Combined Sprint Interval, Plyometric, and Strength Training in Adolescent Soccer Players: Effects on Measures of Speed, Strength, Power, Change of Direction, and Anaerobic Capacity

Association between Sprint and Jump Performance and Maximum Strength in Standing Calf Raise or Squat in Elite Youth Soccer Players

Soccer is a complex sports discipline that requires players to engage in diverse high-intensity and multidirectional activities. The optimization of strength and conditioning programs requires a comprehensive understanding of the physical attributes influencing player performance. While previous research has demonstrated the influence of knee and hip extensor muscles on the performance in sprints and other explosive movements, this study aimed to establish the relationship between plantar flexor muscle strength and high-intensity actions. Back squat (BS) and calf raise (CR) one-repetition maxima as well as linear sprint (5-, 10-, 30 m) and drop jump performance from different heights (15, 30, 45 and 60 cm) were measured in 45 elite youth players (age: 16.62 ± 1.1 years). Results showed significant negative correlations between BS strength and sprint times (r = -0.60 to -0.61), confirming the importance of lower limb extensor muscle strength in short-distance sprints. While no significant correlations were found with sprint performances, CR strength was significantly associated with drop jump test results from 45 and 60 cm drop height (r = 0.36 to 0.46). These findings demonstrate that isolated CR strength positively influences the performance in actions involving rapid stretch-shortening cycles, which suggests that current strength and conditioning programs for youth soccer players should be extended to also include exercises specifically targeting the plantar flexor muscles. While this cross-sectional study provides novel insights into the complex interplay between muscle strength and soccer-specific performance, its findings need to be corroborated in longitudinal studies directly testing the impact of plantar flexor strength training.

Supervised Offseason Training Programs are able to mitigate the Effects of Detraining in Youth Men Soccer Players Physical Fitness: A Randomized Parallel Controlled Study

This study aimed to analyze the effects of three off-season training programs on the aerobic capacity, countermovement jump (CMJ), and linear sprint performance of young male soccer players. The study employed a randomized multi-arm design, consisting of three experimental groups: i) a high-intensity interval training (HIIT) group; (ii) a plyometric jump training (PJT) group; and (iii) a HIIT+PJT group; and an inactive control group. Fifty-eight under-19 male soccer players (aged 17.6 ±0.6 years) were randomly assigned to participate in a 3-week offseason training program exclusively performing HIIT, PJT, or a combination of both, while the fourth group remained inactive. Players underwent assessments twice, using the Yo-Yo Intermittent Recovery Test - Level 1 (YYIRT), CMJ, and 30-meter linear sprint. Significant interactions between time and groups were found in CMJ (p<0.001), YYIRT (p<0.001), and 30-m sprint (p<0.001). Group*time interaction revealed that the control group was significantly different from HIIT (p<0.001), PJT (p<0.001), and HIIT+PJT (p<0.001) considering the CMJ. Moreover, the control group was significantly different from HIIT (p=0.037) in YYIRT. Finally, the control group was significantly different from HIIT (p=0.024), PJT (p<0.001), and HIIT+PJT (p=0.021) considering the 30-m sprint. In conclusion, off-season training programs are effective in significantly reducing declines in CMJ and sprint performance compared to maintaining training cessation. However, in the YYIRT, only HIIT seems to be significantly superior to maintaining inactivity. To mitigate aerobic performance declines, incorporating HIIT sessions twice weekly during the offseason is advisable. To enhance or maintain jump performance, integrating at least one session of PJT weekly is beneficial.

Intra- and Inter-Seasonal Fitness and Training Load Variations of Elite U20 Soccer Players

Inherent physical and anthropometric traits of elite soccer players, influenced by nature and nurture, account for the emergence of performances across time. Purpose: The present study aimed to evaluate inter- and intraseasonal differences and the influence of playing position on training and fitness metrics in talented young soccer players. Methods: A total of 74 male players from U20 teams of a single elite club were tested both at beginning, during, and at the end of three consecutive competitive seasons. Players under went anthropometric measurement and were tested for aerobic, jumping, and sprinting performances; the GPS-derived measures of metabolic power (MP) and equivalent distance index (ED) of every athlete were analyzed. Results: Difference between teams emerged in Mognoni's test, while it did not in countermovement jump and anthropometrics. ED was different across seasons. The model selection criteria revealed that the Bosco-Vittori test achieved the best fit. BMI and countermovement jump (CMJ) increased, and fat mass decreased, during season; different intraseasonal trends for CMJ. MP was slightly greater in midfielder. Conclusion: Network approaches in modeling performance metrics in sports team could unveil original interconnections between performance factors. In addition, the authors support multiparametric longitudinal assessments and a huge database of sports data for facilitating talent identification.

