For adolescent soccer players, good sprinting and jumping abilities are crucial for their athletic performance. The application of plyometric training on boosting explosive strength in adolescent ...soccer players is contingent upon the maturation phase, which can mediate the training-induced adaptations.
This systematic review and meta-analysis aim to explore the maturation effect of plyometric training on the lower limb explosive power of adolescent soccer players, with vertical countermovement jump (CMJ) and 20-m sprint as the main outcome indicators.
An extensive search of the literature was carried out on various databases including PubMed, Web of Science, Scopus, ProQuest, and the China National Knowledge Infrastructure (CNKI), covering the time period from the establishment of each database to February 6, 2023. The search was conducted using English keywords such as ‘Plyometric,’ ‘Adolescent,’ ‘football,’ and ‘Explosive strength.’ This study utilized the Cochrane risk of bias assessment tool to conduct a standardized quality evaluation of all the included literature. Additionally, the Review Manager 5.4 software was employed to perform data analysis on all the extracted data.
A total of 17 studies involving 681 adolescent soccer players aged 10 to 19 were included. Plyometric training significantly improved CMJ performance across different maturation stages, especially in the post-peak height velocity stage (POST-PHV) MD = 4.35, 95 % CI (2.11, 6.59), P < 0.01, I2 = 60 %. The pre-peak height velocity stage (PRE-PHV) showed the next best improvement MD = 3.00, 95 % CI (1.63, 4.37), while the middle-peak height velocity stage (MID-PHV) showed the least improvement MD = 2.79, 95 % CI (1.16, 4.41), P < 0.01, I2 = 49 %. However, improvements in 20 m sprint ability were only observed in the PRE-PHV MD = −0.06, 95 % CI (−0.12, 0), P < 0.01, I2 = 0 % and MID-PHV MD = −0.18, 95 % CI (−0.27, −0.08), P < 0.01, I2 = 0 % stages.
Plyometric training serves as a potent strategy for boosting the lower limb explosive strength of adolescent soccer players, and the training effect is closely related to the players' biological maturity. Considering biological maturity is a key aspect that this study deems essential for the formulation of effective training programs for these adolescent players.
ABSTRACTVan Hooren, B and Zolotarjova, J. The difference between countermovement and squat jump performancesa review of underlying mechanisms with practical applications. J Strength Cond Res ...31(7)2011–2020, 2017—Two movements that are widely used to monitor athletic performance are the countermovement jump (CMJ) and squat jump (SJ). Countermovement jump performance is almost always better than SJ performance, and the difference in performance is thought to reflect an effective utilization of the stretch-shortening cycle. However, the mechanisms responsible for the performance-enhancing effect of the stretch-shortening cycle are frequently undefined. Uncovering and understanding these mechanisms is essential to make an inference regarding the difference between the jumps. Therefore, we will review the potential mechanisms that explain the better performance in a CMJ as compared with a SJ. It is concluded that the difference in performance may primarily be related to the greater uptake of muscle slack and the buildup of stimulation during the countermovement in a CMJ. Elastic energy may also have a small contribution to an enhanced CMJ performance. Therefore, a larger difference between the jumps is not necessarily a better indicator of high-intensity sports performance. Although a larger difference may reflect the utilization of elastic energy in a small-amplitude CMJ as a result of a well-developed capability to co-activate muscles and quickly build up stimulation, a larger difference may also reflect a poor capability to reduce the degree of muscle slack and build up stimulation in the SJ. Because the capability to reduce the degree of muscle slack and quickly build up stimulation in the SJ may be especially important to high-intensity sports performance, training protocols might concentrate on attaining a smaller difference between the jumps.
Purpose: approbation of a complex of speed-strength characteristics for monitoring the dynamics of strength exercises of the world’s leading armwrestlers weighing over 100 kg.
Material and Methods. ...The study involved the 3 best arm wrestlers in the world weighing over 100 kg (116.00 ± 18.03 kg) in 2017–2020. Four power test exercises have been identified that ensure the performance of a competitive action in arm wrestling: flexion of the fingers, stretch with a hammer, hook and bending the hand. These exercises were performed with the left and right hands. Strength indicators in all test exercises were measured with an FL1K 0.5N, 1000N electric strain gauge dynamometer, Kern & Sohn GmbH (China) with an accuracy class of up to 50 g, fixed on a specialized armwrestling table using a specially made an author’s block device. In the course of statistical analysis, the following parameters were determined and calculated: maximum (F) and relative (F1 = ƩF / m) strength, kg; total strength index in four strength exercises (ƩF = F1 + F2 + F3 + F4), kg; time to reach maximum strength (Ʃt = t1 + t2 + t3 + t4), s; speed-strength index (J = ƩF / Ʃt), kg/ms; average strength, index of four exercises ( = ƩF / 4), kg; total strength gradient of four exercises (Ʃt0,5F), ms; speed-strength index in the first 500 ms (J500 = ƩF500 / Ʃt500), kg/ms; time to reach 1 kg force (t1 = Ʃt0.5F / (0.5×F)), ms/kg; Pearson’s correlation analysis; Factor analysis.
