Effects of an Initial Muscle Strength Level on Sports Performance Changes in Collegiate Soccer Players

High-Intensity Interval Training Combined with High-Load Strength Training Improves Aerobic Fitness, Match Goals and Match Result during the In-Season Period in Under-19 Soccer Players

This study compared the effects of adding a weekly session of either strength training followed by high-intensity interval training (HIIT) or high load plyometric training followed by small-sided games (SSG) on aerobic fitness, goals scored and conceded, and match results. Twenty-nine players from two youth elite teams competing in an under 19 (U19) first division league took part in the study. Of those, 16 players from one team followed the HIIT program (age: 17.8 ± 0.6 years) and 13 players from the other team trained once a week, following the SSG program (age: 18.0 ± 0.6 years). The training intervention lasted for 11 weeks and was applied once per week. For the HIIT team it included high-load strength training (80-95% of 1 RM) followed by high-intensity intermittent running, whereas for the SSG team (n = 13) it included plyometric exercises followed by SSG. Aerobic fitness was assessed before and after the intervention, while goals scored and conceded, as well as match results during the intervention period, were compared with the 11-week period preceding it. Only the HIIT team improved Yo-Yo IR2 performance (running distance: from 902.5 ± 147.5 to 1092.5 ± 155.8 m, p < 0.001) while there was no change for the SSG group. Moreover, during the 11-week intervention, the HIIT team improved the number of goals scored in the last 30 min of the game compared with the pre-intervention period (0.36 ± 0.50 to 1.27 ± 0.90 per match, p < 0.05) and the scored vs. conceded goals were higher in the second half (1.36 ± 1.03 vs. 0.27 ± 0.47, p < 0.05). No significant differences were found for these parameters in the SSG team. Regarding match result, the HIIT team increased the proportion of wins from 5 wins in 11 matches (or 45%) in the pre-intervention period to 9 wins in 11 matches (or 82%) during the intervention period, while this profile remained unchanged for the SSG team. In conclusion, the present study demonstrated that the HIIT program performed once per week was superior to SSG as it improves aerobic fitness, scored and conceded goals, and match result during the in-season period.

Skeletal Muscle Adaptations and Performance Outcomes Following a Step and Exponential Taper in Strength Athletes

Before major athletic events, a taper is often prescribed to facilitate recovery and enhance performance. However, it is unknown which taper model is most effective for peaking maximal strength and positively augmenting skeletal muscle. Thus, the purpose of this study was to compare performance outcomes and skeletal muscle adaptations following a step vs. an exponential taper in strength athletes. Sixteen powerlifters (24.0 ± 4.0 years, 174.4 ± 8.2 cm, 89.8 ± 21.4 kg) participated in a 6-week training program aimed at peaking maximal strength on back squat [initial 1-repetition-maximum (1RM): 174.7 ± 33.4 kg], bench press (118.5 ± 29.9 kg), and deadlift (189.9 ± 41.2 kg). Powerlifters were matched based on relative maximal strength, and randomly assigned to either (a) 1-week overreach and 1-week step taper or (b) 1-week overreach and 3-week exponential taper. Athletes were tested pre- and post-training on measures of body composition, jumping performance, isometric squat, and 1RM. Whole muscle size was assessed at the proximal, middle, and distal vastus lateralis using ultrasonography and microbiopsies at the middle vastus lateralis site. Muscle samples (n = 15) were analyzed for fiber size, fiber type [myosin-heavy chain (MHC)-I, -IIA, -IIX, hybrid-I/IIA] using whole muscle immunohistochemistry and single fiber dot blots, gene expression, and microRNA abundance. There were significant main time effects for 1RM squat (p < 0.001), bench press (p < 0.001), and deadlift, (p = 0.024), powerlifting total (p < 0.001), Wilks Score (p < 0.001), squat jump peak-power scaled to body mass (p = 0.001), body mass (p = 0.005), fat mass (p = 0.002), and fat mass index (p = 0.002). There were significant main time effects for medial whole muscle cross-sectional area (mCSA) (p = 0.006) and averaged sites (p < 0.001). There was also a significant interaction for MHC-IIA fiber cross-sectional area (fCSA) (p = 0.014) with post hoc comparisons revealing increases following the step-taper only (p = 0.002). There were significant main time effects for single-fiber MHC-I% (p = 0.015) and MHC-IIA% (p = 0.033), as well as for MyoD (p = 0.002), MyoG (p = 0.037), and miR-499a (p = 0.033). Overall, increases in whole mCSA, fCSA, MHC-IIA fCSA, and MHC transitions appeared to favor the step taper group. An overreach followed by a step taper appears to produce a myocellular environment that enhances skeletal muscle adaptations, whereas an exponential taper may favor neuromuscular performance.

