Humeral Torsion in Relation to Shoulder Range of Motion in Elite Field Hockey Players.

CONTEXT: Sport-specific adaptations in shoulder rotation range of motion (ROM) and the relationship with humeral torsion have been described in overhead-throwing sports. However, information is lacking for other shoulder-loading sports such as field hockey. Therefore, this study's purpose was to evaluate humeral torsion in elite, male field hockey players and explore its association with shoulder ROM. DESIGN: Cross-sectional study. METHODS: Twenty-five male, elite field hockey players were included. Humeral torsion and shoulder external and internal rotation ROM were evaluated bilaterally by ultrasound and an inclinometer smartphone application, respectively. RESULTS: Field hockey players showed a significantly increased humeral retroversion on the dominant compared with the nondominant side (P < .001; Cohen d = 1.75), along with a significantly increased external (P = .004; Cohen d = -0.64) and decreased internal rotation ROM (P = .003; Cohen d = 0.65). This finding illustrates a shift in total shoulder rotational ROM arc. Correlation analysis showed a significant moderate association between the increased humeral retroversion and decreased internal rotation ROM on the dominant side (r = .523). CONCLUSIONS: Elite male field hockey athletes show sport-specific adaptations regarding humeral torsion and shoulder rotation ROM, similar to throwing athletes. These findings increase our insight into the field hockey athlete's shoulder, which is essential to optimize performance and assist in correctly interpreting shoulder rotational ROM measurements.

The effect of fatigue on spike jump biomechanics in view of patellar tendon loading in volleyball.

BACKGROUND AND OBJECTIVE: Patellar tendinopathy (PT) is a highly prevalent overuse injury in volleyball and is often linked with overloading of the patellar tendon. Little is known, however, about whether and how patellar tendon loading is affected by fatigue during the most challenging jump activity in volleyball. Therefore, this study investigates the effect of a high-intensity, intermittent fatigue protocol on movement alterations in terms of patellar tendon loading during a volleyball spike jump. METHODS: Forty-three male volleyball players participated in this study. Three-dimensional full-body kinematics and kinetics were collected when performing a spike jump before and after the fatigue protocol. Sagittal plane joint angles, joint work and patellar tendon loading were calculated and analyzed with curve analyses using paired sample t-tests to investigate fatigue effects (p < 0.05). RESULTS: Fatigue induced a stiffer lower extremity landing strategy together with prolonged pelvis-trunk flexion compared to baseline (p = 0.001-0.005). Decreased patellar tendon forces (p = 0.001-0.010) and less eccentric knee joint work (-5%, p < 0.001) were observed after the fatigue protocol compared to baseline. CONCLUSION: Protective strategies seem to be utilized in a fatigued state to avoid additional tensile forces acting on the patellar tendon, including proximal compensations and stiff lower extremity landings. We hypothesize that players might be more prone for developing PT if eccentric patellar tendon loads are high in the non-fatigued state and/or these loads are somehow not decreased after fatigue.

Subacromial space outlet in female patients with multidirectional instability based on hypermobile Ehlers-Danlos syndrome and hypermobility spectrum disorder measured by ultrasound.

OBJECTIVE: The objective of the study was to compare the acromiohumeral distance (AHD) between patients diagnosed with hypermobility type of the Ehlers-Danlos syndrome (hEDS) or hypermobility spectrum disorder (HSD) and healthy controls by evaluating the relative amount the tendon occupies in the subacromial area. Furthermore, the aim was to evaluate if there was a change in AHD with arm elevation within and between groups. METHODS: Twenty-nine female patients with hEDS/HSD (aged 34 ± 12.9 years) and 20 healthy controls (aged 33 ± 10.8 years) participated in the study. The supraspinatus tendon (SST) thickness and AHD were measured using ultrasound. The interplay between the SST and the AHD was expressed as the occupation ratio (OcAHD), calculated as the SST thickness as a percentage of AHD. The measures were performed in the resting position and in subsequently 45° and 60° of active arm elevation in the scapular plane. RESULTS: The main finding is that patients with hEDS/HSD have a larger subacromial space outlet compared with the controls when measured by ultrasound. Furthermore, in both groups, we found an increased OcAHD during active arm elevation compared with the resting position, which indicates that similar mechanisms occur for patients with hEDS/HSD and healthy controls. CONCLUSION: Patients with hEDS/HSD have a larger available subacromial space outlet compared with healthy individuals. OcAHD increased during active arm elevation compared with the resting position in both groups. This knowledge is important when designing rehabilitation exercise programs for shoulder instability patients with abnormal glenohumeral biomechanics.

