Isokinetic Analysis of the Internal and External Rotator Muscles of the Shoulder in Male Handball Players

Objectives:The aim of this study was to investigate the effects of limb dominance and gender on isometric, eccentric and concentric strength of the shoulder internal and external rotator muscles in adolescent volleyball players.Methods:Forty adolescent volleyball players [Male: 23( Age: 15.5±1.4 yrs, Body weight: 72±10.2 kg, Height: 184.4±7.6 cm, BMI: 20.9±2.6 kg/m2), Female: ( Age: 16.7±0.9 yrs, Body weight: 60.7±8.2 kg, Height: 172.5±5.3 cm, BMI: 20.4±2.3 kg/m2) participated in this study. Isomed 2000 isokinetic dynamometer was used to measure muscle strength testing. Isometric strength testing of shoulder internal and external rotator muscles were performed at 90 ° shoulder abduction and external rotation position. In the same position, concentric and eccentric muscle testing was performed at 90°/s angular velocity. Strength outcomes were recorded as Nm/kg. 2-way repeated measures of ANOVA was used for statistical analysis.Results:Dominance by gender interaction was not found significant for internal rotator (IR) and external rotator (ER) muscles' strength (IR: F(1,72)=2.87, p=0.06, ER: F(1,72)=1.98, p=0.15). There was a significant strength by dominance interaction for internal rotator muscles (F(2,72)=18.52, p<0.001). Isometric strength was greater in dominant limb (p<0.001)while concentric strength was found greater in non-dominant limb(p=0.006). Eccentric strength was found similar for limbs (p=0.18). IR muscles showed greater strength during eccentric (1.03±0.05), concentric (0.76±0.03) and isometric test (0.69±0.03), respectively. On the other hand, external rotators showed greater strength during eccentric (0.49±0.4), isometric (0.40±0.3) and concentric test (0.36±0.3), respectively. There was no significant gender effect on the strength (IR: F(2,72)=0.31, p=0.73, ER: F(2,72)=0.42, p=0.66).Conclusion:The strength of shoulder internal and external rotator muscles do not differ according to gender in adolescent volleyball players. Limb dominance has an effect on the strength of internal rotator muscles while it has no effect on the strength of external rotators. Both muscle groups show greater strength during eccentric testing.

BackgroundMuscle strength and endurance of the shoulder rotators is important for overhead throwing performance and dynamic glenohumeral stability. Isokinetic assessment of shoulder internal and external rotators is commonly used by...

Objectives: In accordance with the multiple causes of impingement syndrome being a major injury of the swimmers' shoulder, choosing an effective method in preventing shoulder injury is important. The purpose of this study was to compare the effect of eight weeks open and closed kinetic chain exercises on muscle torque of internal and external rotators of shoulder in elite swimmers. Methods: In this study, 45 swimmers were selected based on the inclusion criteria and divided randomly and equally into three groups of open chain, closed chain exercises, and control. Both open and closed chain groups performed their own exercises three times a week for eight weeks, but no upper extremity exercises were given to the control group. Before the training, the pick torque of the external and internal rotators of shoulder were measured by the isokinetic HUMAC NORM machine at various speeds of 60, 120 and 180 degrees/s. After eight weeks of practice, the variables were re-measured. Shapiro-Wilk test was used for data normalization, one-way ANOVA and Tukey post hoc testes were used accordingly to compare the groups and to show the intra-group difference (P < 0.05). Results: The results of this study showed that eight weeks of open and closed chain training improved the torque of internal and external shoulder rotator muscles at 60, 120 and 180 degrees per second (P < 0.05). There was a significant difference between open chain and closed chain exercises, and the effect of open chain was more than closed chain training (P < 0.05). Conclusions: According to this study, it can be concluded that open and closed kinetic chain exercises improve the torque of the external and internal rotating muscles in swimmers. They also suggest that kinetic chain exercises are more effective than closed kinetic chain exercises in this regard so could be prescribed for swimmers.

