The relationship between thoracic posture and ultrasound echo intensity of muscles spanning this region in healthy men and women

Purpose: Skeletal muscle echogenicity intensity (EI) is considered a measure of muscle quality, being associated with old age and pathologies. Whether EI variations can be identified in healthy adults, due to habitual shortened or elongated muscle position is unknown. Thus, this study aimed to assess the relationship between thoracic kyphosis angulation and EI scores of muscles spanning this region ((Lower Trapezius (LT), Rhomboid Major (RM), Erector Spine (ES)) in healthy young people and in addition to examine the relationship between the change in thoracic kyphosis angle from relaxed to upright position (∆°) and the EI of these muscles. Methods: Thoracic kyphosis in relaxed and erect standing was measured using a digital inclinometer in 29 healthy adults (16 women, 13 men), aged 25–35 years. The thoracic kyphosis angles including the difference between relaxed and erect postures (∆°) were correlated to the EI scores of right and left LT, RM and ES. Results: No significant differences in EI were found between the 3 muscles EI or between sides, hence they were pooled together to a total thoracic EI score (TTEI). Although the TTEI did not correlate with relaxed or erect thoracic kyphosis, it was significantly but negatively correlated with ∆° in the entire group: Pearson’s correlation coefficient of r = −0.544; p = .01 and in men; r = −0.732; p = .01, failing to reach significance in women; r = −0.457. Conclusion: The negative association between the EI of the explored muscles and ∆° could imply a possible relationship between these muscles range of movement excursions and their composition.