Comparison of Maitland and Kaltenborn mobilization techniques for improving shoulder pain and range of motion in frozen shoulders

[Purpose] This study compared the use of the Maitland mobilization and Kaltenborn mobilization techniques for improving pain and range of motion in patients with frozen shoulders. [Subjects and Methods] The subjects were 20 patients with frozen shoulder who visited Hospital H, Ulsan, Korea. The subjects were divided randomly into two groups to receive Maitland or Kaltenborn mobilization to the affected shoulder. Grade III anteroposterior oscillation and posterior translation were used for the Maitland and Kaltenborn mobilization groups, respectively. Pain and range of motion of external and internal rotation were evaluated pre- and post-intervention in both groups. Paired t-tests were used to compare the pre- and post-intervention results in both groups, and independent t-tests were used to compare groups. [Results] Both groups exhibited significant decreases in pain post-intervention. Moreover, the range of motion of internal and external rotation increased significantly post-intervention in both groups. However, there was no significant difference between groups with respect to pain improvement or range of motion. [Conclusion] The posterior Maitland and Kaltenborn mobilization techniques are effective for improving pain and range of motion in frozen shoulder patients. Therefore, we recommend both techniques for such patients.Key words: Maitland mobilization, Kaltenborn mobilization, Frozen shoulder     

Reliability of stiffness measured in glenohumeral joint and its application to assess the effect of end-range mobilization in subjects with adhesive capsulitis

End-range mobilization techniques are recommended for the treatment of patients with hypomobile joints. The purposes of this study were (1) to assess the reliability of a glenohumeral (GH) stiffness measurement technique and (2) apply the measurement technique on subjects with adhesive capsulitis to compare the GH end-range stiffness and rotational range of motions (ROMs) before and immediately after the application of end-range translational mobilization techniques. Fifteen normal subjects were recruited for assessment of test–retest reliability. Four men and two women with adhesive capsulitis in the glenohumeral joint (mean disease duration=6.5 months, SD=2.7) were treated with end-range mobilization by an experienced physical therapist. The passive abduction angles, rotational ROM and GH joint stiffness were measured by the same observer before and immediately after end-range mobilization treatment. The test–retest reliability was assessed and revealed good to excellent reliability in anterior–posterior glenohumeral joint stiffness and fair to excellent reliability of GH stiffness in posterior–anterior direction. The GH joint stiffness decreased and passive abduction range of motion increased immediately after end-range mobilization of the shoulder joint. The use of intensive mobilization techniques may help to decrease the risk of further stiffness or joint contracture progression in patients with adhesive capsulitis.     

Does restriction of glenohumeral horizontal adduction reflect posterior capsule thickening of the throwing shoulder?

[Purpose] Glenohumeral posterior capsule tightness possibly relates to posterior capsule thickness (PCT). The purpose of the current study was to analyze the relationships between PCT and glenohumeral range of motion (ROM) in horizontal adduction (HAdd) and internal rotation (IR). [Subjects and Methods] This study recruited 39 healthy collegiate baseball players. We measured PCT by using ultrasonography and ROM of the glenohumeral joint of the throwing shoulder by using a digital inclinometer. Pearson’s correlation coefficients were calculated between PCT and HAdd or IR ROM. [Results] There was no correlation between PCT and HAdd ROM, but PCT was significantly correlated with IR ROM. [Conclusion] This result indicates that posterior shoulder capsule tightness only relates to IR ROM, and that restricted HAdd ROM might reflect tightness of other tissue, such as the posterior deltoid.Key words: Capsule thickness, Horizontal adduction, Internal rotation     

The influence of gastrocnemius stretching combined with joint mobilization on weight-bearing ankle dorsiflexion passive range of motion

[Purpose] The purpose of this study was to investigate the effect of gastrocnemius stretching combined with talocrural joint mobilization on weight-bearing ankle dorsiflexion passive range of motion. [Subjects] Eleven male subjects with bilateral limited ankle dorsiflexion passive range of motion with knee extended participated in this study. [Methods] All subjects received talocrural joint mobilization while performing gastrocnemius stretching. Ankle dorsiflexion passive range of motion was measured using an inclinometer under weight-bearing conditions before and immediately after intervention. A paired t-test was used to analyze the difference between weight-bearing ankle dorsiflexion passive range of motion pre- and post-intervention. [Results] A significant increase in weight-bearing ankle dorsiflexion passive range of motion was found post-intervention compared with pre-intervention. [Conclusion] These findings demonstrate that gastrocnemius stretching combined with joint mobilization is effective for increasing weight-bearing ankle dorsiflexion passive range of motion.Key words: Gastrocnemius stretching, Talocrural joint mobilization, Weight-bearing ankle dorsiflexion     

