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Objectives: Although the belly press and lift off tests are recommended to assess subscapularis function, shoulder internal rotation (IR) exercises performed in other shoulder positions are more commonly used to restore subscapularis function. It is not known if shoulder IR exercises specifically activate subscapularis to the same degree as the lift off and belly press tests, and thus have the potential to effect subscapularis strength gains. Therefore, the aim was to compare subscapularis activation levels with those of other shoulder internal rotator muscles during the belly press and lift off tests and shoulder IR exercise positions., Design: Original research., Methods: Twenty asymptomatic volunteers performed maximal isometric contractions during the belly press and lift off tests and shoulder IR performed at 90° and 0° abduction in an upright position and supported at 90° abduction in supine. Muscle activation levels were recorded using a combination of indwelling and surface electrodes. Data were normalized to maximum voluntary contractions and averaged., Results: Moderate average subscapularis activation levels were recorded during all shoulder IR tasks examined with no significant difference between tasks (p=0.18). The belly press test was the only IR task in which subscapularis activation levels were significantly higher than all other shoulder internal rotator muscles (p<0.05)., Conclusions: Shoulder IR exercises activate subscapularis to similar moderate levels as the belly press and lift off tests and therefore, have similar potential to strengthen subscapularis. However, the belly press test, with significantly higher subscapularis activation than other shoulder internal rotators, more specifically targets subscapularis., (Copyright © 2016. Published by Elsevier Ltd.)

Objectives: Optimal shoulder rotation range of motion (ROM) for swimming is unknown. The primary aim of this study was to examine shoulder rotation ROM in elite swimmers, including the influence of humeral torsion on rotation ROM, in order to establish optimal shoulder rotation parameters for swimming. In addition, we examined the relationship between rotation ROM and shoulder pain., Design: Descriptive cohort study., Methods: Seventy elite Australian swimmers provided shoulder pain history data prior to measurement of humeral torsion and passive and active shoulder rotation ROM. Repeated measure analyses of variance were used to investigate within and between participant differences for all variables. Associations between humeral torsion and rotation ROM were investigated using Pearson's correlation coefficient. Multiple regression analysis was utilised to examine the associations between rotation ROM and shoulder pain., Results: Average humeral torsion angles of 27±10° (dominant side) and 31±10° (non-dominant side) were demonstrated in this elite swimming cohort. In general, increased humeral torsion was positively associated with increased internal rotation (IR) and decreased external rotation (ER) ROM. There were significant differences in both IR and ER ROM measured passively and actively (F 2,136 ≥93.1, p<0.001) with passive ROM greater than active ROM (p<0.001) and active IR ROM measured in supine greater than measured in prone (p<0.001). There were no associations between any rotation ROM variables and current or history of shoulder pain (r 2 =0.058; p=0.46)., Conclusions: Humeral torsion angle and passive shoulder IR ROM were similar while passive ER ROM was greater in elite swimmers compared to reported normal population values., (Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Objectives: Load is used to increasingly challenge muscle function and has been shown to increase muscle activity levels with no change in activation patterns during shoulder flexion, extension, adduction and rotation. However, the effect of load during shoulder abduction, a movement commonly used in assessment of shoulder dysfunction and to improve shoulder function, has not been comprehensively examined. Therefore, the purpose of this study was to determine if load influences shoulder muscle activation patterns and levels during scapular plane abduction in normal subjects., Design: Experimental study., Methods: Fourteen volunteers performed shoulder abduction in the scapular plane at 25%, 50% and 75% of maximum load. Eight shoulder muscles were investigated using a combination of indwelling and surface electromyographic recordings: middle deltoid, infraspinatus, subscapularis, supraspinatus, serratus anterior, upper and lower trapezius and rhomboid major., Results: All muscles tested showed increasing average muscle activation levels with increasing load and strong correlations in the activation patterns between loads., Conclusions: Increasing shoulder abduction load not only increases activity in middle deltoid but also in the rotator cuff (infraspinatus, subscapularis, supraspinatus) and axioscapular (serratus anterior, upper and lower trapezius, rhomboid major) muscles. The functional stabilising role of both the rotator cuff and axioscapular muscles is considered an important contribution to the increased activation levels in these muscle groups as they function to counterbalance potential translation forces produced by other muscles during shoulder abduction. The activation patterns of all shoulder muscle groups during abduction can be trained at low load and progressively challenged with increasing load., (Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Background: Physical symptoms present in a large percentage of instrumental musicians at all levels of expertise, yet the impact of these symptoms on patterns of muscle use and perceived exertion during performance is still unclear., Purpose: Quantify the effects of physical symptoms on muscle activity