A systematic review of resistance training methodologies for the development of lower body concentric mean power, peak power, and mean propulsive power in team-sport athletes

This study aimed to systematically review training methods prescribed to develop lower-body power, determine their effectiveness for the development of lower-body mechanical power and their implementation in an annual training cycle amongst team-sport athletes. The absolute and relative outcome values of concentric mean power, peak power and mean propulsive power were extracted from 19 studies. Outcomes were assessed using baseline to post intervention percent change, effect sizes, and the level of evidence concerning the method's effectiveness. A thorough analysis of the literature indicated that, based on the high level of evidence, traditional (e.g., strength training alone) and combination training (e.g., complex and contrast) methods should be considered. Further, optimal load and velocity-based training can be implemented if coaches have access to the appropriate equipment to monitor movement velocity and mechanical power in every session. This is of particular importance in periods of the season where high volumes of technical-tactical training and congested fixture periods are present. Also, flywheel, eccentric overload and weightlifting methods have been shown to be effective although the level of evidence is low. Future research should expand on current training practices whilst adequately reporting actual training loads from sport-specific training and games alongside strength-power training protocols.

Optimizing the Explosive Force of the Elite Level Football-Tennis Players through Plyometric and Specific Exercises

The aim of the research was to implement an athletic program to improve the explosive force in order to optimize physical fitness at the level of elite football-tennis players and evaluate the progress made through specific tests using the Opto Jump. The research included 10 elite European and world-class players, on whom an experimental program was applied in order to improve the explosive force of the limbs in conditions of speed, endurance, and dynamic balance. Study tests: five vertical jumps on the spot, on the left/right leg; five back and forth jumps on the left/right leg; five left/right side jumps on the left/right leg; vertical jumps on both legs 60 s; BFS vertical jumps. For each test, the following parameters specific to the explosive force were statistically analyzed: contact time (s); flight time (s); jump height (cm), jump power (w/kg); RSI—Reactive Strength Index, defined as Height (m/s). In the study, the average value of the parameters specific to the jumps performed in each test was taken into account. During the study, the tests were performed and processed on the Opto Jump device and software. In all tests of the experiment monitored through Opto Jump, significant progress was made in the final test compared to the initial one, which demonstrates the efficiency of the physical training program implemented for the development of explosive force, with an impact on the sports performance of elite players. The most relevant results obtained for the left leg regarding the improvement of the explosive force of the lower limbs materialized in the jump height parameter was in the test of five vertical jumps on one leg on the spot, and for the right leg in the tests of: five back and forth jumps and five left/right side jumps. The most significant advances in the study were in the tests, in descending order of their weight: 60 s vertical jumps on both legs; five back-and-forth jumps and five left/right side jumps, five vertical jumps on one leg standing, and BFS vertical jumps.

Troubleshooting a Nonresponder: Guidance for the Strength and Conditioning Coach

Ideally an athlete would continue to improve performance indefinitely over time, however improvement slows as the athlete approaches their genetic limits. Measuring performance is complex—performance may be temporarily depressed following aggressive training for multiple reasons, physiological and psychosocial. This reality may be vexing to the strength and conditioning coach, who, as a service provider, must answer to sport coaches about an athlete’s progress. Recently an evaluation mechanism for strength and conditioning coaches was proposed, in part to help coaches establish their effectiveness within the organization. Without formal guidance and realistic expectations, if an athlete is not bigger, leaner, stronger, etc. as a result of training within a specified timeframe, blame is often placed upon the strength and conditioning coach. The purpose of this article is to explore possible causes of what may be perceived as athlete non-responses to training and to provide guidance for the coach on how to handle those issues within their domain. A process of investigation is recommended, along with resources to assist coaches as they consider a broad range of issues, including enhancing existing testing methods, improving athlete behaviors, and adjusting processes designed to bring about performance improvement.

