(49) EFFECT OF MATURITY ON RATE OF CHANGE OF NEUROMUSCULAR PERFORMANCE IN MALE YOUTH SOCCER PLAYERS

Introduction: Muscular strength and plyometric ability develop naturally in youth through growth and maturation. Resistance and plyometric training have also shown a synergistic effect with natural growth processes to produce augmented performance throughout maturation. However, little is known of the natural changes in kinetic mechanisms that support natural improvements in neuromuscular qualities, particularly in very young athletes.

Purpose: To assess the effects of maturity upon the rate of change of strength and plyometric ability in early and late pre-peak height velocity (PHV) and circa-PHV soccer players.

Methods: 54 participants (age: 11.86 ± 2.10 yrs; height; 151.2 ± 14.9 cm; body mass; 41.44 ± 11.04 kg; maturity offset: -1.77 ± 1.65 yrs) from the academy of a Welsh Premiership soccer club agreed to take part in the study. Participants were categorized early pre-PHV (Maturity Offset (MO) < -3.0), late pre-PHV (-2.5 < MO < -1.0) or circa-PHV (-0.5 < MO < +1.0). P</span>articipants performed three trials of a 30 cm drop jump (DJ), an isometric mid-thigh pull (IMTP) and a countermovement jump (CMJ)) on force plates sampling at 1000 Hz. Ground reaction force data were processed to calculate the following variables; jump height (JH), ground contact time (GCT), time to take-off, reactive strength index (RSI), reactive strength index modified (RSImod), peak force (PF), peak braking force (PBF), peak propulsive force (PPF), timing of PBF, ratio of PBF:PPF and spring-like correlation (SLC). Pearson correlations between maturity offset and kinetic outcomes were conducted to determine rates of change in kinetic variables within maturity groups.

Results: There were no significant associations between any mechanistic variables in either the drop jump, or countermovement jump and maturity offset in any maturity group (p > .05). IMTP peak force was significantly associated with MO at all stages of maturity (early pre-PHV, r(16) = .854; late pre-PHV, r(17) = .553; circa-PHV, r(15) = .737, p < .01). CMJ JH (r(15) = 0.549, p < .05), DJ JH (r(15) = 0.514, p < .05) and DJ RSI (r(15) = 0.500, p < .05) were significantly associated with MO in circa-PHV only.

Conclusion: Maximal isometric force increases throughout all stages of early maturation, but this does not result in natural improvements in jump performance (CMJ JH, DJ JH and RSI) until youth begin their pubertal growth spurt. Natural increases in jump performance observed during the growth spurt are driven by enhancement of concentric force biased mechanisms since there were no associations with the velocity elements (ground contact time and time to take-off) of ratio variables such as RSI and RSImod.

PRACTICAL APPLICATION: While the trainability of both strength and plyometric ability have previously been demonstrated in pre-PHV and circa-PHV youth, it would appear that only strength experiences natural growth-related improvements during early and late pre-PHV. Plyometric performance measures do not appear to improve through natural development until the pubertal growth spurt. The particular potence of plyometric training for pre-PHV youth previously reported might be due to the absence of natural development of the mechanisms of the stretch-shortening cycle in the early stages of maturation that facilitate plyometric performance. This lends further advocacy for early engagement in plyometric training for young athletes and extends this advice to early pre-PHV youth.


Acknowledgements: None