Effects of augmented trunk stabilization with external compression support on shoulder and scapular muscle activity and maximum strength during isometric shoulder abduction

Comparisons of test-retest reliability of infraspinatus strength during wiper exercise with and without external fixation in individuals of scapular dyskinesis

BackgroundThe wiper exercise in a side-lying position is commonly used in clinical settings to assess the strength of the infraspinatus muscle. In addition, a reliable test of infraspinatus strength is important for individuals with scapular dyskinesis.ObjectiveThe purpose is to compare the test-retest reliability of infraspinatus strength during the wiper exercise with and without external fixations in individuals with scapular dyskinesis.MethodsThirty individuals with scapular dyskinesis participated. A dynamometer was utilized to measure the strength of the infraspinatus during the wiper exercise with and without external fixation applied to the posterior superior iliac spine (PSIS) and spinous process of a fourth thoracic vertebra (T4). The intra-class correlation coefficients (ICC 3,1) were used to compare the reliability of infraspinatus strength measurement.ResultsThe reliability for infraspinatus strength measurement was higher with external fixation than without external fixation. The ICC value during wiper exercise with external fixation was 0.99 (95% confidence interval: 0.96-0.99; P < 0.01), and the average strength was 7.35 ± 2.2 kg. In contrast, the ICC value during wiper exercise without external fixation was 0.79 (95% confidence interval: 0.49-0.93; P < 0.01), and the average strength was 5.86 ± 1.45 kg.ConclusionIn individuals with scapular dyskinesis, the infraspinatus strength measurement during the wiper exercise with external fixation is recommended to improve the test-retest reliability.

Effect of scapular posterior tilting exercise on scapular muscle activities in men and women with a rounded shoulder posture

Round-shoulder posture (RSP) is a common postural condition, characterized by protraction, downward rotation, anterior tilting and internal rotation of the scapula. RSP can lead to shoulder dysfunction. Different methods have been proposed for rehabilitating and correcting the altered posture in RSP including stretching, strengthening exercises, and shoulder brace or taping. However, the findings are controversial and studies are ongoing to develop more effective method. The present study is aimed at investigating the effects of scapular posterior tilting (SPT) exercise in different support positions on scapular muscle activities in men and women with RSP. In a prospective observational clinical study, we assessed demographic, basic clinical parameters and study variables of the subjects with RSP (n = 20) (men/women = 9/11) attending Daegu University in Gyeongsan, South Korea. To do so, we compared electromyographic (EMG) activities of lower trapezius and serratus anterior muscles between men and women with RSP during SPT exercise on four different support surfaces to determine any difference in the EMG activities. The results revealed that women showed significant differences in EMG activities in the lower and left upper trapezius and serratus anterior muscles, while men showed significant differences in EMG activity only in the lower trapezius muscle during SPT exercise on four different surfaces (P < 0.05). The post-hoc analysis revealed significantly greater EMG activity values in the lower trapezius and serratus anterior muscles during SPT exercise on the upper body unstable surface and whole-body unstable surface (p < 0.05). Independent t-tests after the Bonferroni correction showed no significant differences in muscle activities between men and women on the four different surfaces (p > 0.0125).

Influence of external fixation on the isomeric strength of the shoulder flexors in individuals with scapular elevation

BACKGROUND

Sufficient shoulder flexor strength is necessary for accurate movement of the shoulder joint because several factors can cause compensatory movements of the scapula.

OBJECTIVE

We investigated the influence of external fixation on the isometric shoulder flexors strength (ISFS) in individuals with and without scapular elevation (SE) during shoulder flexion.

METHODS

The healthy and SE groups included 29 individuals. The ISFS was measured using a tensiometer (kg) under conditions of with and without external fixation, in a random order. The change in the ISFS (the strength difference with and without external fixation) was compared between the healthy and SE groups using an independent t-test.

RESULTS

The change in the ISFS differed significantly between the healthy and SE groups (3.5% and 32.3%, respectively; p= 0.001).

