Is there a relation between rotator cuff injury and core stability?

Motor alterations in the kinetic chain in individuals with chronic shoulder pain

BACKGROUND

Shoulder pain may be related to biomechanical dysfunctions in the kinetic chain.

OBJECTIVE

To compare the mobility and muscular endurance of thoracolumbar spine and hip, and the neuromuscular control of the lower extremity of individuals with and without shoulder pain and to determine the discriminative capacity between groups of these variables.

DESIGN

A cross-sectional study.

METHOD

One hundred and two individuals with and without shoulder pain were evaluated to range of motion (ROM) of the thoracolumbar spine and hips, the muscular endurance time of the thoracolumbar spine and hips muscles, and the neuromuscular control of the lower extremity, by the Star Excursion Balance Test (SEBT).

RESULTS

Individuals with shoulder pain presented lower ROM and muscular endurance time in all tests evaluated (p < 0.01-p = 0.03), greater perception of pain during all ROM and muscle endurance (p < 0.01-p = 0.04) evaluations, and less neuromuscular control of the lower extremity in the compound reach (p < 0.01-p = 0.01), anterior and posteromedial (p < 0.01-p = 0.04) directions of the SEBT on both sides. The anterior reach direction of the SEBT of the contralateral limb to the shoulder pain (AUC=0.80, cut-off point=47.7%) presented excellent capacity to discriminate individuals with shoulder pain, while the other variables showed between acceptable and small capacity (AUC=0.58-0.76).

CONCLUSION

Individuals with chronic shoulder pain presented alterations in joint mobility, muscular endurance time of the thoracolumbar spine and hips and neuromuscular control of the lower extremity. The anterior reach of the SEBT of the contralateral limb showed excellent discriminative capacity.

Relationship between upper limb physical performance tests and muscle strength of scapular, shoulder and spine stabilizers: A cross-sectional study

INTRODUCTION

Performance tests of the upper limb have been frequently used in the evaluation of individuals to identify risk of injury and to determine improvement in physical performance. Understanding the variables related to the performance of the tests is important for better applicability and interpretation of test results. The aim of this cross-sectional study was to investige the correlation between isometric strength of scapular, shoulder and spine muscles with physical performance test of upper limb in men and women.

EXPERIMENTAL

Forty-nine healthy and physically conditioned individuals, men (n = 24) (22,7 ± 3,2 years; 74,6 ± 8,1 Kg; 176,7 ± 7,1 cm) women (n = 25) (23 ± 2,7 years; 61,5 ± 9,1 Kg; 163,2 ± 5,6 cm), were evaluated for shoulder abductor isometric strength (S-ABD); Middle (MT) and lower (LT) trapezium; lateral shoulder rotators (S-LR); flexors (T-FLEX), lateral incliners (T-INCL), and trunk extenders (T-EXT). Evaluation of upper limb physical performance was carried out by Upper Quarter Y Balance test (YBT-UQ) and Chain upper extremity stability test (CKC-UEST). Pearson's test (r values) p ≤ 0.05 was used to analyze the correlation.

RESULTS

The results reveal strong correlations between S-ABD and CKC-UEST in male group; and strong correlations in female group between S-ABD strength with CKC-UEST; and S-LR with all YBT-UQ directions and score and between T-EXT strength with CKC-UEST.

CONCLUSION

Therefore, strength of shoulder and spine stabilizers influences performance in upper limb tests, but with different correlations as to sex. To improve test performance, it may be important to increase the strength of the shoulder and spine muscles.

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.

Biomechanical analysis of the closed kinetic chain upper extremity stability test in healthy young adults

OBJECTIVES

To compare kinematic and ground reaction force (GRF) patterns between the dominant and non-dominant limbs in males and females conducting the closed kinetic chain upper extremity stability test (CKCUEST).

DESIGN

Descriptive.

SETTING

Biomechanics laboratory.

PARTICIPANTS

Sixteen male and sixteen female healthy and physically active young adults.

MAIN OUTCOME MEASURES

Hand contact and flight times, peak and average vertical (vGRF) and medial-lateral (mlGRF) ground reaction forces, medial-lateral (ML) distance and ML velocity per repetition, three-dimensional (3D) distance and 3D velocity per repetition, and average number of touches per trial during the CKCUEST.

RESULTS

Only peak and average mlGRF were statistically different between limbs. Males and females were statistically different across every measured variable. ML and 3D velocities were the only variables strongly correlated to the number of touches achieved.

CONCLUSIONS

Both sexes were symmetrical between limbs in all but mlGRF; however, there were distinct differences in both kinematics and GRF patterns between sexes that may be attributed to differences in the testing position between males and females.