and perceived exertion in skilled violinists during a range of bowing actions., Methods: Fifty-five professional or university (undergraduate or postgraduate) violinists performed 5 randomly ordered 45-second musical excerpts designed to elicit a range of right arm bowing actions. Surface electromyography data were obtained from 16 muscles of the trunk, shoulder, and right arm during each excerpt performance. Sites of current physical symptoms were reported using a pre-test questionnaire. Average rating of perceived exertion (RPE) for the excerpt performances was obtained immediately after the final excerpt performance., Results: Right upper trapezius muscle activity levels were significantly reduced in participants reporting right shoulder symptoms (p<0.05). Violinists with right wrist symptoms displayed global increases in average muscle activity across all investigated muscles (p<0.03). RPE did not differ significantly between any groups of symptomatic and asymptomatic participants., Conclusion: Differential muscle activity patterns appear between right shoulder symptomatic, right wrist symptomatic, and asymptomatic violinists, presenting the possibility of altered biomechanical responses to physical symptoms that vary with symptom location.

Background: The use of global positioning system (GPS) devices with the inclusion of microsenor technology in rugby league enables measurement of player activity profiles to understand the demands of match-play and optimise on-field performance., Objective: The aim of this review was to systematically review the use of GPS and microsensor technology to quantify player activity profiles in match-play, and conduct a meta-analysis of relevant movement variables in order to present the contemporary and emerging themes within rugby league., Methods: A systematic search of electronic databases (MEDLINE, SPORTDiscus, CINAHL, Web of Science, Scopus, ScienceDirect, EMBASE, and Google Scholar) from the earliest record to February 2015 was conducted. Permutations of key words included GPS, microtechnology, activity profiles, match demands (movement or physical demands), and rugby league. A meta-analysis was conducted to provide a pooled mean and confidence intervals on comparable data from at least three studies., Results: Twenty-seven studies met the eligibility criteria and included 1270 male participants. The studies reported on GPS use in elite competition (n = 16) with limited representation of other competition standards: sub-elite (n = 6), amateur (n = 1) and junior (n = 3). All studies reported on movement variables (distance, relative distance, speed and accelerations), with studies analysing movement at high speed (n = 18, 66.7%), evaluating collision or impact variables (n = 15, 55.6%) and determining the metabolic energy (n = 2, 7.4%) associated with rugby league match-play. Activity profiles of varying positions, positional groups and levels of rugby league competition were described. Meta-analysis indicated that the total distance covered by backs and adjustables were both greater than forward positions, but adjustables covered greater relative distance than forwards and backs. Speed zones were typically categorised into six speed zones ranging from 0 to 36 km·h(-1), or into low- and high-intensity movement. Vast inconsistencies were apparent across studies in categorising movement at high speed, posing difficulties for comparison. Meta-analysis indicated that, although the number of repeated high-intensity effort (RHIE) bouts in elite players were similar to sub-elite (and both greater than juniors), the number of efforts per RHIE were significantly greater in elite than sub-elite players. Differential pacing strategies were adopted according to player selection (whole-match vs. interchange), time period within match-play and match outcome, in order to maintain high-intensity performance or to challenge for a win. Sizeable inconsistencies were also identified in the definitions of reported collisions (classified as mild, moderate and heavy) and impacts (six zone categories provided by manufacturer), making comparisons across studies difficult. Collision profiles were different between competition standard and position where elite players and forwards sustained more moderate- and high-intensity collisions than sub-elite players and backs, respectively. The recent inclusion of GPS-derived metabolic indices to activity profiles has also accentuated the distinctive workloads of positional groups during match-play where adjustables demonstrate the highest energy expenditure and metabolic power., Conclusions: This review and the results of the meta-analysis have demonstrated that positional groups have varied kinematic and metabolic demands. During match play, forwards sustain the greatest number of collisions and RHIE bouts, outside backs participate in more high-speed running and cover the greatest distance, and adjustables work at high intensity covering the greatest relative distance with the highest metabolic cost. Therefore, specific training for each positional group should address their match requirements. In addition, sub-elite players exhibit lower intensity of play compared with elite players, as indicated by lower relative distance and less number of efforts per RHIE bout despite similarities in total distance covered and number of RHIE bouts. To prepare them for elite-level play, their training should incorporate higher intensity drills in which greater relative distance and number of efforts per RHIE bout are performed. Furthermore, the lack of consistency in the definition of speed zones, high-intensity movement, collisions and impacts, underscores the difficulties encountered in meaningful comparisons of player activity profiles between studies. Consensus of these definitions would facilitate direct comparisons within rugby league.

