Different weight bearing push-up plus exercises with and without isometric horizontal abduction in subjects with scapular winging: A randomized trial

Comparison of the Effects of Isometric Horizontal Abduction on Shoulder Muscle Activity During Wall Push-Up Plus and Wall Slide in Individuals With Scapular Winging

CONTEXT

Wall push-up plus (WPP) and wall slide (WS) are commonly prescribed in early rehabilitation to increase serratus anterior (SA) muscle activity. For individuals with scapular winging (SW), synergistic muscles such as upper trapezius (UT) and pectoralis major (PM) may compensate for weak SA during scapular movement. However, no studies have applied isometric horizontal abduction (IHA) during WS in individuals with SW nor have compared it with WPP with IHA.

OBJECTIVES

This study compared the effects of IHA on shoulder muscle activity during WPP and WS exercises in individuals with SW.

DESIGN

Cross-sectional study; 2-way repeated-measures analysis of variance was used to assess the statistical significance of observed differences in SA, UT, PM, lower trapezius (LT), and infraspinatus (IS) muscle activities.

SETTING

Research laboratory.

PATIENTS

We recruited 30 individuals with SW comprising 20 men and 10 women.

INTERVENTIONS

The individuals performed WPP and WS exercises with and without IHA using Thera-Band.

MAIN OUTCOME MEASURES

Surface electromyography was used to measure muscle activity of the SA, UT, PM, LT, and IS during the isometric phase of WPP and WS. Maximal voluntary isometric contractions were recorded to normalize electromyographic data.

RESULTS

There was no significant interaction between IHA application and exercise type for any of the shoulder muscles. IHA application increased SA (P = .008), UT (P = .001), LT (P = .009), and IS (P = .000) activities and decreased PM (P = .001) activity compared with those without IHA. WS exercises elicited higher PM (P = .017) and LT (P = .011) activities than WPP.

CONCLUSION

WPP and WS with IHA may be effective in increasing the muscle activities of shoulder stabilizers and preventing overactivation of PM activity. WPP may be recommended for individuals with overactivated PM, whereas WS may be used to increase LT activity.

The acute effects of vibratory stimuli during exercise on the sensorimotor control of the shoulder complex: A pilot study

BACKGROUND

Functional stability of the shoulder requires a balance of active forces, passive forces, and control subsystems of the joint complex. Although whole-body vibration enhances shoulder muscle function and proprioception, the impact of vibration on the sensorimotor control of the shoulder joint remains unclear.

OBJECTIVE

To investigate the acute effect of vibratory stimuli on the sensorimotor control of the shoulder joint.

METHODS

Fifteen male participants (age, 22.7 ± 2.3 years) were included and performed the exercise in a modified push-up position with partial weight-bearing on a vibration platform with and without vibratory stimuli. The vibration protocol included six sets lasting for 30 s each with a 30-s rest between sets. The main outcome measures included the upper limb static stability test, Upper Quarter Y Balance Test (UQYBT), and electromyography data of the upper limb.

RESULTS

Vibratory stimuli resulted in an increased UQYBT score (all directions; P< 0.01) and infraspinatus, serratus anterior, and lower trapezius muscle activity (P< 0.05) between pre- and post-exercise versus the control condition. Stabilometric parameters showed no significant interaction between condition and time.

CONCLUSIONS

Vibratory stimuli could maximize training benefits while limiting injury risk for athletes. Our findings could guide the development of rehabilitation programs for patients with shoulder instability.

Shoulder muscle activation during scapular protraction exercise with arm rotation

BACKGROUND

The role of the serratus anterior is to maintain scapular stability. To strengthen this muscle, scapular protraction exercises are typically performed. Although the angle of arm rotation leads to changes in shoulder muscle activation, the arm rotation position is not normally determined.

OBJECTIVE

To investigate if scapular muscle activations were changed by combining arm external rotation during scapular protraction exercises.

METHODS

Thirty-four healthy men were enrolled in this study. Participants were instructed to perform scapular protraction exercises at 90∘ and 120∘ of shoulder flexion while in the standing and supine positions. Two different arm rotation angles were used: the thumb-up position (neutral position) and the maximum arm external rotation (ER) position. The percentages of maximum voluntary contractions (%MVCs) were measured, and %MVCs in the neutral and arm ER positions were compared.

RESULTS

Muscle activities of the middle serratus anterior (MSA) and lower serratus anterior (LSA) in the arm ER position were significantly higher than those in the neutral position during all tasks. The highest MSA and LSA positions were observed with the arm ER position of 120∘ while standing.

CONCLUSIONS

Scapular protraction exercises with arm ER resulted in a higher serratus anterior activity.

The infraspinatus muscle activity during pitching motion in baseball players with shoulder instability

BACKGROUND

Shoulder microinstability is often overlooked, which can be problematic, especially in overhead athletes. The slipping phenomenon is defined as posterior or lateral sliding of the humeral head in an elevated arm. When the shoulder is close to the end range of stability, the infraspinatus is highly activated and keeps the shoulder in the glenoid cavity. This study aimed to examine the characteristic physical function and infraspinatus activity during the pitching motion in baseball pitchers with shoulder instability.

METHODS

Twenty-one male baseball pitchers participated and were divided into 2 groups based on radiograph findings at zero position: slipped (group S) and nonslipped (group N) groups. Physical function using Hara test and infraspinatus muscle activity during pitching were evaluated.

RESULTS

The infraspinatus muscle activity during the acceleration phase was significantly greater in group S (59.5 ± 33.0%MVC) than in group N (33.0 ± 16.9%MVC) (P < .05). Positive rate of the Hara test in group S was significantly high in the loose test and elbow push test.

CONCLUSIONS

This study shows that baseball pitchers with slipping phenomenon have capsular laxity and scapular instability that indicate high infraspinatus muscle activity during the acceleration phase. Therefore, repetitive pitching with hyperactivity of the infraspinatus on the slipping shoulder may cause fatigue and dysfunction.

Electromyographic activity of the serratus anterior and pectoralis major during isometric scapular protraction at different resistance intensities in subjects with and without a winged scapula

BACKGROUND

During maximal isometric protraction, it is important to determine the optimal resistance intensity in subjects with a winged scapula, for inducing isolated activity of the serratus anterior against the pectoralis major, which is activated as a synergistic muscle. The aim of the present study was to determine electromyographic activities of the serratus anterior and pectoralis major muscles during isometric shoulder protraction at different levels in subjects with and without a winged scapula.

METHODS

Thirty male subjects performed isometric shoulder protraction in a sitting position at different resistance intensity levels (100%, 80%, and 60% of maximal protraction strength). Surface electromyographic data of the serratus anterior and pectoralis major muscles were gathered simultaneously using fixed instrumentation to measure isometric shoulder protraction.

FINDINGS

Muscle activity of the serratus anterior in subjects without a winged scapula was significantly greater than that of subjects with a winged scapula across all three conditions, whereas muscle activity of the pectoralis major was lower in subjects without a winged scapula. In addition, winged scapula muscle activity corresponding to maximal protraction was significantly greater than that in the submaximal condition.

INTERPRETATION

In a clinical setting, submaximal resistance can be more optimal than maximal effort during isometric shoulder protraction in individuals with a winged scapula.