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Several warm-up activities are used to prepare soccer players for training and games. However, few studies have focused on comparing different activities (strength vs. stretching) in young and amateur athletes, especially for performance improvement in explosive actions. Thus, in order to compare the effect of four conditioning activities on jump and sprint performances, 12 soccer athletes (age: 19±0.8; weight (kg): 72.8±8.0; height (cm): 180±6.7) performed four warm-up activities: strength exercise (cluster system), combined exercise, plyometric exercise, and static stretching (control). The countermovement jump (CMJ) and 30-meter run (30-m Sprint) were performed 10 min after each experimental condition. A ONE-WAY ANOVA test of repeated measures was conducted with a Tukey's post-hoc test to compare the conditions. The strength conditioning activity protocol (33.68±2.87) showed a significant difference for the CMJ from static stretching (30.96±3.16) (p>0.05). There were significant differences regarding the 30-m Sprint test between strength conditioning (4.72±0.19) and combined activities (4.71±0.21) compared to static stretching (4.84±0.21) (p>0.05). In conclusion, the combined conditioning activity and strength protocols can be chosen in warm-up activities instead of static stretching (control condition) for improved immediate sprint and jump abilities in amateur soccer players.

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BACKGROUND: The reactive strength index (RSI) is meaningfully associated with independent markers of athletic (e.g., linear sprint speed) and neuromuscular performance [e.g., stretch-shortening cycle (SSC)]. Plyometric jump training (PJT) is particularly suitable to improve the RSI due to exercises performed in the SSC. However, no literature review has attempted to meta-analyse the large number of studies regarding the potential effects of PJT on the RSI in healthy individuals across the lifespan. OBJECTIVE: The aim of this systematic review with meta-analysis was to examine the effects of PJT on the RSI of healthy individuals across the lifespan compared with active/specific-active controls. METHODS: Three electronic databases (PubMed, Scopus, Web of Science) were searched up to May 2022. According to the PICOS approach, the eligibility criteria were: (1) healthy participants, (2) PJT interventions of ≥ 3 weeks, (3) active (e.g., athletes involved in standard training) and specific-active (e.g., individuals using heavy resistance training) control group(s), (4) a measure of jump-based RSI pre-post training, and (5) controlled studies with multi-groups in randomised and non-randomised designs. The Physiotherapy Evidence Database (PEDro) scale was used to assess the risk of bias. The random-effects model was used to compute the meta-analyses, reporting Hedges' g effect sizes (ES) with 95% confidence intervals (95% CIs). Statistical significance was set at p ≤ 0.05. Subgroup analyses were performed (chronological age; PJT duration, frequency, number of sessions, total number of jumps; randomization). A meta-regression was conducted to verify if PJT frequency, duration, and total number of sessions predicted the effects of PJT on the RSI. Certainty or confidence in the body of evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Potential adverse health effects derived from PJT were researched and reported. RESULTS: Sixty-one articles were meta-analysed, with a median PEDro score of 6.0, a low risk of bias and good methodological quality, comprising 2576 participants with an age range of 8.1-73.1 years (males, ~ 78%; aged under 18 years, ~ 60%); 42 studies included participants with a sport background (e.g., soccer, runners). The PJT duration ranged from 4 to 96 weeks, with one to three weekly exercise sessions. The RSI testing protocols involved the use of contact mats (n = 42) and force platforms (n = 19). Most studies reported RSI as mm/ms (n = 25 studies) from drop jump analysis (n = 47 studies). In general, PJT groups improved RSI compared to controls: ES = 0.54, 95% CI 0.46-0.62, p < 0.001. Training-induced RSI changes were greater (p = 0.023) for adults [i.e., age ≥ 18 years (group mean)] compared with youth. PJT was more effective with a duration of > 7 weeks versus ≤ 7 weeks, > 14 total PJT sessions versus ≤ 14 sessions, and three weekly sessions versus < three sessions (p = 0.027-0.060). Similar RSI improvements were noted after ≤ 1080 versus > 1080 total jumps, and for non-randomised versus randomised studies. Heterogeneity (I2) was low (0.0-22.2%) in nine analyses and moderate in three analyses (29.1-58.1%). According to the meta-regression, none of the analysed training variables explained the effects of PJT on RSI (p = 0.714-0.984, R2 = 0.0). The certainty of the evidence was moderate for the main analysis, and low-to-moderate across the moderator analyses. Most studies did not report soreness, pain, injury or related adverse effects related to PJT. CONCLUSIONS: The effects of PJT on the RSI were greater compared with active/specific-active controls, including traditional sport-specific training as well as alternative training interventions (e.g., high-load slow-speed resistance training). This conclusion is derived from 61 articles with low risk of bias (good methodological quality), low heterogeneity, and moderate certainty of evidence, comprising 2576 participants. PJT-related improvements on RSI were greater for adults versus youths, after > 7 training weeks versus ≤ 7 weeks, with > 14 total PJT versus ≤ 14 sessions, and with three versus < three weekly sessions.

