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Previous studies have shown that postural orientations of the neck, such as flexed or forward head postures, are associated with heightened activity of the dorsal neck muscles. While these studies describe the impact of variations in neck posture alone, there is scant literature regarding the effect of neck posture on muscle activity when combined with upper limb activities such as lifting. The purpose of this study was to evaluate the effect of three different neck postures on the activity of the different layers of the dorsal neck muscles during a lifting task. Ultrasound measurements of dorsal neck muscle deformation were compared over two time points (rest, during lift) during a lifting task performed in three different neck postural conditions (neutral, flexed and forward head posture) in 21 healthy subjects. Data were analysed by post-process speckle tracking analysis. Results demonstrated significantly greater muscle deformation induced by flexed and forward head postures, compared to the neutral posture, for all dorsal neck muscles at rest (p

The aim of the study was to analyse values of the maximal forces of pushing, lifting, handgrip and torques of pronation and supination as well as to develop predictive equations expressing maximal force in relation to upper limb posture for four upper limb activities (pushing, lifting, pronation and supination). Twelve right-hand dominant men participated in the experimental study. All of them were healthy and had no history of hand dysfunction. They exerted maximal forces of the above-mentioned five different upper limb activities in 24 upper limb postures. Each upper limb posture was defined by seven angles. The analysis showed an influence of each of the seven angles on the exerted force. On the basis of the measurements obtained in the experimental study, predictive equations of the maximal force of pushing and lifting as well as torques of pronation and supination, in relation to the seven angles defining upper limb posture, were established. They make it possible to calculate maximal forces or torques in relation to upper limb posture and the type of upper limb activity. They can help designers in designing a workplace and therapists in measuring and comparing patients’ capabilities. Relevance to industry Values of maximum force obtained by calculations on the basis of predictive equations can contribute to normative data of maximum forces. The values of maximum forces of different types and for different upper limb postures are very crucial for the design as well as the assessment of work stands.