Strategies for controlling axial shoulder rotation change shoulder muscle activity during external rotation exercises.

BACKGROUND: The infraspinatus muscle has a crucial role in shoulder stability. Although axial shoulder rotation is useful for selective activation of the infraspinatus, no study has examined the influence of exercise position on axial shoulder rotation during shoulder external rotation (ER) exercises. Thus, this study investigated the muscle activity in the infraspinatus, posterior deltoid, and middle trapezius during shoulder ER exercises performed with and without controlled axial shoulder rotation in 2 different positions. METHODS: Twenty healthy subjects performed prone external rotation (PER) exercises with and without pressure biofeedback and seated external rotation (SITER) exercises with and without posterior humeral head gliding. Muscle activity during each ER exercise was measured using surface electromyography. RESULTS: Exercise strategy (P < .001) and position (P < .001) had a significant main effect on muscle activity in the infraspinatus and posterior deltoid. However, no significant interaction between strategy and position was observed. For muscle activity in the middle trapezius, strategy and position had a significant interaction effect (P = .014). Muscle activity in the infraspinatus increased significantly with the use of strategies to control axial shoulder rotation, whereas muscle activity in the posterior deltoid and middle trapezius decreased significantly. For all 3 muscles, greater activity was observed in the prone position than the seated position. CONCLUSION: We suggest that PER with pressure biofeedback can be useful to improve selective activation of the infraspinatus muscle while further eliciting infraspinatus muscle activity.

Effects of Visual Biofeedback on Symmetrical Movements During Bridge Exercise With Sling.

CONTEXT: Asymmetrical movements of trunk and lower-extremity are common during the bridge exercise on the unstable condition. However, no studies have investigated whether visual biofeedback of pressing pressure on the unstable surface changes muscle activation patterns of trunk and hip extensors and pelvic rotation during the bridge exercise. OBJECTIVE: To investigate how visual biofeedback of pressing pressure influences symmetrical activity of lumbar and hip extensor and pelvic rotation. DESIGN: Cross-sectional study. SETTING: Laboratory. PARTICIPANTS: Twenty healthy males participated in this study. INTERVENTIONS: The participants performed 2 versions of the bridge exercise: the standard bridge exercise and the bridge exercise with visual biofeedback using amount of pressing pressure on the sling. MAIN OUTCOME MEASURES: Surface electromyography was used to measure the symmetry (ie, the difference between dominant and nondominant sides) of muscle activation in the bilateral erector spinae, gluteus maximus, and hamstring muscles, and motion sensors were used to assess pelvic rotation. Symmetry of pressing pressure was measured using a tension meter. RESULTS: The differences between the dominant and nondominant pressing pressures and differences between the electromyography activity of the dominant and nondominant erector spinae, gluteus maximus, and hamstring were significantly smaller during the bridge exercise with visual biofeedback than during the standard bridge exercise (P < .05). In addition, there was significantly less pelvic rotation during the bridge exercise with visual biofeedback than during the standard bridge exercise (P < .05). CONCLUSIONS: The present findings suggest that visual biofeedback strategy may be a useful method for enhancing the symmetrical activation of the erector spinae, gluteus maximus, and hamstring and for reducing pelvic rotation during the bridge exercise on the unstable surface.

Effects of self-stretching with mobilization on shoulder range of motion in individuals with glenohumeral internal rotation deficits: a randomized controlled trial.

BACKGROUND: The combined effects of cross-body stretching and dorsal glide mobilization have not been examined previously, although both stretching and mobilization maneuvers are effective for improving shoulder range of motion (ROM). Thus, the aim of this study was to demonstrate the effects of stretching with mobilization (SWM) on glenohumeral (GH) internal rotation (IR) and horizontal adduction (HA) ROM. METHODS: Forty individuals with GH IR deficits were randomized to perform simultaneous combined cross-body stretching and dorsal glide mobilization (SWM group, comprising 10 male and 10 female patients) or cross-body stretching alone (stretching group, comprising 10 male and 10 female patients). GH IR ROM, HA ROM, and shoulder mobility were assessed before and immediately following interventions. Group and time differences were analyzed using 2-way repeated-measures analysis of variance. RESULTS: Greater changes in GH IR ROM (6°, P < .001), HA ROM (10°, P < .001), and shoulder mobility (-2 cm, P = .018) were observed in the SWM group than in the stretching group, although significant increases were observed in GH IR ROM (SWM group, P < .001; stretching group, P < .001), HA ROM (SWM group, P < .001; stretching group, P = .042), and shoulder mobility (SWM group, P < .001; stretching group, P < .001) after both interventions. CONCLUSION: This study shows that SWM could be a useful exercise for shoulder ROM recovery in individuals with GH IR deficits.