CONCLUSION

These findings suggest that external fixation should be considered during shoulder flexion to determine the ISFS accurately in individuals with compensated SE.

Feedforward co-activation of trunk muscles during rapid shoulder movements

Background

Shoulder movements that involve unilateral and bilateral flexion, extension, abduction, and asymmetrical flexion-extension cause the activity of trunk muscles. There has not been a fixed consensus on the onset of deep trunk muscle activities including the psoas major (PM), quadratus lumborum (QL), transversus abdominis (TrA), and lumbar multifidus (MF) during shoulder movements. The purpose of this study was to measure the onset of electromyographic activity of the deep trunk muscles during rapid shoulder movements and clarify the coordinated activity pattern of the deep trunk muscles during 11 shoulder movements.

Methods

Thirteen men participated in this study. The onset of activity of the right deep trunk muscles (PM, QL, TrA, and MF) were measured using fine-wire electrodes, and those of the right and left deltoid (anterior, middle, and posterior) and right superficial trunk muscles (rectus abdominis, external oblique [EO], and internal oblique [IO]) were measured using surface electrodes as participants performed 6 types of unilateral, 3 types of bilateral, and 2 types of asymmetrical rapid shoulder movements. We defined feedforward activation as the onset of activity of trunk muscle before or within +50 ms onset of the deltoid muscle and feedback activation as that after +50 ms. A 1-way analysis of variance was performed to compare the onset of activity of each muscle during each shoulder movement.

Results

The mean onset of activity of the PM (26.0 ms), QL (13.1 ms), TrA (−19.7 ms), and MF (20.4 ms) muscles demonstrated feedforward activation during left shoulder flexion. The onset of activity of the TrA (1.6-48.7 ms), rectus abdominis (−1.7 to 17.3 ms), and EO (5.6–40.8 ms) muscles demonstrated feedforward activation during left, right, and bilateral shoulder extension. The onset of activity of the PM (22.9 ms), QL (23.0 ms), TrA (18.9 ms), and EO (15.4 ms) demonstrated feedforward activation during left shoulder abduction, while that of the IO (4.4–10.9 ms) only demonstrated feedforward activation during right and bilateral shoulder abduction. The onset of activity of the TrA (−27.6 ms) and IO (−23.9 ms) demonstrated feedforward activation during left shoulder flexion-right shoulder extension, and that of the MF (33.4 ms) and EO (−17.2 ms), during left shoulder extension-right shoulder flexion.

Conclusion

Rapid shoulder movements occur with coordinated muscle activation of the deep trunk muscles depending on the direction of shoulder movements. Feedforward activation of single or combined deep trunk muscles may facilitate rapid shoulder movements.

Effect of conscious abdominal contraction on the activation of periscapular muscles in individuals with subacromial pain syndrome

BACKGROUND

Synergism between shoulder and trunk muscles seems to be effective to increase periscapular muscle activation in asymptomatic subjects. The influence of conscious contraction of the abdominal muscles has not yet been studied in non-athlete subjects with pain. The study aimed to investigate the effect of the instruction for conscious activation of the abdominal muscles on the activity of the scapulothoracic muscles during shoulder exercises in subjects with subacromial pain syndrome.

METHOD

Thirty subjects with unilateral pain (mean age 52 ± 11 years) participated in this study. Three isometric and five dynamic exercises for the scapulothoracic muscles were assessed. The group without instruction just repeated the exercises, while the instruction group was evaluated before and after conscious abdominal training. The linear mixed model analysis was used to compare the muscle activation between groups.

FINDINGS

Differences between groups after the conscious abdominal contraction for activation of middle and lower trapezius on the symptomatic side in the "Full can"(p = 0.03; effect size:0.92 middle trapezius); (p = 0.02; effect size:0.96 lower trapezius) and "Knee Push" (p = 0.01; effect size:0.75 lower trapezius). For asymptomatic side, the exercises "External Rotation Kneeling" (p = 0.04; effect size: 0.81 lower trapezius); (p = 0.00; effect size: 2.09 serratus anterior), "Knee Push" (p = 0.04; effect size:1.24 serratus anterior) and "Wall Slide" (p = 0.01; effect size: 1.03 serratus anterior).

