The Development of Movement Competency, Strength, and Power in Male Youth Athletes

Natural growth and maturation have been demonstrated to influence movement competency, strength, and power performance in males. However, little is known with regards to how maturational status influences these athletic qualities follow short- and long-term training responsiveness. Most screening tools for assessing movement competency in youth are extensive and require analysis of multiple movements which tends to be impractical for strength and conditioning coaches. Analysis of a single multi-joint movement pattern such as the back-squat is likely a more impactful and practical method to assess movement competency in youth. Previous research on strength and power performance in youth often assess singular external measures such as one repetition max (1RM) or jump height. Little data exists regarding the strength and power kinetics in youth athletes and how they alter through growth and maturation. Reporting changes to force-time data from performance tests which assess a wide range of kinetic variables can help develop a greater understanding of maturation’s role in training. Therefore, the aim of this thesis was to investigate the interaction between natural growth and maturation with short- and long-term adaptations to movement competency and strength and power kinetics in youth male athletes. Study 1 examined the effects of a 4-week neuromuscular training program on movement competency in pre- and post- peak height velocity (PHV) males using the back-squat assessment (BSA). Significant within-group improvements in movement competency were made by both the pre- (5.0 to 3.0, ES = 0.48) and post-PHV (2.0 to 1.0, ES = 0.58) cohorts. Additionally, intra-rater reliability was tested by rating BSA total score across three separate sessions. Intra-class correlations (ICC) revealed very strong agreement for BSA total score in pre- (ICC ≥ 0.81) and post-PHV (ICC ≥ 0.97) groups across all sessions, but systematic bias 4 was evident in the pre-PHV group for sessions 1 to 2. Study 2 examined the maturational differences between pre-, circa-, and post-PHV male athletes in movement competency, isometric strength, and dynamic jump power. Increased maturity led to significant, moderate to large increases in allometrically scaled peak force (PFallo) in the isometric and dynamic tests but only a small increase in BSA total score. Trends from the kinetic force-time variables indicate the largest differences in strength and power likely occur around the adolescent growth spurt. Study 3 investigated the training response of a 12-week neuromuscular training program on isometric and dynamic kinetic force-time variables in pre- and post-PHV males. There were significant increases in isometric peak force and peak rate of force development by the post-PHV group, while the pre-PHV group improved in the concentric force-time variables within the dynamic jump tests. Findings indicate that responsiveness to short-term training differs between males of different maturity groups for isometric strength and dynamic power tests. Study 4 investigated how a twice- and once weekly training frequency during a 6-month combined training intervention affects movement competency, strength, and power in male athletes. A twice-weekly training frequency resulted in superior gains to movement competency, isometric strength, and concentric jump performance over once-weekly training. The overall findings of this thesis highlight that training responsiveness to short- and long-term interventions varies across stages of maturation but significant improvements in movement competency and force generating abilities for isometric strength and dynamic jump performance are modifiable at all developmental stages.