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ABSTRACT The aim of the present study was to find out the effect of varied plyometric training (land plyometric training, aqua plyometric training and weighted vest aqua-plyometric training) on anaerobic power of school athletes. A total of forty eight (n= 48) district level school athletes were randomly selected. All the subjects were divided into four equal groups: i) land plyometric training group (n=12), ii) aqua plyometric training group (n=12), iii) aqua-plyometric training with weighted vest group (n=12) and iv) control group (n=12). The varied plyometric training was intervened for fourteen weeks in the respective training groups. In the present study, anaerobic power was considered as the dependent variable, and it was measured by Margaria-Kalamen power test. To draw statistical inferences on anaerobic power among the groups in pre and post intervention conditions, ANCOVA was used, followed by Tukey's LSD post-hoc test. The significance of the means was tested at the 0.05 level. Different plyometric training groups improved significantly with respect to the control group in anaerobic power. Therefore, various plyometric training was found as an effective means for developing anaerobic power. A significant difference was also observed between the aqua-plyometric training with weighted vest group and land plyometric training group in anaerobic power. However, rest of the experimental groups didn't differ significantly. Aqua-plyometric training with weighted vest is a more effective training method than land plyometric training for improving the anaerobic power of the school athletes.

RESUMO O objetivo do presente estudo foi descobrir o efeito do treinamento pliométrico variado (treinamento pliométrico terrestre, treinamento aquapliométrico e treinamento aquapliométrico com colete ponderado) na potência anaeróbica de atletas escolares. Um total de quarenta e oito (n= 48) atletas escolares de nível distrital foram selecionados aleatoriamente. Todos os sujeitos foram divididos em quatro grupos iguais: i) grupo treinamento pliométrico terrestre (n=12), ii) grupo treinamento aquapliométrico (n=12), iii) grupo treinamento aquapliométrico com colete ponderado (n=12) e iv) grupo controle (n=12). O treino pliométrico variado foi intervencionado durante quatorze semanas nos respectivos grupos de treino. No presente estudo, a potência anaeróbia foi considerada como variável dependente e foi mensurada pelo teste de potência de Margaria-Kalamen. Para fazer inferências estatísticas sobre a potência anaeróbica entre os grupos nas condições pré e pós-intervenção, foi utilizada a ANCOVA, seguida do teste post-hoc de Tukey LSD. A significância das médias foi testada no nível 0,05. Diferentes grupos de treinamento pliométrico melhoraram significativamente em relação ao grupo controle na potência anaeróbica. Portanto, vários treinamentos pliométricos foram encontrados como um meio eficaz para o desenvolvimento da potência anaeróbica. Uma diferença significativa também foi observada entre o grupo de treinamento aquapliométrico com colete ponderado e o grupo de treinamento pliométrico terrestre na potência anaeróbica. No entanto, o resto dos grupos experimentais não diferiram significativamente. O treinamento aquapliométrico com colete ponderado é um método de treinamento mais eficaz do que o treinamento pliométrico terrestre para melhorar a potência anaeróbica dos atletas escolares.

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This systematic review and meta-analysis aimed to assess the effects of jump training (JT) on measures of physical fitness and athletic performances in endurance runners. Controlled studies which involved healthy endurance runners, of any age and sex, were considered. A random-effects model was used to calculate effect sizes (ES; Hedge's g). Means and standard deviations of outcomes were converted to ES with alongside 95% confidence intervals (95%CI). Twenty-one moderate-to-high quality studies were included in the meta-analysis, and these included 511 participants. The main analyses revealed a significant moderate improvement in time-trial performance (i.e. distances between 2.0 and 5.0 km; ES = 0.88), without enhancements in maximal oxygen consumption (VO2max), velocity at VO2max, velocity at submaximal lactate levels, heart rate at submaximal velocities, stride rate at submaximal velocities, stiffness, total body mass or maximal strength performance. However, significant small-to-moderate improvements were noted for jump performance, rate of force development, sprint performance, reactive strength, and running economy (ES = 0.36-0.73; p < 0.001 to 0.031; I2 = 0.0% to 49.3%). JT is effective in improving physical fitness and athletic performance in endurance runners. Improvements in time-trial performance after JT may be mediated through improvements in force generating capabilities and running economy.

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This meta-analysis aimed to assess the effects of plyometric jump training (PJT) on volleyball players' vertical jump height (VJH), comparing changes with those observed in a matched control group. A literature search in the databases of PubMed, MEDLINE, Web of Science, and SCOPUS was conducted. Only randomized-controlled trials and studies that included a pre-to-post intervention assessment of VJH were included. They involved only healthy volleyball players with no restrictions on age or sex. Data were independently extracted from the included studies by two authors. The Physiotherapy Evidence Database scale was used to assess the risk of bias, and methodological quality, of eligible studies included in the review. From 7,081 records, 14 studies were meta-analysed. A moderate Cohen's d effect size (ES = 0.82, p <0.001) was observed for VJH, with moderate heterogeneity (I2 = 34.4%, p = 0.09) and no publication bias (Egger's test, p = 0.59). Analyses of moderator variables revealed no significant differences for PJT program duration (≤8 vs. >8 weeks, ES = 0.79 vs. 0.87, respectively), frequency (≤2 vs. >2 sessions/week, ES = 0.83 vs. 0.78, respectively), total number of sessions (≤16 vs. >16 sessions, ES = 0.73 vs. 0.92, respectively), sex (female vs. male, ES = 1.3 vs. 0.5, respectively), age (≥19 vs. <19 years of age, ES = 0.89 vs. 0.70, respectively), and volume (>2,000 vs. <2,000 jumps, ES = 0.76 vs. 0.79, respectively). In conclusion, PJT appears to be effective in inducing improvements in volleyball players' VJH. Improvements in VJH may be achieved by both male and female volleyball players, in different age groups, with programs of relatively low volume and frequency. Though PJT seems to be safe for volleyball players, it is recommended that an individualized approach, according to player position, is adopted with some players (e.g. libero) less prepared to sustain PJT loads.