Background: Warm-up is commonly recommended for injury prevention and performance enhancement across all activities, yet this recommendation is not supported by evidence for repetitive submaximal activities such as instrumental music performance., Purpose: The objective of this study is to quantify the effects of cardiovascular, core muscle, and musical warm-ups on muscle activity levels, musical performance, and subjective experience in skilled violinists., Methods: Fifty-five undergraduate, postgraduate, or professional violinists performed five randomly ordered 45-s musical excerpts of varying physical demands both before and after a randomly assigned 15-min, moderate-intensity cardiovascular, core muscle, musical (technical violin exercises), or inactive control warm-up protocol. Surface EMG data were obtained for 16 muscles of the trunk, shoulders, and right arm during each musical performance. Sound recording and perceived exertion (RPE) data were also obtained. Sound recordings were randomly ordered and rated for performance quality by blinded adjudicators. Questionnaire data regarding participant pain sites and fitness levels were used to stratify participants according to pain and fitness levels. Data were analyzed using two- and three-factor ANCOVA (surface EMG and sound recording) and Wilcoxon matched pairs tests (RPE)., Results: None of the three warm-up protocols had significant effects on muscle activity levels (P ≥ 0.10). Performance quality did not significantly increase (P ≥ 0.21). RPE significantly decreased (P < 0.05) after warm-up for each of the three experimental warm-ups; control condition RPE did not significantly decrease (P > 0.23)., Conclusion: Acute physiological and musical benefits from cardiovascular, core muscle, and musical warm-ups in skilled violinists are limited to decreases in RPE. This investigation provides data from the performing arts in support of sports medical evidence suggesting that warm-up only effectively enhances maximal strength and power performance.

Study Design: Observational laboratory study., Background: Abduction is a movement commonly used in the assessment of shoulder dysfunction and prescription of exercises to improve shoulder function. Abduction in the scapular and coronal planes are used interchangeably. It is not known if the activation of individual shoulder muscles differ between abduction performed in these planes and therefore, if they represent different tests/exercises., Objective: To quantify and compare the muscle activation patterns and levels for each shoulder muscle during abduction performed in the scapular plane with that performed in the coronal (scapular -30°) and scapular +30° planes., Methods: Electromyographic recordings were taken from eight shoulder muscles of fourteen healthy volunteers during shoulder abduction in the scapular and coronal planes and in a plane 30° anterior to the scapular plane (scapular +30°) at 50% of maximum load., Results: Similar average muscle activation levels were demonstrated during abduction in the scapular plane and within a 30° arc of this plane for all muscles except: middle deltoid (5% MVC higher activation in the coronal and 4% MVC lower activation in the scapular +30° plane) and upper trapezius (6% MVC lower activation in the scapular +30° plane). Activation patterns between planes for all muscles were similar (ICC(3,1) ≥ 0.87)., Conclusions: Abduction can be performed within a 30° arc of the scapular plane with no change in shoulder muscle activation patterns. Only middle deltoid activation levels change between the scapular and coronal planes and middle deltoid and upper trapezius between the scapular and scapular +30° planes., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Because of its superficial location surface electrodes are commonly used to record latissimus dorsi (LD) activity. Despite the fact that the recommended electrode placement is over the belly where LD is quite thin no studies have investigated the possibility of signal contamination from muscles lying deep to LD. Therefore, the aim of this study was to determine the validity of using surface electrodes to record activity from LD. Eight asymptomatic subjects performed ramped isometric (0-100% maximum load) and dynamic (70% maximum load) shoulder tasks. Intramuscular electrodes were inserted into LD and the adjacent erector spinae. Surface electrodes were placed over LD around the intramuscular electrodes. Results indicated that while there was no difference in activity level or activation pattern (ICC>0.94) recorded by the two electrode types during shoulder tasks in which LD would be expected to be active (extension and adduction), significantly lower (p<0.05) LD activity was recorded via intramuscular electrodes during the shoulder flexion and abduction tasks. Therefore, recordings of LD activity by surface electrodes overestimate LD activity during shoulder tasks when this muscle would be expected to be activated at minimum levels. Erector spinae immediately deep to LD was confirmed as a