Short-Term Periodized Programming May Improve Strength, Power, Jump Kinetics, and Sprint Efficiency in Soccer

The purpose of this study was to examine if short-term periodized programming may improve strength, power, jump kinetics, and sprint efficiency in soccer. Seventeen players (19.6 ± 1.6 yrs; 73.8 ± 8.2 kg; 1.77 ± 0.6 m) were divided into two groups based on mean isometric midthigh pull peak force (IPF) (stronger and weaker) and squat jump (SJ) peak power (PP) (higher power and lower power). Eight weaker players were included in the lower power group, while six stronger players were included in the higher power group. Block periodization was adopted to design strength training consisting of 3-week strength endurance and 4-week maximum strength blocks. Performance data included SJ with polyvinyl chloride pipe (SJ0), 20 kgs bar (SJ20), and 40 kgs (SJ40) bar and 20 m sprint across three time points (baseline: T_B; post-block 1: T₁; post-block 2: T₂). Stronger group showed significant increases from T_B to T₂ in SJ20 peak power (PP), net impulse, and allometrically-scaled PP (p = 0.005 to 0.01, ES = 0.32 to 0.49). Weaker group demonstrated moderate to large increases from T_B to T₂ in SJ20, allometrically-scaled peak force (PF), PP, and allometrically-scaled PP (p = <0.001 to 0.04, ES = 1.41 to 1.74). Lower power group showed significant increases from T_B to T₂ in SJ20 allometrically-scaled PF, net impulse, PP, and allometrically-scaled PP (p = <0.001 to 0.026, ES = 1.06 to 2.01). Weaker and less powerful soccer players can benefit from strength-focused training to improve loaded SJ kinetics associating with force production.

Associations of Body Composition, Maximum Strength, Power Characteristics with Sprinting, Jumping, and Intermittent Endurance Performance in Male Intercollegiate Soccer Players

The purpose of this study was to determine the relationships between body composition, strength, power characteristics, sprinting, jumping, and intermittent endurance performance in collegiate male players. Twenty-three players participated (19.7 ± 1.6 yrs; 71.8 ± 7.1 kg; 176.5 ± 5.1 cm). Measurements of interest in body composition included body fat percentage (BF%), lean body mass (LBM), and body mass (BM). Power characteristics were measured with an unloaded squat jump (SJ0) and loaded SJ at 20 kg (SJ20) and 40 kg (SJ40), and unloaded countermovement jump (CMJ0). Power assessments included peak power (PP) and PP allometrically scaled (PPa). Strength characteristics were assessed using isometric mid-thigh pull. Strength assessment included isometric peak force (IPF) and IPF allometrically scaled (IPFa). Performance measures included 10m and 20 m sprint time, CMJ0 jump-height, and Yo-Yo intermittent endurance test level 1 distance. Significant correlations ranging from moderate to very large were found for LBM and CMJ jump height (CM0 JH) (p = 0.01, r = 0.50); BF% and sprint times at 10 m (p = 0.03, r = 0.44) and 20 m (p = 0.02, r = 0.50). PP and PPa from SJ0 and CMJ0 were significantly correlated to 10m sprint time (p < 0.05, r = -0.45 to -0.53) and 20 m sprint time (p < 0.05, r = -0.40 to -0.49). Our findings agree with previous literature in that body composition and power characteristics are directly related to soccer-related performance.

Kinematics and Kinetics of Bulgarian-Bag-Overloaded Sprints in Young Athletes

Background: Effective sprinting requires large acceleration capabilities. To accelerate, large amount of force must be produced and applied effectively. The use of different implements such as sleds and vests can increase the amount of force produced and alter sprinting effectiveness. We propose the use of increasing overload via the Bulgarian Bag (BB) as a means to modify athletes’ sprint and acutely increase force and power production. Methods: 24 young athletes performed three sprints over 20 m in three different conditions: unloaded (BW) and loaded with BB weighing 2.5% (BB2.5) and 5% (BB5) of the athlete’s body mass. Sprint times at 2.5, 5, 10, 15, and 20 m were acquired and used to compute the force–velocity relationship for the sprints. Maximal velocity (V0), peak force (F0), peak power (PP), and decrease in ratio of force (D_RF) were computed. Results: the additional load caused a decrease in sprint times (p < 0.05) and V0 (p = 0.028), conversely no differences were found for F0 (p = 0.21), PP (p = 0.50), and D_RF (p = 0.83). Conclusions: Based on those findings, BB can be an alternative method to effectively overload sprint training toward improving sprinting performance.