Correlation Analysis of Craniovertebral Angle and Scapular Index with Muscle Tone, Pulmonary Function, Balance Control, and Proprioception

Forward head posture and altered scapular alignment are associated with musculoskeletal dysfunctions and impaired physical performance. However, the relationship between postural alignment indices and physiological function in young adults remains unexplored. A total of 54 healthy participants (mean age: 21.88 ± 2.06 years) were evaluated. Craniovertebral angle (CVA) and scapular index were measured as indicators of postural alignment. Upper trapezius muscle tone was assessed using the MyotonPRO device. Pulmonary function parameters, including the forced vital capacity (FVC) and forced expiratory volume in one second (FEV₁)/FVC, were measured using spirometry. Balance control was evaluated using the Tetrax system, and cervical proprioception was assessed using joint position error (JPE) tests. CVA showed statistically significant but weak correlations with the muscle tone (r = −0.191), weight distribution index in the eyes-open condition (r = −0.199), and cervical flexion JPE (r = −0.198) and a positive correlation with FVC (r = 0.251) (p < 0.05). Scapular index showed a positive correlation with FEV₁/FVC (r = 0.241) and a negative correlation with balance control (r = −0.213) (p < 0.05). Improved postural alignment, as reflected by a higher CVA and scapular index, was associated with reduced muscle tone, enhanced pulmonary function, better balance control, and more accurate cervical proprioception.