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Institute
Transcranial alternating-current stimulation (tACS) in the frequency range of 1–100 Hz has come to be used routinely in electroencephalogram (EEG) studies of brain function through entrainment of neuronal oscillations. It turned out, however, to be highly non-trivial to remove the strong stimulation signal, including its harmonic and non-harmonic distortions, as well as various induced higher-order artifacts from the EEG data recorded during the stimulation. In this paper, we discuss some of the problems encountered and present methodological approaches aimed at overcoming them. To illustrate the mechanisms of artifact induction and the proposed removal strategies, we use data obtained with the help of a schematic demonstrator setup as well as human-subject data.
In the application of range of motion (ROM) tests there is little agreement on the number of repetitions to be measured and the number of preceding warm-up protocols. In stretch training a plateau in ROM gains can be seen after four to five repetitions. With increasing number of repetitions, the gain in ROM is reduced. This study examines the question of whether such an effect occurs in common ROM tests. Twenty-two healthy sport students (10 m/12 f.) with an average age of 25.3 ± 1.94 years (average height 174.1 ± 9.8 cm; weight 66.6 ± 11.3 kg and BMI 21.9 ± 2.0 kg/cm2) volunteered in this study. Each subject performed five ROM tests in a randomized order—measured either via a tape measure or a digital inclinometer: Tape measure was used to evaluate the Fingertip-to-Floor test (FtF) and the Lateral Inclination test (LI). Retroflexion of the trunk modified after Janda (RF), Thomas test (TT) and a Shoulder test modified after Janda (ST) were evaluated with a digital inclinometer. In order to show general acute effects within 20 repetitions we performed ANOVA/Friedman-test with multiple comparisons. A non-linear regression was then performed to identify a plateau formation. Significance level was set at 5%. In seven out of eight ROM tests (five tests in total with three tests measured both left and right sides) significant flexibility gains were observed (FtF: p < 0.001; LI-left/right: p < 0.001/0.001; RF: p = 0.009; ST-left/right: p < 0.001/p = 0.003; TT-left: p < 0.001). A non-linear regression with random effects was successfully applied on FtF, RF, LI-left/right, ST-left and TT-left and thus, indicate a gradual decline in the amount of gained ROM. An acute effect was observed in most ROM tests, which is characterized by a gradual decline of ROM gain. For those tests, we can state that the acute effect described in the stretching literature also applies to the performance of typical ROM tests. Since a non-linear behavior was shown, it is the decision of the practitioner to weigh up between measurement accuracy and expenditure. Researchers and practitioners should consider this when applying ROM assessments to healthy young adults.
Background: Running is a popular sport with high injury rates. Although risk factors have intensively been investigated, synthesized knowledge about the differences in injury rates of female and male runners is scarce. Objective: To systematically investigate the differences in injury rates and characteristics between female and male runners. Methods: Database searches (PubMed, Web of Science, PEDro, SPORTDiscus) were conducted according to PRISMA guidelines using the keywords “running AND injur*”. Prospective studies reporting running related injury rates for both sexes were included. A random-effects meta-analysis was used to pool the risk ratios (RR) for the occurrence of injuries in female vs. male runners. Potential moderators (effect modifiers) were analysed using meta-regression. Results: After removal of duplicates, 12,215 articles were screened. Thirty-eight studies were included and the OR of 31 could be pooled in the quantitative analysis. The overall injury rate was 20.8 (95% CI 19.9–21.7) injuries per 100 female runners and 20.4 (95% CI 19.7–21.1) injuries per 100 male runners. Meta-analysis revealed no differences between sexes for overall injuries reported per 100 runners (RR 0.99, 95% CI 0.90–1.10, n = 24) and per hours or athlete exposure (RR 0.94, 95% CI 0.69–1.27, n = 6). Female sex was associated with a more frequent occurrence of bone stress injury (RR (for males) 0.52, 95% CI 0.36–0.76, n = 5) while male runners had higher risk for Achilles tendinopathies (RR 1. 86, 95% CI 1.25–2.79, n = 2). Meta-regression showed an association between a higher injury risk and competition distances of 10 km and shorter in female runners (RR 1.08, 95% CI 1.00–1.69). Conclusion: Differences between female and male runners in specific injury diagnoses should be considered in the development of individualised and sex-specific prevention and rehabilitation strategies to manage running-related injuries.
Individual differences in general cognitive ability (i.e., intelligence) have been linked to individual variations in the modular organization of functional brain networks. However, these analyses have been limited to static (time-averaged) connectivity, and have not yet addressed whether dynamic changes in the configuration of brain networks relate to general intelligence. Here, we used multiband functional MRI resting-state data (N = 281) and estimated subject-specific time-varying functional connectivity networks. Modularity optimization was applied to determine individual time-variant module partitions and to assess fluctuations in modularity across time. We show that higher intelligence, indexed by an established composite measure, the Wechsler Abbreviated Scale of Intelligence (WASI), is associated with higher temporal stability (lower temporal variability) of brain network modularity. Post-hoc analyses reveal that subjects with higher intelligence scores engage in fewer periods of extremely high modularity — which are characterized by greater disconnection of task-positive from task-negative networks. Further, we show that brain regions of the dorsal attention network contribute most to the observed effect. In sum, our study suggests that investigating the temporal dynamics of functional brain network topology contributes to our understanding of the neural bases of general cognitive abilities.
