Reliability of Dynamic Shoulder Strength Test Battery Using Multi-Joint Isokinetic Device.

This study aimed to determine the absolute and relative reliability of concentric and eccentric flexion, extension, horizontal abduction, and adduction movements of the shoulder using a functional electromechanical dynamometer (FEMD). Forty-three active male university students (23.51 ± 4.72 years) were examined for concentric and eccentric strength of shoulder flexion, extension, horizontal abduction, and horizontal adduction with an isokinetic test at 0.80 m·s-1. Relative reliability was determined by intraclass correlation coefficients (ICCs) with 95% confidence intervals. Absolute reliability was quantified by the standard error of measurement (SEM) and coefficient of variation (CV). Reliability was very high to extremely high for all movements on concentric and eccentric strength measurements (ICC: 0.76-0.94, SEM: 0.63-6.57%, CV: 9.40-19.63%). The results of this study provide compelling evidence for the absolute and relative reliability of concentric and eccentric flexion, extension, horizontal abduction, and horizontal adduction shoulder isokinetic strength tests in asymptomatic adults. The mean concentric force was the most reliable strength value for all tests.

Isometric Shoulder Testing Using a Forcemeter Is a Reliable Method of Strength Evaluation.

Isometric strength testing using a digital dynamometer is reliable for muscle function evaluation. It allows us to objectify manual strength assessment measurement. We tested intra- and inter-observer reliability of a user-friendly efficient digital dynamometer-the Forcemeter-equipped with a computer program to monitor the measurements and to store the data. Abduction, forward flexion, and external and internal rotation of both shoulders were tested three times in 20 healthy volunteers with no record of shoulder trauma. Isometric contracture was recorded in newtons. The first and the third test were carried out by Examiner A (intra-rater reliability); the second test, by Examiner B (inter-rater reliability). Good reliability was shown for intra-class correlation coefficient (ICC) values which mean moderate to high correlations (r = 0.66-0.93) for both examiners. Moderate to high correlations (r = 0.72-0.91) were found for comparisons between the results obtained by Examiner A.

Association of Scapular Dyskinesis with Neck and Shoulder Function and Training Period in Brazilian Ju-Jitsu Athletes.

Background and Objectives: Neck and shoulder injuries are common in Brazilian ju-jitsu (BJJ) athletes, and scapular dyskinesis (SD) is associated with these injuries. This study aimed to investigate the prevalence of SD in BJJ athletes, their neck and shoulder function and strength, and the BJJ training period. Materials and Methods: Forty-eight BJJ athletes participated in the study. Years of experience with BJJ, belt, shoulder internal and external rotation strength, neck strength, neck disability index (NDI), and SD were measured. Results: Approximately 31 BJJ athletes (64.6%) showed SD, and the nondominant arm showed a more obvious SD (n = 22, 45.8%) than the dominant arm (n = 18, 37.5%). Those with over five years of BJJ training experience showed a significantly higher rate of SD (p = 0.006) than those with less than five years of experience. Shoulder isometric internal rotation strength was significantly weaker in the obvious SD group than in the normal SD group (p = 0.014). Neck isometric strength and NDI did not differ significantly between individuals with or without SD. Conclusions: SD was common among BJJ athletes, and more experienced BJJ athletes exhibited higher rates of SD. Shoulder rotational strength was weaker with SD. Further studies are necessary on the neck and shoulders of BJJ athletes with SD.

Angle-Specific Isokinetic Shoulder Rotational Strength Can be Reliably Assessed in Collision and Contact Athletes.