The Immediate Effect of Humerus Anatomical Neck-shaft Rotation on Glenohumeral Joint Contracture

[Purpose] Elderly female patients with glenohumeral joint (GHJ) contracture, forced into prolonged immobility were examined. Range of motion exercises using humerus anatomical neck-shaft rotation were performed, and the immediate effect and adaptation were investigated. [Subjects and Methods] A total of ten individuals with a mean age of 79.4 ± 11.0 years were included in this study. The controlled intervention involved conventional range of motion exercises, and the experimental intervention involved humerus anatomical neck-shaft rotation. Each exercise was performed 30 times. Shoulder joint flexion and abduction and external rotation of the GHJ range of motion were measured with the scapula fixed. Each change in range of motion was compared using ANOVA; less than 5% was considered significant. [Results] After the experimental intervention, significant increases were seen in shoulder joint flexion, abduction, and external rotation ranges of motion. [Conclusion] Therefore, this method was effective as a means of improving the range of motion of the GHJ.Key words: Shoulder joint, Contracture, Humerus anatomical neck-shaft rotation     

Soft Tissue Mobilization and PNF Improve Range of Motion and Minimize Pain Level in Shoulder Impingement

[Purpose] The aim of this study was to evaluate the effects of soft tissue mobilization and PNF on pain level, and shoulder ROM in patients with shoulder impingement syndrome. [Subjects and Methods] Thirty patients with painful and limited glenohumeral ROM activities were selected. The subjects were randomly assigned to an experimental group (n=15), which received treatment consisting of soft tissues mobilization and the PNF technique. The control group received an ultrasound treatment. Pain level, glenohumeral external rotation and overhead reach were measured before and after the intervention in groups. [Results] The experimental group showed a significant reduction in pain level in comparison with the control group. The values for Shoulder external rotation showed a significant improvement. The mean value for overhead reach in the experimental group significantly increased. [Conclusion] The combination of soft tissue mobilization for the subscapularis for 7 minutes and 5 repetitions of the contract-relax PNF technique for the shoulder internal rotator muscles followed by 5 repetitions of a PNF facilitated abduction and external rotation diagonal pattern was found to be effective in reducing pain and improving glenohumeral external rotation and overhead reach during a single intervention session.Key words: Shoulder pain, PNF, Soft tissue mobilization     

Comparison of high-grade and low-grade mobilization techniques in the management of adhesive capsulitis of the shoulder: randomized controlled trial

BACKGROUND AND PURPOSE: In many physical therapy programs for subjects with adhesive capsulitis of the shoulder, mobilization techniques are an important part of the intervention. The purpose of this study was to compare the effectiveness of high-grade mobilization techniques (HGMT) with that of low-grade mobilization techniques (LGMT) in subjects with adhesive capsulitis of the shoulder. SUBJECTS: One hundred subjects with unilateral adhesive capsulitis lasting 3 months or more and a > or =50% decrease in passive joint mobility relative to the nonaffected side were enrolled in this study. METHODS: Subjects randomly assigned to the HGMT group were treated with intensive passive mobilization techniques in end-range positions of the glenohumeral joint, and subjects in the LGMT group were treated with passive mobilization techniques within the pain-free zone. The duration of treatment was a maximum of 12 weeks (24 sessions) in both groups. Subjects were assessed at baseline and at 3, 6, and 12 months by a masked assessor. Primary outcome measures included active and passive range of motion and shoulder disability (Shoulder Rating Questionnaire [SRQ] and Shoulder Disability Questionnaire [SDQ]). An analysis of covariance with adjustments for baseline values and a general linear mixed-effect model for repeated measurements were used to compare the change scores for the 2 treatment groups at the various time points and over the total period of 1 year, respectively. RESULTS: Overall, subjects in both groups improved over 12 months. Statistically significant greater change scores were found in the HGMT group for passive abduction (at the time points 3 and 12 months), and for active and passive external rotation (at 12 months). A statistically significant difference in trend between both groups over the total follow-up period of 12 months was found for passive external rotation, SRQ, and SDQ with greater change scores in the HGMT group. DISCUSSION AND CONCLUSION: In subjects with adhesive capsulitis of the shoulder, HGMTs appear to be more effective in improving glenohumeral joint mobility and reducing disability than LGMTs, with the overall differences between the 2 interventions being small.     

