Mobility impairment, muscle imbalance, muscle weakness, scapular asymmetry and shoulder injury in elite volleyball athletes

BACKGROUND: The aim of this study was to evaluate the relationship between shoulder mobility, rotator muscles' strength and scapular symmetry, and shoulder injuries and/or pain in elite volleyball athletes. METHODS: An isokinetic shoulder muscle strength test, which was performed at speeds of 60/sec and 180/sec, and shoulder mobility and scapula lateral slide tests were conducted bilaterally on 16 subjects, who represented the England elite volleyball players. The subjects also prospectively completed monthly questionnaires during the competition season to report on their shoulder condition. RESULTS: The results showed that the active range of shoulder internal rotation and concentric external rotators' strength in the dominant arm were significantly less, than in the non-dominant arms, but the internal rotators were significantly stronger in both concentric and eccentric tests at both testing speeds. Seven of 16 subjects indicated overt shoulder injury or pain during their training season, nine subjects had shoulder mobility impairment, seven had muscle imbalance, 13 had relative muscle weakness and five had scapular asymmetry. The association between shoulder muscle strength imbalance (eccentric external < concentric internal) of rotators in the dominant arm and shoulder injuries was statistically significant (Fisher's exact test, p<0.05). CONCLUSIONS: We conclude that rotator muscle strength imbalance may play an important role in shoulder injuries in high-level volleyball players.     

Isokinetic performance and shoulder mobility in elite volleyball athletes from the United Kingdom

OBJECTIVES: To evaluate the differences in strength and mobility of shoulder rotator muscles in the dominant and non-dominant shoulders of elite volleyball players. METHODS: Isokinetic muscle strength tests were performed at speeds of 60 and 120 degrees/s, and shoulder mobility was examined in ten players from the England national men's volleyball squad. The subjects also completed a questionnaire that included a visual prompt and analogue pain scale. RESULTS: The range of motion of internal rotation on the dominant side was less than that on the non-dominant side (p < 0.01). The average peak strength at 60 degrees/s external eccentric contraction was lower than that of internal concentric contraction in the dominant arm, but was higher in the non-dominant arm. Six of the ten subjects reported a shoulder problem, described as a diffuse pain located laterally on the dominant shoulder. CONCLUSIONS: These elite volleyball players had a lower range of motion (internal rotation) and relative muscle imbalance in the dominant compared with the non-dominant shoulder.     

Isokinetic eccentric-to-concentric strength ratios of the shoulder rotator muscles in throwers and nonthrowers

BACKGROUND: One of the possible mechanisms leading to shoulder injury may be a strength imbalance between those muscles that accelerate the upper limb and those responsible for deceleration. Many studies have examined shoulder balance through a concentric strength ratio of external and internal shoulder rotator muscles. HYPOTHESIS: A functional external eccentric-to-internal concentric ratio may be a better identifier of muscular imbalance in dominant and nondominant shoulders of throwers and nonthrowers. STUDY DESIGN: Controlled laboratory study. METHODS: Eccentric external and concentric internal peak torques were measured bilaterally in 59 men (16 throwers and 43 nonthrowers) at 300 deg/sec. Subjects were tested in the supine position with the shoulder abducted to 90 degrees and the elbow flexed to 90 degrees. RESULTS: Throwers exhibited significantly lower ratios than nonthrowers in their dominant limb; there was no difference between groups for the nondominant limb. CONCLUSIONS: The lower ratio in the throwers' dominant limb was attributed to significantly greater concentric internal rotation torques without concomitant eccentric external torque gains. Clinical Relevance: Rehabilitation and injury prevention regimens that include functional exercises to improve eccentric external rotation strength may bring more balance to the dominant shoulder of throwing athletes.     

