Relationship between the degree of forward head posture and the shear elastic modulus of the upper trapezius in young men, and the difference in these variables between those with and without neck/shoulder pain and/or stiffness

[Purpose] To investigate the relationship between the degree of forward head posture (FHP) and stiffness of the upper trapezius (UT) in young men, and the difference in these variables between those with and without neck/shoulder pain and/or stiffness. [Participants and Methods] In this cross-sectional study, we measured the craniovertebral angle (CVA) to evaluate the degree of FHP, and used ultrasound shear wave elastography to measure the shear elastic modulus of the UT (SEMUT) to evaluate muscle stiffness in 40 young men. We evaluated the relationship between the CVA and SEMUT in all participants. We compared the CVA and SEMUT between participants with and without neck/shoulder pain and/or stiffness. [Results] There was a weak negative correlation between the CVA and SEMUT in the total cohort (ρ=-0.338). However, the CVA and SEMUT did not significantly differ between participants with and without neck/shoulder pain and/or stiffness. [Conclusion] Our results suggest that a greater degree of FHP might lead to greater neck/shoulder muscle stiffness. However, the subjective symptoms of neck/shoulder pain and/or stiffness in young men were not consistent with the objective measurements of the CVA and SEMUT, which suggests that clinicians should assess both the subjective symptoms and objective measurements.