Assessment of shoulder external rotation range-of-motion on throwing athletes: the effects of testing end-range determination (active versus passive)

Abstract

The purpose of this study was to compare the effects of active or passive end-range determination (supine position) for external rotation range of motion (ROM) in overhead throwing athletes and verify if athletes’ ROM is similar to non-athletes. Kinematic data from the dominant shoulder of 24 healthy male subjects, divided into two groups (12 athletes and 12 non-athletes) were recorded at end-range external rotation, thoracohumeral and glenohumeral external rotation angles were compared and a 2-way repeated-measures ANOVA was used to calculate the effects of end-range determination (passive versus active) across groups (athlete and non-athlete). A significant main effect (p?<?0.001) on both thoracohumeral and glenohumeral external end-range angles was observed while the highest end-range determination values were associated with passive motion. No differences were observed between the athletic or non-athletic groups for either thoracohumeral (p?=?0.784) or glenohumeral (p?=?0.364) motion.     

THE EFFECTS OF A DAILY STRETCHING PROTOCOL ON PASSIVE GLENOHUMERAL INTERNAL ROTATION IN OVERHEAD THROWING COLLEGIATE ATHLETES

Introduction/Purpose:

Shoulder dysfunction and injury are common in throwing athletes. Loss of internal rotation has been correlated to shoulder pathologies. The purpose of this study was to assess the effects of a stretching protocol on passive internal rotation. The purpose of this study was assess the effects of a stretching protocol on passive internal rotation motion in the throwing shoulders of collegiate baseball players.

Study Design:

Pre-Post, intervention, using a within subjects comparison of a convenience sample.

Methods:

Glenohumeral internal rotation and external rotation of the throwing and non-throwing shoulders of NCAA Division I baseball players were measured using a universal goniometer. Determinations were made as to the degree of Glenohumeral Internal Rotation Deficit (GIRD) in the throwing shoulder. A daily (5 days per week), 12-week posterior capsule stretching program was administered. Post-stretching internal rotation and external rotation measures were again obtained. The coaches and athletic trainers of the included team monitored the players for shoulder injuries and innings of training/competition lost due to shoulder injuries during the 12 week intervention.

Results:

A significant increase in range of motion was found for dominant arm internal rotation (IR) and total range of motion (TOT) following the stretching program. No statistically significant improvement in range of motion was found for external rotation (ER), non-throwing arm internal rotation (NDIR), non-throwing arm external rotation (NDER), and non-throwing arm total motion (NDTOT).

Conclusions:

Implementation of a posterior capsule stretching program may be helpful to facilitate increased passive internal rotation range of motion at the glenohumeral joint. Further research should be performed using a control group not receiving the stretching program in order to more completely establish the impact of stretching on measures of passive glenohumeral range of motion.

Level of Evidence:

1b     

Quantification of shoulder tightness and associated shoulder kinematics and functional deficits in patients with stiff shoulders

Measurement of anterior/posterior shoulder tightness, humeral external/internal rotation range of motion (ROM), scapular upward rotation/tipping ROM, and functional limitations were made in 46 patients with unilateral stiff shoulders (SSs) using a clinical measurement (shoulder tightness), a three-dimensional electromagnetic tracking device (shoulder ROM), and self-reports of function. Patients with SSs in their dominant shoulder demonstrated statistically greater posterior shoulder tightness compared to nondominant shoulder. Control dominant shoulders demonstrated decreased internal ROM as compared with control nondominant shoulders (p=0.021). In SSs, significant relationships were found between humeral internal rotation ROM and posterior shoulder tightness (R=0.49, p<0.0005), humeral external rotation ROM and anterior shoulder tightness (R=0.59, p=0.0002), scapular tipping and anterior shoulder tightness (R=0.57, p=0.004). Specifically, in patients with dominant SSs, posterior shoulder tightness and functional limitation were related (R=0.56, p=0.002). In patients with dominant involved shoulders, emphasise on posterior tightness stretch may improve functional ability directly. In addition to stretching program in patients with SSs, internal rotation ROM of control dominant shoulder is also important to consider in the rehabilitation of patients with SSs.     

