Sex-Specific Associations Between Sagittal Spinal Alignment and Postural Control in Recreational Strength-Trained Young Adults: A Cross-Sectional Observational Study

Background/Objectives: Strength training is a widely recommended form of physical activity due to its extensive health benefits and positive effects on musculoskeletal function, although improper technique and balance deficits may increase injury risk. While sex differences in spinal curvature and postural control have been identified in the general population, it remains unclear whether these differences persist among recreationally strength-trained individuals. This cross-sectional study investigated sex-specific differences in sagittal spinal alignment and static balance and examined potential associations between spinal curvature and postural control in trained young adults. The authors hypothesized that sex-related differences would persist despite regular training and that relationships between spinal alignment and balance would demonstrate sex-specific patterns. Methods: This cross-sectional study included 124 young adults (59.7% men and 40.3% women). Anthropometric measurements included height, weight, waist circumference, and hip circumference. Sagittal spinal curvature was assessed using an electronic inclinometer, and balance parameters were evaluated using a stabilometric platform under eyes-open and eyes-closed conditions. Results: Statistically significant sex-related differences were observed in sacral angle (p < 0.001) and lumbar lordosis (p = 0.02). Balance assessment revealed significant differences between sexes in several parameters under eyes-open conditions (p < 0.05), as well as in mean COP velocity in the anteroposterior direction under eyes-closed conditions (p = 0.003). In women, sacral inclination was positively but weakly correlated with selected balance parameters (r = 0.299–0.306, all p < 0.05), indicating an association between spinal alignment and postural control. Conclusions: The findings indicate sex-specific differences in sagittal spinal curvature and balance, with sacral alignment associated with balance performance in women. Differences in selected balance parameters were also observed independently of spinal curvature. These results highlight the importance of considering sex and spinal biomechanics when assessing postural control in strength-trained individuals and support further research in larger, more diverse populations with varying training experience and age ranges.