Zoekresultaten

The effect of work pace on workload, motor variability and fatigue during simulated light assembly work

This study investigated the effect of work pace on workload, motor variability and fatigue during light assembly work. Upper extremity kinematics and electromyography (EMG) were obtained on a cycle-to-cycle basis for eight participants during two conditions, corresponding to "normal" and "high" work pace according to a predetermined time system for engineering. Indicators of fatigue, pain sensitivity and performance were recorded before, during and after the task. The level and variability of muscle activity did not differ according to work pace, and manifestations of muscle fatigue or changed pain sensitivity were not observed. In the high work pace, however, participants moved more efficiently, they showed more variability in wrist speed and acceleration, but they also made more errors. These results suggest that an increased work pace, within the range addressed here, will not have any substantial adverse effects on acute motor performance and fatigue in light, cyclic assembly work.STATEMENT OF RELEVANCE: In the manufacturing industry, work pace is a key issue in production system design and hence of interest to ergonomists as well as engineers. In this laboratory study, increasing the work pace did not show adverse effects in terms of biomechanical exposures and muscle fatigue, but it did lead to more errors. For the industrial engineer, this observation suggests that an increase in work pace might diminish production quality, even without any noticeable fatigue being experienced by the operators.

Feasibility of muscle activity assessment with surface electromyography during bed cycling exercise in intensive care unit patients

Cervical dystonia: Disability and the value of physical therapy

Cervical dystonia (CD) is a neurological movement disorder characterized by involuntary muscle contractions causing abnormal postures and/or twisting movements of the head and neck.Patients may also experience non-motor symptoms including pain, anxiety and depression. The main treatment option is botulinum toxin (BoNT) injections in affected muscles to improve head postures and reduce pain. In addition to BoNT treatment, patients are often referred for physical therapy (PT), but there is little evidence regarding the long-term effectiveness.Despite remarkable improvements during the last decades, there are still many unmet needs that remain open in the treatment of cervical dystonia (CD). The first goal of this thesis was to assess clinical issues in BoNT treatment that need further improvement and to define clinical recommendations for clinicians. The second goal was to explore which determinants play an important role in disability of CD patients and the third goal was to develop a specialized PT program and to evaluate its effects on disability.Results showed that BoNT treatment can be further improved despite all the evidence for its effectiveness. Further research is needed towards optimal treatment intervals, dose equivalence between different BoNT formulations, the use of supportive techniques like electromyography or ultrasound and managing side effects. Secondly, we found that psychological factors are important determinants of disability. Finally, we found that PT is a valuable addition to BoNT treatment to improve disability and pain. Based on these findings, a multidisciplinary treatment approach to further improve the treatment and quality of life for CD patients is recommended.

Clinical practice: evidence-based recommendations for the treatment of Cervical Dystonia with Botulinum Toxin

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.

Responses in knee joint muscle activation patterns to different perturbations during gait in healthy subjects

PURPOSE: To compare the responses in knee joint muscle activation patterns to different perturbations during gait in healthy subjects.SCOPE: Nine healthy participants were subjected to perturbed walking on a split-belt treadmill. Four perturbation types were applied, each at five intensities. The activations of seven muscles surrounding the knee were measured using surface EMG. The responses in muscle activation were expressed by calculating mean, peak, co-contraction (CCI) and perturbation responses (PR) values. PR captures the responses relative to unperturbed gait. Statistical parametric mapping analysis was used to compare the muscle activation patterns between conditions.RESULTS: Perturbations evoked only small responses in muscle activation, though higher perturbation intensities yielded a higher mean activation in five muscles, as well as higher PR. Different types of perturbation led to different responses in the rectus femoris, medial gastrocnemius and lateral gastrocnemius. The participants had lower CCI just before perturbation compared to the same phase of unperturbed gait.CONCLUSIONS: Healthy participants respond to different perturbations during gait with small adaptations in their knee joint muscle activation patterns. This study provides insights in how the muscles are activated to stabilize the knee when challenged. Furthermore it could guide future studies in determining aberrant muscle activation in patients with knee disorders.

Objective parameters to measure (in)stability of the knee joint during gait

BACKGROUND: Instability of the knee joint during gait is frequently reported by patients with knee osteoarthritis or an anterior cruciate ligament rupture. The assessment of instability in clinical practice and clinical research studies mainly relies on self-reporting. Alternatively, parameters measured with gait analysis have been explored as suitable objective indicators of dynamic knee (in)stability.RESEARCH QUESTION: This literature review aimed to establish an inventory of objective parameters of knee stability during gait.METHODS: Five electronic databases (Pubmed, Embase, Cochrane, Cinahl and SPORTDiscuss) were systematically searched, with keywords concerning knee, stability and gait. Eligible studies used an objective parameter(s) to assess knee (in)stability during gait, being stated in the introduction or methods section. Out of 10717 studies, 89 studies were considered eligible.RESULTS: Fourteen different patient populations were investigated with kinematic, kinetic and/or electromyography measurements during (challenged) gait. Thirty-three possible objective parameters were identified for knee stability, of which the majority was based on kinematic (14 parameters) or electromyography (12 parameters) measurements. Thirty-nine studies used challenged gait (i.e. external perturbations, downhill walking) to provoke knee joint instability. Limited or conflicting results were reported on the validity of the 33 parameters.SIGNIFICANCE: In conclusion, a large number of different candidates for an objective knee stability gait parameter were found in literature, all without compelling evidence. A clear conceptual definition for dynamic knee joint stability is lacking, for which we suggest : "The capacity to respond to a challenge during gait within the natural boundaries of the knee". Furthermore biomechanical gait laboratory protocols should be harmonized, to enable future developments on clinically relevant measure(s) of knee stability during gait.