Context: Tennis playing generates specific adaptations, particularly at the dominant shoulder. It remains to be established whether shoulder strength balance can be restored by sling-based training for adolescent recreational tennis players. Objective: We added a sling-based exercise for shoulder external rotators to investigate its effects on external rotator muscle strength, on internal rotator muscle strength, on glenohumeral range of motion and on tennis serve performance. Design: Test-retest design. Setting: Tennis training sports facilities. Participants: Twelve adolescent male players volunteered to participate in this study (age: 13.3 ± 0.5 years; height: 1.64 ± 0.07 cm, mass: 51.7 ± 5.8 kg, International Tennis Number: 8). Intervention: The procedure spanned 10 weeks. For the first five weeks, players performed their regular training (RT) twice a week. For the last five weeks, a sling-based exercise (SE) for strengthening the shoulder external rotator muscles was added to their regular training. Main Outcome Measures: Maximal isometric strength of shoulder external and internal rotator muscles and glenohumeral range of motion in external and internal rotation were assessed in both shoulders. Serve performance was also evaluated by accuracy and post-impact ball velocity, using a radar gun. Results: No change was found in any measurement after the RT period. Significant increases in external (~+5%; p<0.001) and internal (~+2%; p<0.05) rotator muscle strength and in external/internal strength ratio (~+4%; p<0.001) were observed after the SE period. Serve velocity and accuracy were significantly improved after SE (~+2% and ~+24%, respectively; p<0.05 for both), while no clinically meaningful alterations in ranges of motion were observed. Conclusions: Prophylactic intervention through sling-based exercise for strengthening shoulder external rotator muscles appears effective in restoring strength balance at the dominant shoulder, and may prevent adolescent tennis players from sustaining degenerative shoulder problems which could later impair their performance of daily and work-related tasks.

The aim of the investigation was to: 1) compare shoulder external/internal rotator muscles’ peak torques and average power values and their ratios in the dominant and non-dominant arm; 2) determine correlations between shoulder rotator muscles’ peak torques, average power and ball-throwing speed in handball players. Fourteen 14 to 15-year-old male athletes with injury-free shoulders participated in the study (body height: 176 ± 7 cm, body mass 63 ± 9 kg). The tests were carried out by an isokinetic dynamometer system in the shoulder internal and external rotation movements at angular velocities of 60°/s, 90°/s and 240°/s during concentric contractions. The eccentric external– concentric internal rotator muscle contractions were performed at the velocity of 90°/s. The player threw a ball at maximal speed keeping both feet on the floor. The speed was recorded with reflected light rays. Training in handball does not cause significant side asymmetry in shoulder external/internal rotator muscle peak torques or the average power ratio. Positive correlations between isokinetic characteristics of the shoulder internal and external rotator muscles and ball-throwing speed were determined. The power produced by internal rotator muscles during concentric contractions after eccentric contractions of external rotator muscles was significantly greater in the dominant than in the non-dominant arm. Thus, it may be concluded that the shoulder eccentric external/concentric internal rotator muscle power ratio is significantly greater than this ratio in the concentric contractions of these muscles.

Feint movement is an important factor for offensive players to outplay their guard, and score. So far, there is no evidence of feint biomechanical analysis on a sample of elite players in handball or other team sports. Therefore, this study aimed to investigate kinematic parameters of single side fake movement between elite and professional level handball players. The sample of participants consisted of 10 handball players divided into two subsamples: elite handball players (100.00 ± 8.00 kg; 196.00 ± 4.64 cm) and professional handball players (91.20 ± 3.42 kg; 192.4 ± 7.30 cm). The kinematic analysis was conducted using a GAIT—LaBACS software system. Variables consisted of two phases (fake phase and actual phase) of feint single change of direction. Both phases included seven kinematic parameters that were observed. Statistical analysis included descriptive statistic parameters. The differences between elite and professional handball players were analyzed by multivariate and univariate variance analysis. Results showed significant differences between elite and professional players (λ = 0.44, p = 0.00), in fake phase (i.e., 1. Phase). The results also indicate that in there is no statistically significant difference between both groups (λ = 0.64, p = 0.22). Two variables had significant differences between elite and professional players (i.e., step length of the stride leg (p = 0.02) and moving the leg opposite the throwing arm in space (p = 0.00)). To conclude, the article examines specific movement patterns of single side fake movement in elite players and the confirmed importance of efficient skill execution in top level handball. On the contrary, less skilled players use more space for the same technical element.