Background: Handball referees play an important role during a handball match. Surprisingly, not much is known about their sports-related injuries and resulting pain, therefore the purpose of our study was to focus on injuries and sports-related pain in referees in German handball leagues. Methods: During the 2018/19 national German handball season, referees of the German Federation of Handball (DHB) were contacted and asked to complete an injury and pain questionnaire on the penultimate matchday of the first and the second round of the season. Results: Seventy referees participated in the study. One in three referees reported an injury during the last year and perceived some form of pain. Of those suffering from pain, 16.7% referees reported chronic pain disorders. During the season, 31.4% of referees incurred an injury and the majority of the 70 referees officiated despite pain (n = 43). Prospectively-enrolled data suggested an incidence of 11.6 (95% CI: 10.3 to 13.0) injuries per 1000 match hours, and 19.0 (95% CI: 16.8 to 21.3) sports-related pain events per 1000 match hours. The most common injuries were foot and knee injuries and a substantial number of the referees (n = 25) reported taking analgesics for the pain. Conclusion: German handball referees are at risk of sports-related injuries with subsequent pain. Considering the injury profile, the incidence of sports-related pain events, and the high physiological demands of refereeing, it appears that prevention programs should be developed and integrated into the routine of the referee.
With our research, we contribute to the research on proactive work behavior in two ways. First, we examine a person's gender as a boundary condition for proactive behavior at work. Based on social role theory, we argue that women are less likely to receive credit for showing personal initiative (PI) than men. Second, we examine agency and communion as underlying mechanisms that translate PI into a person's evaluation and drive backlash effects. The hypotheses were tested in two complementary experimental studies (Study 1; N = 114, Study 2: N = 163) using simulated job interviews. Our results show that PI relates to better evaluations (likeability, perceived competence, performance evaluations, expected success and hireability) of the job applicant and that these effects are mediated by agency and communion. Further, we find backlash effects for women high in agency and men high in communion on likeability (Study 2). The implications of these results for organizations and future research are discussed.
The papers in this Special Issue Part I “Revisioning, Rethinking, Restructuring Gender at Work: Quo Vadis Gender Stereotypes?” focus on the current state of gender inequality, particularly stereotypes. We present studies showing that differences in gender stereotypes still exist, confirm disadvantages for women in male-dominated roles and sectors and when the employment sector is not specified, but also disadvantages for men in female-dominated roles and sectors. In contrast to this general trend, one paper in Part II of this Special Issue found a preference for women over men as job candidates in their study. Incongruence emerged as a striking common theme to explain these gender differences, whereby some studies focused on the perceived incongruence from the actor's perspective and how external factors contribute to these perceptions, whereas others looked at the perceived incongruence from the observer's perspective. We summarize the papers and briefly discuss the key points of Part I at the end of this editorial.
Based on stereotype threat and stereotype lift theory, this study explores implicit stereotype threat effects of gender stereotypes on the performance of primary school children in mathematics. Moreover, effects of implicit gender stereotypical cues (gender-specific task material) on motivational aspects were explored, which have revealed mixed results in stereotype threat research in the past. N = 151 German primary school children (47.7% female; mean age: M = 9.81, SD = 0.60) calculated either stereotypical or neutral mathematical text problems before motivational aspects were assessed. Contradicting our expectations, results neither revealed a stereotype threat effect on girls’ performance nor a lift effect on the boys. Instead, girls calculating stereotypical tasks outperformed girls in the control group, whereas boys’ performance did not significantly differ compared to the control group. Regarding motivational aspects, only traditional gender differences emerged as girls reported significantly more pressure and tension calculating the mathematical tasks. The discussion focuses on the way in which stereotypes can affect children’s cognitive performance and in turn, their mathematical performance.
Background: Hebb repetition learning is a form of long-term serial order learning that can occur when sequences of items in an immediate serial recall task are repeated. Repetition improves performance because of the gradual integration of serial order information from short-term memory into a more stable long-term memory trace.
Aims: The current study assessed whether adolescents with non-specific intellectual disabilities showed Hebb repetition effects, and if their magnitude was equivalent to those of children with typical development, matched for mental age.
Methods: Two immediate serial recall Hebb repetition learning tasks using verbal and visuospatial materials were presented to 47 adolescents with intellectual disabilities (11–15 years) and 47 individually mental age-matched children with typical development (4–10 years).
Results: Both groups showed Hebb repetition learning effects of similar magnitude, albeit with some reservations. Evidence for Hebb repetition learning was found for both verbal and visuospatial materials; for our measure of Hebb learning the effects were larger for verbal than visuospatial materials.
Conclusions: The findings suggested that adolescents with intellectual disabilities may show implicit long-term serial-order learning broadly commensurate with mental age level. The benefits of using repetition in educational contexts for adolescents with intellectual disabilities are considered.
Based on the stressor-detachment model, previous research has assumed that work-related ICT use in the evening impairs psychological detachment. However, since most of the studies to date have assessed cross-sectional relationships, little is known about the actual direction of effects. In this 5-day diary study, we implemented a day-level longitudinal model to shed light on the causal relationships between work-related ICT use, detachment, and task progress (N = 340 employees, N = 1289 day-level cases). We also investigated the role of unfinished work tasks because we assumed, based on boundary theory, that they are a driving force leading to impaired detachment and work-related ICT use in the evening. Contrary to current research consensus but in line with our expectations, we found that low psychological detachment increased work-related ICT use and task progress. We found no evidence for reversed lagged effects. These results applied both to planned and unplanned ICT use. Furthermore, our results support the notion that unfinished work tasks precede ICT use and detachment. Thus, our findings suggest that work-related ICT use should not be treated as a stressor in its own right in the stressor-detachment model. Instead, it needs to be investigated as a behavioral outcome that employees engage in when they cannot detach from work.