The Characterization Of The Transition Phase During A 180° Change Of Direction Task

Abstract

The evaluation of change of direction ability should not merely rely on the measurement of total sprinting time, but it should focus also on the understanding of specific movement patterns. PURPOSE: To evaluate the transition phase (TP) during a 180° change of direction (COD) task. METHODS: 14 recreational basketball athletes (age: 21.4±2.6 years) were evaluated during a 10-m COD test. TP has been identified considering 3 consecutive steps (i.e., final decelerating foot contact [DFC], turning foot contact [TFC], first accelerating foot contact [AFC]), using two force platforms. Differences in total (TCT), braking (BCT), and propulsive (PCT) contact time, vertical braking (VBGRF) and propulsive (VPGRF) ground reaction force (relative to body mass), and vertical braking (VBI), propulsive (VPI), and total (VTI) impulse (relative to body mass) were evaluated in relation to leg preference, the 3 steps, and groups (slower vs. faster defined as those below and above the 50th percentile of total sprinting time). RESULTS: No differences emerged for leg preference. TP (1.199±0.11 s) contributed for an average of 42.6±3.4% to the total sprinting time (2.817±0.14 s), with DFC involving only a braking action, whilst TFC and AFC comprising both a braking and propulsive action. Differences (p<0.05) among the 3 steps emerged for TCT (DFC: 0.380±0.07 s; TFC: 0.525±0.06 s; and AFC: 0.303±0.04 s), VBGRF (DFC: 22.7±7.5 N·kg-1; TFC: 20.3±2.8 N·kg-1; and AFC: 8.1±2.7 N·kg-1), VBI (DFC: 2.1±0.4 m·s-1; TFC: 2.5±0.5 m·s-1; and AFC: 0.4±0.2 m·s-1), and VTI (DFC: 2.1±0.4 m·s-1; TFC: 5.6±0.6 m·s-1; and AFC: 2.6±0.3 m·s-1). Furthermore, differences (p<0.05) between TCF and AFC were evident for VPGRF (TFC: 14±1.2 N·kg-1; and AFC: 15.6±1.7 N·kg-1) and VPI (TFC: 3.1±0.6 m·s-1; and AFC: 2.2±0.4 m·s-1). Differences between groups emerged in the TFC only, with faster individuals demonstrating shorter TCT (0.489±0.1 s) and PCT (0.281±0.1 s), and lower VPI (2.8±0.5 m·s-1) compared to slower individuals (TCT: 0.542±0.1 s; PT: 0.339±0.1 s; and VPI 3.4±0.6 m·s-1). CONCLUSIONS: Findings revealed specific movement patterns during the TP of a COD task and the central role played by the turning step in differentiating faster and slower recreational basketball athletes, with potential further implications for future testing and training procedures.