Influence of ankle dorsiflexion range of motion on heel-rise time during gait.

[Purpose] The purpose of this study was to examine the correlation between weight-bearing (WB) and non-WB ankle dorsiflexion (DF) range of motion (ROM) and ankle movement during gait, including heel-rise time and ankle DF at heel-rise. [Subjects and Methods] Thirty healthy male subjects were recruited for this study. Ankle DF ROM of both feet was measured under the WB and non-WB conditions. Heel-rise time and ankle DF at heel-rise in both feet during gait were measured using a motion analysis system. Pearson product moment correlations were used to identify correlation ankle DF ROM and ankle movement during gait. [Results] Heel-rise time and ankle DF at heel rise were significantly correlated with WB ankle DF ROM. However, no correlations were found between ankle movement during gait and non-WB ankle DF ROM. [Conclusion] These findings demonstrate that WB ankle DF ROM measurements can be used to predict heel-rise time and ankle DF at heel-rise.

Reproducibility of isometric shoulder protraction and retraction strength measurements in normal subjects and individuals with winged scapula.

BACKGROUND: The strength of the shoulder protractors and retractors may be compromised in individuals with winged scapula (IwWS). However, no standard approach to measuring the strength of these muscles has been described. The aim of this study was to study the intra-rater and inter-rater reproducibility of a fixed-base isometric dynamometer and to describe cutoff scores for clinically meaningful change for protraction and retraction isometric strength. METHOD: Twice during a week, 20 normal subjects and 20 IwWS were tested by 2 independent raters. RESULTS: IwWS were significantly weaker (P < .001) than control subjects in their protraction and retraction isometric strength. Excellent intra-rater and inter-rater correlations were obtained in most combinations, leading to low cutoff scores for meaningful change expressed in terms of the smallest real difference. CONCLUSION: When it is properly used, the technique described in this paper is recommended as an effective clinical tool for the quantitative assessment of protraction and retraction isometric strength, both for status determination and for monitoring of change in IwWS during and after rehabilitation.

Effects of spring-loaded crutches on gastrocnemius activity and upward displacement of the body during gait.

[Purpose] This study investigated the effects of spring-loaded crutches on gastrocnemius muscle activity and upper body displacement in the sagittal plane during gait. [Subjects and Methods] The study involved 12 healthy males. All subjects performed crutch gait by using spring-loaded crutches and axillary crutches. During this gait, the gastrocnemius muscle activity was measured using a wireless electromyography system, and upward displacement of the body was measured using a three-dimensional motion analysis system. [Results] The gastrocnemius activity was significantly lower but upward displacement of the body was significantly greater with the spring-loaded crutches than with axillary crutches. [Conclusion] Spring-loaded crutches allow efficient crutch gait and involve less effort from the gastrocnemius muscle.

Differences in performance on the functional movement screen between chronic low back pain patients and healthy control subjects.

[Purpose] Differences in scores on the Functional Movement Screen between patients with chronic lower back pain and healthy control subjects were investigated. [Subjects and Methods] In all, 20 chronic lower back pain patients and 20 healthy control subjects were recruited. Chronic lower back pain patients and healthy controls performed the Functional Movement Screen (deep squat, hurdle step, inline lunge, shoulder mobility, active straight leg raise, trunk stability pushup, and rotary stability). The Mann-Whitney test was used to analyze differences in Functional Movement Screen scores between the two groups. [Results] Chronic lower back pain patients scored lower on the Functional Movement Screen total composite compared with healthy control subjects. Chronic lower back pain patients scored lower on Functional Movement Screen subtests including the deep squat, hurdle step, active straight leg raise, and rotary stability tests. [Conclusion] The deep squat, hurdle step, active straight leg raise, and rotary stability tasks of the Functional Movement Screen can be recommended as a functional assessment tools to identify functional deficits in chronic lower back pain patients.