Electromyographic analysis of selected shoulder muscles during a series of exercises commonly used in patients with symptomatic degenerative rotator cuff tears.

BACKGROUND: In the nonoperative treatment of degenerative rotator cuff (RC) tears, exercise therapy is advocated. Exercises focusing on strengthening the anterior deltoid (AD) and the scapular muscles are proposed to compensate for RC dysfunction. However, the amount of electromyographic (EMG) activity in these muscles during these exercises remains unclear. Moreover, it is unknown whether muscle activity levels during these exercises alter with increasing age. Therefore, the purpose of this study was to evaluate EMG activity in the deltoid and scapular muscles during 2 series of commonly used shoulder rehabilitation exercises and assess possible age-related changes in muscle activity. METHODS: Fifty-five healthy participants (aged 18-60 years) participated in this study. Surface EMG activity was measured in 8 shoulder girdle muscles during a progression of a closed chain elevation program (bench and wall slides) and during a progression of previously published AD exercises. In addition, muscle activity was compared between 3 age categories (18-32 years, 33-46 years, and 47-60 years). RESULTS: The proposed progressions exhibited increasing activity from <10% of maximal voluntary isometric contraction to >20% of maximal voluntary isometric contraction for the AD for both exercise programs and for the middle deltoid, upper trapezius, and middle trapezius during the closed chain elevation exercises. Activity levels in the other muscles remained <20% throughout the progression. Age-related analysis revealed increased activity in the AD, infraspinatus, and middle trapezius and decreased lower trapezius activity during the bench and wall slides. No age-related changes were noted for the AD exercises. CONCLUSION: These findings may assist the clinician in prescribing appropriate progressive exercise programs for patients with symptomatic RC tears.

Home-based exercise therapy for treating shoulder instability in patients with hypermobile Ehlers-Danlos syndrome/hypermobility spectrum disorders. A randomized trial.

PURPOSE: To investigate the effectiveness of two home-based exercise programs for treating multidirectional shoulder instability (MDI) in patients diagnosed with Hypermobile Ehlers-Danlos syndrome (hEDS) or Hypermobility Spectrum Disorders (HSD). METHODS: Twenty-one hEDS/HSD patients with MDI were recruited from the Center for Medical Genetics of the Ghent University Hospital. Patients were randomly assigned to either the experimental or the control group. Both groups received a 6-month home-based exercise program. The primary outcome measure was the Western Ontario Shoulder Index (WOSI). Secondary outcomes included the Disabilities of the Arm, Shoulder and Hand (DASH), Tampa Scale for Kinesiophobia (TSK), Patient-Specific Functional Scale (PSFS), Global Rating of Change (GROC), and pain pressure thresholds. Outcomes were assessed at baseline, after 6 weeks, 12 weeks, and 24 weeks. RESULTS: Significant main effects for time were observed for all questionnaires, except for the TSK (p = 0.12). Patients improved 240 and 325 points on the WOSI after 12 (p = 0.02) and 24 weeks (p = 0.001), respectively. Additionally, patients improved 8.6 points on the DASH (p = 0.002), 4.3 points on the PSFS (p = 0.01), and 1.02 points on the GROC (p = 0.001) after 24 weeks. CONCLUSION: No significant differences were found between group A and B. Both home-based exercise programs led to significant improvements in shoulder function. IMPLICATIONS FOR REHABILITATIONHome-based exercise therapy may be effective for treating MDI in the hEDS/HSD population.Home-based training is beneficial for improving shoulder function, but a multidisciplinary, supervised approach might be more effective for altering kinesiophobia in this patient population.

Scapulothoracic muscle activity during kinetic chain variations of a prone elevation exercise.