An increased understanding of rotational strength as a potential prognostic factor for injury in contact and collision athletes may be important in planning return to sport. The aim of this study was to (1) determine the test-retest reliability of clinically relevant, angle-specific rotational and peak torque measurements in a cohort of uninjured collision and contact athletes; (2) develop a normal descriptive profile of angle-specific rotational torque measurements in the same cohort; and (3) examine the effects of direction and joint angle on shoulder rotational strength interlimb asymmetries. Twenty-three collision and contact athletes were recruited for the interday reliability substudy and 47 athletes were recruited for the remaining substudies. We used intraclass correlation coefficients with 95% confidence intervals to quantify interday reliability of all variables. We used a 2-way repeated-measures analysis of variance to analyze differences in absolute interlimb asymmetries. Interday reliability for the isokinetic strength variables was good to excellent (0.78-0.90) on the dominant side and moderate to good (0.63-0.86) on the nondominant side. Maximum angle-specific torque (as well as peak torque) can be measured reliably in internally and externally rotated positions. A normal profile of clinically relevant, angle-specific shoulder rotational torque measurements for collision and contact athletes has been established which provides a reference when assessing shoulder strength in this population.

Grip and shoulder strength correlation with validated outcome instruments in patients with rotator cuff tears.

HYPOTHESIS/BACKGROUND: The ability to better define preoperatively the extent of rotator cuff (RC) dysfunction is desired. The study's purpose was to prospectively examine the relationships between absolute and percentage loss (affected compared to unaffected) of grip and shoulder strength, and RC dysfunction. METHODS: Forty-seven consecutive patients with proven RC tears participated in this study. Prior to surgery, bilateral strengths of grip, shoulder abduction, and shoulder external rotation (ER) were measured with a handheld dynamometer, and subjective outcome measures were gathered. RC tear size was determined via arthroscopy. Patient-reported outcomes were gathered on the day of the examination or via e-mail following initial evaluation. Descriptive statistics, difference analysis, and correlation coefficients (reported as either direct or negative) were used to analyze data. Grip, abduction and ER strengths, and percentage loss of grip, abduction, and ER strengths (percentage loss affected vs. unaffected), and tear size were analyzed in relation to all of the scores on selected subjective outcome measurement tools. The P value was set at .05. RESULTS: Fair direct correlations were found between grip strength and the Veterans RAND 12-Item Health Survey (VR-12) mental health scores, ER strength and Simple Shoulder Test (SST), abduction strength, and both the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) function score and SST score. Abduction and ER strengths were also found to possess a fair direct correlation. Fair negative correlations were found between the ASES function score and each of the following: percentage loss of abduction strength, percentage loss of ER strength, and tear size in centimeters. Another fair negative correlation was found between the Single Assessment Numerical Evaluation (SANE) score and tear size in centimeters. DISCUSSION: Our findings suggest that as shoulder strength decreases, ipsilateral shoulder RC dysfunction increases. Grip strength was not related to shoulder RC dysfunction. CONCLUSION: Grip strength was not found to correlate with RC tears. Those with decreased abduction and ER strengths and low ASES scores should be considered more likely to have an RC tear.

Deltoid muscle contribution to shoulder flexion and abduction strength: an experimental approach.