Concentric and eccentric muscle fatigue of the shoulder rotators

Previous research has demonstrated fatigue resistance for eccentric compared with concentric muscle contractions in the lower extremity. The purpose of this study was to determine if eccentric fatigue resistance was also evident in the internal and external rotators of the shoulder. Ten subjects performed three sets of 32 maximum isokinetic contractions in shoulder internal and external rotation at 120 degrees /s. One arm performed eccentric contractions and the contralateral arm performed concentric contractions. Subjects were also tested for isometric strength prior to and immediately following the isokinetic contractions. Percent change in isokinetic torque (first five repetitions versus last five for each set) and isometric torque was compared between the arms performing eccentric and concentric contractions. Fatigue with isokinetic contractions was not different between eccentric and concentric internal rotation (25 % vs. 26 %, p = 0.76) and external rotation (24 % vs. 32 %, p = 0.11). Similarly, fatigue with isometric contractions was not different between eccentric and concentric internal rotation (11 % vs. 5 %. p = 0.33) and external rotation (15 % vs. 7 %, p = 0.07). These results indicate that unlike previously described fatigue resistance for eccentric muscle contractions in the quadriceps, dorsiflexors and plantarflexors, fatigue was not different between eccentric and concentric muscle contractions of the internal and external rotators of the shoulder.     

Relation entre le lancer de balle et la force isocinétique des rotateurs d'épaule chez le handballeur de haut niveau

Objectives. – The aim of this study was to calculate correlations between isokinetic torque of the internal and external dominant shoulder rotators and ball velocity in high-level handball players.Synthesis of facts. – Internal and external shoulder rotators were examined in twenty-one national level handball male players on the concentric mode action at 60, and 120°/second. External rotators were examined on the eccentric action at 60 and 120°/second. Concentric ratio ERcon/IRcon and mixed ratio ERecc/IRcon were calculated. Ball velocity was measured in three types of throw: throw in seated position, standing throw and throw with three meter running jump. After statistical analysis using the Spearman correlation coefficient, no correlation was found between strength of internal and external shoulder rotators and ball velocity. The relationship between ball velocity of the throw in seating position and concentric and mixed ratios at 60 and 120°/second was significant (P < 0.01).Conclusion. – Peak torque of internal and external rotators of the dominant shoulder was not a good indicator of throwing velocity.     

Isokinetic performance at diagonal pattern and shoulder mobility in elite overhead athletes

The purpose of this study was to measure isokinetically glenohumeral joint movement peak torque and work in professional basketball, volleyball, handball and baseball players and determine whether significant differences exist between the dominant and non-dominant extremity in athletes and controls. Eighty healthy professional overhead athletes (basketball, volleyball, handball and baseball players) and 20 controls were tested bilaterally on a CYBEX 6000 isokinetic dynamometer at 60 degrees and 180 degrees s(-1) for diagonal pattern of the glenohumeral joint. A standardized protocol and testing guidelines were strictly followed. The range of motion of internal rotation (IR) on the dominant side of baseball players was significantly smaller than those on the dominant side of basketball, handball and volleyball players, and controls (P<0.01). Flexion/abduction/external rotation were consistently higher on the dominant arm (8.5%) for peak torque at 60 degrees s(-1) in baseball players, and bilateral ratios were lower on the dominant arm (14.8%) for peak torque at 180 degrees s(-1) in basketball players. The results of this study are important for the application and interpretation of isokinetic data and flexibility and mobility characteristics on unilaterally dominant overhead athletes. Functional weakness in external rotators, mobility impairments in IR and muscle imbalance have been shown in the dominant arm of these overhead athletes.     

Shoulder functional ratio in elite junior tennis players

ObjectiveTo evaluate shoulder rotation strength and compare the functional ratio between shoulders of elite junior tennis players.DesignThis cross-sectional study evaluated muscular rotation performance of 40 junior tennis players (26 male and 14 female) with an isokinetic dynamometer.Main outcome measuresStrength variables of external (ER) and internal rotators (IR) in concentric and eccentric modes were considered. For the peak torque functional ratio, the eccentric strength of the ER and the concentric strength of the IR were calculated.ResultsAll variables related to IR were significantly higher on the dominant compared to the non-dominant side in males and females (p < 0.05), but only boys exhibited this dominance effect in ER (p < 0.05 and p < 0.001). Regarding functional ratios, they were significantly lower for the dominant shoulder (p < 0.001) and below 1.00 for both groups, indicating that the eccentric strength of the ER was not greater than the concentric strength of the IR.ConclusionElite junior tennis players without shoulder injury have shoulder rotation muscle strength imbalances that alter the normal functional ratio between rotator cuff muscles. Although these differences do not seem to affect the athletic performance, detection and prevention with exercise programs at an early age are recommended.     