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Ramirez-Campillo, R, Alvarez, C, Gentil, P, Loturco, I, Sanchez-Sanchez, J, Izquierdo, M, Moran, J, Nakamura, FY, Chaabene, H, and Granacher, U. Sequencing effects of plyometric training applied before or after regular soccer training on measures of physical fitness in young players. J Strength Cond Res 34(7): 1959-1966, 2020-To compare the effects of short-term (i.e., 7 weeks) plyometric jump training applied before (PJT-B) or after (PJT-A) soccer practice on components of physical fitness in young soccer players, a single-blind randomized controlled trial was conducted. Postpubertal boys aged 17.0 ± 0.5 years were allocated to 3 groups: PJT-B (n = 12), PJT-A (n = 14), and control (CON; n = 12). The outcome measures included tests to evaluate 20-m speed, standing long jump (SLJ), squat jump (SJ), countermovement jump (CMJ), and drop jump (DJ), 20-m multistage shuttle run endurance (MSSRT), and Illinois change-of-direction speed (ICODT). Although the CON performed soccer-specific training, the PJT-A and PJT-B groups conducted the same soccer-specific sessions but replaced ∼11% of their time with plyometric training. The PJT-B group performed plyometric exercises after a warm-up program, and the PJT-A group conducted plyometric exercises ∼10 minutes after the completion of soccer training. Analyses of variance were used to detect differences between groups in all variables for pretraining and posttraining tests. Main effects of time (all p < 0.01; d = 0.19-0.79) and group × time interactions (all p ≤ 0.05; d = 0.17-0.76) were observed for all examined variables. Post hoc analyses revealed significant increases in the PJT-B group (SLJ: 9.4%, d = 1.7; CMJ: 11.2%, d = 0.75; 20-m MSSRT: 9.0%, d = 0.77) and the PJT-A group (SLJ: 3.1%, d = 0.7; CMJ: 4.9%, d = 0.27; 20-m MSSRT: 9.0%, d = 0.76). Post hoc analyses also revealed significant increases in the PJT-B group (20-m speed: -7.4%, d = 0.75; 20-cm DJ reactive strength index: 19.1%, d = 1.4; SJ: 6.3%, d = 0.44; ICODT results: -4.2%, d = 1.1). In general, our study revealed that plyometric training is effective in improving measures of physical fitness in young male soccer players when combined with regular soccer training. More specifically, larger training-induced effects on physical fitness were registered if plyometric training was conducted before soccer-specific training.

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Andrade, DC, Manzo, O, Beltrán, AR, Álvarez, C, Del Rio, R, Toledo, C, Moran, J, and Ramirez-Campillo, R. Kinematic and neuromuscular measures of intensity during plyometric jumps. J Strength Cond Res 34(12): 3395-3402, 2020-The aim of this study was to assess jumping performance and neuromuscular activity in lower limb muscles after drop jumps (DJs) from different drop heights (intensity) and during continuous jumping (fatigue), using markers such as reactive strength, jump height, mechanical power and surface electromyography (sEMG). The eccentric (EC) and concentric (CON) sEMG from the medial gastrocnemius (MG), biceps femoris (BF), and rectus (R) muscles were assessed during all tests. In a cross-sectional, randomized study, 11 volleyball players (age 24.4 ± 3.2 years) completed 20-90-cm (DJ20 to DJ90) DJs and a 60-second continuous jump test. A 1-way analysis of variance test was used for comparisons, with Sidak post hoc. The α level was <0.05. Reactive strength was greater for DJ40 compared with DJ90 (p ≤ 0.05; effect size (ES): 1.27). In addition, jump height was greater for DJ40 and DJ60 compared with DJ20 (p ≤ 0.05; ES: 1.26 and 1.27, respectively). No clear pattern of neuromuscular activity appeared during DJ20 to DJ90: some muscles showed greater, lower, or no change with increasing heights for both agonist and antagonist muscles, as well as for EC and CON activity. Mechanical power, but not reactive strength, was reduced in the 60-second jump test (p ≤ 0.05; ES: 3.46). No changes were observed in sEMG for any muscle during the EC phase nor for the R muscle during the CON phase of the 60-second jump test. However, for both MG and BF, CON sEMG was reduced during the 60-second jump test (p ≤ 0.05; ES: 5.10 and 4.61, respectively). In conclusion, jumping performance and neuromuscular markers are sensitive to DJ height (intensity), although not in a clear dose-response fashion. In addition, markers such as mechanical power and sEMG are, especially sensitive to the effects of continuous jumping (fatigue). Therefore, increasing the drop height during DJ does not ensure a greater training intensity and a combination of different drop heights may be required to elicit adaptations.

