This study investigated temporal changes in movement strategy and performance during fatiguing short-cycle work. Eighteen participants performed six 7-min work blocks with repetitive reaching movements at 0.5 Hz, each followed by a 5.5-min rest break for a total duration of 1 h. Electromyography (EMG) was collected continuously from the upper trapezius muscle, the temporal movement strategy and timing errors were obtained on a cycle-to-cycle basis, and perceived fatigue was rated before and after each work block. Clear signs of fatigue according to subjective ratings and EMG manifestations developed within each work block, as well as during the entire hour. For most participants, timing errors gradually increased, as did the waiting time at the near target. Changes in temporal movement strategy were negatively correlated with changes in the level and variability of EMG, suggesting that an adaptive temporal strategy offset the development of unstable motor solutions in this fatiguing, short-cycle work.Practitioner Summary: Sustained performance of operators is essential to maintain competitiveness. In this study of repetitive work, participants gradually changed their temporal movement strategy, for possibly alleviating the effects of fatigue. This suggests that in order to effectively counteract fatigue and sustain performance, industrial production should allow extensive spatial and temporal flexibility.
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Background: Currently, the Ponseti method is the gold standard for treatment of clubfeet. For long-term func- tional evaluation of this method, gait analysis can be performed. Previous studies have assessed gait differences between Ponseti treated clubfeet and healthy controls. Research question/purpose: The aims of this systematic review were to compare the gait kinetics of Ponseti treated clubfeet with healthy controls and to compare the gait kinetics between clubfoot patients treated with the Ponseti method or surgically. Methods: A systematic search was performed in Embase, Medline Ovid, Web of Science, Scopus, Cochrane, Cinahl ebsco, and Google scholar, for studies reporting on gait kinetics in children with clubfeet treated with the Ponseti method. Studies were excluded if they only used EMG or pedobarography. Data were extracted and a risk of bias was assessed. Meta-analyses and qualitative analyses were performed. Results: Nine studies were included, of which five were included in the meta-analyses. The meta-analyses showed that ankle plantarflexor moment (95% CI -0.25 to -0.19) and ankle power (95% CI -0.89 to -0.60, were significantly lower in the Ponseti treated clubfeet compared to the healthy controls. No significant difference was found in ankle dorsiflexor and plantarflexor moment, and ankle power between clubfeet treated with surgery compared to the Ponseti method. Significance: Differences in gait kinetics are present when comparing Ponseti treated clubfeet with healthy controls. However, there is no significant difference between surgically and Ponseti treated clubfeet. These results give more insight in the possibilities of improving the gait pattern of patients treated for clubfeet.
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Meer politieke aandacht voor verduurzaming van bedrijventerreinen is onmisbaar voor het dichterbij halen van de klimaatdoelstellingen.
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The paper discusses the results of a case study on the effect of players' facial responses when playing a casual game. In order to do so, it measures the facial responses in casual games by recording facial EMG and analyzing players' facial expressions using FACS. It investigates which one of the two measurements is more effective to measure emotional responses in casual games. The results of this case study show that playing a casual game causes the players to respond with both facial expressions and facial EMG activity and that both measurements are needed in order to get a good understanding of the players' emotional responses to casual game events.