BACKGROUND: The rotator cuff (RC) and the deltoid muscle are 2 synergistic units that enable the functionally demanding movements of the shoulder. A number of biomechanical studies assume similar force contribution of the force couple (RC and deltoid) over the whole range of motion, whereas others propose position-dependent force distribution. There is a lack of in vivo data regarding the deltoid's contribution to shoulder flexion and abduction strength. This study aimed to create reliable in vivo data quantifying the deltoid's contribution to shoulder flexion and abduction strength throughout the range of motion. METHODS: Active range of motion and isometric muscle strength of shoulder abduction and flexion in 0°, 30°, 60°, 90°, and 120° of abduction/flexion as well as internal and external rotation in 0° and 90° of abduction were obtained in 12 healthy volunteers on the dominant arm before and after an ultrasound-guided isolated axillary nerve block. Needle electromyography was performed before and after the block to confirm deltoid paralysis. Radiographs of the shoulder and an ultrasonographic examination were used to exclude relevant shoulder pathologies. RESULTS: Active range of motion showed a minimal to moderate reduction to 94% and 88% of the preintervention value for abduction and flexion. Internal and external rotation amplitude was not impaired. The abduction strength was significantly reduced to 76% at 0° (P = .002) and to 25% at 120° (P < .001) of abduction. The flexion strength was significantly reduced to 64% at 30° (P < .001) and to 30% at 120° (P < .001) of flexion. The strength reduction was linear, depending on the flexion/abduction angle. The maximal external rotation strength showed a significant decrease to 53% in 90° (P < .001) of abduction, whereas in adduction no strength loss was observed (P = .09). The internal rotation strength remained unaffected in 0° and 90° of abduction (P = .28; P = .13). CONCLUSION: The deltoid shows a linear contribution to maximal shoulder strength depending on the abduction or flexion angle, ranging from 24% in 0° to 75% in 120° of abduction and from 11% in 0° to 70% in 120° of flexion, respectively. The overall contribution to abduction strength is higher than to flexion strength. The combination of deltoid muscle and teres minor contributes about 50% to external rotation strength in 90° of abduction. The internal rotation strength is not influenced by a deltoid paralysis. This study highlights the position-dependent contribution of the shoulder muscles to strength development and thereby provides an empirical approach to better understand human shoulder kinematics.

Serratus Anterior Fatigue Reduces Scapular Posterior Tilt and External Rotation During Arm Elevation.

CONTEXT: Fatigue of the scapular stabilizing muscles resulting from repeated arm motion has been reported to alter scapular kinematics, which could result in shoulder pathology, especially impingement. OBJECTIVE: This study aimed to examine the effects of fatigue of the serratus anterior muscle on scapular kinematics, specifically, decrease scapular posterior tilt and upward scapular rotation during arm elevation. DESIGN: Repeated measures. SETTING: Laboratory. PARTICIPANTS: Thirty participants were included in the investigation. INTERVENTIONS: Scapular kinematics and shoulder strength were measured before and immediately following a serratus anterior fatigue protocol. MAIN OUTCOME: Scapular 3-dimensional position during arm elevation. RESULTS: No difference in upward rotation of the scapula between prefatigue and postfatigue conditions (ascending: P = .188; descending: P = .798). Scapular posterior tilt decreased during arm elevation following the fatigue protocol between 60° and 90° and 90° and 120° of arm elevation during the ascent (P = .004) and the descent (P = .013). Fatigue by arm elevation angle interaction was found for clavicular elevation during the ascent (P = .050) between 90° and 120° of arm elevation. Scapular internal rotation increased during the ascent (P = .027). There was no difference in clavicular protraction between the prefatigue and postfatigue conditions (ascending: P ≤ .001; descending: P ≤ .001). CONCLUSION: Fatigue of the serratus anterior decreases posterior scapular tilt and greater clavicular elevation and scapular internal rotation at higher arm elevation angles. These findings are consistent with the scapular kinematic patterns associated with shoulder pain. Improving serratus anterior endurance might delay the changes in scapular kinematics associated with repeated arm motion and shoulder injury mechanisms.

The relationship of shoulder elevation strength to patient-reported outcome after anatomic total shoulder arthroplasty.

