The Associations Between Lateral Jumps and 180° Change of Direction Performance: Considering for the Effect of Sex and Maturation
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Change of direction (COD) abilities are essential for field- and court-based sport athletes and often are critical determining factors of success. With rising competitiveness in sports, there is an increased emphasis on youth athletic development to gain performance advantages. As such, assessing and monitoring COD abilities in youth athletes regularly and efficiently is critical to coaches. Previous researchers have demonstrated significant associations between jump and COD performance enabling coaches practical and reliable methods of assessing leg muscle qualities. Predominantly, jumps used to assess leg power have been conducted vertically and horizontally, but rarely in the lateral direction. Additionally, these assessments are often applied to mixed populations uniformly, without considering the confounding effect of sex or maturation, despite known differences in physical development. The overarching research question of this thesis was “Can single-leg lateral jumps be used as a predictor of 180° COD performance among youth male and female athletes pre-, circa-, and post-peak height velocity (PHV)?”. The first aim was to review and critique the current literature that has investigated the relationships between lateral jumps and COD performance. The second aim was to determine between-session reliability of two lateral jump tasks and a 180° COD task. The third aim was to quantify the relationship between the lateral jump tasks and the 180-degree COD task. First, a literature review was conducted systematically to identify relevant articles. Eleven experimental studies were found and reviewed. The main conclusions drawn from these articles were: (1) moderate to strong relationships (r>0.55) were observed between lateral jump and COD assessments, suggesting both tasks share some similar neuromuscular qualities that contribute to lateral performance; and (2) there is a paucity of research investigating the relationship between lateral jump performance variables and COD performance, while considering how this relationship may be affected by sex and maturation. Next, a three-week repeated measures study design was used to determine between-session variability of single-leg lateral countermovement jumps, single-leg lateral reactive jumps and 180° COD. Coefficients of variation (CV) and intraclass correlation co-efficient (ICC) were used to quantify variability over three occasions separated by seven days. The main findings were: (1) the two lateral jumps and 180° COD assessments demonstrated acceptable variability (CV = 3.2-5.5%; ICC = 0.84-0.90) in kinematic variables; and, (2) only the single-leg lateral reactive jump assessments were found to have acceptable reliability (CV = 7.1-13.8%; ICC = 0.70-0.89) in kinetic variables. Lastly, a cross-sectional study was implemented to quantify the associations between vertical, horizontal, and lateral jump variables, with 180° COD performance across 73 youth athletes of different sexes and maturation stages. Additionally, kinematic and kinetic performance variables of all assessments were used to create stepwise linear regression models that predict 180° COD performance by subgroup. The main findings were: (1) linear sprinting was the most effective predictor of 180° COD performance across all subgroups; and, (2) the best jump predictors of 180° COD performance was the horizontal jump in males, the vertical jump in females, the vertical jump and lateral reactive jump in pre-PHV and circa-PHV participants, and the horizontal jump, and lateral reactive jump in post-PHV participants.