Relationship between timing variables and plant foot kinetics during change of direction movements
Australian Strength and Conditioning Association
Faculty of Health, Engineering and Science
School of Exercise and Health Sciences/Centre for Exercise and Sports Science Research
It is well established the importance of lower body strength and power to produce the necessary amount of force required to create subsequent rapid movements to influence performance outcomes. Increased force production during the propulsive phase of athletic movements has resulted in increased vertical jump height, and improved acceleration ability during sprinting. Further, stronger athletes have been found to produce greater force and impulse during movement that directly benefits performance, however the relationship between lower body strength and change of direction (COD) ability has yet to be examined. Several studies have shown significant differences in total running time between genders, starters and non-starters and novice and elite athletes during COD tests, collectively identifying lower body strength as an important physical attribute to improve performance. However, the precise influence of lower body strength during COD movements is still uncertain, with previous studies reporting both significant and non-significant relationships with improvements in COD performance. The inconsistent relationship between strength and COD performance may be explained by the many variations (number of directional changes, the degree of directional change, force application, the distance and amount of straight line sprinting) between different COD protocols, which makes direct comparisons between tests and variables somewhat difficult. Further, these investigations have examined the correlation between lower body strength qualities and total running time during COD protocols, failing to identify how the underlying mechanisms (force and impulse), as a result of increased lower body strength influences the actual COD performance (often times termed the “cut”). Previous investigations have described COD movements as a function of whole body interactions, requiring a combination of physical, biomechanical and cognitive parameters, to produce a skillful performance. Skill or skillful performance is said to arise when an athlete is able to control the individual components and manipulate the degrees of freedom of the movement to meet the demands of the situation. Although COD performance is a multidimensional skill, an athlete’s ability to shift, reposition their center of mass (COM) and rapidly accelerate is a fundamental element of the overall performance. Therefore, breaking down the movement into components, similar to sprinting research and measuring an athlete’s ability to re-accelerate after the initial deceleration phase may provide a greater understanding of COD ability than total running time alone which encompasses varying amounts of straight line sprinting. Therefore, the purpose of the present study was to determine the correlation between specific timing variables; total time, post COD stride velocity, and kinetic variables (propulsive force and impulse) between both stronger and weaker subjects during a COD movement.