Reliability of a Barre-Mounted Dynamometer-Stabilizing Device in Measuring Dance-Specific Muscle Performance

BACKGROUND: Hand-held dynamometry is considered an efficient, effective, and portable means of objectively measuring lower extremity strength; however, it has yet to be studied specific to dance-relevant muscle performance. Also, dynamometry is often criticized for variability in results based on tester strength and sex. Use of an external stabilizing device has been suggested to minimize differences in outcomes between male and female testers by reducing variability associated with tester strength limitations. Therefore, this study used a barre-mounted, portable dynamometer stabilizing device to improve consistency of results among different testers for assessing hip and lower extremity muscle performance in dance-relevant positions. OBJECTIVE: To assess the intra and inter-rater reliability of a barre-mounted dynamometer stabilizing device in measuring muscle performance in common dance maneuvers. METHODS: Two testers assessed muscle performance of three common dance maneuvers-—développé en avant, à la secondé, and arabesque-—on 11 pre-professional and professional dancers on two separate occasions to establish intra- and inter-rater reliability of the barre-mounted dynamometer stabilizing device. RESULTS: Intra-rater reliability was moderate to high and inter-rater reliability of the device was excellent, with intraclass correlation coefficients ranging from 0.527–0.851 and 0.834–0.953, respectively, for all positions. CONCLUSIONS: The barre-mounted stabilizing device shows promise in mitigating tester strength or fatigue in assessing muscle performance of dancers. Initial assessment of the device suggests further study may be indicated to improve generalizability to applications of larger-scale muscle performance screening and assessment in dancers or other athletic populations who engage in movements that require extensive hip range of motion and multi-joint stability. CLINICAL RELEVANCE: Using a portable, barre-mounted stabilizing device in assessing multi-joint lower extremity muscle performance in dancers improves consistency of testing results. Application of this testing device into wider scale screenings could assist in developing normative data for a population that is lacking

Muscle Activity During the Star Excursion Balance Test in Healthy Adults

Purpose: To determine electromyographic (EMG) activity of the hip and the trunk muscles during the Star Excursion Balance Test (SEBT) performance in 8 reach directions

Hip and Trunk Muscle Activity During the Star Excursion Balance Test in Healthy Adults

CONTEXT: Dynamic balance is a measure of core stability. Deficits in the dynamic balance have been related to injuries in the athletic populations. The Star Excursion Balance Test (SEBT) is suggested to measure and improve dynamic balance when used as a rehabilitative tool. OBJECTIVE: To determine the electromyographic activity of the hip and the trunk muscles during the SEBT. DESIGN: Descriptive. SETTING: University campus. PARTICIPANTS: Twenty-two healthy adults (11 males and 11 females; 23.3 [3.8] y, 170.3 [7.6] cm, 67.8 [10.3] kg, and 15.1% [5.0%] body fat). INTERVENTION: Surface electromyographic data were collected on 22 healthy adults of the erector spinae, external oblique, and rectus abdominis bilaterally, and gluteus medius and gluteus maximus muscle of the stance leg. A 2-way repeated measures analysis of variance was used to determine the interaction between the percentage maximal voluntary isometric contraction (%MVIC) and the reach directions. The %MVIC for each muscle was compared across the 8 reach directions using the Sidak post hoc test with α at .05. MAIN OUTCOME MEASURES: %MVIC. RESULTS: Significant differences were observed for all the 8 muscles. Highest electromyographic activity was found for the tested muscles in the following reach directions-ipsilateral external oblique (44.5% [38.4%]): anterolateral; contralateral external oblique (52.3% [40.8%]): medial; ipsilateral rectus abdominis (8% [6.6%]): anterior; contralateral rectus abdominis (8% [5.3%]): anteromedial; ipsilateral erector spinae (46.4% [20.2%]): posterolateral; contralateral erector spinae (33.5% [11.3%]): posteromedial; gluteus maximus (27.4% [11.7%]): posterior; and gluteus medius (54.6% [26.1%]): medial direction. CONCLUSIONS: Trunk and hip muscle activation was direction dependent during the SEBT. This information can be used during rehabilitation of the hip and the trunk muscles

Reliability and Criterion Validity of Ultrasonic Measurements of the Supraspinatus and Infraspinatus Cross-Sectional Area

Purpose/Background: Diagnostic ultrasound (US) offers a cost-effective and accessible means of evaluating the cross-sectional area (CSA) of muscles as compared to the gold standard of Magnetic Resonance Imaging (MRI). Muscle CSA is directly related to the amount of force a muscle can produce. Rotator cuff CSA is especially important when considering the strength and function of the shoulder joint. The present study aims to test the validity, same-day and between day intra-rater reliability of US CSA measures of the supraspinatus (SS) and infraspinatus (IS) muscles of the shoulder compared to MRI. Number of Subjects: Thirty-two, right-hand dominant subjects were prospectively enrolled and completed this study (22 male, mean age, 43 years