BACKGROUND: Most patient-reported outcome measures (PROMs) used to assess outcomes after anatomic total shoulder arthroplasty (aTSA) focus on pain and function. Although strength is considered an important component of function, only the Constant-Murley score (CMS) includes an objective measurement of shoulder strength. The purpose of this study was to evaluate the relationship between shoulder elevation strength (SES) and PROMs after aTSA for the treatment of primary glenohumeral osteoarthritis (GHOA). METHODS: This was a retrospective analysis of 605 patients enrolled in a multicenter clinical database who underwent aTSA to treat primary GHOA. Patients were evaluated preoperatively and at 24 months after surgery. Outcome was assessed with the CMS, American Shoulder and Elbow Surgeons score, Western Ontario Osteoarthritis of the Shoulder score, Single Assessment Numeric Evaluation score, and patient satisfaction. Relationships between SES and outcomes were investigated. RESULTS: The correlations between SES and the PROMs before and after treatment were very weak and weak, respectively (r ≤ 0.262 for all). The strength of the correlations between the absolute and adjusted CMS and the other PROMs varied from weak to moderate (r = 0.180 to r = 0.455), and the strength of the correlations was greater postoperatively. With the strength component removed from the CMS, the correlations between the CMS and other PROMs were stronger (r = 0.194 to r = 0.495). CONCLUSIONS: Although measurement of SES provides objective information about shoulder function and outcome related to the treatment of primary GHOA with aTSA, the actual relevance to patients is unclear as the correlations between SES and PROMs were weak. Furthermore, the variable correlations between the CMS and PROMs call into question the exclusive use of the CMS and support the use of other PROMs that may more accurately reflect patient perception of outcome.

Elite male field hockey players have symmetric isokinetic glenohumeral strength profiles, but show asymmetry in scapular muscle strength.

Shoulders of elite field hockey players are loaded continuously during play. However, shoulder girdle muscle performance in this population has never been examined yet. This study aimed to compare isokinetic shoulder girdle performance in elite male field hockey players to matched controls, with respect to strength, endurance and muscle balance. The complete male national field hockey team of Belgium (n = 25) was included and matched to a gender- and age-matched control group of healthy participants (n = 25). A Biodex system-4 dynamometer was used to measure glenohumeral and scapular muscle strength at 2 velocities in a concentric/concentric mode. With the main outcome measures being isokinetic strength values, peak force (protraction-retraction), peak torque (rotations), fatigue index and agonist/antagonist ratio's. Measurement results showed that elite male field hockey players were stronger than their matched controls, for both the rotational and the protraction-retraction movement. Concerning rotational strength, symmetrical findings were established, contrary to scapular strength, where side differences were noted. At low velocity, retraction peak force was higher on the dominant side. Protraction peak force was higher on the non-dominant side when measured at high velocity. In conclusion, elite field hockey players have a symmetrical rotational strength profile, in contrast to their scapular strength profile.

Supraspinatus tendon micromorphology in individuals with subacromial pain syndrome.

STUDY DESIGN: Cross-sectional cohort. INTRODUCTION: Tendon collagen organization can be estimated by peak spatial frequency radius (PSFR) on ultrasound images. Characterizing PSFR can define the contribution of collagen disruption to shoulder symptoms. PURPOSE OF THE STUDY: The purpose of this was to characterize the (1) supraspinatus tendon PSFR in participants with subacromial pain syndrome (SPS) and healthy controls; (2) PSFR between participants grouped on a tendon visual quality score; and (3) relationship between PSFR with patient-reported pain, function, and shoulder strength. METHODS: Participants with SPS (n = 20) and age, sex, and arm-dominance-matched healthy controls (n = 20) completed strength testing in scaption and external rotation, and patient-reported pain, and functional outcomes. Supraspinatus tendon ultrasound images were acquired, and PSFR was calculated for a region of interest 15 mm medial to the supraspinatus footprint. PSFR was compared between groups using an independent t-test and an analysis of variance to compare between 3 groups for visually qualitatively rated tendon abnormalities. Relationships between PSFR with pain, function, and strength were assessed using Pearson correlation coefficient. RESULTS: Supraspinatus tendon PSFR was not different between groups (P = .190) or tendon qualitative ratings (P = .556). No relationship was found between PSFR and pain, functional loss, and strength (P > .05). CONCLUSIONS: Collagen disruption (PSFR) measured via ultrasound images of the supraspinatus tendon was not different between participants with SPS or in those with visually rated tendon defects. PSFR is not related to shoulder pain, function, and strength, suggesting that supraspinatus tendon collagen disorganization may not be a contributing factor to shoulder SPS. However, collagen disruption may not be isolated to a single region of interest. LEVEL OF EVIDENCE: 3b: case-control study.

