Author(s): KYRIACOU ROSSI, A., IERONYMIDES, D., HADJICHARALAMBOUS, M., AVLONITI, A., CHATZINIKOLAOU, A., ZARAS, N., Institution: DEMOCRITUS UNIVERSITY OF THRACE, Country: CYPRUS, Abstract-ID: 2480

INTRODUCTION:
In soccer, muscular strength is a determinant factor of performance. Stronger athletes may benefit from high-velocity-oriented strength training aimed at shifting the high-velocity region of the force–velocity curve, whereas weaker athletes may require a greater emphasis on maximal strength development to shift upward the entire force-velocity profile. The purpose of the study was to investigate the effects of strength-level-based organization of strength and power training on neuromuscular performance in youth soccer players.
METHODS:
Twenty-six male U16–U17 high-level youth soccer players completed baseline squat one-repetition maximum (1RM) testing and were divided into a stronger (SG, n=12) and a weaker group (WG, n=14). Over a 12-week in-season period, both groups performed one complex training session combining heavy resistance exercises with plyometric or ballistic exercises, whereas SG completed an additional power training session and WG an additional heavy strength session. Pre- and post-measurements included body composition, squat-1RM strength, leg extension isometric peak torque (IPT) and rate of torque development (RTD), countermovement jump (CMJ), drop jump (DJ), linear speed, repeated sprint ability (RSA), agility, shot velocity, and GPS-derived running metrics including top speed, maximal acceleration-deceleration, and aerobic capacity. A two-way repeated measures ANOVA (group x time) was used for the determination of pre- and post-differences.
RESULTS:
Both groups significantly improved the percentage of body fat (SG: -2.6%, p=0.01; WG: -2.4%, p=0.001) and lean mass (SG: 3.3%, p=0.005; WG: 4.35%, p=0.01). Squat 1RM strength relative to mass increased significantly in both groups (SG: 18.2%, p=0.001; WG: 27.19%, p=0.001). IPT relative to mass (SG: 10.3%, p=0.021; WG: 2.8%, p=0.03) and RTD increased for both groups (p<0.05). CMJ (SG: 5.7%, p=0.01; WG: 6%, p=0.05) and DJ reactive strength index increased in both groups (SG: 25.1%, p=0.004; WG: 26.2%, p=0.01). Linear sprint improved only in SG (30m: -1.3%, p=0.042), while RSA total time (SG: -2.7%, p=0.002; WG: -3.4%, p=0.01) and best time trial (SG: -2.4%, p=0.002; WG: -3.6%, p=0.01) improved for both groups. Shot velocity increased in both groups (SG: 8%, p=0.03; WG: 5.9%, p=0.01) while both groups increased top speed (SG: 3.2%, p=0.031; WG: 3.45%, p=0.014), maximal acceleration (SG: 7.3%, p=0.028; WG: 6.3%, p=0.01), and deceleration (SG: 7.7%, p=0.045; WG: 16.1%, p=0.003). Aerobic capacity significantly increased for both groups (SG: 1.6%, p=0.033; WG: 1.3%, p=0.047).
CONCLUSION:
Organizing the in-season strength and power training according to the athletes’ relative strength level is an effective strategy to enhance neuromuscular and physical performance in high-level youth soccer players. Strength and conditioning practitioners may consider allocating additional weekly training volume toward maximal strength development in weaker youth players and toward velocity-oriented power training in stronger players.