The Influence of Pain on Rotator Cuff CrossSectional Area

Purpose/Background: Rotator cuff weakness is a common finding in patients with shoulder pain. Weakness may be a result of aging, neuropathy, full-thickness rotator cuff tearing, decreased voluntary activation due to inhibition, or muscle atrophy. Rotator cuff atrophy is not uncommon in the presence of a rotator cuff tear but can also be seen in aging populations and overhead athletes with intact rotator cuffs. The primary aim of this study was to compare the cross-sectional area (CSA) of the supraspinatus (SS) and infraspinatus (IS) muscles and SS tendon thickness between painful and non-painful shoulders. Secondarily, we aimed to determine if there was a difference in SS and IS CSA between dominant and non-dominant shoulders. Lastly, we explored the relationship of SS and IS CSA to rotator cuff endurance and isometric strength. We hypothesized that there would be a significant difference in the CSA between dominant and non-dominant shoulders and between painful and non-painful shoulders. Furthermore, we believed that age and weight would covary with muscle CSA. We also hypothesized that there would be a significant difference in muscle CSA, strength and endurance in painful and non-painful shoulders based on chronicity of pain; however, we did not believe we would discover a difference in endurance and strength between non-painful dominant and non-dominant shoulders Methods/Appriach: This was a cross-sectional study. Demographic information, the PENN shoulder score and the modified Constant score were collected at the time of testing. 24 subjects were recruited for this study: Twelve right hand dominant subjects with unilateral, right shoulder pain were recruited into the shoulder pain group. Subjects were excluded if they were found to have a full-thickness rotator cuff tear. Twelve healthy controls matched by gender, age, height and weight were recruited into the non-painful control group. All subjects underwent a diagnostic ultrasound evaluation of bilateral shoulders to determine the CSA of the SS and IS muscles, and tendon thickness. Additionally, shoulder endurance and isometric strength were evaluated with hand-held dynamometry and the posterior shoulder endurance test (PSET). Results: Independent sample t-tests found no significant differences in age, height or weight between groups (p\u3c0.05). 2x2 mixed-model analyses of variance (ANOVA) found no significant differences in SS and IS CSA and SS tendon thickness between painful and non-painful shoulders, and between dominant and non-dominant shoulders in all subjects (p\u3e0.05). However, there were significant differences shoulder strength and endurance between painful shoulders and non-painful shoulders in the painful group and the painful shoulder in the shoulder pain group and the dominant and non-dominant shoulders in the control group (p\u3c0.05). Conclusions: This study showed that there is no significant difference in SS and IS CSA and SS tendon thickness between subjects with moderate shoulder pain and disability and non-painful shoulders. Additionally, differences between dominant and non-dominant shoulders were not found. The results of this study suggest that rotator cuff weakness in subjects with moderate shoulder pain and intact rotator cuffs is not due to decreased rotator cuff CSA

Effects of Lower Extremity and Trunk Muscle Recruitment on Serratus Anterior Muscle Activation in Healthy Male Adults

Background: Poor activation of the serratus anterior (SA) muscle may result in abnormal shoulder rhythm, and secondarily contribute to impingement and rotator cuff tears. Sequential activation of the trunk, pelvis, and lower extremity (LE) muscles is required to facilitate the transfer of appropriate forces from these body segments to the upper extremity. Myofascial connections that exist in the body, and LE and trunk muscles (TM) activity may influence scapular and upper limb activity. The purpose of this study was to investigate the effect of simultaneous recruitment of the LE muscles and TM on the SA muscle activation when performing a forward punch plus (FPP) and six variations of the FPP exercise. Study Design: Experimental, within‐subject repeated measures. Methods: Surface electromyographic (EMG) activity of the SA, latissimus dorsi, and external oblique muscles on the dominant side, bilateral gluteus maximus muscles, and contra‐lateral femoral adductor muscles were analyzed in forward punch plus (FPP) movement and six variations in twenty one healthy male adults. The percentage of maximum voluntary isometric contraction (%MVIC) for each muscle was compared across various exercises using a 1‐way repeated –measures analysis of variance with Sidak pair wise comparison as post‐hoc test (p \u3c 0.05). Results: Pairwise comparisons found that the EMG activity of the serratus anterior (SA) during the FPP with contralateral closed chain leg extension (CCLE), FPP with ipsilateral closed chain leg extension (ICLE), FPP with closed chain serape effect (CS), and FPP with open chain serape effect (OS) showed significantly higher EMG activity than the FPP. Conclusions: Simultaneous recruitment of the lower extremity and trunk muscles increases the activation of the SA muscle during the FPP exercise. Clinical Relevance: Rehabilitation clinicians should have understanding of the kinetic chain relationships between the LE, the trunk, and the upper extremity while prescribing exercises. The results of this study may improve clinicians\u27 ability to integrate the kinetic chain model in a shoulder rehabilitation program