INTERPRETATION

Conscious contraction of the abdominal muscle immediately alter the activation of the serratus anterior muscle during closed kinetic chain exercises on the asymptomatic side and increased activation of trapezius on the symptomatic side during shoulder open kinetic chain exercise.

Use of unstable surfaces and conscious abdominal contraction on the activity of periscapular muscles

Background/aims

Core training has been recommended in shoulder rehabilitation programs. However, the evidence on this topic is still scarce. The aim of this study was to investigate the effect of conscious abdominal contraction combined with unstable surfaces on electromyographic activity of periscapular muscles during the plus phase of a push-up.

Methods

A total of 20 male participants (22.8 ± 2.5 years) were evaluated. Electromyographic signals were collected from the upper, middle and lower trapezius, serratus anterior, and external and internal oblique muscles during push-up exercises on a stable and unstable surface with and without the conscious abdominal contraction. Each participant performed four variations of the plus phase of a push-up.

Results

The results demonstrated that the conscious abdominal contraction caused an increase in the electromyographic activity of external oblique, internal oblique, serratus anterior and lower trapezius muscles (P≤0.008). The unstable surface caused only a relevant increase in electromyographic activity of the abdominal muscles (P≤0.025). Combining the two strategies did not increase the electromyographic activity of any muscles (P≥0.238).

Conclusions

The conscious abdominal contraction seems to be a viable strategy to increase the electromyographic activity of the periscapular muscles.

Efficacy of Abdominal Control Feedback and Scapula Stabilization Exercises in Participants With Forward Head, Round Shoulder Postures and Neck Movement Impairment

BACKGROUND

Signs and symptoms of impaired function of the musculoskeletal system may be targeted by treating dysfunction located elsewhere.

HYPOTHESIS

Abdominal control feedback and scapular stabilization exercise interventions would result in positive changes in pain intensity, strength, electromyography, and flexion-relaxation phenomena in women with forward head and round shoulder postures and neck movement impairment.

STUDY DESIGN

Pretest-posttest intervention.

LEVEL OF EVIDENCE

Level 1.

METHODS

A total of 135 women (aged 27.23 ± 1.9 years) with forward head and round shoulder postures were randomized to 3 groups. Group 1 received 6-week scapular stabilization exercises with abdominal control feedback (n = 45), group 2 received 6-week scapular stabilization exercises without abdominal control feedback (n = 45), and group 3 received active self-exercise as a control group (n = 45). Posture, pain, proprioception, strength, and electromyography were assessed before and after the interventions.

RESULTS

There were significant between-group differences in pain, proprioception, strength, and electromyography favoring group 1. There were significant within-group changes in posture, pain, proprioception, strength, and electromyography in both groups 1 and 2. No significant change was observed for muscle strength.

CONCLUSION

The addition of abdominal control feedback to the scapular stabilization exercises was shown to be superior to the scapular stabilization exercises alone for decreasing neck pain and restoring proper proprioception, strength, and electromyography in females with forward head and round shoulder postures and neck movement impairment.

CLINICAL RELEVANCE

The addition of abdominal control feedback to scapular stabilization exercises is superior to scapular stabilization exercises alone on the neck for improving electromyography, strength, and function in females with forward head and round shoulder postures and neck movement impairment.

Structural muscular adaptations in upper limb after stroke: a systematic review

BACKGROUND

Stroke is a leading cause of disability in the adult population, impairing upper limb (UL) movements affecting activities of daily living. Muscle weakness has been associated to disabilities in this population, but much attention is given to central nervous system alterations and less to skeletal muscles.

OBJECTIVE

The objective of this review is to carry out a systematic literature review to identify structural muscle alterations in the UL of poststroke individuals.