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Ramirez-Campillo, R, Álvarez, C, García-Pinillos, F, García-Ramos, A, Loturco, I, Chaabene, H, and Granacher, U. Effects of combined surfaces vs. single-surface plyometric training on soccer players' physical fitness. J Strength Cond Res 34(9): 2644-2653, 2020-The aim of this study was to compare the effects of a 8-week plyometric jump training (PJT) performed on different surfaces (grass, land-dirt, sand, wood, gym mat, and tartan-track) vs. a single-surface PJT (grass) on components of physical fitness (muscle power, speed, and change-of-direction speed [CODS] tasks) and sport-specific performance (i.e., maximal kicking velocity [MKV]) in male soccer players aged 11-14 years. Athletes were randomly assigned to a combined surfaces PJT (PJTc, n = 8), a single-surface PJT (PJTs, n = 8), or an active control (CON, n = 7). Although the PJT group trained on grass, the PJTc trained on 6 different surfaces and equally distributed the total jump volume according to the surface. Pre-post tests were conducted on grass. Significant main effects of time were observed for the countermovement jump, the standing-long-jump, the 20-cm drop jump, 30-m sprint time, CODS, and MKV (all p < 0.001; d = 0.53-0.87). Group × time interactions were identified for all jump tests, MKV, 30-m sprint time, and CODS (all p < 0.001; d = 0.58-0.71) in favor of PJTc. No significant pre-post changes were observed in the CON (all p > 0.05; d = 0.07-0.1). In conclusion, PJT is effective in improving physical fitness in young soccer players when conducted in combination with regular soccer training. Although general fitness testing and PJTs were performed on grass, larger physical fitness improvements were found after PJTc. Thus, PJTc is recommended, as it provides a better overload stimulus compared with more conventional training overload (e.g., increase in training volume or intensity). Future studies still have to address the underlying physiological adaptations after PJTc.

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ABSTRACT This study investigated the effect of plyometric training (PT) on vertical jump in young basketball athletes. A total of 39 athletes were divided into two experimental groups (male - MEG and female - FEG) and two control groups (male - MCG and female - FCG). The My Jump app quantified jump height from flight time. Data analysis relied on repeated measures ANOVA, Cohen's effect size (ES) and magnitude-based inference, with a level of significance of p≤ 0.05. Results showed that the MEG and the MCG obtained significant improvements in the countermovement jump (CMJ) and in the squat jump (SJ). The FEG and the FCG presented significant differences in the SJ, with interaction effect; as for the CMJ, only the FEG showed improvements with interaction effect. Concerning ES, the MEG showed greater effects in the CMJ and in the SJ compared to the MCG; within the FEG, the ES was greater only for the CMJ in comparison with the FCG. Qualitative responses showed that PT is likely beneficial for the MEG, whereas for the FEG it is likely beneficial in the SJ, and very likely beneficial in the CMJ. It is concluded that PT brought about positive effects on the MEG and on the FEG, both in the CMJ and in the SJ. In the control groups, both obtained significant improvements in the SJ, but only the MCG showed an improvement in the CMJ. Furthermore, results were better in the MEG and in the FEG compared to the MGC and to the FCG. Thus, PT is suitable for vertical jump enhancement in young basketball athletes.

RESUMO Este estudo investigou o efeito do treinamento pliométrico (TP) no salto vertical em atletas jovens de basquete. Participaram 39 atletas, divididos em dois grupos experimentais (masculino - GEM e feminino - GEF) e dois grupos controle (masculino - GCM e feminino - GCF). O aplicativo My Jump quantificou a altura do salto a partir do tempo de voo. Para análise dos dados utilizou-se anova de medidas repetidas, tamanho de efeito de Cohen (TE) e a inferência baseada na magnitude, com nível de significância (p≤ 0,05). Os resultados indicam que o GEM e GCM apresentaram melhoras significativas no countermovement jump (CMJ) e squart jump (SJ). O GEF e GCF apresentaram diferenças significativas no SJ com efeito de interação, no CMJ apenas o GEF apresentou melhoras com efeito de interação. No TE, o GEM apresentou maiores efeitos no CMJ e SJ quando comparado ao GCM, no GEF, o TE foi maior somente no CMJ em relação ao GCF. As respostas qualitativas mostraram que o TP é provavelmente benéfico no GEM, já no GEF, mostrou que é provavelmente benéfico no SJ e muito provavelmente benéfico no CMJ. Conclui-se que o TP promoveu efeitos positivos no GEM e GEF, tanto no CMJ quanto no SJ. Nos grupos controles, ambos obtiveram melhorias significativas no SJ, porém no CMJ, somente o GCM apresentou aumento. Ademais, os resultados foram maiores no GEM e GEF em comparação com o GCM e GCF. Assim, o TP é indicado para potencializar o salto vertical em atletas jovens de basquete.

