Variable long-term developmental trajectories of short sprint speed and jumping height in English Premier League academy soccer players: an applied case study

Growth and maturation can affect physical performance over the long term, making the appraisal of athletic ability difficult. Using a previously published method, we sought to longitudinally track youth soccer players to assess the developmental trajectory of athletic performance over a six-year period in an English Premier League academy. Age-specific z-scores were calculated for sprint and jump performance from a sample of male youth soccer players (n = 140). A case study approach was used to analyse the longitudinal curves of the six players with the longest tenure. A regression equation for each fitness variable facilitated comparison of participants to the wider sample. The trajectories of the sprint times of players 1 and 3 were characterised by a marked difference in respective performance levels up until peak height velocity (PHV) when player 1 achieved a substantial increase in sprint speed and player 3 experienced a large decrease. Player 5 was consistently a better performer than player 2 until PHV when the sprint and jump performance of the former markedly decreased and he was overtaken by the latter. Fluctuations in players’ physical performance can occur quickly and in drastic fashion. Coaches must be aware that suppressed, or inflated, performance could be temporary and selection and deselection decisions should not be made based on information gathered over a short time period.