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Patterns of load-sharing between the shoulder muscles during isometric flexion tasks were studied by using both a biomechanical shoulder model and electromyographic (EMG) recordings of ten subjects. The effect of changes in several model parameters and shoulder stiffness constraints on the predicted load-sharing patterns were studied, while the arm(More)
Our aim was to study whether the myoelectric signals can be better modelled as outputs of a nonlinear dynamic system rather than as random stochastic signals. Both the nonlinear predictability and the dimensionality of the signals were studied using methods of nonlinear dynamics. The signals were measured from the biceps brachii muscle during both fatiguing(More)
The validity of the 'Portable Ergonomic Observation' method (PEO) was investigated against posture measurements based on continuous optoelectronic and video recordings made simultaneously with the observation. Work postures and actions during different frequently changing tasks were analyzed using both methods. In general, a high agreement between measured(More)
Linear and curvilinear electromyogram (EMG) normalization methods were compared among ten healthy men during a simulated work cycle demanding attention and static holding of the arm ('Solitaire test'). Maximal voluntary contractions (MVC) and gradually increasing contractions up to 70% of MVC were used for normalization in different arm postures. The test(More)
A static shoulder model including a novel muscular synergy principle for computing load sharing between the shoulder muscles is presented. This principle is feasible especially when analysing endurance-type activities. According to the principle, time elapsed from the start of the activity decreases the allowable muscle stress levels on the basis of the(More)
The objective of this study was to compare the effects of using a forearm or wrist support on muscular load in the forearm and neck–shoulder region during work with a computer mouse. Fourteen 35-to 50-year-old healthy women who worked with a video display unit for at least 4 hr a day in an office and who also used a computer mouse for at least 2 hr a day(More)
BACKGROUND Different types of exercises can help manage chronic neck pain. Supervised exercise interventions are widely used, but these protocols require substantial resources. The aim of this trial, which focused on adherence, was to evaluate two home exercise interventions. METHODS This parallel group randomized controlled trial included 57 women(More)
UNLABELLED Surface electromyography (EMG) is commonly used to study the loading of the forearm. Pro-supination movements cause surface electrodes to move in relation to the underlying muscles. We studied the effects of different electrode locations and forearm postures on the association between the EMG signals and external hand load in a laboratory(More)