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The effects of plyometric jump training on the physical fitness of male youth (age = 10-17 years) soccer players was examined in relation to inter-set recovery intervals and the maturity of the players in a single-blind, randomized-and controlled crossover trial. Jumping tests and kicking velocities were measured before (T0), after a 6 week control period (T1), after 6 weeks of plyometrics (T2), after 6 weeks of wash-out (T3), and after a further 6 weeks of plyometrics (T4). Subjects were divided into pre- and post- peak-height-velocity (PHV) groups, and were randomly assigned to 30 s or 120 s inter-set intervals during periods T2 and T4. Any changes in jumping and maximum kicking velocities during T1 and T3, had trivial effect sizes (0.01-0.15), but small to moderate improvements (effect size = 0.20-0.99) were observed in both groups during T2 and T4. Gains in pre-PHV players were similar for the two inter-set intervals, but gains in post-PHV players were greater (p < 0.05) with an inter-set recovery of 120 s than with a 30 s recovery. We conclude that plyometric jump training improves the physical fitness of adolescents, irrespective of their maturity, but that in older individuals gains are greater with a longer inter-set recovery interval.

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OBJECTIVE: This study aimed to verify the acute and prolonged effects of stretch-shortening cycle exercise (SSC) on performance and neuromuscular function following a 4-km cycling time trial (4-km TT). METHODS: On separate days, individuals performed a 4-km TT without any previous exercise (CON), immediately (ACUTE) and 48 h after (PROL) SSC protocol (i.e., 100-drop jumps). Neuromuscular function was measured at baseline SSC (baseline), before (pre-TT) and after (post-TT) 4-km TT. Muscle soreness and inflammatory responses also were assessed. RESULTS: The endurance performance was impaired in both ACUTE (- 2.3 ± 1.8%) and PROL (- 1.8 ± 2.4%) compared with CON. The SSC protocol caused also an acute reduction in neuromuscular function, with a greater decrease in potentiated quadriceps twitch-force (Qtw.pot - 49 ± 16%) and voluntary activation (VA - 6.5 ± 7%) compared for CON and PROL at pre-TT. The neuromuscular function was fully recovered 48 h after SSC protocol. Muscle soreness and IL-10 were elevated only 48 h after SSC protocol. At post-TT, Qtw.pot remained lower in ACUTE (- 52 ± 14%) compared to CON (- 29 ± 7%) and PROL (- 31 ± 16%). CONCLUSION: These findings demonstrate that impairment in endurance performance induced by prior SSC protocol was mediated by two distinct mechanisms, where the acute impairment was related to an exacerbated degree of peripheral and central fatigue, and the prolonged impairment was due to elevated perceived muscle soreness.

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A pliometria utiliza a capacidade reativa do sistema neuromuscular para aumentar a potência do movimento partindo de uma contração excêntrica para uma concêntrica. A isometria referese a uma modalidade estática de treinamento, ou seja, não há alteração no comprimento da fibra muscular. O handebol é uma modalidade esportiva coletiva que envolve uma grande quantidade e variedade de movimentação associada à manipulação de bola e interação com outros atletas. Em termos de movimentação, o handebol pode ser considerado um esporte completo, pois utiliza uma rica combinação das habilidades motoras fundamentais e "naturais" do repertório motor do ser humano. O objetivo da pesquisa é analisar a influência de 4 semanas de treinamento pliométrico e isométrico na força explosiva de jovens atletas de handebol. A amostra contou com 10 mulheres, com média de idade de 16,1 ± 0,56 anos, praticantes de handebol há pelo menos três meses. O protocolo de avaliação utilizado foi: salto horizontal (SH) para mensurar força explosiva de membro inferior. As meninas foram divididas em dois grupos estatisticamente iguais, o grupo pliométrico (GP) e o isométrico (GI). Os dados foram analisados através de testet pareado e Effect Size (magnitude de efeito), além do manual Proesp. Inicialmente os testes apresentaram os seguintes resultados: o GP mostrou 1,32 ± 0,13m no SH e o GI 1,41 ± 0,10m. Após quatro semanas de treinamento foram refeitos os testes e o GP evidenciou 1,37 ± 0,08m no SH e o GI 1,43 ± 0,09m. Estatisticamente as mudanças não se apresentaram significativas, a magnitude do efeito os resultados de força explosiva de membros inferiores mostraramse superficiais. Concluise então que apesar de estatisticamente insignificantes, ambos os métodos apresentam pequena evolução na força explosiva de membros inferiores, e cabe analisar maior tempo dos métodos nesses ganhos e também analisar uma proposta concomitante entre ambos os métodos

Plyometrics uses the reactive capacity of the neuromuscular system to increase the power of movement from an eccentric to a concentric contraction. Isometry refers to a static mode of training, ie there is no change in muscle fiber length. Handball is a collective sport that involves a large amount and variety of movement associated with ball manipulation and interaction with other athletes. In terms of movement, handball can be considered a complete sport because it uses a rich combination of fundamental and "natural" motor skills of the human motor repertoire. The aim of this research is to analyze the influence of a 4 week plyometric and isometric training on the explosive strength of young handball athletes. The sample consisted of 10 women, with an average age of 16.1 ± 0.56 years, who had been practicing handball for at least three months. The evaluation protocol used was: horizontal jump (HS) to measure lower limb explosive strength. The girls were divided into two statistically equal groups, the plyometric group (GP) and the isometric group (GI). Data were analyzed using paired ttest and Effect Size, as well as the Proesp manual. Initially the tests presented the following results: GP showed 1.32 ± 0.13m in HS and GI 1.41 ± 0.10m. After four weeks of training, the tests were redone and the GP showed 1.37 ± 0.08m in HS and the GI 1.43 ± 0.09m. Statistically the changes were not significant, the magnitude of the effect and the lower explosive strength results were superficial. It is concluded that, although statistically insignificant, both methods present little evolution in the explosive force of lower limbs, and it is necessary to further analyze the methods in these gains and also to analyze the concurrent proposal between both methods.

