn, Estonia). The sternocleidomastoid, upper trapezius, cervical extensor, and masseter muscles were selected to determine the reliability of the device. Measurements were performed by 2 examiners to determine interrater reliability; for intrarater reliability, an examiner repeated the measurements 1 week after the first measurements.

RESULTS

The results revealed moderate to excellent intrarater and interrater reliability (intraclass correlation coefficients: 0.50-0.95) in measuring muscle mechanic properties. The standard error of measurement in the tested muscles ranged from 0.3 to 0.8 Hz for frequency, from 7.4 to 20.9 N/m for stiffness, from 0.1 to 0.2 for decrement, and from 0.8 to 1.4 ms for relaxation time. The minimum detectable change ranged from 0.8 to 2.2 Hz for frequency, from 20.5 to 57.9 N/m for stiffness, from 0.2 to 0.6 for decrement, from 2.2 to 3.9 ms for relaxation time, and from 0.2 to 0.3 for creep. In addition, the coefficients of variation were below 9.1% for all the assessed parameters.

CONCLUSION

The obtained results demonstrate that the MyotonPRO device is a reliable and repeatable tool to quantify the frequency, stiffness, decrement, relation time, and creep of the neck and orofacial muscles in asymptomatic individuals.

Eccentric Exercise Reduces Upper Trapezius Muscle Stiffness Assessed by Shear Wave Elastography and Myotonometry

In this study, we tested the hypotheses that unaccustomed eccentric exercise (ECC) would reduce the elastic modulus and dynamic stiffness of the upper trapezius muscle and that these changes would correlate with increases in muscle thickness, reflecting muscle edema. Shear wave elastography was used to measure elastic modulus, dynamic stiffness was assessed using myotonometry, and muscle thickness was measured using ultrasonography. All measurements were performed at four locations over the upper trapezius before and 24 h after a single bout of ECC. Fourteen healthy participants (11 males and 3 females; 23.2 ± 3.0 years; height 175.1 ± 10.4 cm; body mass 73.8 ± 11.3 kg) took part in the study. Overall, ECC resulted in decreased elastic modulus (from 45.8 ± 1.6 to 39.4 ± 1.2 kPa, p < 0.01) and dynamic muscle stiffness (from 369.0 ± 7.3 to 302.6 ± 6.0 N/m, p < 0.01). Additionally, ECC resulted in increased muscle thickness (from 6.9 ± 0.4 to 7.3 ± 0.4 mm, p < 0.01). Spatial changes (across the four locations) were found for elastic modulus, stiffness and thickness. No significant correlations were found between changes in measures of muscle stiffness, or between changes in stiffness and changes in thickness. In conclusion, the present pilot study showed that ECC altered biomechanical muscle properties, reflected by decreased elastic modulus and dynamic muscle stiffness 24 h after ECC.

Influence of Foam Rolling Velocity on Knee Range of Motion and Tissue Stiffness: A Randomized, Controlled Crossover Trial

CONTEXT

Foam rolling (FR) increases joint range of motion (RoM), but the optimal training parameters are unknown.

OBJECTIVE

To investigate the effect of FR velocity on RoM and tissue stiffness.

DESIGN

Randomized, controlled crossover trial.

SETTING

University.

PARTICIPANTS

A total of 17 healthy, physically active adults (10 females; 25 [2] y).

INTERVENTIONS

(1) Four 45-second high-velocity FR of the anterior thigh (FAST-FR), (2) four 45-second slow-velocity FR of the anterior thigh (SLOW-FR), and (3) inactive control.

OUTCOME MEASURES

Maximal knee-flexion RoM (ultrasonic movement analysis) and anterior thigh tissue stiffness (semielectronic tissue compliance meter) assessed pre, immediately post (T0), as well as 5 (T5) and 10 (T10) minutes postintervention. Statistical analysis included Friedman tests with adjusted post hoc comparisons (Wilcoxon tests).

