Global biomechanical evaluation during work and daily-life activities

Advances in technology in the last decades have provided the opportunity to observe human behaviour in the three dimensional space with great spatial accuracy. Optoelectronic techniques for measurements of human motions have been developed. However, it is found that, in the work environments, these methods are complicated to set up and can only be easily applied in laboratory. On the other hand, electronic sensors such as accelerometers and gyroscopes, have been developed and applied to solve the relevant outdoor application problems of the image-based methods. These sensors have been evaluated for the 3D measurement of trunk, lower and upper segments, during posture, walking and rising from a chair, in both normal and pathological conditions. In the present study we used a device including accelerometers and gyroscopes in order to calculate the angular behaviour of the pelvis on the sagittal, frontal and horizontal plane, during the following tasks: walking, gait initiation, gait termination, seat-to-stand and stand-to-seat, squat, standing anterior and lateral reaching and grasping, anterior and lateral trunk flexion and trunk rotation. The assessment of pelvis during posture and movement is important in improving our understanding of the motor strategies at work and preventing injuries (i.e. low back pain) and mechanical whole body fatigue. The calculated angles were compared to that computed by a high-quality optical motion analysis system (SMART-E System, BTS, Milan, Italy) consisting of eight infra-red cameras (operating at 120 fps) to detect the movements in three-dimensional space of three retro-reflective markers (15 mm diameter). For the comparison of the Range of Motions (ROMs) we used the root mean squared error (RMS) whereas the Coefficient of Multiple Correlation (CMC) was used to evaluate overall waveform similarity of instantaneous angle curves. Preliminary results showed a high similarity between the extracted angle tracks (anterior-posterior behaviour on the sagittal plane, pelvic obliquity and intra-extra rotation of the pelvis) in all of the acquired tasks. We also found low errors in the computation of the corresponding ROMs. This study suggests to apply an accurate, inexpensive and simple method to measure the kinematics of the pelvis during common work and daily-life activities.