La pliometría utiliza la capacidad reactiva del sistema neuromuscular para aumentar el poder de movimiento de una contracción excéntrica a una concéntrica. La isometría se refiere a un modo estático de entrenamiento, es decir, no hay cambios en la longitud de la fibra muscular. El balonmano es un deporte colectivo que involucra una gran cantidad y variedad de movimientos asociados con la manipulación del balón y la interacción con otros atletas. En términos de movimiento, el balonmano puede considerarse un deporte completo porque utiliza una rica combinación de las habilidades motoras fundamentales y "naturales" del repertorio motor humano. El objetivo de esta investigación es analizar la influencia de 4 semanas de entrenamiento pliométrico e isométrico en la fuerza explosiva de los jóvenes atletas de balonmano. La muestra consistió en 10 mujeres, con una edad promedio de 16.1 ± 0.56 años, que habían practicado balonmano durante al menos tres meses. El protocolo de evaluación utilizado fue: salto horizontal (HS) para medir la fuerza explosiva de la extremidad inferior. Las niñas se dividieron en dos grupos estadísticamente iguales, el grupo pliométrico (GP) y el grupo isométrico (GI). Los datos se analizaron usando la prueba t pareada y el Tamaño del efecto, así como el manual Proesp. Inicialmente, las pruebas presentaron los siguientes resultados: GP mostró 1.32 ± 0.13m en HS y GI 1.41 ± 0.10m. Después de cuatro semanas de entrenamiento, las pruebas se rehicieron y el GP mostró 1.37 ± 0.08m en HS y el GI 1.43 ± 0.09m. Estadísticamente, los cambios no fueron significativos, la magnitud del efecto y los resultados de menor fuerza explosiva fueron superficiales. Se concluye que, aunque estadísticamente insignificante, ambos métodos presentan poca evolución en la fuerza explosiva de las extremidades inferiores, y es necesario analizar un mayor tiempo de los métodos en estas ganancias y también analizar una propuesta concurrente entre ambos métodos.

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Ramirez-Campillo, R, Alvarez, C, García-Pinillos, F, Sanchez-Sanchez, J, Yanci, J, Castillo, D, Loturco, I, Chaabene, H, Moran, J, and Izquierdo, M. Optimal reactive strength index: is it an accurate variable to optimize plyometric training effects on measures of physical fitness in young soccer players? J Strength Cond Res 32(4): 885-893, 2018-This study aimed to compare the effects of drop-jump training using a fixed drop-box height (i.e., 30-cm [FIXED]) vs. an optimal (OPT) drop-box height (i.e., 10-cm to 40-cm: generating an OPT reactive strength index [RSI]) in youth soccer players' physical fitness. Athletes were randomly allocated to a control group (n = 24; age = 13.7 years), a fixed drop-box height group (FIXED, n = 25; age = 13.9 years), or an OPT drop-box height group (OPT, n = 24; age = 13.1 years). Before and after 7 weeks of training, tests for the assessment of jumping (countermovement jump [CMJ], 5 multiple bounds), speed (20-m sprint time), change of direction ability (CODA [Illinois test]), strength {RSI and 5 maximal squat repetition test (5 repetition maximum [RM])}, endurance (2.4-km time trial), and kicking ability (maximal kicking distance) were undertaken. Analyses revealed main effects of time for all dependent variables (p < 0.001, d = 0.24-0.72), except for 20-m sprint time. Analyses also revealed group × time interactions for CMJ (p < 0.001, d = 0.51), depth jump (DJ) (p < 0.001, d = 0.30), 20-m sprint time (p < 0.001, d = 0.25), CODA (p < 0.001, d = 0.22), and 5RM (p < 0.01, d = 0.16). Post hoc analyses revealed increases for the FIXED group (CMJ: 7.4%, d = 0.36; DJ: 19.2%, d = 0.49; CODA: -3.1%, d = -0.21; 5RM: 10.5%, d = 0.32) and the OPT group (CMJ: 16.7%, d = 0.76; DJ: 36.1%, d = 0.79; CODA: -4.4%, d = -0.34; 5RM: 18.1%, d = 0.47). Post hoc analyses also revealed increases for the OPT group in 20-m sprint time (-3.7%, d = 0.27). Therefore, to maximize the effects of plyometric training, an OPT approach is recommended. However, using adequate fixed drop-box heights may provide a rational and practical alternative.