METHOD

The search was performed in December, 2017. MEDLINE, PubMed, SCOPUS, CINAHL, and Science Direct were used as electronic databases. There was no restriction regarding language and publication dates. Studies conducted on poststroke subjects and results on UL skeletal muscle alterations identified by imaging tests were included.

RESULTS

Seven studies were included. The sample size and the variables varied among the studies. All the studies compared the paretic UL with the nonparetic UL and one of the studies also compared healthy subjects. Ultrasonography was the most used measurement tool to assess muscle adaptation.

CONCLUSIONS

This review demonstrated little evidence with poor to fair quality on the structural muscle adaptations in the poststroke subjects, showing muscle atrophy, a higher stiffness, and amount of fibrous and fat tissue without alterations in lean tissue of distal muscles of the paretic UL compared to the nonparetic limb. However, the nonparetic side also presented alterations, which makes it an inappropriate comparison. Thus, well-designed studies addressing this issue are required.

Comparison of shoulder strength in males with and without myofascial trigger points in the upper trapezius

BACKGROUND

This study was conducted in order to compare the strength of scapular elevator and shoulder abductor with and without restricted scapular elevation between male subjects with and without myofascial trigger points in the upper trapezius.

METHODS

In total, 15 male subjects with myofascial trigger points, and 15age- and weight-matched male subjects without myofascial trigger points in the upper trapezius. Each subject was measured in the strength of maximum isometric scapular elevation and shoulder abduction with and without restricted scapular elevation. Maximum isometric contractions were measured using the Smart KEMA strength measurement system. Independent t-tests were used to compare shoulder strength values between the myofascial trigger points and non- myofascial trigger points groups.

FINDING

The results showed that shoulder abductor strength in the group with myofascial trigger points (5.64kgf) was significantly lower than in the group without myofascial trigger points (11.96kgf) when scapular elevation was restricted (p<0.05). However, there was no significant difference in the strength of the scapular elevator or shoulder abductor between groups (p>0.05).

INTERPRETATION

These findings suggest that decreased strength in the shoulder abductor with restricted scapular elevation should be considered in evaluating and treating individuals with myofascial trigger points of the upper trapezius.

Kinematic Analysis of a Drinking Task in Chronic Hemiparetic Patients Using Features Analysis and Statistical Parametric Mapping

OBJECTIVE

To compare sitting posture and movement strategies between chronic hemiparetic and healthy subjects while performing a drinking task, using statistical parametric mapping (SPM) and feature analysis.

DESIGN

Cross-sectional study.

SETTING

A university physical therapy department.

PARTICIPANTS

Participants (N=26) consisted of chronic hemiparetic (n=13) and healthy individuals (n=13) matched for sex and age.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The drinking task was divided into phases: reaching, transporting the glass to mouth, transporting the glass to table, and returning to initial position. An SPM 2-sample t test was used to compare the entire kinematic waveforms of different joint angles (trunk, scapulothoracic, humerothoracic, elbow). Joint angles at the beginning and end of the motion, movement time, peak velocity timing, trajectory deviation, normalized integrated jerk, and range of motion were extracted from the motion data. Group differences for these parameters were analyzed using independent t tests.

RESULTS

At the static posture and beginning of the reaching phase, patients showed a shoulder position more deviated from the midline and externally rotated with increased scapula protraction, medial rotation, anterior tilting, trunk anterior flexion and inclination to the paretic side. Altered spatiotemporal variables throughout the task were found in all phases, except for the returning phase. Patients returned to a similar posture as the task onset, except for the scapula, which was normalized after the reaching phase.

CONCLUSIONS

Chronic hemiparetic subjects showed more deviations in the proximal joints during seated posture and reaching. However, the scapular movement drew nearer to the healthy individuals' patterns after the first phase, showing an interesting point to consider in rehabilitation programs.

Increased strength of the scapular stabilizer and lumbar muscles after twelve weeks of Pilates training using the Reformer machine: A pilot study

OBJECTIVE

The aim of this work was to analyze muscle strength in Pilates novices who used the Reformer equipment during twelve training sessions.