Shoulder strength, power, and endurance in college tennis players.

Twenty-four college tennis players were tested for bilateral shoulder internal/external rotation strength on a Cybex 340 isokinetic dynamometer; they were positioned supine with the glenohumeral joint abducted to 90 degrees. Subjects produced significantly (P less than 0.01) more torque in internal rotation at 60 and 300 deg/sec in the dominant arm compared to the nondominant arm. Subjects also produced significantly more power in internal rotation at 60 deg/sec in the dominant arm. No significant differences between the dominant and nondominant arms were seen in internal rotation power at 300 deg/sec or in the internal rotation endurance ratio. No significant differences were seen in external rotation on any measurement. By significantly increasing the strength of the dominant shoulder in internal rotation without subsequent strengthening of the external rotators, muscle imbalances may be created in the dominant arm that could possibly affect the tennis player's predisposition to injuries caused by overloading of the shoulder joint. This study suggests that external rotation strengthening exercises should be implemented in tennis conditioning programs to maintain muscle strength balance, and possibly reduce the chance of overload injury.     

Isokinetic dynamometry applied to shoulder rotators – Velocity limitations in eccentric evaluations

The objectives of this study were to evaluate if collegiate overhead athletes, with and without shoulder pain, and non-athletes could reach a preset velocity in internal and external shoulder rotation isokinetic evaluations; and to evaluate the correlation between torque and velocity. Controlled laboratory study, cross-sectional. Evaluations were performed using the isokinetic dynamometer Biodex System 3. Participants were assessed seated, with the arm at 90° of shoulder abduction and 90° of elbow flexion, from neutral rotation to 90° of external rotation. Five maximal contractions of isokinetic concentric and reactive eccentric internal and external rotation were performed at the velocities 90°/s, 180°/s and 240°/s. Data were processed with using MatLab. Most participants did not reach the isokinetic phase during eccentric tests at 180°/s and 240°/s, particularly in the external rotators evaluation. High correlations between torque and velocity of eccentric tests were found. The groups presented no differences in maximal velocity attained in trials which preset velocity was not reached. These results call into question the use of reactive eccentric tests at velocities higher than 180°/s for the isokinetic evaluation of shoulder external rotators in collegiate overhead athletes and non-athletes in this specific position. In such cases, careful evaluation of the velocity is recommended to determine if the isokinetic phase was reached.     

Reliability of shoulder rotators isokinetic strength imbalance measured using the Biodex dynamometer

BackgroundIsokinetic assessment of shoulder internal and external rotators is commonly used by clinicians to assess muscle performance and to guide rehabilitation. The reliability of isokinetic assessment is fundamental to track small but clinically relevant changes.ObjectivesWe aimed to analyze the absolute and relative reliability of strength imbalance indices such as peak torque ratios (ERconc/IRconc, ERecc/IRecc, ERecc/IRcon, IRecc/ERcon), bilateral concentric and eccentric strength ratios, and to examine the reliability of external rotator and internal rotator peak torque measured using a Biodex^® dynamometer in the seated position.DesignCross-sectional laboratory study.MethodsForty-six healthy participants were tested twice with seven days between sessions, at 60 °/s and 120 °/s concentrically, and 30 °/s eccentrically.ResultsLow to moderate relative reliability (intraclass correlation coefficient: 0.25–0.81) was found for unilateral and bilateral strength imbalance ratios. High intraclass correlation coefficient values (0.87–0.97) were found for peak torque. Concerning absolute reliability, the standard error of measurement ranged from 9.1 to 25.6% for strength imbalance ratios and from 7.7 to 14.5% for peak torque measurements, and minimal detectable change ranged from 25.2 to 71% for strength imbalance ratios and from 21.3 to 40.2% for peak torque measurements.ConclusionsThe standard error of measurement and minimal detectable change reported in the present study should be taken into account when evaluating the individual longitudinal changes in clinical practice.     