Is isokinetic shoulder strength a determinant of serve ball velocity in tennis?

The tennis serve is closely related to the quality of the tennis match. However, the isokinetic parameters associated with the tennis serve are still unclear. The aim of this study was to investigate the relationships between ball velocity and isokinetic shoulder strength in tennis serve and to determine isokinetic strength parameters that can predict tennis serve velocity. A total of 13 elite male athletes (16.8 ± 1.5 years) voluntarily participated in the study. The athletes' shoulder internal-external rotation, extension-flexion and abduction-adduction strengths were measured with 5-5-15 repetitions at 60°/s, 180°/s, 240°/s angular velocities. Later, the athletes' 1st, 2nd, and average serve ball speeds were determined using a handheld radar gun. Significant correlations were found between ball speed and isokinetic tennis serve strength (r = 0.556-0.819; p < 0.05). The correlations between ball speed and isokinetic strength performance were higher at 180°/s and 240°/s angular velocities. Extension (240°/s; r = 0.819), flexion (180°/s; r = 0.755), abduction (240°/s; r = 0.733), adduction (240°/s; r = 0.684) and internal rotation (180°/s; r = 0.803) were highly correlated with ball velocity. These findings suggest that strength training to increase the ball speed of the tennis serve should be performed fast at high angular velocities and planning should focus on the strength of extension, flexion, abduction, adduction and internal rotation.

The Effect of Blood Flow Restriction Therapy on Shoulder Function Following Shoulder Stabilization Surgery: A Case Series.

Background: Traumatic shoulder instability is a common injury in athletes and military personnel. Surgical stabilization reduces recurrence, but athletes often return to sport before recovering upper extremity rotational strength and sport-specific abilities. Blood flow restriction (BFR) may stimulate muscle growth without the need for heavy resistance training post-surgically. Hypothesis/Purpose: To observe changes in shoulder strength, self-reported function, upper extremity performance, and range of motion (ROM) in military cadets recovering from shoulder stabilization surgery who completed a standard rehabilitation program with six weeks of BFR training. Study Design: Prospective case series. Methods: Military cadets who underwent shoulder stabilization surgery completed six weeks of upper extremity BFR training, beginning post-op week six. Primary outcomes were shoulder isometric strength and patient-reported function assessed at 6-weeks, 12-weeks, and 6-months postoperatively. Secondary outcomes included shoulder ROM assessed at each timepoint and the Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST), the Upper Extremity Y-Balance Test (UQYBT), and the Unilateral Seated Shotput Test (USPT) assessed at the six-month follow-up. Results: Twenty cadets performed an average 10.9 BFR training sessions over six weeks. Statistically significant and clinically meaningful increases in surgical extremity external rotation strength (p < 0.001; mean difference, .049; 95% CI: .021, .077), abduction strength (p < 0.001; mean difference, .079; 95% CI: .050, .108), and internal rotation strength (p < 0.001; mean difference, .060; CI: .028, .093) occurred from six to 12 weeks postoperatively. Statistically significant and clinically meaningful improvements were reported on the Single Assessment Numeric Evaluation (p < 0.001; mean difference, 17.7; CI: 9.4, 25.9) and Shoulder Pain and Disability Index (p < 0.001; mean difference, -31.1; CI: -44.2, -18.0) from six to 12 weeks postoperatively. Additionally, over 70 percent of participants met reference values on two to three performance tests at 6-months. Conclusion: While the degree of improvement attributable to the addition of BFR is unknown, the clinically meaningful improvements in shoulder strength, self-reported function, and upper extremity performance warrant further exploration of BFR during upper extremity rehabilitation. Level of Evidence: 4, Case Series.

Normalized Isometric Shoulder Strength as a Predictor of Ball Velocity in Youth Baseball Players.

