Investigating the Influence of Modifiable Physical Measures on the Elbow Varus Torque - Ball Velocity Relationship in Collegiate Baseball Pitchers.

Background: The mechanism of ulnar collateral ligament (UCL) injury during pitching is excessive elbow varus torque (EVT). The EVT-ball velocity (T-V) relationship allows concurrent assessment of player performance and UCL injury risk. Modifiable physical capacities may underlie individual variation seen in the T-V relationship.

Awareness of Visual Offset Reduces but Does Not Eliminate Joint Repositioning Errors in Virtual Reality.

The present study investigated the effect of visual offset (visuo-proprioceptive mismatch) in joint repositioning task in a three-dimensional virtual reality (VR) environment when participants were instructed to ignore vision. Twenty-five physically healthy young individuals performed shoulder joint position sense test. Repositioning accuracy was tested under two visual conditions, accurate and offset visions, and two instructions, no guidance or ignore vision.

Usage and acceptability of data normalization in baseball pitching.

In baseball pitching biomechanics, kinetic values are commonly ratio 'normalised' by dividing by mass or mass*height to allow for comparison between athletes of different sizes. However, creating a normalised ratio variable should meet certain statistical assumptions. Our purpose was to determine if elbow valgus torque predicted by pitching velocity is influenced by normalisation using regression model comparison with and without normalised torque values.

Experimentally Induced Pain Results in Reduced Activity of the Rotator Cuff Muscles in Healthy Subjects.

Shoulder pain is a complex, prevalent problem that is multifactorial in nature. While there are many potential causes, one common suspect is the rotator cuff musculature. The purpose of the present study was to induce pain in the supraspinatus muscle of healthy subjects and observe the resulting changes in muscle activity.

Collegiate baseball pitchers demonstrate a relationship between ball velocity and elbow varus torque, both within and across pitchers.

High elbow varus torque during baseball pitching has been identified as a potential cause of ulnar collateral ligament injury in baseball pitchers. In general, elbow varus torque increases as ball velocity increases across pitchers. However, studies incorporating within-subject analyses report that not all professional pitchers have a positive relationship between elbow varus torque and ball velocity (T-V relationship).

Peripheral sensitization is demonstrated in subacromial pain syndrome, with central sensitization found only in females.

The objective of this study was to explore whether hypersensitivity in patients with subacromial pain syndrome (SPS) manifests purely as localized peripheral sensitization or central sensitization, is influenced by the presence of subacromial pain, and presents similarly in male and female patients. Pressure pain threshold was assessed in both a patient cohort with unilateral SPS and an uninjured matched control group. Control subjects were assessed twice, with a 15 minute rest period between testing, while patients were assessed at baseline and after an almost instantaneous reduction in pain arising from an anesthetic injection in patients.

Weakness in patients with subacromial pain syndrome is local and more pronounced in females.

Background: Subacromial pain syndrome is the predominant cause of shoulder pain, accounting for approximately half of all shoulder complaints. This population presents with weakness of the involved shoulder. However, there is a gap in our understanding of how pain contributes to this weakness, and whether there are sex related differences.

Submaximal contractions can serve as a reliable technique for shoulder electromyography normalization.

There are a number of ways to normalize electromyographical data, the most common of which is using a maximal contraction as a reference. However, this technique is not always practical. The purpose of the present study was to assess the reliability of an electromyographical data normalization technique using standardized submaximal contractions.

Muscle Activity Before and After Subacromial Injection.

Context: Shoulder muscle activation in patients with subacromial impingement is highly cited and variable in the literature. Differences between studies could be due to artifacts introduced by normalization practices in the presence of pain. Ultimately, this lack of knowledge pertaining to pathogenesis limits the clinical treatment and restoration of muscular function.

Joint Position Accuracy Is Influenced by Visuoproprioceptive Congruency in Virtual Reality.

Weighted integration of visual and proprioceptive information is important in movement planning and execution. The present study used a virtual reality system to determine how upper limb movement consistency and accuracy are altered when (a) vision of the limb is removed and (b) proprioception and vision of the limb are misaligned. A one degree of freedom upper limb movement task was performed under three visual conditions of the limb; accurate vision, no vision, and offset vision.

Shoulder Joint Position Sense Can Be Reduced by Sensory Reference Frame Transformations.

Joint position sense (JPS) is commonly evaluated using an angle replication protocol with vision occluded. However, multiple sources of sensory information are integrated when moving limbs accurately, not just proprioception. The purpose of this study was to examine different availability of vision during an active JPS protocol at the shoulder.

Clinical Outcomes and Shoulder Kinematics for the "Gray Zone" Extra-articular Scapula Fracture in 5 Patients.

Aims: There is a subset of scapula fractures, which can be considered in the "gray zone," where treatment guidelines are not clear-cut, based on published literature. Our paper presents the outcomes of five such scapula fractures treated non-operatively.

Methods: Adult patients who had been treated non-operatively at our institution for an isolated scapula fracture from 2003-2012 were found using Current Procedural Terminology (CPT) codes.

Shoulder and elbow joint position sense assessment using a mobile app in subjects with and without shoulder pain - between-days reliability.