Upper extremity range of motion and isokinetic strength of the internal and external shoulder rotators in major league baseball players

Forty-one professional baseball players volunteered for upper extremity range of motion measurements and isokinetic testing for internal and external shoulder rotation. Pitchers demonstrated 9 degrees more external shoulder rotation with the arm abducted, 5 degrees more forearm pronation, and 9 degrees less shoulder extension on the dominant side compared with the dominant side of position players. Pitchers also demonstrated 9 degrees more external rotation in abduction, 5 degrees less shoulder flexion, 11 degrees less horizontal extension, 15 degrees less internal rotation in abduction, 6 degrees less elbow extension, 4 degrees less elbow flexion, and 5 degrees less forearm supination on the dominant side compared with their nondominant side. Position players demonstrated 8 degrees more external rotation in abduction, 14 degrees less horizontal extension, and 8 degrees less elbow extension on the dominant side compared with their nondominant side. Greater torque was produced by pitchers compared with position players for the dominant and nondominant arm at all test speeds for both mean peak and mean average torque. Greater torque was produced by the dominant arm compared with the nondominant arm also at all test speeds for both of these measurements. No difference was found between the rotation ratios for either arm, for either group, for all speeds.     

Comparaison de la force isocinétique des rotateurs de l'épaule chez les sportifs de haut niveau pratiquant la voile et les sujets témoins appariés

ObjectiveTo describe and to compare the internal and external shoulder rotators torque in high-level sailors and in matched control subject.MethodsTwo populations of 18 male and right-hand were age, weight and high-matched. The internal and external shoulder rotators isokinetic parameters were compared at the angular speed of 60 and 120°/s and with a test of 50 repetitions at 300°/s angular speed. This last evaluation was chosen to get closer the efforts to line a sail.ResultsInternal and external rotators peak torque and work of shoulder is significantly in favour the sailors. The internal rotators peak torque is significantly higher on the dominating side only in sailors. The team members, who line sails, develop a torque and a work more important than skippers and tacticians.ConclusionsHigh-level sailors present a lot of torque of shoulder rotators especially at the dominant side. These isokinetic results could serve as reference parameters for the recruitment of team members according to the place of navigation.     

Analysis of the presence and influence of Glenohumeral Internal Rotation Deficit on posterior stiffness and isometric shoulder rotators strength ratio in recreational and amateur handball players

ObjectiveTo determine whether recreational and amateur handball players exhibit Glenohumeral Internal Rotation Deficit (GIRD), and if it is accompanied by posterior stiffness and changes in shoulder rotators strength.DesignCross-Sectional Study;SettingResearch laboratory.ParticipantsIndoor and beach handball players, members of handball teams or engaged in some handball recreational group.Main outcome measuresRange of motion (ROM) of internal rotation (IR) and horizontal adduction (HA), and isometric internal and external rotators strength. Based on the ROM of internal rotation, they were allocated to groups with and without GIRD.ResultsThe dominant shoulder of GIRD group obtained a lower ROM of IR compared to the non-dominant shoulder of the same group (p < 0.01) and to the dominant (p = 0.02) and non-dominant (p = 0.01) shoulders of the group without GIRD. Less horizontal adduction was observed in both groups (p = 0.01), as well as greater external rotator strength (p = 0.01) and external/internal rotators strength ratio (p < 0.04) in the dominant shoulder. The rotators strength ratio was greater in GIRD group (p < 0.01).ConclusionsThe present study showed the dominant shoulder had greater posterior stiffness and external rotator strength, regardless of GIRD. Also the group with GIRD showed higher rotators strength ratio.     

Concentric versus eccentric isokinetic strengthening of the rotator cuff. Objective data versus functional test

Twenty-two male and female college varsity tennis players trained for 6 weeks, one group using eccentric isokinetic internal and external shoulder rotation, and the second group using concentric isokinetic internal and external shoulder rotation. Subjects pretested and posttested both concentrically and eccentrically, so that training overflow and specificity could be examined. Three maximally hit tennis serves made before and after training, which were analyzed by high speed cinematography to obtain ball velocity, served as a functional performance measurement. Statistical analysis of peak torque (newton meters) and peak torque to body weight ratio have revealed significant concentric strength gains (P less than 0.005) in the concentric as well as the eccentric training groups. Eccentric strength gains were demonstrated by the concentric training group at selected speeds (P less than 0.05 and P less than 0.005) but were not generated in the eccentric group at the P less than 0.05 significance level. Functional test analysis shows an increase in maximal serve velocity at a significance level of P less than 0.005 in the concentric training group, with no significant (P greater than 0.01) increases in the eccentric group.     

