Relationship between 3D and 2D sagittal plane running kinematics during initial contact

Abstract

Approach: Both 2D and 3D biomechanical analyses (BA) offer valuable insights into running technique. While BA3D is considered the gold standard, it requires substantial investments, whereas BA2D is cost-effective and increasingly employed in clinical settings. The primary aim of this study was to establish correlations between sagittal plane angles derived from BA2D and BA3D for the pelvis, hip, knee, and ankle during the initial contact phase of running. Methods: Twelve runners, consisting of six females (34.0 ± 5.0 years, 53.0 ± 9.5 kg, and 162.0 ± 6.0 cm) and six males (32.0 ± 3.0 years, 70.0 ± 6.2 kg, and 175.0 ± 8.0 cm), underwent initial contact kinematics assessment using BA3D (Vicon Nexus 1.8 and Polygon 4 plug-in gait model) and BA2D (Kinovea, Version 0.9.3). Correlations between measurements were determined through linear regression (R²), mean differences, Bland & Altman analysis (B&A), Pearson correlation coefficient (r) between BA2D and BA3D, and intraclass correlation coefficient (ICC). Results: The following results were obtained: Pelvis R² = 0.67, B&A = 7.32° ± 3.69°, r = 0.818 (sufficient, p < 0.001); Hip: R² = 0.48, B&A = 18.39° ± 5.56°, r = 0.690 (moderate, p = 0.123); Knee: R² = 0.13, B&A = 2.54° ± 5.38°, r = 0.364 (insufficient, p < 0.001); Ankle R² = 0.15, B&A = -4.89° ± 4.22°, r = 0.386 (insufficient, p < 0.001). ICC for pelvis = 0.470; hip = 0.286; knee = 0.322; ankle = 0.213 (all statistically considered poor). Conclusion: The setup used during data collection can be easily reproduced by other professionals in a clinical setting. A low difference between BA2D and BA3D methods was observed based on B&A analysis. A linear relationship with moderate variability was established according to the Pearson correlation coefficient and coefficient of determination. However, poor agreement between BA3D and BA2D was found, as indicated by ICC. Therefore, caution is warranted when interpreting BA2D results relative to BA3D. The present study does not recommend other researchers to compare their BA2D with BA3D results conducted by different software than those used in our methods, this type of data must be considered individually across studies.