effect size was more than three times larger in the slackline. The SOM analysis, followed by a k-means clustering and marginal homogeneity test, showed that the balance coordination pattern was significantly different between pre-and post-test for the slackline task only (χ 2 = 82.247; p < 0.001). The shift in balance coordination on the slackline could be characterized by an increase in range of motion and a decrease in velocity and frequency in nearly all degrees of freedom simultaneously. The observation of low transfer of coordination strategies to the flamingo task adds further evidence for the task-specificity principle of balance training, meaning that slackline training alone will be insufficient to increase postural control in other challenging situations.

In this study, three-dimensional kinematics and performance were analyzed for male and female top level and junior elite volleyball players in a spike, which is an essential offensive volleyball action. Top level players had higher impact speeds and jumping height than junior elite players for both genders and the male players had higher impact speeds and jumping height than the female players for both levels of expertise. For the analysis of the three-dimensional kinematics of the pelvis, trunk, shoulder and elbow angles and angular velocities, Statistical Parametric Mapping was used. No differences were observed for the orientation angles of pelvis and trunk, indicating a set of invariant kinematics. The pelvis and trunk angular velocities on the other hand did show many interesting differences throughout the approach, cocking and acceleration phase of the spike. The shoulder and elbow angles and angular velocities also illustrated the different strategies used for generating high impact speeds. An important conclusion was that interaction effects between gender and level of expertise were mostly observed in variables from the shoulder and elbow, whereas pelvis and trunk velocities only presented significant main effects. These differences suggest how the motion pattern of the young elite athletes will change over the following years when they gradually make the change towards the highest competitive levels.

Specificity (SP) and sensitivity (SE) answer the question ‘what is the chance of a positive or negative test in response to the presence or absence of a clinical condition?’. Related to SP and SE are the diagnostic procedures of SNOUT and SPIN. SNOUT is the acronym for ‘Sensitive test when Negative rules OUT the disease’, SPIN for, ‘Specific test when Positive rules IN the disease’. SE and SP are incomplete because for clinical diagnosis, the question of concern should actually be: ‘what is the chance that the clinical condition will be present or absent in the context of a positive or negative test result?’. The latter statement is related to the concepts of Positive and Negative Predictive Value (PPV and NPV). However, PPV and NPV are predictive values not only dependent on SE and SP but also largely dependent on the prevalence in the examined population. Consequently, predictive values from one study should not be transferred to some other setting with a different prevalence. Prevalence affects PPV and NPV differently. PPV is increasing, while NPV decreases with the increase of the prevalence. This makes prevalence the nemesis in the application of the predictive values. Therefore, another variable has been introduced to evaluate the strength of a diagnostic test, namely the likelihood ratio. Likelihood ratios determine how much more likely a particular test result is among people who have the clinical condition of interest than it is among people who do not have the condition. LIKELIHOOD RATIO (LR) is the ratio of two probabilities. This letter illustrates the limitations of the concepts of SE, SP, NPV, PPV and the LRs in context of specific shoulder tests.

Shoulder exoskeletons potentially reduce overuse injuries in industrial settings including overhead work or lifting tasks. Previous studies evaluated these devices primarily in laboratory setting, but evidence of their effectiveness outside the lab is lacking. The present study aimed to evaluate the effectiveness of two passive shoulder exoskeletons and explore the transfer of laboratory-based results to the field. Four industrial workers performed controlled and in-field evaluations without and with two exoskeletons, ShoulderX and Skelex in a randomized order. The exoskeletons decreased upper trapezius activity (up to 46%) and heart rate in isolated tasks. In the field, the effects of both exoskeletons were less prominent (up to 26% upper trapezius activity reduction) while lifting windscreens weighing 13.1 and 17.0 kg. ShoulderX received high discomfort scores in the shoulder region and usability of both exoskeletons was moderate. Overall, both exoskeletons positively affected the isolated tasks, but in the field the support of both exoskeletons was limited. Skelex, which performed worse in the isolated tasks compared to ShoulderX, seemed to provide the most support during the in-field situations. Exoskeleton interface improvements are required to improve comfort and usability. Laboratorybased evaluations of exoskeletons should be interpreted with caution, since the effect of an exoskeleton is task Manuscript

Objective Over the course of the twenty-first century, work-related musculoskeletal disorders are still persisting among blue collar workers. At present, no epidemiological overview exists. Therefore, a systematic review and meta-analysis was performed on the epidemiology of work-related musculoskeletal disorders (WMSD) within Europe’s secondary industries. Methods Five databases were screened, yielding 34 studies for the qualitative analysis and 17 for the quantitative analysis. Twelve subgroups of WMSDs were obtained for the meta-analysis by means of predefined inclusion criteria: back (overall), upper back, lower back, neck, shoulder, neck/shoulder, elbow, wrist/hand, leg (overall), hip, knee, and ankle/feet. Results The most prevalent WMSDs were located at the back (overall), shoulder/neck, neck, shoulder, lower back and wrist WMSDs with mean 12-month prevalence values of 60, 54, 51, 50, 47, and 42%, respectively. The food industry was in the majority of subgroups the most prominent researched sector and was frequently associated with high prevalence values of WMSDs. Incidence ratios of upper limb WMSDs ranged between 0.04 and 0.26. Incidence ratios could not be calculated for other anatomical regions due to the lack of sufficient articles. Conclusion WMSDs are still highly present among blue collar workers. Relatively high prevalence values and low incidence ratios indicate a limited onset of WMSDs with however long-term complaints.