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Recently, there has been a proliferation of published articles on the effect of plyometric jump training, including several review articles and meta-analyses. However, these types of research articles are generally of narrow scope. Furthermore, methodological limitations among studies (e.g., a lack of active/passive control groups) prevent the generalization of results, and these factors need to be addressed by researchers. On that basis, the aims of this scoping review were to (1) characterize the main elements of plyometric jump training studies (e.g., training protocols) and (2) provide future directions for research. From 648 potentially relevant articles, 242 were eligible for inclusion in this review. The main issues identified related to an insufficient number of studies conducted in females, youths, and individual sports (~ 24.0, ~ 37.0, and ~ 12.0% of overall studies, respectively); insufficient reporting of effect size values and training prescription (~ 34.0 and ~ 55.0% of overall studies, respectively); and studies missing an active/passive control group and randomization (~ 40.0 and ~ 20.0% of overall studies, respectively). Furthermore, plyometric jump training was often combined with other training methods and added to participants' daily training routines (~ 47.0 and ~ 39.0% of overall studies, respectively), thus distorting conclusions on its independent effects. Additionally, most studies lasted no longer than 7 weeks. In future, researchers are advised to conduct plyometric training studies of high methodological quality (e.g., randomized controlled trials). More research is needed in females, youth, and individual sports. Finally, the identification of specific dose-response relationships following plyometric training is needed to specifically tailor intervention programs, particularly in the long term.

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BACKGROUND: Parameters related to the anaerobic capacity and power may be important for the performance of many sports whose skills are related to high-intensity and short-duration efforts. Although plyometric training (PT) has been widely used in the regular strength and conditioning programs of young athletes, its effects on anaerobic performance are still controversial. Therefore, the purpose of the present study was to evaluate the effects of PT in anaerobic performance in young athletes. METHODS: Twenty-nine adolescent athletes participated in this 10-week study. Baseline and post intervention testing included Flying Start 30 m Sprint Test (F30), 1600 m, and Running-based Anaerobic Sprint Test (RAST). Subjects were divided in two groups: one completed only their regular training sessions, thus serving as the control (CON, N.=15), whereas the other performed the regular training plus twice-weekly low-volume plyometric training (PLYO, N.=14). RESULTS: PLYO groups had significant increases in all variables analyzed. The novel findings were the increase in F30 performance (4.22% for PLYO vs. 1.08% for CON), the decreases in Fatigue Index (9.9% for PLYO vs. 1.53% for CON), and increases in minimum (19.41% for PLYO vs. 0.29 for CON), mean (14.7% for PLYO vs. 0.16% for CON) and peak power (10.88% for PLYO vs. 0.81% for CON) during the RAST Test. CONCLUSIONS: Considering that anaerobic performance is an important feature in many sports, our results suggests that coaches involved with strength and conditioning of youth athletes should consider the inclusion PT in their training periodization.

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The combination of strength (ST) and plyometric training (PT) has been shown to be effective for improving sport-specific performance. However, there is no consensus about the most effective way to combine these methods in the same training session to produce greater improvements in neuromuscular performance of soccer players. Thus, the purpose of this study was to compare the effects of different combinations of ST and PT sequences on strength, jump, speed, and agility capacities of elite young soccer players. Twenty-seven soccer players (age: 18.9 ± 0.6 years) participated in an 8-week resistance training program and were divided into 3 groups: complex training (CP) (ST before PT), traditional training (TD) (PT before ST), and contrast training (CT) (ST and PT performed alternately, set by set). The experimental design took place during the competitive period of the season. The ST composed of half-squat exercises performed at 60-80% of 1 repetition maximum (1RM); the PT composed of drop jump exercises executed in a range from 30 to 45 cm. After the experimental period, the maximum dynamic strength (half-squat 1RM) and vertical jump ability (countermovement jump height) increased similarly and significantly in the CP, TD, and CT (48.6, 46.3, and 53% and 13, 14.2, and 14.7%, respectively). Importantly, whereas the TD group presented a significant decrease in sprinting speed in 10 (7%) and 20 m (6%), the other groups did not show this response. Furthermore, no significant alterations were observed in agility performance in any experimental group. In conclusion, in young soccer players, different combinations and sequences of ST and PT sets result in similar performance improvements in muscle strength and jump ability. However, it is suggested that the use of the CP and CT methods is more indicated to maintain/maximize the sprint performance of these athletes.