source of crosstalk contamination., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Most previous studies of associated reactions (ARs) in people with cerebral palsy have used observation scales, such as recording the degree of movement through observation. The sensitive quantitative method can detect ARs that are not amply visible. The aim of this study was to provide quantitative measures of ARs during a visual pursuit position tracking task. Twenty-three hemiplegia (H) (mean +/- SD: 21y 8m +/- 11y 10m), twelve quadriplegia (Q) (21y 5m +/- 10y 3m) and twenty-two subjects with normal development (N) (21y 2m +/- 10y 10m) participated in the study. An upper limb visual pursuit tracking task was used to study ARs. The participants were required to follow a moving target with a response cursor via elbow flexion and extension movements. The occurrence of ARs was quantified by the overall coherence between the movements of tracking and non-tracking limbs and the amount of movement due to ARs was quantified by the amplitude of movement the non-tracking limbs. The amplitude of movement of the non-tracking limb indicated that the amount of ARs was larger in the Q group than the H and N groups with no significant differences between the H and N groups. The amplitude of movement of the non-tracking limb was larger during non-dominant than dominant tracking in all three groups. Some movements in the non-tracking limb were correlated with the tracking limb (correlated ARs) and some movements that were not correlated with the tracking limb (uncorrelated ARs). The correlated ARs comprised less than 40% of the total ARs for all three groups. Correlated ARs were negatively associated with clinical evaluations, but not the uncorrelated ARs. The correlated and uncorrelated ARs appear to have different relationships with clinical evaluations, implying the effect of ARs on upper limb activities could be varied.

The sleep-wake cycle is a process not only dictated by homeostatic and circadian factors but also by social and environmental influences. Thus, the total sleep time partly reflects sleep need, which is integral to the dynamics of sleep loss recovery. This study explored the nature of the observed oscillations in total sleep time in healthy adults under spontaneous living conditions. Actigraph-measured sleep data for 13 healthy young male adults were collected over 14 consecutive days and analyzed for habitual sleep duration. The total sleep time periodicity was modeled using the cosinor method for each individual across the 14 days. The findings confirm the existence of periodicity in habitual sleep duration as there were clear periodic patterns in the majority of the participants. Although exclusive to each individual, the observed oscillations may be a resultant response of homeostatic sleep need, circadian timing, and/or social and environmental influences. These findings instigate further indepth studies into the periodicity of sleep duration in healthy individuals to provide a better understanding of sleep need in short versus long sleepers, in predicting work performance, and reducing sleepiness-related accidents following shift work, and how this periodicity may impact sleep treatment outcome in clinical populations.

In quantitative gait analysis, two types of variability of kinematic waveforms with identifiably different sources may be distinguished: variability of the offset values (mean or DC values) of the waveforms and variability of the waveform patterns. Offset variability is influenced by the repeatability of the motor performance as well as by additional factors related to reliability and errors of measurement, such as individual differences in the mean posture chosen for the performance and factors related to the definition and measurement of the reference position for each angle. All of these factors may have a considerable effect on the coefficient of variation, a measure that is commonly employed to assess kinematic variability. Waveform pattern variability, in contrast, is more manifestly determined by the repeatability of the motor performance and is less subject to factors related to offset value. Hence, we propose that offset variability and pattern variability be evaluated separately and outline an approach to accomplish this by first removing the mean value of raw kinematic waveforms before averaging across trials or subjects. Independent measurement of pattern variability and offset variability is shown to yield values that are markedly different from the traditional coefficient of variation, which reflects all sources of variability in a single measure. The benefit of the procedures proposed here is that they help to differentiate among largely independent causes of variability of kinematic waveforms and to quantify their relative magnitudes. By way of illustration, in a group of subjects with low-arched feet, where waveform offsets are of particular interest, midfoot and ankle rotation angles showed smaller pattern variability and larger offset variability than normal.