Results. As a result of the study, the main data on the speed-strength indicators of armwrestlers were obtained and analyzed. In the process of testing, according to the indicators of time periods and these efforts of dynamic strength, the features of the manifestation of explosive, fast and slow strength of arm wrestlers weighing over 100 kg were established. Determining the relationship between
strength and speed-strength indicators using factor analysis made it possible to establish two factors that determine the overall variance of the sample. The first factor with a contribution of 70.9 % to the total sample formed the temporal characteristics of effort in test exercises, such as the time to reach maximum effort (r = 0.979), speed-strength index (r = 0.986), force gradient. (r = 0.986) and the time to reach a force of 1 kg (r = 0.979). The second factor with a factor loading of 29.1 % was the maximum force (r = 0.960), the average test strength (r = 0.961) and the achieved force in 500 ms (r = 0.716). Thus, the results of the correlation and factorial analyzes of the strength and speed-strength indicators of armwrestlers weighing more than 100 kg indicate the priority of the temporal characteristics of efforts over strength in a competitive exercise.
Conclusions. The study made it possible to test a complex of speed-strength indicators for monitoring the functional state of the world’s leading armwrestlers weighing over 100 kg, an approved system of criteria for time and power characteristics of efforts in competitive exercises allows you to monitor the state of athletes to monitor and predict success in armwrestling. The author’s device used in the study made it possible to automate the process of measurements with high mobility, as well as immediately create a database
on the power and speed-strength capabilities of armwrestlers with high accuracy.
The evaluation of rate of force development during rapid contractions has recently become quite popular for characterising explosive strength of athletes, elderly individuals and patients. The main ...aims of this narrative review are to describe the neuromuscular determinants of rate of force development and to discuss various methodological considerations inherent to its evaluation for research and clinical purposes. Rate of force development (1) seems to be mainly determined by the capacity to produce maximal voluntary activation in the early phase of an explosive contraction (first 50–75 ms), particularly as a result of increased motor unit discharge rate; (2) can be improved by both explosive-type and heavy-resistance strength training in different subject populations, mainly through an improvement in rapid muscle activation; (3) is quite difficult to evaluate in a valid and reliable way. Therefore, we provide evidence-based practical recommendations for rational quantification of rate of force development in both laboratory and clinical settings.
Play can be considered a part of the social world of both children and adults. Taking into account the playful behavior of young school students and their enjoyment of playing, the judicious ...application (in terms of intensity, volume, application period) of a training program consisting of dynamic games with running content and jumping, will cause a significant increase in the manifestation indices of acceleration speed, agility and explosive strength in primary school students. The subjects of our research are 171 primary school children, of which 90 children are part of the experimental group (G.E.) and 81 of the subjects are part of the control group (G.C.). The results obtained for all the control samples used by the subjects from the two experimental groups confirm the correctness of the methods and means used. The values of the effect size (E.S.) obtained in the subjects of the experimental group (both in the case of girls and boys) confirm that the difference between the averages recorded in the two tests (T.I. and T.F.) is statistically significant.
Abstract
Beattie, K and Ruddock, AD. The role of strength on punch impact force in boxing.
J Strength Cond Res
36(10): 2957–2969, 2022—The ability to punch with a high impact force is beneficial to ...boxers as there is an increased likelihood of success. Punch impact force differentiates between performance level, weight class, gender, and punch type in competitive boxers. Although technique is likely to play a major role in punch impact force, the capabilities of the neuromuscular system may also be a limiting factor. This review examines the role of strength on punch impact force in amateur and professional boxers. The maximal strength qualities of the lower body, as well as explosive strength qualities of both the upper and lower body, are largely associated with punch impact force in elite amateur boxers. Specifically, elite amateur boxers who punch with “high” impact forces have greater levels of lower-body maximal strength and explosive strength when compared with elite amateurs who punch with “low” impact forces. However, the maximal strength capabilities of the upper body are not associated with punch impact force and does not differentiate between elite boxers who punch with “high” and “low” impact forces. Therefore, based off the present evidence, this review recommends that for boxers who aim to develop their punch impact force, it may be advantageous to emphasize both maximal and explosive strength development of the legs, with only an explosive strength focus in the upper body. However, it is important to highlight that, to date, there are a lack of experimental studies in both elite amateur and professional boxing. Furthermore, there is a dearth of research in female boxing. Future experimental studies are needed to infer causality regarding the role that strength training has on punch impact force in both elite amateur and professional boxers.