THE RELATIONSHIP BETWEEN PASSIVE GLENOHUMERAL TOTAL ROTATION AND THE STRENGTH OF THE INTERNAL AND EXTERNAL ROTATOR MUSCLES,A PRELIMINARY STUDY

Background

There is little research on how the amount of shoulder joint range of motion, specifically glenohumeral rotation, may be related to the muscle strength of the rotator cuff muscles. A long held belief is that a joint with excessive range of motion needs sufficient muscular strength for stability. However, no studies have examined this concept.

Purpose

The purpose of this study was to see if total arc of glenohumeral joint rotation (External rotation [ER]+Internal rotation [IR]) could predict peak isometric muscle strength of the IR or ER muscles of the shoulder.

Study Design

Cross‐sectional study design

Methods

Fifty‐three participants (41 females, 12 males) participated in the study. Passive glenohumeral joint internal rotation and external rotation motion was measured for each participant with a standard goniometer. Isometric muscle force of the ER and IR muscles were tested using a handheld dynamometer in three positions: end range ER, neutral 0°, and end range IR. Data were analyzed using a non‐parametric tree based regression method (CART) and then cross‐validated.

Results

The results showed that those with an increased total arc of motion of glenohumeral rotation (greater than 165.0°) had less muscle isometric muscle strength in all tests positions than those with less glenohumeral rotation.

Conclusion

Decreased force of the ER and IR muscles of the shoulder was noted in those with increased total arc glenohumeral rotation ( > 165.0°), specifically those with increased glenohumeral internal rotation ( > 80.0°) when compared to those with glenohumeral rotation ( < 165.0°) and glenohumeral internal rotation ( < 80.0°). Future studies should include more males and attempt to develop strategies to assist those with larger excursions of shoulder rotation who may be at risk of developing shoulder problems.

Level of Evidence

Level 2     

Immediate effect of thermal capsulorrhaphy on glenohumeral joint mobility

OBJECTIVES: To evaluate the effects of anterior thermal capsulorrhaphy of the glenohumeral joint by monitoring changes of magnitudes of the anterior and posterior displacements of the humeral head and ranges of motion of abduction and rotation in fresh cadaver shoulders. DESIGN: Single session repeated-measures design. BACKGROUND: Following thermal shrinkage anterior and posterior displacements of the head of humerus were decreased. However, no studies were focused on the ranges of motion of abduction and rotation of the shoulder joint immediately. The mobility of abduction and rotation are also important indexes for glenohumeral function. METHODS AND MEASURES: Nine fresh frozen shoulder specimens were used. The dorsal and ventral displacements of humeral head and ranges of motion of abduction and rotation of glenohumeral joint before and after thermal capsulorrhaphy were performed and monitored. Changes after thermal treatment in these linear and angular displacement variables were calculated as outcome measures. RESULTS: After anterior thermal capsulorrhaphy, significant (P < 0.001) decreases were found in displacements (-1.80 mm in dorsal direction and -1.24 mm in ventral direction), rotation range of motion (-3.93 degrees in lateral rotation and -2.60 degrees in medial rotation), and abduction range of motion (-3.15 degrees ). CONCLUSIONS: The results from cadaveric experiments showed that anterior thermal capsulorrhaphy immediately reduced the dorsal and ventral displacements and ranges of abduction and rotation of glenohumeral joint by a small amount. RELEVANCE: Radiofrequency electrosurgical system combined with arthroscopy has the potential to decrease the translations of the humeral head as well as the rotational range of motion of the glenohumeral joint.     

Changes in abduction and rotation range of motion in response to simulated dorsal and ventral translational mobilization of the glenohumeral joint

