Comparison of Muscle Activity During a Ring Muscle Up and a Bar Muscle Up.

The muscle up (MU) is a variation of a common gymnastics movement that combines a pull up and a dip. It can be performed on a bar (BMU) or a set of rings (RMU). The difference in upper extremity muscle recruitment (MR) between BMU and RMU has not been evaluated. Therefore, the purpose of this study was to compare the MR of select muscles during BMU and RMU. Ten active males (27.6 ± 7.9 years) performed 5 repetitions of BMU and RMU in randomized order. Muscle recruitment of the upper (UT) and lower trapezius (LT), serratus anterior (SA), pectoralis major (PM), latissimus dorsi (LD), triceps brachii (TB), biceps brachii (BB), and forearm flexors (FF) was assessed using electromyography. A 2 × 2 ANOVA (ring vs bar, pull phase vs push phase) with repeated measures was performed for each muscle. Least significant differences post hoc tests were performed when a significant interaction effect occurred. The RMU significantly elicited more muscle activation in the UT (p = 0.007), BB (p = 0.001), and FF (p = 0.001) during the pull phase. The RMU also significantly elicited more muscle activation in the TB (p = 0.025) and BB (p = 0.001) during the push phase. These results suggest that the instability of the RMU primarily increases the required recruitment of the upper limbs but does not significantly change the recruitment of the shoulder stabilizers. Appropriate upper limb development is needed to perform the RMU and the BMU may be a better technique to learn first due to its lower difficulty.

Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized Clinical Trial.

Background: Previous research has demonstrated the benefits of both stabilization and non-stabilization of the scapula during stretching in individuals with posterior shoulder tightness, but limited evidence exists in patients with shoulder pain. Hypothesis/Purpose: The aim of this study was to determine the effect of stabilized scapular stretching on patients with shoulder pain. The primary hypothesis of this study is that stabilized scapular stretching will improve glenohumeral motion and pain compared to non-stabilized stretch program. A secondary hypothesis of this study is that stabilized scapular stretching will produce greater improvement in function compared to the non-stabilized stretching program. Study Design: Randomized Clinical Trial. Methods: Sixteen patients with sub-acromial pain associated with tendinopathy and associated pathologies presenting to physical therapy were randomized into two groups (stabilized or non-stabilized scapular stretching). Baseline pain and range of motion were measured prior to and following each treatment session for three visits that occurred over the course five to seventeen days depending on the patients availability. The dependent measurements were stabilized horizontal adduction, stabilized internal rotation, stabilized shoulder flexion, non-stabilized shoulder flexion, and current pain level. Results: Patients in the scapular stabilization stretching group increased horizontal adduction 40° (CI95 31, 48°) compared to the non-stabilization stretching group increase of 8° (CI95 0, 17°) over the course of the three treatments (p<0.001). Similarly, the stabilized stretching group increased internal rotation 48° (CI95 26, 69°) compared to the non-stabilized stretching group increase of 26° (CI95 4, 48°) (p=0.001). Pain decreased in the stabilized stretching group by 1.4 points (CI95 -0.4, 3.2) but increased slightly in non-stabilized group by -0.5 points (CI95 -2.3, 1.3) which was not a clinically meaningful change. (p=0.03). Conclusion: Stabilized scapular stretching was more effective than non-stabilized stretching at gaining shoulder mobility in patients with shoulder pain. Benefits were immediate and sustained between treatment sessions. Stretching interventions improved range of motion but had limited effect on shoulder pain. Level of Evidence: 2.

Line Hops and Side Hold Rotation Tests Load Both Anterior and Posterior Shoulder: A Biomechanical Study.

BACKGROUND: Clinical tests should replicate the stressful positions encountered during sport participation. Evaluating the kinetic and electromyographical demands of clinical tests enables clinicians to choose appropriate tests for specific sports. PURPOSE: To describe the shoulder forces and muscle activation levels during closed chain functional tests of Line Hops (LH) and Side Hold Rotation (SHR). STUDY DESIGN: Descriptive biomechanical study. METHODS: Ten asymptomatic participants were examined in a university laboratory. Two functional tests were evaluated using three-dimensional video analysis and electromyography to measure shoulder forces, moments, and muscular activity levels. RESULTS: SHR produced a peak average posterior translation force of 4.84 N/kg (CI95 4.32-5.36N/kg) and a peak average anterior translational force of 1.57 N/kg (CI95 1.10-2.01N/kg). High levels of serratus anterior (98% maximum voluntary isometric contraction (MVIC) and infraspinatus (52 %MVIC) were recorded during SHR. LH produced a posterior translational force of 4.25 N/kg (CI95 3.44-5.06N/kg). High levels of serratus anterior (105 %MVIC) and infraspinatus (87 %MVIC) were recorded during the push off phase of this activity. CONCLUSIONS: LH and SHR placed large posterior translational forces that approached half of a person's bodyweight on shoulder structures. SHR produced an anterior translation force at extremes of horizontal abduction placing approximately 18% of bodyweight on shoulder structures. The LH test required the serratus anterior to provide power to push the upper torso of the ground while both the serratus and the infraspinatus provides scapular and humeral stability, respectively. LEVEL OF EVIDENCE: 4: Case series.