Objectives: To determine between-days reliability and the minimal detectable change for shoulder and elbow joint position sense assessment using a validated mobile app, in subjects with and without shoulder pain.

Design: Reliability study.

Setting: Clinical measurement.

Force perception at the shoulder after a unilateral suprascapular nerve block.

There are two key sources of information that can be used to match forces-the centrally generated sense of effort and afferent signals from mechanical receptors located in peripheral tissues. There is currently no consensus on which source of information is more important for matching forces. The corollary discharge hypothesis argues that subjects match forces using the centrally generated sense of effort.

Feasibility of using a fully immersive virtual reality system for kinematic data collection.

Commercially-available Virtual Reality (VR) systems have the potential to be effective tools for simultaneous visual manipulation and kinematic data collection. Previously, these systems have been integrated with research-grade motion capture systems to provide both functionalities; however, they are yet to be used as stand-alone systems for kinematic data collection. The present study aimed to validate the HTC VIVE VR system for kinematic data collection by evaluating the accuracy of its position and orientation signals.

An Investigation Into Force Sense at the Shoulder.

Proprioception is assessed more often through joint position sense and kinesthesia than force sense. The purpose of this study is to investigate force sense at the shoulder. A total of 12 subjects were recruited.

The contribution of the supraspinatus muscle at sub-maximal contractions.

During maximum effort, the supraspinatus muscle contributes approximately 50% of the torque need to elevate the arm, but this has not been examined at sub-maximal levels. The purpose of this study was to determine the contribution of the supraspinatus muscle to shoulder elevation at sub-maximal levels. Seven healthy subjects (four males, three females) performed isometric ramp contractions at the shoulder.

No Relationship Between Joint Position Sense and Force Sense at the Shoulder.

In practice, a single test is used to quantify an individual's proprioception. Previous studies have not found a correlation between joint position sense (JPS) and force sense (FS), which are submodalities of proprioception. The purpose of the present study is to determine if root mean square (RMS) error in JPS and FS are related at the shoulder, controlling for external load and elevation angle.

Subacromial Anesthetics Increase Proprioceptive Deficit in the Shoulder and Elbow in Patients With Subacromial Impingement Syndrome.

Shoulder proprioception gives information regarding arm joint position and movement direction. Several studies have investigated shoulder proprioceptive acuity in patients with subacromial impingement syndrome (SIS); however, differences in protocols and between-subjects designs have limited scientific inferences regarding proprioception and SIS. We aimed to determine within-subject differences in shoulder and elbow proprioceptive acuity in 17 patients with stage 2 SIS following treatment of a local anesthetic injection.

College Pitchers Demonstrate Directional Differences in Shoulder Joint Position Sense Compared With Controls.

Context: The relationship between overhead throwing and its effect on proprioception is not well understood. It is important to gain a better understanding of how these are related, to protect overhead athletes from an increased risk of injury.

Objective: To investigate proprioceptive alterations in the overhead thrower's shoulder.

Deltoid Electromyography is Reliable During Submaximal Isometric Ramp Contractions.

The EMG and load relationship is commonly measured with multiple submaximal isometric contractions. This method is both time consuming and may introduce fatigue. The purpose of this study was to determine if the electromyography (EMG) amplitude from the middle deltoid was reliable during isometric ramp contractions (IRCs) at different angles of elevation and rates of force application.

Errors in Shoulder Joint Position Sense Mainly Come from the Glenohumeral Joint.

While synchronous movement of the glenohumeral and scapulothoracic joints has been emphasized in previous kinematics studies, most investigations of shoulder joint position sense have treated the shoulder complex as a single joint. The purposes of this study were to investigate the joint position sense errors of the humerothoracic, glenohumeral, and scapulothoracic joints at different elevation angles and to examine whether the errors of the glenohumeral and scapulothoracic joints contribute to the errors of the humerothoracic joint. Fifty-one subjects with healthy shoulders were recruited.

Exercises focusing on rotator cuff and scapular muscles do not improve shoulder joint position sense in healthy subjects.

Proprioception is essential for shoulder neuromuscular control and shoulder stability. Exercise of the rotator cuff and scapulothoracic muscles is an important part of shoulder rehabilitation. The purpose of this study was to investigate the effect of rotator cuff and scapulothoracic muscle exercises on shoulder joint position sense.

Normalization to Maximal Voluntary Contraction is Influenced by Subacromial Pain.

In this study, we aimed to determine if electromyography (EMG) normalization to maximal voluntary isometric contractions (MVIC) was influenced by subacromial pain in patients with subacromial impingement syndrome. Patients performed MVICs in unique testing positions for each shoulder muscle tested before and after subacromial injection of local anesthetic. In addition to collection of MVIC data, EMG data during an arm elevation task were recorded before and after injection.

Ankle Movements During Supine Kicking in Infants Born Preterm.

Background: Knowledge of musculoskeletal factors that influence supine kicking of infants born preterm has implications for early intervention.

Hypotheses: Differences exist between infants born preterm and full-term in ankle kinematics during supine kicking, which are attributable to passive measures of the gastrocnemius/soleus (g/s) muscle tendon unit (MTU).

Subjects: Twenty infants born full-term and 22 born preterm were measured at term, 6 weeks, and 12 weeks of age.