BACKGROUND: Despite increased awareness of factors related to athletic performance and injury prevention, youth and adolescent baseball players continue to report injuries at alarming rates. Upper extremity muscle strength is an integral part of physical assessment and injury prevention in baseball players, however minimal data exists in youth populations. Changes in anthropometric measures, inherent in physically developing athletes, have been shown to impact strength measures, however normalization methodology is rarely reported. PURPOSE: The purposes of this study were to 1) compare the measurement properties of five potential methods for normalizing isometric shoulder strength in a cohort of 9-12 year old male baseball players and 2) examine the relationship between normalized isometric shoulder strength and ball velocity in a cohort of 9-12 year old male baseball players. STUDY DESIGN: Prospective cohort study (n=159). METHODS: Baseline and follow up height, weight and bilateral ulnar length measurements were assessed followed by isometric strength in both the dominant and non-dominant shoulders. Strength measures included scapular plane abduction (scaption), external rotation (ER) at 0°, ER and internal rotation (IR) at 90°. Ball velocity was assessed as a measure of throwing performance. Intraclass correlation coefficients (ICC2,1), standard errors of measurement (SEM) and minimal detectable change (MDC95) were calculated for all strength measures. Repeated measures ANOVA were conducted comparing changes in normalized strength using five separate anthropometric measures: weight, height, body mass index, ulnar length and % of non-dominant shoulder strength. Linear regression models were used to examine the relationships between normalized isometric shoulder strength and ball velocity. Statistical significance was set a priori at α=0.05. RESULTS: Shoulder strength normalized using ulnar length was the only method that demonstrated excellent reliability (ICC2,1 0.98-0.99) and detected significant changes between strength in each of the four measures tested (SEM 0.39-0.69 Nm). Modest but significant correlations were observed between scaption and ball velocity (r2 = 0.27, p < 0.001) and ER at 0° and ball velocity (r2 = 0.23, p < 0.001). CONCLUSION: Ulnar length was the most stable and reliable normalization method for assessing isometric shoulder strength in youth baseball players. In addition, normalized scaption strength was the most significant predictor of ball velocity, followed by ER at 0° strength in this population. LEVEL OF EVIDENCE: Level 2b (etiology).

The Correlation Between the Strength of the Shoulder and Trunk Muscular Systems in Elite Adolescent Water Polo Athletes.

Introduction Water polo is a competitive team sport played in the water between two teams of seven players each. Water polo players must have swimming speed, strong abdominal and back muscles, and strong shoulder muscles to cope with this sport's special conditions. In this study, we investigate the possible association of shoulder and trunk muscle systems in adolescent water polo athletes of high demands. Materials and methods The research included 42 water polo players aged 14-16, who train regularly for at least five years, six times a week, and participate in national championships and national teams. The athletes were evaluated on the strength and torque of these muscular systems using the isokinetic dynamometer Biodex System 4 Pro (Biodex Medical Systems, Inc, Shirley, NY). The correlation of the results was done using the statistical package SPSS 21. Results The correlations revealed statistically significant differences in trunk extension in combination with the shoulder external/internal rotation ratio. Also, most of the correlations occurred between the trunk and non-dominant limb of the athletes and, more often, in the female athletes. Furthermore, for the hand grip, the male athletes showed a greater difference in strength between the dominant and the non-dominant member than female athletes. Finally, the evaluation of the trunk extension/flexion ratio and external/internal rotation ratio for the shoulder joint showed that many athletes are outside the normal range and need targeted strengthening. Conclusion The negative correlation coefficient between trunk extension/flexion and shoulder external/internal rotation indicates that the trunk extension mechanism helps for better internal rotation of the shoulder. Therefore, water polo players should focus on the training of the stretching mechanism of the trunk and also give weight to achieving a balance between the competing muscular systems of the trunk and the shoulder. Thus, athletes can maximize their skills and, at the same time, protect themselves from injuries.