METHODS

Twenty-four healthy young female volunteers, who were non-smokers and did not exercise regularly, were split into a control group (mean age 28 ± 4 years and BMI 24.55 ± 3.21 kg/m²) and a training group (mean age 29 ± 4 years and BMI 22.69 ± 2.87 kgm²). The data were checked for normality using the Kolmogorov-Smirnov test, and were then analyzed using the t-test (p < 0.05).

RESULTS

After the training sessions, there were statistically significant differences between the groups for the scapular stabilizer muscles (p = 0.0263) and the lumbar muscles (p = 0.0001). For the scapular stabilizers, the initial/final values were 14.69 ± 2.80/14.79 ± 2.89 (control group) and 15.99 ± 3.54/17.44 ± 2.88 (Pilates group). The corresponding values for the lumbar muscles were 53.83 ± 11.66/53.28 ± 11.14 (control group) and 54.75 ± 10.27/64.80 ± 10.20 (Pilates group).

CONCLUSION

After twelve sessions of Pilates with the Reformer equipment, there were improvements in lumbar extensor and scapular stabilizer strength. Several benefits are reported by practitioners of Pilates, but until now, there has been limited scientific evidence of the improvement of strength in the trunk and limbs after application of the technique.

Comparison of maximum voluntary isometric contraction of the biceps on various posture and respiration conditions for normalization of electromyography data

[Purpose] Maximum voluntary isometric contraction can increase the reliability of electromyography data by controlling respiration; however, many studies that use normalization of electromyography data fail to account for this. This study aims to check changes in maximum voluntary isometric contraction based on changes in posture and respiration conditions. [Subjects and Methods] Twenty-two healthy volunteers were included in this study. Using 22 healthy subjects, MVIC of the biceps brachii muscle was measured in three respiration conditions: (1) Maximum voluntary isometric contraction during inspiration after maximal expiration, (2) Maximum voluntary isometric contraction during expiration after maximal inspiration and (3) Maximum voluntary isometric contraction during the Valsalva maneuver. The subjects were in tested in standing and supine postures under all three respiration conditions. [Results] A significant difference was observed in the standing and supine postures based on the respiration condition. A significant difference was observed in the maximum voluntary isometric contraction during inspiration after maximal expiration and maximum voluntary isometric contraction during the Valsalva maneuver conditions when the subjects were in the supine posture. [Conclusion] It is necessary to apply the same respiration condition and the same posture to each subject when measuring Maximum voluntary isometric contraction for the normalization of electromyography data.

Torque steadiness and muscle activation are bilaterally impaired during shoulder abduction and flexion in chronic post-stroke subjects

OBJECTIVE

To characterize sensorimotor control and muscle activation in the shoulder of chronic hemiparetic during abduction and flexion in maximal and submaximal isometric contractions. Furthermore, to correlate submaximal sensorimotor control with motor impairment and degree of shoulder subluxation.

METHODS

Thirteen chronic hemiparetic post-stroke age-gender matched with healthy were included. Isometric torques were assessed using a dynamometer. Electromyographic activity of the anterior and middle deltoid, upper trapezius, pectoralis major and serratus anterior muscles were collected. Variables were calculated for torque: peak, time to target, standard deviation (SD), coefficient of variation (CV), and standard error (RMSE); for muscle activity: maximum and minimum values, range and coefficient of activation. Motor impairment was determined by Fugl-Meyer and shoulder subluxation was measured with a caliper.

RESULTS

Paretic and non-paretic limbs reduced peak and muscle activation during maximal isometric contraction. Paretic limb generated lower force when compared with non-paretic and control. Paretic and non-paretic presented higher values of SD, CV, RMSE, and CV for prime mover muscles and minimum values for all muscles during steadiness. No correlation was found between sensorimotor control, motor impairment and shoulder subluxation.

CONCLUSION

Chronic hemiparetic presented bilateral deficits in sensorimotor and muscle control during maximal and submaximal shoulder abduction and flexion.