Retrograde Training: Effects on Lower Body Strength and Power

Backward walking and running on positive grades (retrograde training) represents a closed kinetic chain exercise used by rehabilitation specialists for patellofemoral-related injuries. To date, no longitudinal studies exist to support it use. This investigation examined the effects of retrograde training on lower body strength and power in recreational athletes aged 18-50 years over 6 weeks. Thirty-seven subjects were divided into two groups. Group 1 performed retrograde training 3 days∙wk^-1 using treadmill speeds, grades and bout durations ranging from 1.6-4.9 m∙sec^-1, 2.5-27.5% and 10-30 seconds, respectively (RG, n=19). Group 2 was a control group who continued their normal training (CON, n=18). Pre- and posttests assessed a variety of unilateral and bilateral measures including vertical and linear jumps, one repetition maximum leg press strength, and positive and negative power during weighted squat jumping on a horizontal leg press with a force plate. RG improved significantly in all tests (P<0.05). Mean effect size (ES) of the relative improvement in a majority of tests revealed a moderate to very large ES of RG training (ES range: 0.77-2.71). We conclude retrograde training effective for improving lower body strength and power in recreational athletes.

Targeted Lipidomics and Inflammation Response to Six Weeks of Sprint Interval Training in Male Adolescents

Lipids play an important role in coordinating and regulating metabolic and inflammatory processes. Sprint interval training (SIT) is widely used to improve sports performance and health outcomes, but the current understanding of SIT-induced lipid metabolism and the corresponding systemic inflammatory status modification remains controversial and limited, especially in male adolescents. To answer these questions, twelve untrained male adolescents were recruited and underwent 6 weeks of SIT. The pre- and post-training testing included analyses of peak oxygen consumption (VO2peak), biometric data (weight and body composition), serum biochemical parameters (fasting blood glucose, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triacylglycerol, testosterone, and cortisol), inflammatory markers, and targeted lipidomics. After the 6-week SIT, the serum C-reactive protein (CRP), interleukin (IL)-1β, IL-2, IL-4, IL-10, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-β significantly decreased (p < 0.05), whereas IL-6 and IL-10/TNF-α significantly increased (p < 0.05). In addition, the targeted lipidomics revealed changes in 296 lipids, of which 33 changed significantly (p < 0.05, fold change > 1.2 or <1/1.2). The correlation analysis revealed that the changes in the inflammatory markers were closely correlated with the changes in some of the lipids, such as LPC, HexCer, and FFA. In conclusion, the 6-week SIT induced significant changes in the inflammatory markers and circulating lipid composition, offering health benefits to the population.

Training to Improve Pro-Agility Performance: A Systematic Review

Effective directional change in sport is imperative to success in key game situations. Change of direction (COD) ability is underpinned by various athletic qualities which can be developed through specific and non-specific training methods. This review examined the effect of specific and non-specific training methods on pro-agility performance, by analysing the intervention type and resulting magnitude of training effects on pro-agility shuttle performance. A total of 20 studies were included for review. Data from 638 subjects and 29 intervention groups involving seven different training methods were extracted and analysed in relation to training method classification and primary outcome measures. Interventions involving sprint training, plyometric training, resistance training, and combined resistance, plyometric, and sprint training were found to produce statistically significant positive change on pro-agility performance per session (p < 0.05). Sprint training (0.108 ES), plyometric training (0.092 ES), resistance training (0.087 ES), and combined resistance, plyometric, and sprint training (0.078 ES) methods were found to have the highest per session training effect. While total time is the typical unit of measure for this test, different types of training may lead to preferential improvements in either acceleration, deceleration, or COD phases of the pro-agility shuttle. Specifically, resisted or inclined sprinting may develop the linear acceleration phases, unilateral resistance training may promote increased strength to overcome the imposed forces during the deceleration and COD phases, multiplanar plyometrics can help enhance stretch-shortening cycle capabilities across different force vectors, and a combination of two or more of these methods may enable simultaneous development of each of these qualities.

