US and sEMG measurements can be used for objective TrA/LM assessment. Correlation results suggest that the relative change of the muscle thickness could be used as the indicator of the muscle activity. Insight into the activity of TrA/LM in pain-free individuals and LBP patients during and after painful episodes may clarify the role of functional abnormalities of these muscles in LBP.

SummaryAim: The purpose was to assess ergonomic risk level in dentistry, which may contribute to manifestation of musculoskeletal disorders (MSD). Methods and Materials: The study included ten dentists, postgraduate students, mean age (33 ± 3.4). Participants were asked to perform typical dental examination in standing and sitting positions. The surface electromyography (EMG) was recorded during dental work from both left and right shoulder muscles: descendent trapezius muscle (T); back muscles: erector spinae muscle (ES); and neck muscles: sternocleidomastoid muscle (SCM) and splenius capitis muscle (SC). Results: High muscles forces, greater than 21% of the maximal voluntary contraction (MVC), which could be indicative of high risk, particularly occurred in muscles SC on both sides of the body in the sitting position. The medium risk level occurred in the same muscles on both sides in standing position. Left and right T muscles were under medium ergonomic risk level in both, sitting and standing working positions. SCM muscles on the left and right side of the body in both working positions were under low risk level, lower than 10% of the MVC. In sitting position, medium risk level occurred in ES muscles on both body sides, while in standing position the risk was low. Conclusion: Dentists are exposed to ergonomic risk. By combining both sitting and standing position the risk can be reduced.

These findings show that risk for increased fatigue and possible injures can be reduced by combining the sitting and standing occupational postures.

Numerous mathematical models of human skeletal muscles have been developed. However, none of them is adopted as a general one and each of them is suggested for some specific purpose. This topic is essential in humanoid robotics, since we firstly need to understand how human moves and acts in order to exploit human movement patterns in robotics and design human like actuators. Simulations in biomechanics are intensively used in research of locomotion, safe human-robot interaction, development of novel robotic actuators, biologically inspired control algorithms, etc. This paper presents two widely adopted muscle models (Hill's and Huxley's model), elaborates their features and demonstrates trade-off between their accuracy and efficiency of computer simulations. The simulation setup contains mathematical representation of passive muscle structures as well as mathematical model of an elastic tendon as a series elastic actuation element. Advanced robot control techniques point out energy consumption as one of the key issues. Therefore, energy store and release mechanism in elastic elements in both tendon and muscle, based on the simulation models, are considered.

Surface electrogastrography (EGG) is a non-invasive technique that is used to record myoelectrical activity of the stomach using cutaneous electrodes placed on the abdomen. Gastric motility assessment by EGG is a candidate for standard clinical procedure based on the quantification of parameters characteristic of gastric motility disorders. Despite its noticeable benefits, EGG is not widely implemented in clinical practice. The main reasons are: (1) lack of standardization of electrode placement, (2) time-consuming diagnostic procedures and (3) a complex multi-channel recording setup. We proposed a methodology in which an easy-to-use single-channel EGG, with a less time-consuming protocol (<1 h), would provide sufficient information for gastric motility assessment. Recordings from the three anatomical landmarks in 20 healthy young subjects were compared under two conditions, fasting and postprandial by evaluating the dominant frequency (DF). Our results showed that there is a statistically significant increase of DF after meal ingestion (p<0.05) in each of the three channels. However, when the study group was divided into two subgroups based on body mass index (BMI), the most appropriate recording location was above the body of the stomach (according to statistical significance p=7.82×10−6). We showed that a less time-consuming recording session with light meal intake could be used for the assessment of gastric myoelectrical activity (GMA).