BACKGROUND: Scapular rehabilitation exercises should target appropriate muscles. Recently, adding external rotation resistance to scapular exercises has gained interest. Moreover, clinical experts advise kinetic chain integration into shoulder rehabilitation exercises. OBJECTIVE: To investigate scapular muscle activity during kinetic chain variations of a prone elevation exercise. METHODS: Activity of the upper (UT), middle (MT), and lower (LT) trapezius and serratus anterior (SA) muscles was determined with surface electromyography (EMG) in 31 asymptomatic participants during six prone elevation exercise variations. Variation was created by adding external rotation resistance, adding trunk extension, or changing exercise position (prone on a Swiss ball with knees or feet supported, or prone on a physiotable). All data were normalized as a percentage of maximal voluntary isometric contraction (% MVIC). For each muscle, a Friedman's ANOVA was conducted to analyse statistical differences in EMG signal intensity between exercises. RESULTS: The LT was moderately (42 - 48% MVIC) and MT highly (63 - 66% MVIC) activated during all exercise variations. No significant differences between exercises for these muscles could be detected. Adding external rotation to a prone elevation exercise decreased UT activity while adding trunk extension increased UT activity. Altering exercise position had no influence on scapular muscle activity except increased UT activity when lying prone on a physiotable with trunk extension. CONCLUSION: Prone elevation exercises are appropriate for facilitating LT and MT activity. Adding external rotation inhibits UT activity while UT facilitation could be achieved when adding trunk extension.

Electromyographic Muscle Activity and Three-Dimensional Scapular Kinematics in Patients With Multidirectional Shoulder Instability: A Study in the Hypermobile Type of the Ehlers-Danlos Syndrome and the Hypermobility Spectrum Disorders.

OBJECTIVE: To investigate differences in electromyography (EMG), muscle activity, and scapular kinematics during elevation in the scapular plane between healthy controls, participants with multidirectional shoulder laxity (MDL), and patients with multidirectional shoulder instability (MDI) who are diagnosed with hypermobile Ehlers-Danlos syndrome (hEDS) or hypermobility spectrum disorder (HSD). METHODS: Twenty-seven women with hEDS/HSD and MDI, 27 female healthy control subjects, and 28 female subjects with MDL participated in this study. Scapular 3-dimensional kinematic data were obtained using 8 Oqus Qualisys cameras. Simultaneously, surface EMG was used to measure muscle activity of the upper, middle, and lower trapezius, infraspinatus, latissimus dorsi, serratus anterior, posterior deltoid, and pectoralis major during arm elevation in the scapular plane. Group differences were assessed using statistical parametric mapping. RESULTS: Regarding scapular kinematics, significantly less upward rotation was observed in hEDS/HSD patients with MDI compared to both healthy controls and MDL subjects. Significantly less posterior tilt was seen in hEDS/HSD patients compared to MDL subjects. Furthermore, significantly higher EMG activity of the infraspinatus, middle trapezius, and posterior deltoid was found in hEDS/HSD patients with MDI. CONCLUSION: hEDS/HSD patients with MDI demonstrate altered scapular kinematics and increased EMG muscle activity compared to subjects without MDI. These findings could serve as a stepping stone for future research regarding treatment strategies in patients whose conditions belong to the hypermobility spectrum.

Effect of Plyometric Training on Sport Performance in Adolescent Overhead Athletes: A Systematic Review.

CONTEXT: Plyometric training has been shown to be beneficial in adolescent overhead athletes. However, existing research on the effects of plyometrics on sport performance has been limited. OBJECTIVE: To systematically review the current literature to investigate whether plyometric training intervention improves upper- and lower-body sport performance. DATA SOURCES: Two electronic databases (MEDLINE and Web of Science) were searched using specific Medical Subject Headings (MeSH) terms up to February 2019, and hand-searching was performed by looking to relevant studies that were cited in other studies. STUDY SELECTION: A total of 932 items were identified and were further assessed for the eligibility in the systematic review. For a study to be eligible, each of the following inclusion criteria had to be met: (1) participants were aged 13 to 18 years and selected from a sports or athletic population and the study (2) involved the evaluation of a plyometric training intervention with an aim to improve sports performance; (3) must have included a control intervention and/or control group; (4) included a quantitative objective measure of sport performance variables concerning throwing, jumping, running, and sprinting; and (5) was published in English. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 3. DATA EXTRACTION: A first screening was conducted based on title and abstract of the articles. In the second screening, the full text of the remaining articles was evaluated for the fulfillment of the inclusion criteria. RESULTS: A total of 14 studies were included in this review. The methodological quality of the included studies ranged from low to moderate. There is moderate evidence that plyometric training intervention improves throwing and jumping performances. There is also preliminary evidence that plyometric training intervention improves sprint performance. CONCLUSION: The current evidence suggests that sport performance consisting of throwing capacity, jumping ability, and sprint performance significantly improved due to plyometric training interventions in adolescent overhead athletes.