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Nobre, GG, de Almeida, MB, Nobre, IG, dos Santos, FK, Brinco, RA, Arruda-Lima, TR, de-Vasconcelos, KL, de-Lima, JG, Borba-Neto, ME, Damasceno-Rodrigues, EM, Santos-Silva, SM, Leandro, CG, and Moura-dos-Santos, MA. Twelve weeks of plyometric training improves motor performance of 7- to 9-year-old boys who were overweight/obese: a randomized controlled intervention. J Strength Cond Res 31(8): 2091-2099, 2017-The prevalence of childhood overweight/obesity has increased, and physical training at school may to be effective to combat this scenario. We analyzed the effects of a protocol of plyometric training on body composition and motor performance of boys who were overweight/obese aged 7-9 years. The sample was randomly assigned into 2 groups: plyometric training group (T, n = 40) and control group (C, n = 19). Training consisted of 20 min·d (twice a week, during 12 weeks) of lower extremity plyometric exercise. Health-related physical fitness was measured by handgrip strength, standing long jump (SLJ), curl-ups, sit and reach, square test, running speed, and mile run test. Gross motor coordination was evaluated by means of the Körperkoordinations-test für Kinder (KTK) tests. Baseline and postintervention differences were investigated, and effect size was estimated through Cohen's d coefficient. Both groups showed increased body weight, height, and sitting height after intervention with a negligible effect size. Only T group showed increased fat-free mass (p = 0.011) compared with baseline values with small effect size. Plyometric training improved handgrip strength (d = 0.23), sit and reach (d = 0.18), curl-ups (d = 0.39), SLJ (d = 0.80), agility (d = 0.48), and time in the mile run test (d = 0.38). For gross motor coordination results, T group showed better performance in all tests after plyometric training with moderate/large effect size. Thus, 12 weeks of PT improved health-related physical fitness components and motor coordination acquisition of 7- to 9-year-old boys who were overweight/obese.

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Yanci, J, Castillo, D, Iturricastillo, A, Ayarra, R, and Nakamura, FY. Effects of two different volume-equated weekly distributed short-term plyometric training programs on futsal players' physical performance. J Strength Cond Res 31(7): 1787-1794, 2017-The aim was to analyze the effect of 2 different plyometric training programs (i.e., 1 vs. 2 sessions per week, same total weekly volume) on physical performance in futsal players. Forty-four futsal players were divided into 3 training groups differing in weekly plyometric training load: the 2 days per week plyometric training group (PT2D, n = 15), the 1 day per week plyometric training group (PT1D, n = 12), and the control group (CG, n = 12) which did not perform plyometric training. The results of this study showed that in-season futsal training per se was capable of improving repeat sprint ability (RSA) (effect size [ES] = -0.59 to -1.53). However, while change of direction ability (CODA) was maintained during the training period (ES = 0.00), 15-m sprint (ES = 0.73), and vertical jump (VJ) performance (ES = -0.30 to -1.37) were significantly impaired. By contrast, PT2D and PT1D plyometric training were effective in improving futsal players' 15-m sprint (ES = -0.64 to -1.00), CODA (ES = -1.83 to -5.50), and horizontal jump (ES = 0.33-0.64) performance. Nonetheless, all groups (i.e., PT2D, PT1D, and CG) presented a reduction in VJ performance (ES = -0.04 to -1.37). Regarding RSA performance, PT1D showed a similar improvement compared with CG (ES = -0.65 to -1.53) after the training intervention, whereas PT2D did not show significant change (ES = -0.04 to -0.38). These results may have considerable practical relevance for the optimal design of plyometric training programs for futsal players, given that a 1-day-per-week plyometric training program is more efficient than a 2-day-per-week plyometric training program to improve the futsal players' physical performance.

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The aim of this study was to compare the effects of a jump training program, with or without haltere type handheld loading, on maximal intensity exercise performance. Youth soccer players (12.1±2.2 y) were assigned to either a jump training group (JG, n=21), a jump training group plus haltere type handheld loading (LJG, n=21), or a control group following only soccer training (CG, n=21). Athletes were evaluated for maximal-intensity performance measures before and after 6 weeks of training, during an in-season training period. The CG achieved a significant change in maximal kicking velocity only (ES=0.11-0.20). Both jump training groups improved in right leg (ES=0.28-0.45) and left leg horizontal countermovement jump with arms (ES=0.32-0.47), horizontal countermovement jump with arms (ES=0.28-0.37), vertical countermovement jump with arms (ES=0.26), 20-cm drop jump reactive strength index (ES=0.20-0.37), and maximal kicking velocity (ES=0.27-0.34). Nevertheless, compared to the CG, only the LJG exhibited greater improvements in all performance tests. Therefore, haltere type handheld loading further enhances performance adaptations during jump training in youth soccer players.

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Training at the optimum power load (OPL) is an effective way to improve neuromuscular abilities of highly trained athletes. The purpose of this study was to test the effects of training using the jump squat (JS) or Olympic push-press (OPP) exercises at the OPL during a short-term preseason on speed-power related abilities in high-level under-20 soccer players. The players were divided into two training groups: JS group (JSG) and OPP group (OPPG). Both groups undertook 12 power-oriented sessions, using solely JS or OPP exercises. Pre- and post-6 weeks of training, athletes performed squat jump (SJ), countermovement jump (CMJ), sprinting speed (5, 10, 20 and 30 m), change of direction (COD) and speed tests. To calculate the transfer effect coefficient (TEC) between JS and MPP OPP and the speed in 5, 10, 20, and 30 m, the ratio between the result gain (effect size [ES]) in the untrained exercise and result gain in the trained exercise was calculated. Magnitude based inference and ES were used to test the meaningful effects. The TEC between JS and VEL 5, 10, 20, and 30 m ranged from 0.77 to 1.29, while the only TEC which could be calculated between OPP and VEL 5 was rather low (0.2). In addition, the training effects of JS on jumping and speed related abilities were superior (ES ranging from small to large) to those caused by OPP (trivial ES). To conclude, the JS exercise is superior to the OPP for improving speed-power abilities in elite young soccer players.

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