Author(s): MAZZEI, S., GUARNIERI, A.1, PRESTA, V.1, LAURENTI, F.1, GOBBI, G.1, KAVANAGH, R.2, MANDORINO, M.2, LACOME, M.3,4, CONDELLO, G.1, Institution: UNIVERSITY OF PARMA, Country: ITALY, Abstract-ID: 2684

INTRODUCTION:
The pubertal growth spurt in youth soccer induces transient disruptions in neuromuscular control and physical performance. This phenomenon requires the monitoring of these physiological changes, optimizing tailored developmental programs to the specific maturity status of each player. The implementation of specific testing protocols could allow a deeper understanding of inter-team maturational variances. Therefore, this study aimed to evaluate the impact of maturity status on neuromuscular efficiency of the lower limbs in elite youth soccer players.
METHODS:
One hundred twenty-one youth soccer players (age: 9–15 years) from an Italian elite team, belonging to 7 age categories (from Under 10 to Under 16), were divided into three groups based on their maturity offset according to Mirwald’s method [1]: pre-PHV (n=63, < -1.0 years to PHV), circa-PHV (n=27, between -1.0 and +1.0 years), and post-PHV (n=31, > +1.0 years). Countermovement jump (CMJ) performance was assessed using two force plates (ForceDecks, FDLite V.2, VALD, Brisbane, Australia). Twenty force-time metrics extracted from the best trial, in terms of jumping height, of three attempts were analysed using a linear mixed model. Maturity offset was included as fixed factor, while the age category as random factor.
RESULTS:
Jumping height significantly differed (p<0.001) among pre-PHV (23.5±3.3 cm), circa-PHV (29.7±4.2 cm), and post-PHV (33.9±3.4 cm). A greater peak power emerged for post-PHV compared to pre-PHV (p<0.001; effect size [ES]=4.56) and circa-PHV (p<0.001; ES=1.95) and for circa-PHV compared to pre-PHV (p<0.001; ES=2.4). Countermovement depth was higher in post-PHV compared to pre-PHV (p=0.003; ES=1.54) and circa-PHV (p=0.028; ES=1.07). Higher eccentric duration (p=0.026; ES=0.97) and Reactive Strength Index (p=0.027; ES=1.44) emerged for post-PHV compared to pre-PHV. The ratio contraction time:eccentric duration was worse in the pre-PHV compared to circa-PHV (p=0.008; ES=0.7) and post-PHV (p=0.002; ES=0.81). No effect emerged for other metrics (i.e., concentric duration, asymmetry indexes, impulses indexes, landing and takeoff peak force).
CONCLUSION:
The current analysis demonstrated the influence of maturation not only on jumping performance, but also on specific force-time metrics obtained from a countermovement jump test. The superior performance of more mature players in the metrics related to the force-time profile (like eccentric contribution, the Reactive Strength Index, and countermovement depth) could explain a greater vertical jumping ability. These results were evident also across different age categories. Consequently, individual maturity status must be integrated into neuromuscular training programs to guarantee physical development, while preventing risk of injury, among youth players and support their soccer-specific performance.

1. Mirwald et al., 2002.