Normative values for internal and external glenohumeral rotation strength in rugby players: A systematic review with meta-analysis.

This systematic review aims to provide normative values for internal and external glenohumeral rotation strength in rugby players. From the inception to March 2021, the search strategy was (strength OR torque) AND shoulder AND rugby using PubMed, Scopus, Web of Science, and SPORTDiscus databases, with no language restrictions. This systematic review includes 15 articles involving 573 rugby players and presenting internal or external glenohumeral rotation strength values. Two main methods are used to assess glenohumeral rotation strength in rugby players: isokinetic and isometric methods; in the isometric method, the upper arm is abducted at either 0° or 90°. Owing to differences in isokinetic procedures and a lack of studies assessing isometric strength when the upper arm is in a neutral position, normative internal or external glenohumeral rotation strength values are only provided for isometric contractions when the upper arm is abducted at 90° based on 311 shoulders of 163 male rugby union players, with 2.04 ± 0.15 N.kg-1 and 2.11 ± 0.13 N.kg-1 for internal and external glenohumeral rotation strength, respectively. These findings may help strength and conditioning coaches and physical therapists, provide objective evidence when deciding whether or not rugby union players should return to sport.

Uncertainty analysis and sensitivity of scapulothoracic joint angles to kinematic model parameters.

The purposes of this study were to determine the influence of kinematic model parameter variability on scapulothoracic angle estimates, and to define which parameters of the kinematic model have the largest effect on scapulothoracic angle estimates. Nominal subject-specific kinematic models of nine participants were implemented. Fifteen parameters of the nominal models relative to the clavicle length, ellipsoid, sternoclavicular and acromioclavicular joint centers, and contact point location were altered from - 1 to 1 cm. Then, scapulothoracic angles were computed during four movements using multibody kinematic optimizations for nominal and altered models. The percentage of scapulothoracic angle variance explained by each parameter of the kinematic model was computed using Effective Algorithm for Computing Global Sensitivity Indices. When altering simultaneously the 15 parameters of the kinematic model, scapulothoracic angles varied up to 50°. For all movements and degrees of freedom, the clavicle length significantly explained the largest part of scapulothoracic angle variance (up to 25%, p < 0.01). In conclusion, kinematic model parameters need to be estimated accurately to avoid any bias in scapulothoracic angle estimates especially in a clinical context. The present sensitivity analysis may also be used as a benchmark for future works focusing on improving shoulder kinematic models. The curves represent mean scapulothoracic angles computed with the nominal model and their variability when kinematic model parameters are altered. The colormap graphs represent the percentage of scapulothoracic angle variance explained by each parameter of the kinematic model.

Closed-loop multibody kinematic optimization coupled with double calibration improves scapular kinematic estimates in asymptomatic population.

Non-invasive methods still need to better estimate scapular kinematics because of soft tissue artifact issue. This study aimed to develop and assess new procedures to estimate scapular kinematics by combining closed kinematic chain optimization and double calibration. Sixteen healthy volunteers performed static postures mimicking analytical and daily living movements. Scapulo-thoracic angles were computed either with a scapula locator (Ref), or with a closed-loop multibody kinematic optimization (Ell) or with double calibration involving linear (DClin), exponential (DCexp) or logarithmic (DClog) correction. Double calibration corrections enforced scapulo-thoracic angles to be the same than those measured with Ref at the end of the movement performed. DClin and DClog significantly (p < 0.01) reduced scapulo-thoracic misorientation for at least the second third of the movement with averaged improvement ranging from 9° to 32°. Moreover, for arm elevation in the sagittal plane, internal rotations and mimicking hair combing, the beneficial effect of DClin and DClog propagates up to half of the movement. To conclude, when a kinematic chain is required, coupling double calibration (using either linear or logarithmic correction), to a closed-loop multibody kinematic optimization is an efficient and fast method in regard with improvement in scapular kinematic estimates in healthy population.