Exploration of the Shoulder Internal Rotation's Influence on Throwing Velocity in Handball Players: A Pilot Study.

The main objective of this study was to test the relationship between shoulder internal rotation strength and standing throwing velocity. A repeated measures cross-sectional study was conducted with 20 professional handball players (mean ± SD; age: 19.28 ± 2.55 years, weight: 81.52 ± 9.66 kg, height: 185 ± 6 cm, BMI: 23.74 ± 1.69). The participants were instructed to perform eight standing throws from the 7 m line of the handball court at maximum velocity to calculate the mean and maximum throwing velocity. An incremental test was performed to calculate the repetition maximum (1-RM) of internal rotation shoulder strength. A Pearson's correlation analysis with a 95% confidence interval (95% CI) was performed to determine whether correlations existed between dominant arm internal rotation strength characteristics and maximum and mean ball-throwing velocity. There is no correlation between the internal rotation strength of the throwing shoulder and the velocity of the ball in the standing handball throw.

Normal Baseline Values for Isometric Shoulder Strength in Scaption for Healthy Filipino Individuals in the 20-30 year Age Group.

INTRODUCTION: Isometric shoulder strength is vital in the management of individuals suffering from shoulder diseases such as rotator cuff tears. Normal values for the working Filipino population who are at risk of developing shoulder problems are lacking. The objective of this study was to determine the isometric baseline isometric shoulder strengths in scaption of healthy Filipino individuals aged 20-30 years old without a history of a shoulder injury. MATERIAL AND METHODS: This is a cross-sectional descriptive study measuring the isometric strength values using the handheld IDO isometer of dominant and non-dominant shoulder of healthy Filipino individuals aged 20 to 30 years old. RESULTS: There is no significant difference in the mean isometric shoulder strength between the dominant and non-dominant arm for both sexes. The male gender scored higher values compared to the female gender and is statistically significant. CONCLUSION: There is no difference in isometric shoulder strength between the dominant and non-dominant shoulder. Strength differences favour the male gender.

Can the history of injury influence shoulder isokinetic torque parameters in volleyball players?

The aim of the present study was to compare shoulder internal rotator and external rotator isokinetic parameters in concentric and eccentric contractions between volleyball players with and without a history of shoulder injury. Thirty male volleyball players participated of this study, divided into two groups: with a history of injury (WHI) in the dominant shoulder (11 athletes; age: 19.4 ± 3.6 years) and no history of injury (NHI) (19 athletes; age: 18.3 ± 2.9 years). The peak torque (PT) and concentric (Con) and eccentric (Ecc) PT angles in internal (IR) and external rotation (ER) at velocities of 60 and 180°/s were measured. The conventional (Con_ER:Con_IR), functional spiking (Ecc_ER:Con_IR), and cocking ratios (Ecc_IR:Con_ER) were calculated. No significant differences were found between groups for PT and PT angle, or for conventional, functional spiking, and cocking ratios. However, the spiking ratio was considered low (0.87) in the WHI group. Moreover, for the spiking ratio in the WHI group, PT at 60°/s occurred at different angles. We conclude that previous injury in shoulder did not affect the peak torque, as well as conventional, spiking or cocking ratio. However, the PT angles at 60°/s used to calculate the spiking ratio shifted due the prior injury.

Shoulder Strength and Closed Kinetic Chain Upper Extremity Stability Test Performance in Division III Collegiate Baseball and Softball Players.