RESULTS

According to omnibus testing, RoM remained unchanged in all 3 conditions and at all time points (P > .05), while differences were found for tissue stiffness (P < .05). Post hoc tests revealed significant decreases following FAST-FR (T5: -17%, T10: -24%; P < .05) and SLOW-FR (T10: -15%; P < .05). The observed stiffness changes were significant in comparison with control (P < .01), but no difference was found between the 2 FR conditions (P > .05).

CONCLUSIONS

FR of the anterior thigh decreases myofascial stiffness regardless of velocity. The lack of effects on RoM contrasts findings of recent literature and warrants further investigation.

Ultrasonographic and Myotonometric Evaluation of the Shoulder Girdle After an Isokinetic Muscle Fatigue Protocol

OBJECTIVES

The aim of the study was to investigate supraspinatus tendon thickness, acromiohumeral distance (AHD), and stiffness/creep measures of the shoulder girdle in overhead asymptomatic athletes in muscle fatigue conditions.

DESIGN

Observational, case series study.

SETTING

Biomechanics and motion analysis lab.

PARTICIPANTS

Twenty-four male overhead volleyball (n = 8), handball (n = 8), and tennis (n = 8) athletes. All subjects were without shoulder injury history.

MAIN OUTCOME MEASURE

The subjects were tested for supraspinatus tendon thickness (in short and long axis), AHD using ultrasound scans and stiffness/creep of upper trapezius, infraspinatus, anterior and posterior deltoid, and pectoralis major using the myotonometer device before and immediately after a fatigue protocol.

INTERVENTION

The fatigue protocol consisted of 3 sets of 32 maximum isokinetic concentric contractions performing shoulder internal and external rotation at isokinetic speed of 120°/s.

RESULTS

A significant increase in supraspinatus tendon thickness (both in short and long axis) (P = .045 and P = .01, respectively) and a reduction in AHD (P = .01) were found after an isokinetic protocol. The stiffness increased significantly in upper trapezius (P ≤ .01), infraspinatus (P = .003), posterior deltoid (P = .047), and pectoralis major (P = .01), whereas the creep showed a significant decrement for upper trapezius (P = .001) and infraspinatus (P = .003).

CONCLUSION

The present study has demonstrated the postexercise fatigue in overhead athletes. The increase of stiffness (reduction of muscle creep) and tendon thickness (simultaneous to the reduction of AHD) may indicate rotator cuff overloading as a primary intrinsic tendon pathology process.

Quantifying cervical and axioscapular muscle stiffness using shear wave elastography

This study aimed to assess intra-rater (intra-session and inter-day) reliability and influence of side dominance and the scapular resting position on the shear modulus (an index of stiffness) of resting cervical and axioscapular muscles. Sixteen healthy participants were recruited. On day one, ultrasound shear wave elastography was used to measure the shear modulus of superficial and deep cervical extensor and axioscapular muscles bilaterally. Clinical assessments of scapular resting position were performed bilaterally. On day two, testing was repeated on the dominant side. Both intra-session and inter-day reliability were good to excellent for shear modulus of superficial muscles, and poor to excellent for deep muscles. Side differences of shear modulus for posterior upper trapezius were statistically significant but clinically irrelevant. The shear modulus of posterior upper trapezius and middle trapezius were significantly correlated with scapular depression. Ultrasound shear wave elastography is a reliable tool for quantitatively assessing stiffness of superficial cervical and axioscapular muscles. The influence of scapular position should be considered in future comparative studies of healthy controls and patients with neck/shoulder pain. This study provides the necessary first step for future studies on assessing and interpreting the stiffness of cervical and axioscapular muscles for neck and shoulder musculoskeletal disorders.

Modulation in Elastic Properties of Upper Trapezius with Varying Neck Angle

Background

Neck and shoulder complaints caused by poor posture may influence upper trapezius stiffness. The relationship between the shear elastic modulus of the upper trapezius and cervical flexion angles is unknown. Therefore, it is essential to assess upper trapezius stiffness during cervical flexion. The objectives of this study were to (1) determine the intra- and interoperator reliabilities of evaluating upper trapezius stiffness and calculate the minimal detectable change (MDC); (2) examine the elastic modulus alterations of the upper trapezius during cervical flexion; and (3) explore the difference of upper trapezius stiffness between the dominant and nondominant sides.