Muscle activity and scapular kinematics in individuals with multidirectional shoulder instability: A systematic review.

BACKGROUND: Several studies reported the importance of glenohumeral and scapular muscle activity and scapular kinematics in multidirectional shoulder instability (MDI), yet a systematic overview is currently lacking. OBJECTIVE: This systematic review evaluates and summarizes the evidence regarding muscle activity and shoulder kinematics in individuals with MDI compared to healthy controls. METHOD: The electronic databases PubMed and Web of Science were searched in September 2020 with key words regarding MDI (population), muscle activity, and glenohumeral and scapular movement patterns (outcomes). All studies that compared muscle activity or scapular kinematics between shoulders with MDI and healthy shoulders were eligible for this review, except for case reports and case series. All articles were screened on the title and abstract, and remaining eligible articles were screened on full text. The risk of bias of included articles was assessed by a checklist for case-control data, as advised by the Cochrane collaboration. RESULTS: After full text screening, 12 articles remained for inclusion and one study was obtained by hand search. According to the guidelines of the Dutch Institute for Healthcare Improvement, most studies were of moderate methodological quality. We found moderate evidence that MDI individuals show increased or prolonged activity of several rotator cuff muscles that control and centre the humeral head. Furthermore, we found evidence of decreased and/or shortened activity of muscles that move or accelerate the arm and shoulder girdle as well as increased and/or lengthened activity of muscles that decelerate the arm and shoulder girdle. The most consistent kinematic finding was that MDI individuals show significantly less upward rotation and more internal rotation of the scapula during elevation of the arm in the scapular plane as compared with controls. Finally, several studies also suggest that the humeral head demonstrates increased translations relative to the glenoid surface. CONCLUSION: There is moderate evidence for altered muscle activity and altered humeral and scapular kinematics in MDI individuals as compared with controls.

Relative Scapular-Muscle Ratios During Maximal Isokinetic Shoulder-Girdle Strength Performance in Elite Field Hockey Players.

CONTEXT: The shoulder joint and girdle are highly loaded during field hockey play. To optimize performance and to better substantiate preventive programs, it is important to gain insight into shoulder-girdle muscle function and balance in this athlete population. OBJECTIVE: To evaluate relative scapular muscle-activity ratios through surface electromyography during maximal isokinetic strength testing in elite male field hockey players compared with nonathletes. DESIGN: Cross-sectional study. SETTING: Institutional laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty-five elite field hockey players from the Belgian National Team and 25 age- and sex-matched nonathletes. INTERVENTION(S): We measured bilateral activity in 4 scapular muscles (upper trapezius [UT], middle trapezius [MT], lower trapezius [LT], and serratus anterior [SA]) during an external-internal rotation and protraction-retraction isokinetic shoulder protocol. MAIN OUTCOME MEASURE(S): Relative scapular muscle-activity ratios, or balance ratios, of the UT : MT, UT : LT, UT : SA, SA : MT, and SA : LT. RESULTS: We noted lower ratios bilaterally in the athlete group compared with the control group for the UT : MT, UT : LT, and SA : MT ratios during protraction, retraction, and external rotation, respectively, and unilaterally (dominant side only) for the UT : LT ratio during protraction. No consistent trend was present for established side differences in the studied balance ratios. CONCLUSIONS: Compared with nonathletes, elite field hockey players had altered intramuscular (within the trapezius) and intermuscular (between the trapezius and SA) balance ratios during maximal shoulder-girdle contractions, with relatively more MT and LT activity. This may reflect a sport-specific adaptation to optimize coordinated activity of the scapulothoracic muscles, meeting the specific demands of field hockey movements and simultaneously better protecting the shoulder against injury. Our results can assist in optimizing high-performance training and in supporting injury-prevention programs, which are key to both successful and long-lasting athletic careers.

