Keira Heavey

This study aimed to assess the influence of growth and maturation on countermovement jump (CMJ) performance using the jump height metric in school sports students over an academic year. Participants were tested at three different time points across the year that corresponded with each school term. A total of 116 participants (school years 10-13) were tested during the study and provided data for at least two out of the three testing points (Females, N= 34, Males, N =82) (mean age = 16.86 ± 6.31 years). All participants were part of the school's performance sport pathway programme. Participants had their anthropometric measurements collected, which included standing height, seated height, and body mass. Participants then performed three CMJ trials on Hawkins Dynamics Portable force plates, with the highest jump height recorded for analysis. The same testing procedure was repeated at each of the three testing periods, which occurred in each school term. The results observed a limited overall influence of growth and maturation on CMJ performance within this cohort, as they were all predominantly post peak height velocity (PHV). However, gender specific differences were evident. The study found males to display a steeper improvement over the academic year in their jump height scores when compared to the females, who had a much shallower rate of improvement and an earlier post PHV performance plateau. The study allowed for the development of normative CMJ jump height benchmark data for school sports students in years 10-13, addressing a gap in the existing literature. While using CMJ testing was practical to implement within a school sport environment, the inclusion of a younger cohort of athletes would be required to capture the full developmental stages that surround PHV. Adopting a multi-year longitudinal design would allow for participants to be tracked across all stages of maturation, therefore facilitating a much more comprehensive examination of the influence that growth and maturation have on CMJ performance.

Briscoe, T, Darrall-Jones, J, Heyward, O, Sawczuk, T, Jones, B, Brindle, T, Barrow, S, Owen, C, Heavey, K, Mackay, L, Cuthbert, K, Pinckney, M, and Scantlebury, S. Ready or not? The anthropometric and physical qualities of youth female rugby league players in England. J Strength Cond Res XX(X): 000–000, 2026—This study aimed to quantify the physical and anthropometric characteristics of U13 to U17 youth female rugby league players, compare between age categories, and assess relationships between characteristics. Eighty amateur youth female players completed a testing battery including anthropometric (body mass and height) and physical (strength [isometric mid-thigh pull], peak power [counter movement jump], linear speed [40 m sprint], momentum, and high-intensity intermittent running [HIIR] ability [30-15 Intermittent Fitness Test]) qualities. Progressive increases were found in body mass, peak power, strength, speed, momentum, and HIIR ability with age, between age group differences were nonsignificant. Large significant (p < 0.01) relationships were found between strength and 10 m (r = 0.54), 20 m (r = 0.59), 30 m (r = 0.59), and 40 m (r = 0.61) momentum. Body mass showed large significant relationships with all momentum distances (10 m: r = 0.54; 20 m: r = 0.59; 30 m: r = 0.59; 40 m: r = 0.61). A large significant (p = <0.01) relationship was found between strength and peak propulsive power (r = 0.59). A moderate negative significant (p < 0.01) relationship was found between body mass and HIIR (r = 0.49). This study provides novel age-specific reference values for practitioners to assess strengths and areas of development in youth female rugby league players. Findings highlight the need for tailored strength and conditioning programs to ensure players are physically prepared to transition through the development pathway, with practitioners focusing on improving physical readiness for the demands of senior competition.