Methods

Twenty healthy male participants were recruited in this study. The shear modulus of the upper trapezius was evaluated by two independent investigators using shear wave elastography (SWE) during cervical flexion at 0° and 50°.

Findings

The intraoperator (intraclass correlation coefficient (ICC) = 0.85–0.86) and interoperator (ICC = 0.94–0.98) reliabilities for measuring the shear elastic modulus of the upper trapezius during the cervical flexion ranged from good to excellent. An increase of 35.58% in upper trapezius stiffness was found at 0° to 50° of cervical flexion, and the MDC was 7.04 kPa. In addition, a significant difference was obtained in the elastic modulus of the upper trapezius muscle between the dominant and nondominant sides (P < 0.05).

Conclusions

Our findings revealed that SWE could quantify the elastic modulus of the upper trapezius and monitor its changes. Therefore, further studies are required to delineate the modulation in upper trapezius muscle stiffness among subjects with neck and shoulder pain.

Changes in Muscle Stiffness of the Trapezius Muscle After Application of Ischemic Compression into Myofascial Trigger Points in Professional Basketball Players

The study aimed to assess the effects of compression trigger point therapy on the stiffness of the trapezius muscle in professional basketball players (Part A), and the reliability of the MyotonPRO device in clinical evaluation of athletes (Part B). Twelve professional basketball players participated in Part A of the study (mean age: 19.8 ± 2.4 years, body height 197 ± 8.2 cm, body mass: 91.8 ± 11.8 kg), with unilateral neck or shoulder pain at the dominant side. Part B tested twelve right-handed male athletes (mean ± SD; age: 20.4 ± 1.2 years; body height: 178.6 ± 7.7 cm; body mass: 73.2 ± 12.6 kg). Stiffness measurements were obtained directly before and after a single session trigger point compression therapy. Measurements were performed bilaterally over 5 points covering the trapezius muscle. The effects were evaluated using a full-factorial repeated measure ANOVA and the Bonferroni post-hoc test for equal variance. A p-value < .05 was considered significant. The RM ANOVA revealed a significant decrease in muscle stiffness for the upper trapezius muscle. Specifically, muscle stiffness decreased from 243.7 ± 30.5 to 215.0 ± 48.5 N/m (11.8%), (p = .008) (Part A). The test-retest relative reliability of trapezius muscle stiffness was found to be high (ICC from 0.821 to 0.913 for measurement points). The average SEM was 23.59 N/m and the MDC 65.34 N/m, respectively (Part B). The present study showed that a single session of compression trigger point therapy can be used to significantly decrease the stiffness of the upper trapezius among professional basketball players.

Playing video games for more than 3 hours a day is associated with shoulder and elbow pain in elite young male baseball players

BACKGROUND

The effect of lifestyle factors on elbow or shoulder pain in young baseball players remains unclear. This study examined the association of game playing and television viewing with elbow or shoulder pain among elite young baseball players.

METHODS

Study participants were young baseball players (age, 9-12 years) who participated in the National Junior Sports Clubs Baseball Festival in 2017. The national tournament invited 16 teams (totaling 210 players) selected based on the results of the regional qualifying tournaments. Self-reported questionnaires were mailed to all players before the tournament. Multiple logistic regression analyses were used to assess the association of video game playing and television viewing behavior with elbow or shoulder pain.

RESULTS

Among the 210 players polled, 200 male players were included in the analysis. The prevalence of elbow or shoulder pain was 30.0%. Playing video games for ≥3 hours/day was significantly associated with elbow or shoulder pain vs. spending <1 hour/day playing video games (odds ratio, 5.59; 95% confidence interval, 1.44-21.64; P = .013). The amount of time spent watching television was not significantly associated with the prevalence of elbow or shoulder pain.

CONCLUSIONS

Playing video games for ≥3 hours/day was associated with elbow or shoulder pain among elite young male baseball players. These findings highlight the effect of lifestyle on elbow and shoulder pain and should be taken into consideration by players, coaches, parents, and clinicians for the prevention of elbow and shoulder pain.