Profiling the isokinetic shoulder rotator muscle strength in 13- to 36-year-old male and female handball players

Background and purpose: Kendall suggests testing the rotator cuff muscles in their maximally shortened position, since one-joint muscles are thought to be strongest. We found little evidence to support this concept. The purpose of this study was to determine if the shoulder internal rotator (IR) and external rotator (ER) muscles are strongest when placed in their shortened length position. Methods: Fifty-three subjects participated. Glenohumeral joint internal rotation and external rotation motion was measured. Muscle strength was then tested using a hand-held dynamometer in four positions: (1) end-range ER; (2) neutral 0°; (3) glenohumeral joint mid-range and (4) end-range IR. Data were analyzed using two repeated measures ANOVA’s. Results: The results suggest that rotator muscle strength is dependent on muscle length. IR strength was weakest at end-range IR in its shortest length; ER muscle strength was weakest at end-range ER in its shortest length. Muscle strength of the IR or ER was not significantly different when comparing neutral 0° to the mid-range position and at their most lengthened position. Conclusion: The IR and ER muscles were found to be weakest when placed in a position of shortest muscle length, while the neutral 0° and mid-range positions were the strongest positions.

The last phases of a competitive game are when shoulder injuries most commonly happen, and fatigue is thought to be a major contributing factor, perhaps because of reduced proprioception and motor control. The purpose of this study was to investigate the effect of concentric fatigue on proprioception, motor control, and performance of the upper limb in handball players. Forty-six right-handed handball players (all males, age 26.1 ± 5.54 years) were included in this test-retest laboratory experiment. Proprioception was assessed using joint reposition sense (JRS), threshold to detection of passive movement (TTDPM), muscle onset latency (MOL), motor control using Y balance test upper quarter (YBT-UQ) and performance using the athletic shoulder test (ASH) before and immediately after fatigue intervention. The fatigue protocol consisted of concentric, maximal effort, isokinetic contractions at 900/sec with sets of 30 repetitions of the shoulder external and internal rotator muscles. Fatigue was determined by a 40% decline in the peak torque over three consecutive contractions despite reinforcing feedback and encouragement. A significant increase in absolute angular error (AAE) was observed in all target angles in both external rotation (ER) and internal rotation (IR) directions (p < 0.01). In addition, there was a significant increase in TTDPM in internal rotation after fatigue intervention (p = 0.020. Variable changes were found in YBT-UQ and ASH tests. Specifically, statistically significant differences were found in anteromedial (AM) (p = 0.041), superolateral (SL) reach directions (p = 0.005), composite score (p = 0.009) in the right hand and inferolateral (IL) reach direction in the left hand (p = 0.020) in the YBT-UQ. In addition, there was a significant reduction in isometric strength (ASH test) in the I position of the right hand (p = 0.010) and all positions of the left hand (p<0.05). Furthermore, there was an increase in MOL scores after fatigue but the increase was not significant (p > 0.05). Concentric fatigue of the rotator cuff muscles induces notable deficits in joint position awareness, kinesthesia, motor control, and performance of the upper extremity in elite male handball players. Although fatigue reduces reflex reaction time the effect is only marginal.

