Electromyographic Analysis of the Shoulder Girdle Musculature during External Rotation Exercises

Background: Implementation of overhead activity, a key component of many professional sports, requires an effective and balanced activation of shoulder girdle muscles particularly during forceful external rotation motions. Purpose: The study aimed to identify activation strategies of 16 shoulder girdle muscles/muscle segments during common shoulder external rotational exercises. Study Design: Cross-Sectional Study Method: EMG was recorded in 30 healthy subjects from 16 shoulder girdle muscles/muscle segments (surface electrode: anterior, middle and posterior deltoid, upper, middle and lower trapezius, serratus anterior, teres major, upper and lower latissimus dorsi, upper and lower pectoralis major; fine wire electrodes: supraspinatus, infraspinatus, subscapularis and rhomboid major) using a telemetric EMG system. Five external rotation (ER) exercises (standing ER at 0o and 90o of abduction, and with under-arm towel roll, prone ER at 90o of abduction, side-lying ER with under-arm towel) were studied. Exercise EMG amplitudes were normalised to EMGmax (EMG at maximal ER force in a standard position). Univariate analysis of variance (ANOVA) and post-hoc analysis applied on EMG activity of each muscle to assess the main effect of exercise condition. Results: Muscular activity differed significantly among the ER exercises (P<0.05 – P<0.001). The highest activation for anterior and middle deltoid, supraspinatus, upper trapezius, and serratus anterior occurred during standing ER at 90o of abduction; for posterior deltoid, middle trapezius, and rhomboid during side-lying ER at 0° of abduction; for lower trapezius, upper and lower latissimus dorsi, subscapularis, and teres major during prone ER at 90o of abduction, and for clavicular and sternal part of pectoralis major during standing ER with Under-Arm Towel. Conclusion: Key glenohumeral and scapular muscles can be optimally activated during the specific ER exercises particularly in positions that stimulate athletic overhead motions. Clinical Relevance: These results enable sport medicine professionals to target specific muscles during shoulder rehabilitation protocols while minimising the effect of others, providing a foundation for optimal evidence-based exercise prescription. They also provide information for tailored muscle training and injury prevention in overhead sports

Posterior shoulder tightness; an intersession reliability study of 3 clinical tests.

Background Although posterior shoulder tightness (PST) has been associated with shoulder pathology and altered glenohumeral joint kinematics, uncertainty remains regarding its cause and definition. To understand the efficacy of treatments for PST, it must be possible to identify people with PST for the purposes of research and clinical decision-making. Clinical tests for PST must demonstrate acceptable levels of measurement reliability in order to identify the condition and to evaluate the response to intervention. There is currently a lack of research describing intersession reliability for measures of PST. The aim of this study was to quantify the inter-session reliability for three clinical tests used to identify PST over a 6–10 week interval. Methods A convenience sample of 26 asymptomatic adult participants (52 shoulders) were recruited from a university setting over a five-month duration. Participants attended the human movement laboratory for measurement of glenohumeral joint internal rotation, horizontal adduction and low flexion on two occasions separated by an interval of 6–10 weeks. Intra-class correlation coefficients were calculated from the mean square values derived from the within-subject, single factor (repeated measures) ANOVA. Test-retest measurement stability was evaluated by calculating the standard error of measurement and the minimum detectable change for each measurement. Results All 3 tests demonstrated good intersession intra-rater reliability (0.86–0.88), and the standard error of measurement (95%) were 7.3° for glenohumeral horizontal adduction, 9.4° for internal rotation, and 6.9° for low flexion. The minimum detectable change for glenohumeral horizontal adduction was 10.2°, internal rotation was 13.3°, and low flexion was 9.7°. Conclusion In this population of people without symptoms, the 3 measures of PST all demonstrated acceptable inter-session reliability. The standard error of measurement and minimum detectable change results can be used to determine if a change in measures of PST are due to measurement error or an actual change over time.Peer reviewe

Kinematic analisys of the knee when climbing up/down stairs in patellofemoral instability