Effects of isometric hip movements on electromyographic activities of the trunk muscles during plank exercises.

[Purpose] The purpose of this study was to investigate the effect of isometric hip adduction and abduction on trunk muscle activity during plank exercises. [Subjects and Methods] Nineteen healthy male subjects were recruited for this study. All subjects performed the traditional plank exercise (TP), plank exercise with isometric hip adduction (PHAD), and plank exercise with isometric hip abduction (PHAB) by using an elastic band. Electromyographic (EMG) activities of the internal oblique (IO) and external oblique (EO) were measured during the 3 plank exercises by using an Electromyography system. [Results] Internal oblique and external oblique muscle activities were significantly greater during plank exercise with isometric hip adduction and plank exercise with isometric hip abduction than during traditional plank exercise. Internal oblique and external oblique muscle activities did not differ between the plank exercise with isometric hip adduction and plank exercise with isometric hip abduction conditions. [Conclusion] These findings demonstrate that loaded isometric hip movements may be a useful strategy to increase trunk muscle activity during plank exercises.

Association of ankle kinematics and performance on the y-balance test with inclinometer measurements on the weight-bearing-lunge test.

CONTEXT: Ankle-dorsiflexion range of motion has often been measured in the weight-bearing condition in the clinical setting; however, little is known about the relationship between the weight-bearing-lunge test (WBLT) and both ankle kinematics and performance on dynamic postural-control tests. OBJECTIVE: To examine whether ankle kinematics and performance on the Lower Quarter Y-Balance Test (YBT-LQ) are correlated with results of the WBLT using an inclinometer and tape measure. DESIGN: Cross-sectional. SETTING: University motion-analysis laboratory. PARTICIPANTS: 30 physically active participants. INTERVENTIONS: None. MAIN OUTCOME MEASURES: The WBLT was evaluated using an inclinometer and a tape measure. The reach distances in the anterior, posteromedial, and posterolateral directions on the YBT-LQ were normalized by limb length. Ankle dorsiflexion during the YBT-LQ was recorded using a 3-dimensional motion-analysis system. Simple linear regression was used to examine the relationship between the WBLT results and both ankle dorsiflexion and the normalized reach distance in each direction on the YBT-LQ. RESULTS: The WBLT results were significantly correlated with ankle dorsiflexion in all directions on the YBT-LQ (P < .05). A strong correlation was found between the inclinometer measurement of the WBLT and ankle dorsiflexion (r = .74, r2 = .55), whereas the tape-measure results on the WBLT were moderately correlated with ankle dorsiflexion (r = .64, r2 = .40) during the anterior reach on the YBT-LQ. Only the normalized anterior reach distance was significantly correlated with the results for the inclinometer (r = .68, r2 = .46) and the tape measure (r = .64, r2 = .41) on the WBLT. CONCLUSIONS: Inclinometer measurements on the WBLT can be an appropriate tool for predicting the amount of ankle dorsiflexion during the YBT-LQ. Furthermore, WBLT should be measured in those who demonstrate poor dynamic balance.

The effects of gait with use of smartphone on repositioning error and curvature of the lumbar spine.

[Purpose] This study evaluated the effect of smartphone use on lumbar spine repositioning error and lumbar curvature while walking on a treadmill. [Subjects] A total of 20 healthy individuals (18 males and 2 females) volunteered for this study. [Methods] The subjects walked for 20 min on a treadmill while using a smartphone. To determine the effect of smartphone use, lumbar repositioning error was measured using an electronic goniometer while lumbar curvature was assessed using a Spinal Mouse before and immediately after treadmill use. Differences in the lumbar repositioning error and lumbar curvature data between the pre- and post-walking were compared using the paired t-test. [Results] The lumbar spine repositioning error was significantly greater post-walking compared with pre-walking (6.70±2.91° vs. 3.02±1.79°). There was no significant difference in lumbar curvature between pre- and post-walking (14.24±3.18° vs. 13.94±3.12°). [Conclusion] These findings indicate that the lumbar repositioning error increased immediately after walking while using a smartphone, but that the lumbar curvature was unchanged.

Comparison of selective electromyographic activity of the superficial lumbar multifidus between prone trunk extension and four-point kneeling arm and leg lift exercises.

