Train the engine or the brakes? Influence of momentum on the change of direction deficit

Purpose: Currently, it is unclear which physical characteristics may underpin the change of direction deficit (COD-D). This investigation sought to determine if momentum, speed-, and jump-based measures may explain variance in COD-D.
Methods: Seventeen males from a professional soccer academy (age: 16.76 ± 0.75 years; height: 1.80 ± 0.06 m; body mass: 72.38 ± 9.57 kg) performed 505 tests on both legs, a 40-m sprint and single leg countermovement and drop jumps.
Results: Regression analyses did not reveal any significant predictors for COD-D on either leg. “Large” relationships were reported between COD-D and 505 time on both limbs (r = 0.65-0.69; p < 0.01) but COD-D was not associated with linear momentum, speed- or jump-based performances. When the cohort was median split by COD-D, effect sizes suggested that the sub-group with the smaller COD-D were 5% faster in the 505 test (d = -1.24; p < 0.001) but 4% slower over 0-10-m (d = 0.79; p = 0.33) and carried 11% less momentum (d = -0.81; p = 0.17).
Conclusion: Individual variance in COD-D may not be explained by speed- and jump-based performance measures within academy soccer players. However, when grouping athletes by COD-D, faster athletes with greater momentum are likely to display a larger COD-D. It may therefore be prudent to recommend more eccentric-biased or technical focused COD training in such athletes and for coaches to view the change of direction action as a specific skill that may not be represented by performance time in a COD test.

Accepted author manuscript version reprinted, by permission, from International Journal of Sports Physiology and Performance, 2020, 16(1), 90-96. https://doi.org/10.1123/ijspp.2019-1007. © Human Kinetics, Inc.