ABSTRACTObjectives: Overhead athletes, such as baseball players, have been shown to have adaptive changes in the shoulder range of motion (ROM) of their dominant arm. Professional handball players are a unique subtype of overhead athletes with very different demands from baseball players. The aim of this study was to determine if professional handball players demonstrate differences in shoulder ROM between their dominant and non-dominant arm and try to relate them with new variables.Methods: Fifty professional male handball players were included and completed a questionnaire regarding age at which they started to play, number of hours they practice a week, field position and arm dominance. ROM measurements were performed including forward flexion (FF), external rotation with the shoulder in abduction (ABER) and with adducted arm (ADER) and internal rotation with shoulder in abduction (IR). Statistical analysis was performed to determine differences in ROM between the dominant and non-dominant shoulder and if there is a relationship between these differences and shoulder load or field position.Results: The dominant arm showed decreased internal rotation (47 vs. 56 degrees, p < 0.001) and increased external rotation both with the arm abducted (99 vs. 88 degrees, p < 0.001) and at the side (62 vs 57 degrees, p = 0.001). This was not correlated with shoulder load for any movement (FF, p = 0.980; ABER, p = 0.741; ADER, p = 0.803; IR, p = 0.085) but was dependent on field position with first line players showing the highest internal rotation deficit (13 degrees vs. 6–7 degrees in the other field positions, p = 0.013).Conclusion: This study showed that professional male handball players with a first line position have a significant risk for developing a glenohumeral internal rotation deficit, similar to the phenomenon seen in baseball pitchers.

The torque generated by the shoulder internal and external rotator muscles duringconcentric isokinetic contractions has been investigated. Recordings were made in three positions: neutral, 90 degrees of flexion, and 90 degrees of abduction; and at three speeds of contraction (60, 120, and 180 /sec) in each of these positions. Twelve healthy female university students were randomly selected from a 100 female volunteer population. Testing was accomplished using an isokinetic dynamometer. A two-way analysis of variance for position and speed was conducted. The greatest torque values for the internal rotator muscles were achieved in the neutral position, while maximum values for the external rotators were developed in 90 of shoulder flexion. The test speed of 60 degrees /sec was shown to produce the highest torque values for the external rotator muscles. However, no difference in test speeds of contraction was found when analyzing the torque values generated by the internal rotator muscles. Implications for strength training are discussed.J Orthop Sports Phys Ther 1987;9(6):217-222.

Introduction The shoulder of handball players suffers from the ongoing repetition of movement that may lead to the development of joint instability and modification of proprioceptive condition [1]. Because the articular components of the shoulder joint are considered to have extreme importance on the static and dynamic stabilisation and quality of proprioceptive information, they may compromise the athlete’s performance [2]. The purpose of our study was to verify if shoulder strength parameters (SSP) and joint position sense (JPS) of shoulder internal and external rotation may contribute to the development of shoulder instability in handball players. Materials and methods A cross-sectional design was implemented. The sample was composed by eleven handball players of both genders (4 females and 7 males), under 18 years of age, that practiced the sport for at least 3 years. For the data collection, an isokinetic dynamometer (Biodex System 3) was used. The evaluation of SSP was implemented prior to JPS at a speed of 60°|sec (3 reps) and 180°|sec (20 reps) of internal rotation (IR) and external rotation (ER), with the shoulder positioned at 90° of abduction. The JPS was evaluated using active and passive positioning, 6 repetitions each, at 3 given external shoulder rotation amplitudes (20, 35 and 75 degrees). Prior to the data collection, all subjects signed an informed consent. This study follows all the principles of the Declaration of Helsinki. Results For the dominant shoulder, the peak torque (PT) at 60°|sec was 41.4 Nm (±12.2) of ER and 40,6 Nm (±17.5) in IR. For the non-dominant shoulder at 60°|sec, the PT was 34.3 Nm (±10.7) of ER and 42.0 Nm (±2.8) in IR. For the dominant shoulder, the PT at 180°|sec was 37.2 Nm (±12.2) of ER and 37.9 Nm (±15.0) in IR. At the non-dominant shoulder, the PT at 180°|secr was 29.8 Nm (±10.8) of ER and 37.2 Nm (±11.6) in IR. At 60°|sec, the range of motion (ROM) was of 89.6° (±3.2) and at 180°|sec, 88.8° (±0.6). On the dominant shoulder, for the passive positioning, a difference was obtained of 6.7° (±5.8) at 75°, of 1.7° (±2.4) at 35°, and of 0° (±2.3°) at 20°. In the active positioning, a difference was obtained of 1.3° (±3.1) at 75°, of 1.0° (±3.6) at 35°, and 1.2° (±2.7) at 20°. On the non-dominant shoulder, we observed the following results, in the passive positioning, 4.7° (±3.7) at 75°, 1.3° (± 4.1) at 35°, and 0.7° (±3.5) at 20°. Finally, in the active positioning we obtained the following results: 0.5 ± 3.4 (75°), 0.7 ± 2.0 (35°) and 2.7 ± 2.4 (20°). Discussion and conclusions Our preliminary results seem to point out that the dominant shoulder improved JPS when compared to the non-dominant. Additionally, we found that during the active positioning athletes had a greater perception of JPS, in comparison to the passive positioning. These results should help on the development of training protocols in handball, to improve shoulder proprioception and help to reduce the risk of injury. Although the results on SSP were not statistically treated, throughout the study protocol the PT seems to decrease significantly. Further studies should help to confirm our results.