[Purpose] This study examined the selective electromyographic activity of the lumbar paraspinal muscles in healthy male and female subjects in the prone trunk extension (PTE) and four-point kneeling arm and leg lift (FPKAL) exercises to determine the most beneficial exercise for selective activation of the lumbar multifidus (LM). [Subjects and Methods] Twenty healthy male and female subjects participated in this study. Surface electromyographic data were collected from the left-side lumbar erector spinae (LES) and LM muscles during PTE and FPKAL exercises. [Results] The LM/LES ratio related to selective activation of the lumbar paraspinal muscles during the FPKAL exercise was higher than that during PTE. [Conclusion] FPKAL exercise is safe and effective for the selective activation of the LM muscle.

Effects of the Neurac(®) technique in patients with acute-phase subacromial impingement syndrome.

[Purpose] This study investigated the effects of the Neurac technique on shoulder pain, function, and range of motion in patients with acute-phase subacromial impingement syndrome. [Subjects] Thirteen patients (seven females and six males) with acute-phase subacromial impingement syndrome participated in this study. [Methods] Shoulder pain, function, and range of motion were assessed before and after the application of the Neurac technique. [Results] Pain and function scores were significantly lower after than before the Neurac intervention. Shoulder range of motion was significantly greater after Neurac intervention than before it. [Conclusion] The Neurac technique is a useful intervention for patients with acute-phase subacromial impingement syndrome.

Effects of kinesio taping on lumbopelvic-hip complex kinematics during forward bending.

[Purpose] The aim of this study was to investigate the effect of kinesio taping (KT) on the kinematics of the lumbo-pelvic-hip complex during forward bending by individuals with reduced hamstring extensibility. [Subjects] Eighteen males with reduced hamstring extensibility were randomly assigned to one of two groups:, the hamstring KT group (n=9), or the sham KT group (n=9). [Methods] The kinematics of the lumbopelvic-hip complex during lumbar forward bending was measured using a motion capture system before and after applying KT. [Results] The angle of lumbar flexion during late lumbar forward bending increased significantly post-KT compared to pre-KT measurements in the hamstring KT group. [Conclusion] These findings suggest that KT does not directly affect an individual's movement during lumbar forward bending.

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.

Immediate effects of an end-range mobilization technique on shoulder range of motion and skin temperature in individuals with posterior shoulder tightness.

[Purpose] This study investigated the effects of an end-range mobilization technique on the range of motion of the glenohumeral internal rotation and the skin temperature of the shoulder in individuals with posterior shoulder tightness. [Subjects] Thirteen subjects with posterior shoulder tightness who had glenohumeral internal rotation deficit ≥ 15° participated. [Methods] All subjects underwent glenohumeral joint end-range mobilization intervention. The internal rotation range of motion of the glenohumeral joint was measured by a goniometer and the shoulder skin temperature was measured by a digital infrared thermographic imaging device before and immediately after the intervention. Paired t-tests were used to analyze the differences in these parameter pre and post-intervention. [Results] The glenohumeral internal rotation range of motion and skin temperature of the posterolateral shoulder in increased significantly post-intervention. [Conclusion] The end-range mobilization technique is effective for increasing the glenohumeral internal rotation range of motion and skin temperature of the shoulder in individuals with posterior shoulder tightness.

EMG Activity in the Abdominal Muscles and the Kinematics of the Lumbar Spine during Unilateral Upper-limb Resistance Exercises under Stable and Unstable Conditions.

[Purpose] We investigated the effects of unstable conditions on the electromyographic (EMG) activity of the rectus abdominis (RA) and the transverse abdominis-internal oblique (TrA-IO) muscles, and lumbar kinematics during unilateral upper-limb resistance exercises using elastic tubing bands. [Subjects] Twelve healthy males were recruited. [Methods] The subjects performed isometric left shoulder abduction using an elastic tubing band in a sitting position on a chair, and on a Swiss ball. During this exercise, EMG activities of the RA and TrA-IO were recorded using a wireless EMG system, and a three-dimensional motion analysis system monitored lumbar kinematics. Differences in EMG activities of the RA and TrA-IO, the ratio of TrA-IO to RA activity, and lumbar kinematics were compared between the stable and unstable conditions using the paired t-test. [Results] Under the unstable condition, the EMG activities of both muscles were significantly greater than that under the stable condition; however the ratio of TrA-IO to RA activity did not significantly differ between the conditions. The lumbar angle significantly differed only in the coronal plane. [Conclusions] These findings indicate that trunk posture should be considered when performing exercises under unstable conditions.