膝关节屈肌和伸肌等速向心、等速离心及等长测试的研究

本文通过运用Ｃｙｂｅｘ－６０００型等速测力系统对２５名健康男青年膝屈肌和伸肌进行等速向心、等速离心及等长测试，来比较膝肌肉向心收缩、离心收缩和等长收缩的功能，并探讨其相互间的关系。结果表明：等速测试时，膝屈肌和伸肌离心收缩的肌力明显大于向心收缩。在膝屈曲６０°时，离心收缩和等长收缩的肌力同样明显大于向心收缩，但离心收缩与等长收缩相比无显著性差异。随运动速度增加，屈肌和伸肌向心收缩的肌力明显下降，而离心收缩的肌力无明显变化。     

Association between polymorphisms of vitamin D receptor gene ApaI, BsmI and TaqI and muscular strength in young Chinese women

The association between the polymorphisms of vitamin D receptor gene ApaI, BsmI and TaqI and isokinetic muscular strength was examined in 109 healthy, young Chinese women. Methods: Genomic DNA was extracted from mouthwash samples and vitamin D receptor genotypes were determined with the established methods. The peak torque of the dominant limb in concentric and eccentric knee extensors and flexors and elbow extensors and flexors was measured using Cybex-Norm-770 isokinetic dynamometer at slow and fast velocities. The distribution frequency of vitamin D receptor gene alleles was analyzed by chi-square test. The difference in muscular strength between VDR genotype groups was analyzed using one-way ANOVA. The ApaI, BsmI and TaqI alleles and genotype frequencies appeared to be in a Hardy-Weinberg equilibrium. Subjects with the vitamin D receptor ApaI null (A allele) mutation (AA) exhibited significantly lower knee and elbow concentric or eccentric peak torque than those with aa homozygous or Aa heterozygous. The BB & Bb group showed significantly higher peak torque in concentric knee flexors than bb group. No association was found between vitamin D receptor gene TaqI and muscular strength. The data indicated that vitamin D receptor gene ApaI and BsmI polymorphisms rather than TaqI polymorphism might be associated with muscular strength.     

Suprascapular neuropathy in volleyball players

BACKGROUND: Suprascapular nerve entrapment with isolated paralysis of the infraspinatus muscle is uncommon. However, this pathology has been reported in volleyball players. Despite a lack of scientific evidence, excessive strain on the nerve is often cited as a possible cause of this syndrome. Previous research has shown a close association between shoulder range of motion and strain on the suprascapular nerve. No clinical studies have so far been designed to examine the association between excessive shoulder mobility and the presence of this pathology. AIM: To study the possible association between the range of motion of the shoulder joint and the presence of suprascapular neuropathy by clinically examining the Belgian male volleyball team with respect to several parameters. METHODS: An electromyographic investigation, a clinical shoulder examination, shoulder range of motion measurements, and an isokinetic concentric peak torque shoulder internal/external rotation strength test were performed in 16 professional players. RESULTS: The electrodiagnostic study showed a severe suprascapular neuropathy in four players which affected only the infraspinatus muscle. In each of these four players, suprascapular nerve entrapment was present on the dominant side. Except for the hypotrophy of the infraspinatus muscle, no significant differences between the affected and non-affected players were observed on clinical examination. Significant differences between the affected and non-affected players were found for range of motion measurements of external rotation, horizontal flexion and forward flexion, and for flexion of the shoulder girdle (protraction); all were found to be higher in the affected players than the non-affected players. CONCLUSIONS: This study suggests an association between increased range of motion of the shoulder joint and the presence of isolated paralysis of the infraspinatus muscle in volleyball players. However, the small number of patients in this study prevents definite conclusions from being drawn.