Differences in Physical Capacity between Junior and Senior Australian Footballers.Kelly Stephen J; Watsford, Mark L; Austin, Damien; Spurrs, Rob W; Pine, Matthew J; Rennie, Michael JJournal of Strength & Conditioning Research: Post Acceptance: September 05, 2017 doi: 10.1519/JSC.0000000000001720 Original Research: PDF Only Abstract The purpose of this study was to profile and compare anthropometric and physical capacities within elite junior and senior Australian football (AF) players of various chronological ages and stages of athletic development. Seventy-nine players, including junior and senior AF players from one professional club were profiled using eleven assessments. Junior players were divided into two groups based on chronological age (under 16 and 18 years) and senior players according to years since drafted to a professional AF team (1-2 years, 3-7 years and 8+ years). Parametric data was assessed using a one way analysis of variance (ANOVA), while non parametric data was assessed using a Kruskal Wallis ANOVA. The magnitude difference between players was measured using Hopkins effect size (ES). Significant differences were evident between under 16 players and all senior player groups for anthropometric (p = 0.001-0.019/ES = 1.25-2.13), absolute strength (p = 0.001-0.01/ES = 1.82-4.46) and relative strength (p = 0.001-0.027/ES = 0.84-3.55). The under 18 players displayed significantly lower absolute strength (p = 0.001-0.012/ES = 1.82-3.79) and relative strength (p = 0.001-0.027/ES = 0.85-4.00) compared to the 3 to 7 and 8+ players. Significant differences were evident between the under 16 players and senior player groups for explosive jumping and throwing tests (p = 0.001-0.017/ES = 1.03-2.99). Minimal differences were evident between all player groups for running assessments, however the under 16 players were significantly slower compared with the 8+ players for the 3km time trial (p < 0.02/ES = 1.31), while both junior player groups covered significantly less distance during the Yo-Yo IR2 (p < 0.02/ES = 1.19 and 1.60). Results from this study display a significant deficit in strength between junior and senior AF players. Copyright (C) 2017 by the National Strength & Conditioning Association.