BACKGROUND AND PURPOSE: Translational mobilization techniques are frequently used by physical therapists as an intervention for patients with limited ranges of motion (ROMs). However, concrete experimental support for such practice is lacking. The purpose of the study was to evaluate the effect of simulated dorsal and ventral translational mobilization (DTM and VTM) of the glenohumeral joint on abduction and rotational ROMs. METHODS: Fourteen fresh frozen shoulder specimens from 5 men and 3 women (mean age=77.3 years, SD=10.1, range=62-91) were used for this study. Each specimen underwent 5 repetitions of DTM and VTM in the plane of scapula simulated by a material testing system (MTS) in the resting position (40 of abduction in neutral rotation) and at the end range of abduction with 100 N of force. Abduction and rotation were assessed as the main outcome measures before and after each mobilization procedure performed and monitored by the MTS (abduction, 4 N m) and by a servomotor attached to the piston of the actuator of the MTS (medial and lateral rotation, 2 N m). RESULTS: There were increases in abduction ROM for both DTM (mean=2.10 , SD=1.76 ) and VTM (mean=2.06 , SD=1.96 ) at the end-range position. No changes were found in the resting position following the same procedure. Small increases were also found in lateral rotation ROM after VTM in the resting position (mean=0.90 , SD=0.92 , t=3.65, P=.003) and in medial rotation ROM after DTM (mean=0.97 , SD=1.45 , t=2.51, P=.026) at the end range of abduction. DISCUSSION AND CONCLUSION: The results indicate that both DTM and VTM procedures applied at the end range of abduction improved glenohumeral abduction range of motion. Whether these changes would result in improved function could not be determined because of the use of a cadaver model.     

The influence of muscle length on one-joint shoulder internal and external rotator muscle strength

Abstract

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.     

A COMPARISON OF RANGE OF MOTION CHANGE ACROSS FOUR POSTERIOR SHOULDER TIGHTNESS MEASUREMENTS AFTER EXTERNAL ROTATOR FATIGUE

Background:

Several glenohumeral joint (GHJ) positions have been recommended for assessing and correcting posterior shoulder tightness (PST) however, there is no agreement on which position is better for differentiating posterior muscle tightness from posterior capsular tightness. The purpose of this study was to compare the range of motion change before and after an external humeral rotator muscle fatigue protocol in order to identify a position that shows maximum range of motion change.

Methods:

ROM changes across four PST measurements were compared before, immediately after, at 24 hours after, and 48 hours after an external rotator fatigue protocol. Muscle stiffness of the infraspinatus and the teres minor (using a myotonometer) and external rotation force production (using hand‐held dynamometry) were measured to verify muscle fatigue.

Results:

There was a statistically significant interaction between measurement and condition (F = 2.47, p = 0.02). The planned one factor repeated measure ANOVA for each condition revealed that ROM change was statistically significant between PST measurements for all conditions. Post hoc comparisons indicated statistically significant greater overall ROM changes in a measurement combining GHJ extension and internal rotation compared to other tested measurements. There was also a main effect of time on infraspinatus muscle stiffness (F = 10.5, p < 0.0001). Post hoc comparison indicated a statistically significant increase in infraspinatus stiffness immediately after the fatigue protocol (p < 0.05).

Conclusion:

Immediate ROM reduction was observed across all the measurements except horizontal adduction (HAD). Maximum ROM reduction after an external rotation fatigue protocol was measured in a position of GHJ extension.

Clinical Relevance:

Posterior muscle tightness may influence the internal rotation range of motion to a greater extent when measured in glenohumeral joint extension.

Levels of Evidence:

II‐B     

Reliability and validity of shoulder tightness measurement in patients with stiff shoulders

The purposes of this study were (1) to examine intratester and intertester reliability of measurement of anterior and posterior shoulder tightness in patients with stiff shoulders (SS), and (2) to assess construct validity by determining the relations between shoulder tightness, shoulder range of motion (ROM), and self-report measures of functional limitation. Anterior and posterior shoulder tightness were measured by two testers in below-chest abduction and cross-chest adduction tests with an inclinometer, respectively, in 16 patients with SS. Both the intratester and intertester reliability for shoulder tightness measurements were good (intratester ICC=0.84 and 0.91; intertester ICC=0.82 and 0.89). The limit of intra-tester and inter-tester agreement (mean, -0.3+/-4.4 degrees ) was acceptable as compared to the standard deviations of the measurements (range, 6.2-7.4 degrees ). Significant relationships between internal rotation and posterior shoulder tightness (R2=0.448, P=0.002), external rotation and anterior shoulder tightness (R2=0.499, P=0.003), and functional disabilities and posterior shoulder tightness (R2=0.432, P=0.006) were found. Significant correlations between shoulder internal rotation and cross-chest adduction, shoulder external rotation and below-chest abduction were observed, indicating that internal and external rotations might be related to posterior and anterior shoulder stiffness. The study also revealed significant relationship between functional disabilities and cross-chest adduction. Below-chest abduction and cross-chest adduction were found to provide reliable data. The construct validity of the abduction and adduction tests is supported by the relationship among these measurements, shoulder ROM, and functional disabilities in patients with SS.     