OBJECTIVE: To analyze and to identify possible gait adaptations by individuals with objective patellofemoral instability when climbing up/down stairs. METHODS: A control group (group A) composed by nine women with mean age = 25 years (±1.87), height = 1.62 m (±0.05) and weight = 56.20 kg (±7.34), and; nine women with objective patellofemoral instability (group B) with mean age = 24 years (±6.02), height = 1.62 m (±0.06) and weight = 60.33 kg (±10.31) were analyzed. The groups underwent kinematic analysis while climbing up/down stairs, in a previously determined area. Images were obtained by six cameras (Qualysis) and data analysis utilized the Q gait software program. RESULTS: Group B presented, in the support phase, less knee flexion when climbing up (p = 0.0268), and lower speed (p = 0.0076/ p =0.0243) and pace (p = 0.0027/ p = 0.0165) when climbing up and down stairs, respectively. CONCLUSION: It is suggested that group B used functional changes such as reduced knee flexion, speed and pace when climbing up and down stairs.OBJETIVO: Analisar e identificar possíveis adaptações da marcha em indivíduos com diagnóstico de instabilidade patelofemoral objetiva, durante a atividade de subida e descida de escada. MÉTODOS: Foram analisados um grupo controle (grupo A), composto por 9 mulheres com média de idade de 25 anos (±1,87), média de altura de 1,62m (±0,05) e média de peso de 56,20kg (±7,34); e, um grupo de 9 mulheres com instabilidade patelofemoral objetiva (grupo B), média de idade de 24 anos (±6,02), média de altura de 1,62m (±0,06) e média de peso de 60,33kg (±10,31). Os grupos foram submetidos a uma análise cinemática, onde as voluntárias subiram e desceram degraus, em uma área previamente selecionada. As imagens foram obtidas por seis câmeras (Qualysis) e a análise dos dados foi realizada através do programa Q gait. RESULTADOS: O grupo B apresentou, no período de apoio, menor flexão do joelho durante a subida (p=0,0268), além de menores velocidade (p=0,0076/ p=0,0243) e cadência (p=0,0027/ p=0,0165) na subida e na descida, respectivamente. CONCLUSÃO: Sugere-se que o grupo B utilizou adaptações funcionais como redução da flexão do joelho, da velocidade e da cadência, durante a subida e a descida de degraus.UNICAMP FCM Departamento de Ortopedia e TraumatologiaUniversidade Federal de São Paulo (UNIFESP)UNIFESPSciEL

Retear of anterior cruciate ligament grafts in female basketball players: a case series

<p>Abstract</p> <p>Background</p> <p>Incidence of anterior cruciate ligament (ACL) injuries in young female basketball players is higher than that in male basketball players. Graft retears are more frequent with the increasing number of ACL reconstructions. The present study aimed to examine the incidence of retears in competitive female basketball players.</p> <p>Methods</p> <p>Sixty-four female basketball players (aged 12 to 29 years) who underwent primary anatomic double-bundle ACL reconstruction using hamstring grafts participated in the study. We investigated incidence, mechanism, and patient characteristics of ACL graft retears. Mann-Whitney <it>U </it>test was used for statistical analysis, and the level of significance was determined at <it>P </it>< 0.05.</p> <p>Results</p> <p>Six patients suffered from ACL graft retear (9.4%). Mean duration between primary ACL reconstruction and incidence of retears was 11.7 months. However, there were no other postoperative graft ruptures after 24 months. Primary injury and retear mechanisms varied by patient. At six months after the primary ACL reconstruction surgery, mean quadriceps and hamstring strengths were 81% and 87%, respectively, indicating favorable recovery of muscle strength. However, preoperative quadriceps and hamstring strength in the retear group were 65% and 71%, respectively. In particular, preoperative quadriceps strength in the retear group demonstrated a lower value than that in the uninjured group (<it>P </it>< 0.05).</p> <p>Conclusions</p> <p>We observed a high incidence of ACL graft retears in competitive female basketball players, as previously reported. Considering the timing of graft retear occurrences, an early return to playing basketball should be avoided following ACL reconstruction. Closer attention should be paid to player preoperative condition, as well as muscle strength and postoperative status.</p

Improving the sensitivity of the hop index in patients with an ACL deficient knee by transforming the hop distance scores