Isokinetic assessment of shoulder complex strength in adolescent elite synchronized swimmers

The aim of the study was to describe the strength symmetry of internal and external rotator muscles and the conventional and functional strength balance ratios between these muscles in adolescent male volleyball players. Twenty-eight male adolescent volleyball players (15.5 ± 1.1 years (15–17 years); 73.2 ± 10.9 kg (55.3–100.1 kg) and 184.9 ± 8.4 cm (170–209 cm)) participated in this cross-sectional study. Concentric and eccentric peak torque of external and internal rotator muscles were measured, and conventional and functional strength balance ratios were calculated. The dominant limb presented significantly higher values for peak torque than the non-dominant limb of internal rotator muscles at concentric action assessed at 60°/s (48.7 ± 13.7 Nm and 43.9 ± 11.6 Nm, p = 0.01 and d value = 0.37) and at 240°/s (44.7 ± 11.2 Nm and 41.1 ± 11.0 Nm, p = 0.03 and d = 0.32). However, there was no difference in the peak torque of external rotator muscle between limbs for either angular speed. Regarding strength balance ratios, neither conventional (74.8 ± 14.3 for dominant limb and 80.1 ± 14.0 for non-dominant limb, p = 0.06 and d = 0.37) nor functional ratio (1.2 ± 0.4 for dominant limb and 1.3 ± 0.5 for non-dominant limb, p = 0.06 and d = 0.22) presented significant contralateral differences. Despite the short practice time, adolescent male volleyball athletes already have significant contralateral differences for internal rotator muscles and conventional ratio tends to be asymmetrical. Thus, preventive shoulder-strengthening programs, focused on the internal rotator muscles of the non-dominant limb, aiming to correct contralateral deficiency and conventional ratio, may be warranted for this population in the process of biological growth, maturation and development.

Introdução: As repetições atribuídas aos ombros, principalmente aos músculos rotadores internos, durante os movimentos de arremesso aumentam o risco de lesão. Assim, é preciso garantir um equilíbrio adequado entre os músculos rotadores internos (RI) e os seus antagonistas, rotadores externos (RE). Objetivo: Descrever a força e equilíbrio muscular rotadores internos e externos dos ombros em praticantes de handebol. Métodos: Estudo seccional descritivo com 58 atletas de handebol. A função muscular foi avaliada pelo dinamômetro isocinético, as variáveis analisadas foram o pico de torque (PT) entre os ombros direito e esquerdo e a relação antagonista/agonista. Resultados: O menor valor do PT nas mulheres variou de 2,18 na velocidade angular de 300º/s (RE) a 33,0 na velocidade angular de 60º/s (RI). Para relação RE/RI o menor valor foi de 0,11 e o maior de 0,79. Já para a sexo masculino o menor valor do PT foi 27,5(RE) na velocidade angular de 300º/s, maior valor de 69,5 (RI) na velocidade angular de 60º/s. E a relação RE/RI variou de 0,54 a 0,71. Conclusão: Foi demonstrado que os maiores valores de força estão no ombro dominante, para ambos os sexos, o que é considerado normal. Contudo, contatamos também um déficit na relação RE/RI acima do ponto de corte indicado pela literatura, sugerindo um significativo desiquilíbrio muscular.