The growth promoting effects of eccentric (ECC) contractions are well documented but it is unknown if the rate of stretch per se plays a role in such muscular responses in healthy aging human ...skeletal muscle. We tested the hypothesis that exercise training of the quadriceps muscle with low rate ECC and high rate ECC contractions in the form of stretch-shortening cycles (SSCs) but at equal total mechanical work would produce rate-specific adaptations in healthy old males age 60–70. Both training programs produced similar improvements in maximal voluntary isometric (6%) and ECC torque (23%) and stretch-shortening cycle function (reduced contraction duration 24% and enhanced elastic energy storage 12%) (p<0.05). The rate of torque development increased 30% only after SSC exercise (p<0.05). Resting testosterone and cortisol levels were unchanged but after each program the acute exercise-induced cortisol levels were 12–15% lower (p<0.05). Both programs increased quadriceps size 2.5% (p<0.05). It is concluded that both ECC and SSC exercise training produces favorable adaptations in healthy old males' quadriceps muscle. Although the rate of muscle tension during the SSC vs. ECC contractions was about 4-fold greater, the total mechanical work seems to regulate the hypetrophic, hormonal, and most of the mechanical adaptations. However, SSC exercise was uniquely effective in improving a key deficiency of aging muscle, i.e., its ability to produce force rapidly.
•Old males exercised with either eccentric or stretch-shortening cycle contractions.•Maximal voluntary strength improved uniformly.•Endocrine and hypertrophic adaptations were stretch rate-independent.•Stretch-shortening cycle function improved similarly after the two interventions.•The stretch-shortening cycle exercise produced superior gains in explosive strength.
Studies examining acute, high‐speed movement performance enhancement following intense muscular contractions (frequently called “post‐activation potentiation”; PAP) often impose a limited warm‐up, ...compromizing external validity. In the present study, the effects on countermovement vertical jump (CMJ) performance of back squat exercises performed with or without elastic bands during warm‐up were compared. After familiarization, fifteen active men visited the laboratory on two occasions under randomized, counterbalanced experimental squat warm‐up conditions: (a) free‐weight resistance (FWR) and (b) variable resistance (VR). After completing a comprehensive task‐specific warm‐up, three maximal CMJs were performed followed by three back squat repetitions completed at 85% of 1‐RM using either FWR or VR Three CMJs were then performed 30 seconds, 4 minutes, 8 minutes, and 12 minutes later. During CMJ trials, hip, knee, and ankle joint kinematics, ground reaction force data and vastus medialis, vastus lateralis, and gluteus maximus electromyograms (EMG) were recorded simultaneously using 3D motion analysis, force platform, and EMG techniques, respectively. No change in any variable occurred after FWR (P > 0.05). Significant increases (P < 0.05) were detected at all time points following VR in CMJ height (5.3%‐6.5%), peak power (4.4%‐5.9%), rate of force development (12.9%‐19.1%), peak concentric knee angular velocity (3.1%‐4.1%), and mean concentric vastus lateralis EMG activity (27.5%‐33.4%). The lack of effect of the free‐weight conditioning contractions suggests that the comprehensive task‐specific warm‐up routine mitigated any further performance augmentation. However, the improved CMJ performance following the use of elastic bands is indicative that specific alterations in force‐time properties of warm‐up exercises may further improve performance.
In the study, the acute effects of two different concurrent training models including high intensity interval training (HIIT) and high intensity interval functional training (HIFT) plus strength ...training (S) on physiological indicators (lactate and heart rate) and performance (balance and explosive power) parameters were examined in soccer players. A total of 13 moderately active young soccer players (19.92; ±1.44 years) participated in the study. In the study, body composition measurements, heart rate, lactate, explosive strength measurement and balance testing were measured. Training models (S+HIIT-S+HIFT) were applied sequentially with a crossover design. The training sessions were conducted with a three-day interval. Parameters were analyzed with SPSS24 (SPSS Inc., Chicago, IL, USA). Repeated Measure Analysis of Variance (ANOVA) was used for repeated measures and Bonferroni Correction was used for pairwise comparisons. Significance level was accepted as p
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