Georgios Antoniou

The annual soccer training cycle consists of preparatory, competitive, and transition periods. The transition phase is usually characterized by a decrease in training volume, which may lead to detraining and declines in physical fitness. The aim of this study was to examine the effects of a structured transitional training program on anthropometric characteristics, aerobic capacity, and jumping performance in young soccer players. Twenty-three under-17 players participated in the study and, following a two-week period of training cessation, completed a three-week program that included aerobic training three times per week (continuous and interval running sessions) and strength progressive resistance training twice per week. Pre- and post-intervention measurements were analyzed using paired-samples t-tests, with statistical significance set at p < 0.05. The results revealed significant reductions in body fat percentage (p = 0.016, d = 0.547), body fat mass (p = 0.018, d = 0.535), and resting systolic blood pressure (p = 0.024, d = 0.507). Additionally, time to reach the anaerobic threshold (p = 0.022, d = −0.515) and movement speed at the anaerobic threshold (p = 0.029, d = −0.487) significantly increased. No significant changes were observed in the remaining variables. These findings indicate that a three-week transition-period training program combining structured aerobic running drills with progressive resistance training can induce favorable adaptations in selected anthropometric and physiological parameters in youth soccer players. However, the lack of a control group should be considered when interpreting the magnitude of the program’s effects.

This study examined the physiological and performance adaptations of association football (soccer) players during a six-week transitional (off-season) period following the competitive season through a remotely supervised, periodized training program. Fifteen male players (19.57 ± 1.14 years; training experience: 13.60 ± 1.81 years) from the Greek Super League 2 completed pre- and post-intervention laboratory assessments, including anthropometry, cardiopulmonary function, isokinetic strength, and jump performance. The program integrated high-intensity interval training, aerobic conditioning, and individualized resistance training, adjusted according to test results. Anthropometric parameters remained stable. Maximal oxygen uptake (VO₂max) increased significantly by 2.8% (56.31 ± 3.87 vs. 57.91 ± 3.02 mL/kg/min), while anaerobic threshold time and velocity declined by 6.2% (472.87 ± 35.06 vs. 443.33 ± 24.69 sec) and anaerobic threshold velocity fell by 6.1% (15.97 ± 1.17 vs. 15.00 ± 0.91 km/h), indicating a partial preservation of aerobic capacity but reductions in submaximal endurance. Isokinetic strength of the quadriceps and hamstrings was maintained across angular velocities, but squat jump height decreased significantly by 4.3% (p = 0.033), suggesting a loss of concentric-only explosive power despite stable countermovement jump performance. These findings indicate that targeted off-season training can maintain overall physical readiness, body composition, and VO₂max, but may require additional endurance and concentric power elements to preserve all performance qualities essential for the competitive season. Overall, the program effectively preserved most performance variables with only minor decrements, representing a favorable outcome for the off-season; however, if greater asymmetries, deficits, or other training targets are identified, more specific adjustments to training intensities, such as the inclusion of additional endurance and concentric-only power elements, may be required to achieve significant improvements.

The transition period in football can negatively affect players’ fitness indicators. However, if appropriate training programs are implemented during this period, these effects can be reversed. The purpose of this study was to investigate the effect of a high-frequency exercise program during the transition period on aerobic capacity, isokinetic torque of the lower limbs, jumping ability, and body composition. The transition period was divided into two phases: the first phase lasted two weeks and involved complete rest from exercise, and the second phase lasted four weeks during which the players completed three aerobic-focused training sessions and two maximum strength training sessions per week. A total of 13 young football players (age 17.8 ± 0.7 years, height 1.78 ± 0.07 m, weight 70.3 ± 8.4 kg) participated in the study. A paired samples t-test was applied, and statistical significance was set at p < 0.05. The results showed that players improved their maximal oxygen uptake (VO₂ max) after the program (p = 0.037, t = −2.348). The performance in countermovement jump performance and in the isokinetic torque of the right quadriceps showed a decline (p = 0.009, t = 3.112 & p = 0.004, t = 2.299, respectively), while no changes were observed in any other parameter (p > 0.05). The findings suggest that a program with these characteristics can counteract the negative effects typically observed during the transition period. Moreover, with specialized stimuli, improvement may also be observed during the transitional period.

Football is a sport in which athletes perform many movements using one of their legs, which is characterized as dominant. This differentiation in usage often creates asymmetries between the limbs, which has been noted to be related to the occurrence of injuries as well as negative effects on performance. To assess these asymmetries, vertical jump tests, as well as tests using an isokinetic dynamometer, were employed. The aim of this study was to examine the relationship between the asymmetries observed in the application of the single-leg countermovement jump (SLCMJ) and those observed through isokinetic strength assessment at 60°/s, 180°/s, and 300°/s in high-level youth football players. The study involved 63 elite youth football players. For statistical analysis, correlation analysis and linear regression analysis were used. The results showed a significant positive correlation between the CMJ Bilateral Asymmetry Index and the BAI Anterior Quadriceps (60°/s) (r = 0.262, p = 0.038, 95% CI [0.016, 0.479]), indicating a small-to-moderate effect size (Fisher’s z = 0.269, SE = 0.129). Additionally, a significant negative correlation was identified between the CMJ Bilateral Asymmetry Index and the BAI Posterior Hamstrings (60°/s) (r = −0.319, p = 0.011, 95% CI [−0.525, −0.077]), demonstrating a moderate inverse relationship (Fisher’s z = −0.331, SE = 0.129). The overall regression model was significant, F(6,56) = 2.42, p = 0.038, R² = 0.206, indicating that the predictors collectively explained approximately 20.6% of the variance in the CMJ Bilateral Asymmetry Index. From the findings of this study, we conclude that the SLCMJ asymmetry index cannot replace the asymmetry index from isokinetic strength tests.