Kinematics of the typical beach flags start for young adult sprinters

This study profiled beach flags start kinematics for experienced young adult sprinters. five males and three females (age = 20.8 ± 2.1 years; height = 1.70 ± 0.06 meters [m]; mass = 63.9 ± 6.0 kilograms) completed four sprints using their competition start technique. a high-speed camera,positioned laterally,filmed the start. data included: start time; hand clearance time; posterior movement from the start line; feet spacing during the start; elbow,hip,knee,trunk lean,and trajectory angles at take-off; and first step length. timing gates recorded 0-2,0-5,and 0-20 m time. spearman's correlations identified variables relating (p ≤ 0.05) to faster start and sprint times. the beach flags start involved sprinters moving 0.18 ± 0.05 m posterior to the start line by flexing both legs underneath the body before turning. following the turn,the feet were positioned 0.47 ± 0.07 apart. this distance negatively correlated with start (ρ = -0.647),0-2 (ρ = - 0.683),and 0-5 m (ρ = -0.766) time. beach flags start kinematics at take-off resembled research analyzing track starts and acceleration. the elbow extension angle (137.62 ± 13.45°) of the opposite arm to the drive leg correlated with 0-2 (ρ = - 0.762),0-5 (ρ = -0.810),and 0-20 m (ρ = -0.810) time. greater arm extension likely assisted with stability during the start,leading to enhanced sprint performance. the drive leg knee extension angle (146.36 ± 2.26°) correlated with start time (ρ = - 0.677),indicating a contribution to a faster start completion. a longer first step following the start related to faster 0-5 m time (ρ = -0.690). sprinters quicker over 0-2 and 0-5 m were also quicker over 20 m (ρ = 0.881-0.952). beach flags sprinters must ensure their start is completed quickly,such that they can attain a high speed throughout the race. © journal of sports science and medicine (2012).