BACKGROUND: The one leg hop for distance is one of the most commonly employed functional tests utilized in the evaluation of the ACL deficient and reconstructed patient. While the reliability of the hop test scores has been well established, validity studies have revealed low sensitivity rates in detecting functional limitations using the hop index (the ratio or percentage of limb performance). However, the impact of the inherent limitations associated with the hop index have not been investigated to date. One specific limitation relates to the impact of the differences in the underlying hop distance scores. Therefore, this pilot study set out to determine: 1) the impact that between limb differences in hop distance has on the sensitivity of the hop index in detecting functional limitations and; 2) whether a logarithmic transformation of the underlying hop distance scores improves the sensitivity of the hop index. METHODS: A cross sectional design involving the evaluation of one leg hop for distance performance in a consecutive sample of 10 ACL deficient males with an isolated ACL tear awaiting reconstructive surgery and nine gender, age-matched controls. RESULTS: In the ACL deficient, the hop index was associated with the distance hopped on the non-injured limb (r = -0.66, p = 0.04) but not on the injured limb. Transformation (logarithmic) of the hop distance scores and re-calculation of the hop index using the transformed scores increased the sensitivity of the hop index in the detection of functional limitations from 20 to 60% and 50 to 70% using the normal limb symmetry reference norms of ≥ 85% and 90% respectively. CONCLUSION: The distance hopped on the non-injured limb is a critical factor in detecting functional limitations using the hop index in patients with an ACL deficient knee. Logarithmic transformation of the hop distance scores minimizes the effect of the arithmetic differences between limbs however; the sensitivity of the hop index in detecting abnormal limb symmetry remains low

Genetic Ancestry-Smoking Interactions and Lung Function in African Americans: A Cohort Study

Background: Smoking tobacco reduces lung function. African Americans have both lower lung function and decreased metabolism of tobacco smoke compared to European Americans. African ancestry is also associated with lower pulmonary function in African Americans. We aimed to determine whether African ancestry modifies the association between smoking and lung function and its rate of decline in African Americans. Methodology/Principal Findings: We evaluated a prospective ongoing cohort of 1,281 African Americans participating in the Health, Aging, and Body Composition (Health ABC) Study initiated in 1997. We also examined an ongoing prospective cohort initiated in 1985 of 1,223 African Americans in the Coronary Artery Disease in Young Adults (CARDIA) Study. Pulmonary function and tobacco smoking exposure were measured at baseline and repeatedly over the follow-up period. Individual genetic ancestry proportions were estimated using ancestry informative markers selected to distinguish European and West African ancestry. African Americans with a high proportion of African ancestry had lower baseline forced expiratory volume in one second (FEV1) per pack-year of smoking (-5.7 ml FEV1/ smoking pack-year) compared with smokers with lower African ancestry (-4.6 ml in FEV1/ smoking pack-year) (interaction P value = 0.17). Longitudinal analyses revealed a suggestive interaction between smoking, and African ancestry on the rate of FEV1 decline in Health ABC and independently replicated in CARDIA. Conclusions/Significance: African American individuals with a high proportion of African ancestry are at greater risk for losing lung function while smoking. © 2012 Aldrich et al

Genetic loci associated with chronic obstructive pulmonary disease overlap with loci for lung function and pulmonary fibrosis.

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality worldwide. We performed a genetic association study in 15,256 cases and 47,936 controls, with replication of select top results (P < 5 × 10(-6)) in 9,498 cases and 9,748 controls. In the combined meta-analysis, we identified 22 loci associated at genome-wide significance, including 13 new associations with COPD. Nine of these 13 loci have been associated with lung function in general population samples, while 4 (EEFSEC, DSP, MTCL1, and SFTPD) are new. We noted two loci shared with pulmonary fibrosis (FAM13A and DSP) but that had opposite risk alleles for COPD. None of our loci overlapped with genome-wide associations for asthma, although one locus has been implicated in joint susceptibility to asthma and obesity. We also identified genetic correlation between COPD and asthma. Our findings highlight new loci associated with COPD, demonstrate the importance of specific loci associated with lung function to COPD, and identify potential regions of genetic overlap between COPD and other respiratory diseases