BACKGROUND: Shoulder strength measured with a handheld dynamometer (HHD) and the Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST) are clinical tools that have been used to measure athlete's performance and track their progress. PURPOSE: The specific aims of this study were to describe baseball (BB) and softball (SB) players isometric strength measures and their performance on the CKCUEST; examine the relationships between strength and the CKCUEST; compare isometric strength measures of the throwing and non-throwing arms; and compare the strength and the CKCUEST measures between BB and SB players. STUDY DESIGN: Observational cohort study. METHODS: Participants included 50 DIII BB and 24 DIII SB players. Shoulder strength for the internal and external rotators were measured using a HHD and the CKCUEST was performed. The CKCUEST score and power were calculated. Descriptive statistics and paired t-tests were used to compare throwing and non-throwing shoulder strength. Independent t-test was used to compare BB and SB players shoulder strength and the CKCUEST measures. RESULTS: The BB players demonstrated significant strength differences between the throwing and non-throwing shoulders and the internal rotators were significantly stronger than the external rotators (p < 0.05), while the strength ratio of the internal and external rotators was not different between arms (p=0.87). The SB players demonstrated no significant strength differences between the throwing and non-throwing shoulders for the internal and external rotators or the strength ratio of the rotators (p > 0.05). There were no significant differences between the strength of the internal and external rotators of the non-throwing shoulder (p=0.075) or the throwing shoulder (p=0.096). The BB players throwing and non-throwing shoulders produced significantly more internal and external force than the SB players (p < 0.001), however, the internal/external rotators strength ratio were similar (p=0.32, p=0.30). The CKCUEST power had inverse and significant correlations (p=0.006, p=0.003) with SB players internal and external rotators, respectively. The CKCUEST power was significantly different between BB and SB players (p < 0.001). CONCLUSION: This study presented shoulder rotator strength and CKCUEST reference values for DIII BB and SB players. BB players demonstrated more strength but overall, less symmetry compared to SB players. CKCUEST power may be considered for the evaluation of athletes. LEVEL OF EVIDENCE: Level III.

Biomechanical and physical determinants of bowling speed in cricket: a novel approach to systematic review and meta-analysis of correlational data.

This systematic review and meta-analysis examined the influence of biomechanical and physical characteristics on ball release speed in cricket using correlation data. Search was conducted across PubMed, Cinhal, Scopus, SportDiscus and Web of Science, with eighteen studies included. The ball release speed had a moderate correlation with overall biomechanical (r = 0.42, p < 0.001) parameters and a strong correlation with physical (r = 0.65, p < 0.001) characteristics. Furthermore, individual biomechanical and physical parameters were also correlated with ball release speed. The run-up speed had a strong correlation (r = 0.50, p < 0.001) and front knee angle at ball release had a moderate correlation (r = 0.40, p < 0.001). Poorer correlations were identified for centre of mass velocity at ball release (r = 0.16, p = 0.134), front knee angle at front foot contact (r = 0.26, p = 0.015) 25 and vertical ground reaction force (r = 0.13, p = 0.659). Strong and significant correlation was found for total arm length (r = 0.65, p < 0.001) and shoulder strength (r = 0.58, p < 0.001). This review highlights the biomechanical and physical parameters that are major determinants of faster ball release speed.

Within-Session Sequence of the Tennis Serve Training in Youth Elite Players.

The influence of muscular fatigue on tennis serve performance within regular training sessions is unclear. Therefore, the aim of the present study was to examine the within-session sequence of the tennis serve in youth tennis. Twenty-five young male (14.9 ± 0.9 years) and female (14.5 ± 0.9 years) players participated in this within-subject crossover study, and they were randomly but sex-matched assigned to different training sequences (serve exercise before tennis training (BTS) or after tennis training (ATS)). Pre- and post-tests included serve velocity performance and accuracy, shoulder strength, and range-of-motion (ROM) performance (internal/external rotation). Results showed that after one week of serve training conducted following the ATS sequence, significant decreases were found in serve performance (e.g., speed and accuracy), with standardized differences ranging from d = 0.29 to 1.13, as well as the shoulder function (strength [d = 0.20 to 1.0] and ROM [d = 0.17 to 0.31]) in both female and male players, compared to the BTS sequence. Based on the present findings, it appears more effective to implement serve training before the regular tennis training in youth players. If applied after training, excessive levels of fatigue may cause shoulder imbalances that could be related to an increased injury risk.