Effect of High-Induction Magnetic Stimulation on Elasticity of the Patellar Tendon

Nowadays, a high-induction magnetic stimulation is starting to be increasingly applied as a biophysical stimulation in the conservative treatment of the degenerative locomotor system diseases. These are mainly in correlation with the changes in soft tissue elasticity, which should be positively influenced by the flow-induced electrical currents of high current density during high-induction magnetic stimulation. This assumption was verified within the interventional and prospective study using the ultrasound elastography. The group consisted of 6 volunteers, whose elasticity of the patellar tendons was measured using the 2D shear-wave ultrasound elastography. The volunteers were then exposed to a 20-minute high-induction magnetic stimulation session with a frequency of 20 Hz, in 2 s package intervals, with a 5 s pause, and a induced electric current density of 100 Am⁻² in the tendons area. A tendon tension was measured five times for all volunteers, where mean tension at the marked area of the tendon, as well as the highest point tension indicated by the Q-Box, was monitored. The measurement results show that high-induction magnetic stimulation has an influence on the patellar tendon tension change, which occurred in the case of all involved volunteers when the patellar tension was decreased.

The application of ultrasound elastography in the shoulder

Ultrasound elastography (EUS) is a recently developed method for the assessment of tissue elasticity by applying mechanical stress and subsequently analyzing tissue displacement with ultrasound. To date, mainly two different techniques are used in clinical practice: strain (compression) EUS and shear wave EUS. However, shear wave EUS has been shown to be more examiner independent and more reliable as this technique allows a quantitative measurement of tissue elasticity. There is increasing evidence that EUS can be used to evaluate mechanical properties of musculoskeletal tissue. Thus, it might be a powerful tool to detect and to monitor pathologic processes affecting the shoulder girdle. As ultrasound is an essential clinical tool for the examination of the shoulder, this review describes the two most important EUS techniques available for clinical use, presenting the published evidence on the applications of EUS for the evaluation of pathologic processes affecting the shoulder joint. In addition, technical issues, limitations, and future perspectives of these methods for the assessment of the shoulder are outlined.

Ultrasound elastography in tendon pathology: state of the art

Elastography assesses the biomechanical and structural properties of tissues by measuring their stiffness. Despite promising results, elastography has not yet earned its place in the daily practice of musculoskeletal radiologists. The purpose of this article is to present and examine the data available to date on ultrasound elastography of the tendons through a review of the literature to provide musculoskeletal radiologists with an overview that may help them better understand and use elastography routinely. The most common techniques in ultrasound elastography are described. Then, the aspects of the physiologic and pathologic tendon are presented and discussed. One must make this technique one's own to better apprehend its contribution to the musculoskeletal imaging field, while bearing in mind that further research will be required before admitting elastography as a reliable and validated tool able to optimize our daily clinical practice.

Assessing the viscoelastic properties of upper trapezius muscle: Intra- and inter-tester reliability and the effect of shoulder elevation

BACKGROUND

Increasing stiffness in the upper trapezius muscle may contribute to imbalance of scapular motion, and result in shoulder and neck discomfort during shoulder flexion. Therefore, it is essential to quantify upper trapezius stiffness in various shoulder positions in order to aid in the prevention of these disorders and to optimize rehabilitation.

OBJECTIVES

The objectives of the present study were to examine the intra and inter-tester reliability of MyotonPRO device in measuring upper trapezius stiffness and its ability to determine changes in stiffness during shoulder flexion.

METHODS

Twenty healthy male subjects (mean age: 28.3±4.8 years) were studied. The stiffness of upper trapezius was quantified using the MyotonPRO device.

RESULTS

The results revealed excellent intra and inter-tester reliability for measuring upper trapezius stiffness with the shoulder in a neutral position, and also found a 14.2% increase in stiffness upon shoulder flexion between 0° and 60° of flexion. Minimal detectable change (MDC) was 26.3 N/m.

CONCLUSIONS

Our findings indicate that MyotonPRO device is a feasible tool to quantify upper trapezius stiffness as well as changes in muscle stiffness. Thus, it is important to assess the changes in upper trapezius muscle stiffness due to pathology or treatments for future studies.