Differences in body positional bilateral symmetry between stance and supine positions, and the impact of attention and awareness on postural symmetry

Background and purpose: Postural asymmetries may cause structural pathological conditions and impaired movement pattern. The influence of body position and awareness towards symmetry has not yet been elucidated. The aim of this study was twofold: First, to compare the body positional bilateral symmetry between standing and supine positions, and second, to examine whether the awareness to symmetry can modify posture perception and body positional bilateral symmetry. Methods: We analyzed the degree of anterior postural alignment symmetry of 34 healthy subjects by photogrammetric method (three photographs in a standing position and three in a supine position). Each photo captured different state of awareness: Subjective Comfortable Posture (SCP), Subjective Perceived Symmetrical Posture (SPSP), and Guided Posture Protocol (GPP). Results: The standing position increased the symmetrical alignment of the neck (p < 0.013) and the upper limbs (p < 0.011). However, the supine position demonstrated increased symmetrical alignment of the upper trunk (p < 0.019) and the feet (p < 0.002). In the standing position, GPP showed greater symmetry of the neck (p < 0.022), the shoulders (p < 0.014), the thorax midline (p < 0.009), the upper trunk (p < 0.000) and the upper limbs (p < 0.029). No significant changes were observed in the supine position between the three states of awareness. Conclusions: Study results indicate that the supine position shows greater degree of upper trunk's symmetrical alignment than the standing position. It also indicates that while standing, focusing attention into symmetry improves body positional bilateral symmetry. These results might have clinical implications when working with patients who suffer from asymmetric posture.