Effects of Concurrent Strength and HIIT-Based Endurance Training on Physical Fitness in Trained Team Sports Players: A Systematic Review and Meta-Analysis

BACKGROUND

Concurrent strength and HIIT-based endurance training (CT) has merit in time-saving in team sports. However, the effect of CT on physical fitness remained equivocal. This meta-analysis aimed to determine whether CT would produce an interference effect on the development of physical fitness when compared to strength training (ST) or HIIT-based endurance training (HET) alone in trained team sports players.

METHODS

A total of 2478 studies from three databases were screened. 52 full texts were reviewed. Seven studies were finally included and then subgroups were used for quantitative analysis.

RESULTS

Compared to ST alone, CT had a significant effect on the development of maximal lower-body strength in trained team sports players (MD 4.20 kg, 95% CI 0.71-7.68, p = 0.02, I² = 20%), but there was no significant difference between the groups on training adaptation in lower-body power (SMD 0.08, 95% CI -0.23-0.39, p = 0.62, I² = 26%). Furthermore, a sub-group analysis based on the internal organization order of CT revealed that there was no statistically significant subgroup effect between CT and ST alone in all parameters.

CONCLUSIONS

Well-designed CT regimens did not interfere with the development of physical fitness of trained team sports players.

Plyometric training effects on physical fitness and muscle damage in high school baseball players

[Purpose]

The objective of this study was to investigate the effects of plyometric training on physical fitness and muscle damage in high school baseball players.

[Methods]

The participants in the study included 21 high school baseball players who are healthy and well-training. The participants were randomly allocated to the plyometric training (n=11) and control (n=10) groups. The plyometric training was applied 3 times a week for a total of 8 weeks and the control group took part in only regular baseball skills training without plyometric training. For physical fitness, measures included maximal strength (left and right hand-grip strength), muscle endurance (sit-up), agility (side-step), power (standing long jump), and balance (left and right Rhomberg test). For muscle damage, creatine kinase (CK) and lactate dehydrogenase (LDH) levels were measured.

[Results]

The results showed a significant interaction effect between time and groups in left hand-grip strength (P = 0.022), side-step (P = 0.004), and standing long jump (P < 0.001) after the 8-week plyometric training, with greater improvement in the plyometric training group than the control group. On the other hand, there was no significant interaction effect between time and groups in right hand-grip strength, situp, left and right Rhomberg test, CK level, and LDH level (P > 0.05).

[Conclusion]

In conclusion, 8-week plyometric training had a positive effect on improving physical fitness, such as maximal strength, agility, and power, in high school baseball players without causing additional muscle damage.

Combined Plyometric and Short Sprint Training in U-15 Male Soccer Players: Effects on Measures of Jump, Speed, Change of Direction, Repeated Sprint, and Balance

This study examined the effect of 8 weeks of biweekly combined plyometric and short sprint training into the typical within-season training schedule of youth male soccer players. Participants were allocated at random to an experimental group (EG; n = 17, age: 14.6 ± 0.5 years, body mass: 60.5 ± 7.1 kg, height: 1.64 ± 0.08 m, body fat: 11.3 ± 1.4%) and a control group (CG; n = 17, age: 14.6 ± 0.4 years, body mass: 61.0 ± 3.9 kg, height: 1.67 ± 0.05 m, body fat: 11.8 ± 1.4%). Measures obtained pre- and post-intervention included vertical and horizontal jump performances (i.e., squat jump (SJ), countermovement jump with aimed arms (CMJA), and five-jump test (FJT)) and sprint performances (i.e., 10 and 30 m sprint). In addition, change-of-direction ability (sprint with 90° Turns (S90°) and sprint 9–3–6–3–9 m with backward and forward running (SBF)), repeated shuttle sprint ability (RSSA), and dynamic balance performance (Y balance test) were measured pre- and post-intervention. The EG experienced higher jump (all p < 0.05; d ≥ 0.71), sprint (all p < 0.05; d ≥ 0.64), change-of-direction ability (all p < 0.05; d ≥ 0.66), RSSA (all parameters except the fatigue index p < 0.01; d ≥ 0.71), and dynamic balance (all p ≤ 0.05; d ≥ 0.50) improvement compared to the CG. Adding biweekly combined plyometric and short sprint training to standard training improves the athletic performance of youth male soccer players (under 15 (U15)).