Strength factors associated with performance in change of direction tasks at different angles

Abstract

Change of direction (COD) ability is a determinant of field and court sports performance and can be quantified using two different methods. Change of direction performance (CODP) is the time taken to complete the whole task of sprinting into a turn, changing direction, and sprinting out of the turn. Change of direction deficit (CODD) is used to isolate COD skill from linear acceleration and deceleration capabilities and is simply the time taken to complete a COD task minus the time to complete a linear sprint of the same distance. Different COD tasks place different demands on the body. During a 180-degree cutting task, the athlete momentarily comes to a complete stop which means that higher levels of force production are required to overcome inertia during the deceleration and reacceleration phases of the COD task. A 45-degree cutting task allows the athlete to maintain running momentum through the COD task and thus requires a smaller change of momentum as they change direction. The demands of a cutting task at 90-degrees fall between the 180-, and 45-degree cutting tasks. Because the physical demands of these tasks are fundamentally different, it follows that different strength qualities may determine performance in COD at different angles. Strength qualities at different points on the force-velocity curve might be related to different task demands. The relationship between isometric, ballistic, plyometric strength and CODP in different COD tasks is yet to be clearly defined. Thus, the study aimed to determine the relationship between different strength factors and performance during COD tasks at different angles. This information can inform training program design to optimise movement capacities for different sports. Twenty male high school rugby players (age = 16.8 ± 1.1 years), twelve male university-level hockey players (age = 20.5 ± 1.7 years), and thirteen university-level female hockey players (age = 20.6 ± 1.5 years) volunteered to be part of this study. Maximal isometric strength was assessed with the isometric squat test. The ballistic strength capabilities of the athletes were evaluated with a countermovement jump. The 10-to-5 repeated jump test was used to evaluate the plyometric strength capabilities of the athletes. The athletes performed a 20-m linear sprint to calculate CODD during the COD tasks. Change of direction ability was assessed using single directional changes at 180-, 90-, and 45-degrees. Pearson’s correlation was used to assess the relationship between the different tests. Stepwise multiple regression analyses were done to determine the best predictor variables during the different COD tasks. There were significant correlations between isometric squat performance and CODP at all angles, but it was only a significant predictor variable for CODD during a 45-degree cutting task. Countermovement jump height showed the strongest relationship among the countermovement jump variables with CODP. Take-off momentum, however, was the countermovement jump performance variable that best predicted performance and only in the 90-degree cutting task. Plyometric strength, as measured by the jump height and peak force relative to body mass during the repeated jump test, had significant correlations with CODP at all angles, and was the best predictor variable during the 180- and 45-degree cutting tasks. It would be of interest to practitioners to improve the athlete’s ability to generate high levels of force as isometric strength underpins ballistic and plyometric performance, but it seems that the ability to produce force as quickly as possible as demonstrated in jump tasks rather than the maximum amount of force that can be produced is a better predictor of performance. Strength and conditioning coaches who want to improve CODP at different angles of directional change need to improve their athletes’ ability to produce high levels of force first and then with the use of plyometric movements increase the ability to produce force as quickly as possible.