University of Technology Sydney. Faculty of Health.This study examined whether substantial changes in either maximal sprinting speed (MSS) or maximal aerobic speed (Vvam-Eval) are related to changes in match running performance activity during match play in highly-trained young soccer players. A retrospective longitudinal research design was used where physical fitness and match analysis data were collected. Data from 44 players (U13-U18; fullbacks [FB, n=12], centre-backs [CB, n=12], mid-fielders [MD, n=11], wide-midfielders [WM, n=5], strikers [S, n=4]) who had substantial changes in either MSS or Vvam-Eval throughout 2 consecutive testing periods (~3 months) were included in the final analysis. For each player, time-motion analyses were performed using a global positioning system (1-Hz) during 2-10 international level games played within 1-2 months from/to each testing period of interest. Match activity profiles were described using both absolute and relative zones. Absolute match running activities were defined as meters per min (m·min-1), low-intensity activities (LIA), high-intensity running (HIR), very high-intensity running (VHIR) and sprint activities (SPRT), where relative match activities were categorized into 5 intensity zones in relation to individual MSS and MAS. Improvements in both MSS and Vvam-Eval were likely associated with either non-substantial or lower magnitude changes in match running performance variables and between playing positions. While in response to using relative thresholds, measures were either unchanged or decreased substantially in response to an increase in MSS and/or MAS. Collectively, the results demonstrate that in match running activities during games do not necessarily match those in physical fitness in highly trained young soccer players. Game tactical and strategic requirements are likely to modulate on-field players’ activity patterns independently of players’ physical capacities
