Race walking angular displacement at increasing speed

Aim: The aim of this study was to describe the angular displacements during race walking (RW) in the three planes of motion and at incremental speeds. In fact, in the literature RW angles have been mostly described, focusing on few speeds and sagittal plane of motion.1 Method: 15 athletes race-walked on a treadmill at incremental speed (2.78 \u2013 4.73 m/s). Kinematic data were recorded at 300 Hz (Vicon MX) by using an 18 markers biomechanical model defining 11 anatomical segments (trunk, arm, forearm, tight, shank, foot). Angular displacement was computed frame by frame and its values at heel strike (HS), midstance (MID) and toe off (TO) were highlighted. Results: Angular displacement in the frontal plane: leg was adducted at HS increasing its angle until MID; adduction started during swing after the sagittal knee extension. The pelvis was in the neutral position at HS, and after a flexion until MID, it extended back to neutral position at TO; during swing phase a specular displacement was shown. The 'shoulder' tilt showed a pattern comparable with pelvic tilt, but flexing in the contralateral side. The arm range of motion was about 30\ub0, starting with an abducted position at HS and reaching the maximal abduction value at TO. The elbow was adducted at HS, abducting during stance with a plateau before TO, before being adducted again. Transverse plane: hip was forward rotated at HS and moved backward during stance reaching a minimum/maximum before TO, while the maximum/minimum was before HS. The shoulder was rotate forward at HS, and rotated backward until TO passing through a neutral position at MID. The angle between the upper and lower trunk reached similar maximal values at HS and TO, whereas it was null at MID. The arm angle showed an asymmetrical pattern, and a higher value at TO than at HS. Sagittal plane: Ankle, knee and hip angles were similar to those reported in the literature. Trunk was in the neutral position at HS, then flexed forward until TO and extended back to HS. The arm was in the most posterior position at HS (of the contralateral leg) still extended at MID, and flexed at HS. The extension was almost three times the flexion. Elbow was flexed at HS, during first stance it extended with maximum at MID, then flexed again to neutral position at TO (neutral position = 90\ub0). Conclusion: Speed influenced angular displacements anticipating their pattern with relation to a reduced stance time phase. No significant changes of angular maximal values between speeds were measured with few exceptions between the slowest and fastest speeds. Finally the further calculation of the angular displacements in the frontal and transverse plane exhibit a comprehensive description of RW kinematics, which seems to be necessary for some angles such as arm and pelvi