Quantifying acromiohumeral distance in elite male field hockey players compared to a non-athletic population.

BACKGROUND: Shoulders of elite field hockey players are loaded continuously during play. Frequent high shoulder loading is known to influence certain shoulder variables, such as acromiohumeral distance. However, the influence of elite field hockey play on acromiohumeral distance is not examined yet. OBJECTIVE: To examine the acromiohumeral distance in elite male field hockey players compared to a non-athletic control group. DESIGN: Cross-sectional study. METHODS: Fifty male participants were included; 25 elite field hockey players (age: 24.0±2.72 years; weight: 77.2±5.29kg; height; 180.5±5.37cm) and 25 age- and gender matched non-athletes (23.0±2.29 years; weight: 75.7±9.53kg; height: 181.8±5.52cm). A Telemed-Colormaster-128 EXT-IZ device was used to bilaterally obtain ultrasound acromiohumeral distance images at 3 different angles of shoulder abduction in the frontal plane. RESULTS: Field hockey players showed a bilateral larger acromiohumeral distance at 45° (mean difference: 1.46mm [95% CI 0.46; 2.46]; p=0.005) and 60° (mean difference: 1.07mm [95% CI 0.21; 1.93]; p=0.016) compared to controls. In both groups, a significant but clinically less relevant, side difference was established for the acromiohumeral distance at 60° (mean difference: 0.79mm [95% CI 0.21; 1.34]; p=0.009). CONCLUSION: With active shoulder abduction, elite field hockey players show a larger acromiohumeral distance in comparison to non-athletic participants. This may be a protective sport-specific adaptation, to better guard the shoulder from injury. Thus, acromiohumeral distance measurement may help physical therapists/coaches decide which athletes could benefit from specific, additional exercises aimed at enlarging the subacromial space.

The effect of five isometric exercises on glenohumeral translations in healthy subjects and patients with the hypermobility type of the ehlers-danlos syndrome (heds) or hypermobility spectrum disorder (hsd) with multidirectional shoulder instability: an observational study.

OBJECTIVES: To examine whether patients, diagnosed with the hypermobility type of the Ehlers-Danlos syndrome (hEDS) or Hypermobility Spectrum Disorder (HSD), with multidirectional shoulder instability (MDI) have increased humeral head translations compared to healthy controls and to describe the direction of the humeral translations during five exercises. DESIGN: Observational study. SETTING: Ghent University Hospital. PARTICIPANTS: Twenty-seven female patients (aged mean (SD) 35 (13) years) with hEDS/HSD and MDI and 20 female healthy controls (aged 34 (11) years) participated in this study. INTERVENTIONS: The acromiohumeral (AHD) and humeralglenoid distance (HGD) were measured using ultrasound during five isometric exercises: shoulder external rotation, shoulder extension, shoulder flexion, elbow extension and holding a 2kg dumbbell. MAIN OUTCOME MEASURES: Ultrasound measures of the AHD and HGD. RESULTS: During isometric shoulder extension, elbow extension and dumbbell loading, patients had a significantly larger change in AHD compared to controls. In patients, the AHD was significantly smaller during isometric shoulder flexion, extension and elbow extension compared to the AHD measured in rest. By contrast, the AHD was significantly larger during isometric external rotation and dumbbell loading compared to the AHD measured in rest. Regarding the HGD, no significant differences between patients and controls were observed. However, significantly smaller HGD values were found in patients during isometric shoulder flexion compared to the HGD in rest. CONCLUSIONS: Isometric external rotation and holding a 2kg dumbbell caused an inferior translation in patients with hEDS/HSD and MDI, whereas isometric shoulder flexion and shoulder/elbow extension respectively led to an anterior-superior and superior translation.