The effect of thoracic spine mobilization and stabilization exercise on the muscular strength and flexibility of the trunk of chronic low back pain patients

[Purpose] To investigate whether thoracic spine mobilization added to stabilization exercises increases the muscular strength and range of motion of the thoracic vertebrae of chronic low-back pain patients. [Subjects] This study enrolled 20 patients with chronic low back pain, who were divided into two groups. Ten subjects were randomly selected for the stabilization exercise group and the remaining 10 subjects received thoracic spine mobilization in addition to performing the stabilization exercises. [Methods] The patients performed stabilization exercises and received thoracic spine mobilization for 12 weeks. The range of motion and isometric muscular strength of the vertebrae of all subjects were measured before and after the intervention. [Results] In the comparison of muscular strength before and after the intervention, the change in muscular strength of the trunk flexors in the stabilization exercise group was 16.0±7.4 Nm, and that of the thoracic spine mobilization group was 34.2±7.6 Nm, a significant difference in each group. In the post-intervention intergroup comparison, the muscular strength of trunk flexors in the stabilization exercise group was 111.1±16.9 Nm, while that of the thoracic spine mobilization group was 125.9±11.3 Nm, a significant difference. Also, the muscular strength of the trunk extensors in the stabilization exercise group was 148.9±31.8 Nm, while that of the thoracic spine mobilization group was 182.9±37.2 Nm, a significant difference. The thoracic spine flexion in the stabilization exercise group was 29.8±9 degrees, while that of the thoracic spine mobilization group was 38.7±6.9 degrees, a significant difference. However, there was no significant difference in lumbar flexion values between the two groups. [Conclusion] Thoracic spine mobilization added to a stabilization exercise increased the muscular strength of patients with chronic low back pain.Key words: Isometric muscle strength, Lumbar stabilization exercise, Thoracic spine mobilization exercise     

Effect of Resistance Training Maintaining the Joint Angle-torque Profile Using a Haptic-based Machine on Shoulder Internal and External Rotation

[Purpose] The aim of this study was to present an individualized resistance training method to enable exercise while maintaining an exercise load that is set according to an individual’s joint angle-torque using a haptic-based resistance training machine. [Methods] Five participants (machine group) performed individualized shoulder internal and external rotation training with a haptic resistance training machine, while another five participants performed general dumbbell-based shoulder internal and external rotation training for eight weeks. Internal and external rotation powers of subjects were measured using an isokinetic machine before and after training. [Results] The average powers of both shoulder internal and external rotation has been improved after training (25.72%, 13.62%). The improvement in power of external rotation in the machine group was significantly higher than that in the control group. [Conclusion] This study proposes a haptic-based individualized rotator cuff muscle training method. The training protocol maintaining the joint angle-torque profile showed better improvement of shoulder internal/external rotation than dumbbell training.Key words: Rotator cuff, Haptic machine     

The influence of various resistance loads on the ratio of activity of the external rotator muscles of the shoulder and the anterior gliding of the humeral head during external rotation exercise

[Purpose] To quantify the ratio of activation of the infraspinatus and posterior deltoid muscles and the anterior gliding motion of the humeral head during external rotation (ER) motions of the shoulder performed in prone position against different external resistance loads. [Subjects] Twenty healthy women between the ages of 20 and 30 years. [Methods] Activity ratio was quantified as the difference in the root mean square of the smoothed electromyography signal (EMG) of the posterior deltoid to the infraspinatus muscle, and anterior gliding pressure of the humeral head using a pressure biofeedback unit (PBU), for three resistance loads: 0, 1 and 2 kg. [Results] There was a significant correlation among all three variables (load, ratio, and pressure). Anterior gliding pressure correlated with the activity ratio, with activity of the posterior deltoid increasing with the magnitude of the resistance load. [Conclusion] There was a positive association between the magnitude of resistance load, activity of the posterior deltoid and anterior gliding pressure of the humeral head. The PBU could be used to facilitate the recruitment of the infraspinatus muscle at higher loads to improve glenohumeral joint stability during ER exercise against higher resistance.Key words: Glenohumeral stability, Rotator cuff, Pressure biofeedback unit (PBU)