Change-of-direction ability in soccer is angle-specific: implications for multi-angle testing and speed deficit...

The ability to change direction is crucial in soccer due to the high frequency of rapid movement adjustments during match play. This study examined the effects of change-of-direction (COD) angle (45°, 90°, 180°) and limb dominance on sprint speed in 18 experienced male soccer players using a multi-angle fieldbased assessment. Athletes completed a 20 m linear sprint and three 20 m COD sprints, each incorporating a single directional change at 15 m. Mean speed was assessed across the 0-10 m, 10-20 m (COD speed), 10-13 m (entry speed), and 13-20 m segments, and percentage COD speed deficit relative to linear sprinting (%CODD) was calculated. Mean speed in the 0-10 m segment was identical between linear and COD sprints (5.18 ± 0.28 to 5.28 ± 0.28 m · s^-1). Using the linear 0-10 m speed as a comparator, %CODD values were positive or near-zero for 45° and 90° (+21.0 ± 12.7% and -2.9 ± 7.7%, respectively), indicating greater COD speed than linear, with a negative value only for 180° (-25.2 ± 4.3%). When COD ability was quantified relative to the 10-20 m segment of the linear sprint (7.53 ± 0.37 m · s^-1), a clear and progressively greater %CODD was observed across angles (45°: -15.6 ± 7.6%; 90°: -32.2 ± 4.7%; 180°: -47.7 ± 2.7%; all p < 0.001). Entry speed declined from 45° to 90° COD (6.55 ± 0.45 to 5.77 ± 0.34 m · s^-1, p < 0.001), with no difference between 90° and 180° (5.79 ± 0.31 m · s^-1, p = 1.0). Kendall's tau correlations showed moderate agreement in %CODD between adjacent angles, but not between 45° and 180°, with no effect of limb dominance (all p > 0.05). In conclusion, %CODD should be calculated using matched linear segments. Angle-dependent and individual variability in %CODD support multi-angle, rather than single-direction, assessment and training.