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PURPOSE: We hypothesized that the initial rate (first 40 ms) of unilateral knee extensor torque development during a maximally fast isometric contraction would depend on the subjects' ability for fast neural activation and that it would predict bilateral jumping performance. METHODS: Nine males (21.8 +/- 0.9 yr, means +/- SD) performed unilateral fast isometric knee extensions (120 degrees knee angle) without countermovement on a dynamometer and bilateral squat jumps (SJ) and countermovement jumps (CMJ) starting from 90 and 120 degrees knee angles (full extension = 180 degrees ). The dynamometer contractions started either from full relaxation or from an isometric pre-tension (15% maximal isometric torque, Tmax). Torque time integral for the first 40 ms after torque onset (TTI-40, normalized to Tmax) and averaged normalized rectified knee extensor EMG for 40 ms before fast torque onset (EMG-40) were used to quantify initial torque rise and voluntary muscle activation. RESULTS: TTI-40 without pre-tension (range: 0.02-0.19% Tmax per second) was significantly lower than TTI-40 with pre-tension, and both were significantly (r = 0.81 and 0.80) related to EMG-40. During jumping, similar significant positive relations were found between jump height and knee extensor EMG during the first 100 ms of the rise in ground reaction force. There also were significant positive linear relations between dynamometer TTI-40 and jump height (r = 0.75 (SJ 90), 0.84 (SJ 120), 0.76 (CMJ 90), and 0.86 (CMJ 120)) but not between dynamometer Tmax and jump height (-0.16 < r < 0.02). CONCLUSION: One-legged TTI-40 to a large extent explained the variation in jump height. The ability to produce a high efferent neural drive before muscle contraction seemed to dominate performance in both the simple single-joint isometric task and the complex multijoint dynamic task.
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In het onderwijs hoeven we niet terug naar het oude ‘normaal’. Een mix van digitaal en offline onderwijs (blended leren) heeft juist veel te bieden. Het blended onderwijs is sinds de Covid-19-pandemie in een stroomversnelling gekomen. Tijdens de tweede lockdown hebben docenten meer ideeën en geven ze hun onderwijs vorm op basis van de kennis uit de eerste lockdown. De lockdown heeft in die zin veel goeds gebracht: de kracht van blended leren kwam onder de aandacht. We hebben gezien dat online en offline samen meer kunnen opleveren. Meer en beter leren voor docent en student.
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Dit artikel ligt momenteel ter beoordeling bij een reviewer van het European Journal of Sport Sciences.
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Interview met Menno van Duin. Bumperkleven, afsnijden op de snelweg, middelvinger opsteken, spugen, boeren, schelden, rommel op straat dumpen of de hond op de stoep laten poepen. Niet netjes. Maar onder invloed van de mensen om ons heen dreigen we zelf soms ook mee te doen aan hufterig gedrag Full text niet op zondag beschikbaar
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UNLABELLED: Reaching movements are initiated by activity of the prime mover, i.e. the first activated arm muscle. We aimed to investigate the relationship between prime mover activity and kinematics of reaching in typically developing (TD) infants in supine and sitting position. Fourteen infants were assessed at 4 and 6 months during reaching in supine and supported sitting. Kinematics and EMG-activity of deltoid, pectoralis major, biceps (BB) and triceps brachii were recorded. Kinematic analysis focused on number of movement units (MUs) and transport MU (MU with longest duration). Prime mover use was variable, but at 6 months a dominance of BB emerged in both testing conditions. Kinematics were also variable, but with increasing age the number of MU decreased and the relative proportion of the transport MU increased. BB as prime mover at 6 months was related to a larger transport MU.CONCLUSION: Between 4 and 6 months BB prime mover dominance emerges which is related to relatively efficient reaching characteristics.
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Cervical dystonia is the most frequent form of focal dystonia. Symptoms often result in pain and functional disability. Local injections of botulinum neurotoxin are currently the treatment of choice for cervical dystonia. Although this treatment has proven effective and is widely applied worldwide, many issues still remain open in the clinical practice. We performed a systematic review of the literature on botulinum toxin treatment for cervical dystonia based on a question-oriented approach, with the aim to provide practical recommendations for the treating clinicians. Key-questions from the clinical practice were explored. Results suggest that while the beneficial effect of botulinum toxin treatment on different aspects of cervical dystonia is well established, robust evidence is still missing concerning some practical aspects, such as doseequivalence between different formulations, optimal treatment intervals, treatment approaches, and the use of supportive techniques including electromyography (EMG) or ultrasounds. Established strategies to prevent or manage common side effects (including excessive muscle weakness, pain at injection site, dysphagia) and potential contraindications to this treatment (pregnancy and lactation, use of anticoagulants, neurological comorbidities) should also be further explored.
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