Differences in Muscle Activities of the Infraspinatus and Posterior Deltoid during Shoulder External Rotation in Open Kinetic Chain and Closed Kinetic Chain Exercises.

[Purpose] This study investigated the changes in electromyographic (EMG) activities of the infraspinatus and posterior deltoid muscles during shoulder external rotation under open kinetic chain (OKC) and closed kinetic chain (CKC) exercise conditions. [Subjects] In total, 15 healthy males participated in this study. [Methods] Subjects performed shoulder external rotations under CKC and OKC conditions while standing with and without weight support provided by a height-adjustable table. Pressure biofeedback was used to ensure a constant amount of weight support. The activities of the infraspinatus and posterior deltoid muscles during shoulder external rotation were measured using a wireless surface EMG system. The paired t-test was used to compare the EMG activities of the infraspinatus and the posterior deltoid muscles and the ratio of the infraspinatus to the posterior deltoid during shoulder external rotation under OKC and CKC conditions. [Results] The EMG activity of the infraspinatus and the ratio of the infraspinatus to the posterior deltoid activities were significantly increased, whereas the posterior deltoid activity was significantly decreased under the CKC condition compared to the OKC condition. [Conclusion] Clinicians should consider the CKC shoulder external rotation exercise when they wish to selectively strengthen the infraspinatus.

Effects of a Home Exercise Program on the Self-report Disability Index and Gait Parameters in Patients with Lumbar Spinal Stenosis.

[Purpose] The present study was performed to identify the effect of a home exercise program on the self-reported disability index and gait parameters in patients with lumbar spinal stenosis (LSS). [Methods] Fifteen patients with LSS were enrolled in this study and were trained in a 4-week home exercise program (40 min/day). All patients were evaluated with three self-reported disability indices (Oswestry Disability Index, Roland-Morris Disability Questionnaire, and Spinal Stenosis Scale), and gait parameters were assessed using a GAITRite system before and after the home exercise program. [Results] Patients with LSS showed significant decreases in the self-reported questionnaire scores and pain intensity after the home exercise program. However, the gait parameters did not significantly change. [Conclusion] These findings suggest that home exercise programs can improve self-reported questionnaire scores and decrease pain in patients with LSS.

Effects of Shoulder Flexion Loaded by an Elastic Tubing Band on EMG Activity of the Gluteal Muscles during Squat Exercises.

[Purpose] We investigated the effects of shoulder flexion loaded by an elastic tubing band during squat exercises, by assessing electromyographic activities of the gluteus maximus and gluteus medius. [Subjects] In total, 17 healthy males were recruited. [Methods] Participants performed squat exercises with and without shoulder flexion loaded by a tubing band. Gluteal muscle activities during the downward and upward phases of the squat exercises were recorded using a surface electromyography (EMG) system. The mean electromyographic activities of the gluteal muscles during squat exercises with and without loaded shoulder flexion were compared using the paired t-test. [Results] Electromyographic activities of the gluteus maximus and gluteus medius were greater in both the upward and downward phases of the squat with loaded shoulder flexion. [Conclusions] The combination of squat and loaded shoulder flexion can be an effective exercise for increasing gluteal muscle activity.

Reliability of measures of scapular protraction strength in the supine and seated positions.

[Purpose] The purpose of this study was to investigate the intra-rater reliability of measures of scapular protraction strength using a novel method. [Subjects] Forty-nine healthy subjects participated in this study. [Methods] Subjects performed maximal isometric scapular protraction on the left and right sides in the supine and seated positions. During scapular protraction, resistance was applied to the olecranon, and the strength of scapular protraction was measured using a load cell. Intra-rater reliability was calculated as the intra-class correlation coefficient (ICC3,1). [Results] High intra-rater reliability scores (0.97-0.98) for scapular protraction strength were observed in the supine and seated positions. [Conclusion] These findings demonstrate that the method described herein may provide a more reliable and convenient method to measure scapular protraction strength than common current practice does.