Cesar Meylan

Effects of In-Season Plyometric Training Within Soccer Practice on Explosive Actions of Young Players

Meylan, C and Malatesta D. Effects of in-season plyometric training within soccer practice on explosive actions of young players. J Strength Cond Res 23(9): 2605-2613, 2009-In soccer, explosive actions such as jumping, sprinting, and changes of direction are essential to optimal performance not only in adults, but also in childrens games. The purpose of the present investigation was to determine the influence of a short-term plyometric training within regular soccer practice on explosive actions of early pubertal soccer players during the in-season. Fourteen children (13.3 ± 0.6 years) were selected as the training group (TG) and 11 children (13.1 ± 0.6 years) were defined as the control group (CG). All children were playing in the same league and trained twice per week for 90 minutes with the same soccer drills. The TG followed an 8-week plyometric program (i.e., jumping, hurdling, bouncing, skipping, and footwork) implemented as a substitute for some soccer drills to obtain the same session duration as CG. At baseline and after training, explosive actions were assessed with the following 6 tests: 10-meter sprint, agility test, 3 vertical jump tests (squat jump [SJ], countermovement jump [CMJ], contact test [CT] and multiple 5 bounds test [MB5]). Plyometric training was associated with significant decreases in 10-m sprint time (−2.1%) and agility test time (−9.6%) and significant increases in jump height for the CMJ (+7.9%) and CT (+10.9%). No significant changes in explosive actions after the 8-week period were recorded for the CG. The current study demonstrated that a plyometric program within regular soccer practice improved explosive actions of young players compared to conventional soccer training only. Therefore, the short-term plyometric program had a beneficial impact on explosive actions, such as sprinting, change of direction, and jumping, which are important determinants of match-winning actions in soccer performance.

Talent Identification in Soccer: The Role of Maturity Status on Physical, Physiological and Technical Characteristics

The purpose of this paper is to provide a review around talent identification in soccer using physiological and technical testing procedures, and to summarise the issues associated with this process. The current research in soccer talent identification, among other sports, demonstrates a systematic bias in selection towards players born early in the year (i.e., relative age effect) and early maturers. From the studies investigating the physiological (e.g., power) and technical (e.g., dribbling) characteristics of players of different maturity status, early maturers had the tendency to perform better in these tests and therefore were likely to be more influential on the game and be recognised as more talented. When considering the current level of play and future success, elite youth and future professional players scored better in physiological and technical testing than recreational youth and future non-professional players, independently of maturity status. However, these testing procedures were not sensitive enough to distinguish youth elite from sub-elite or future national team from professional club players. Collectively, these studies demonstrated the need to use estimates of maturity status and subsequent appropriate analysis of data obtained from physiological and technical testing. When maturity is taken into account, these testing procedures can provide an indication of responsiveness to training load in youth players and an evaluation of potential to become a successful soccer player. However, these testing procedures should not be used as a marker of selection before full maturity is attainted and should be part of a multidimensional approach of talent identification considering the importance of other facets of the game at the highest level (e.g., perceptive-cognitive skills).

Single-leg lateral, horizontal, and vertical jump assessment: reliability, interrelationships, and ability to predict sprint and change-of-direction performance.

Meylan, C, McMaster, T, Cronin, J, Mohammad, NI, Rogers, C, and deKlerk, M. Single-leg lateral, horizontal, and vertical jump assessment: reliability, interrelationships, and ability to predict sprint and change-of-direction performance. J Strength Cond Res 23(4): 1140-1147, 2009-The purposes of this study were to determine the reliability of unilateral vertical, horizontal, and lateral countermovement jump assessments, the interrelationship between these tests, and their usefulness as predictors of sprint (10 m) and change-of-direction (COD) performance for 80 men and women physical education students. Jump performance was assessed on a contact mat and sprint, and COD performances were assessed using timing lights. With regard to the reliability statistics, the largest coefficient of variation (CV) was observed for the vertical jump (CV = 6.7-7.2%) of both genders, whereas the sprint and COD assessments had smallest variability (CV = 0.8 to 2.8%). All intraclass correlation coefficients (ICC) were greater than 0.85, except for the mens COD assessment with the alternate leg. The shared variance between the single-leg vertical, horizontal, and lateral jumps for men and women was less than 50%, indicating that the jumps are relatively independent of one another and represent different leg strength/power qualities. The ability of the jumps to predict sprint and COD performance was limited (R2 < 43%). It would seem that the ability to change direction with 1 leg is relatively independent of a COD with the other leg, especially in the women (R2 < 30%) of this study. However, if 1 jump assessment were selected to predict sprint and COD performance in a test battery, the single-leg horizontal countermovement jump would seem the logical choice, given the results of this study. Many of the findings in this study have interesting diagnostic and training implications for the strength and conditioning coach.

Effect of Vertical, Horizontal, and Combined Plyometric Training on Explosive, Balance, and Endurance Performance of Young Soccer Players

Abstract Ramírez-Campillo, R, Gallardo, F, Henriquez-Olguín, C, Meylan, CMP, Martínez, C, Álvarez, C, Caniuqueo, A, Cadore, EL, and Izquierdo, M. Effect of vertical, horizontal, and combined plyometric training on explosive, balance, and endurance performance of young soccer players. J Strength Cond Res 29(7): 1784–1795, 2015—The aim of this study was to compare the effects of 6 weeks of vertical, horizontal, or combined vertical and horizontal plyometric training on muscle explosive, endurance, and balance performance. Forty young soccer players aged between 10 and 14 years were randomly divided into control (CG; n = 10), vertical plyometric group (VG; n = 10), horizontal plyometric group (HG; n = 10), and combined vertical and horizontal plyometric group (VHG; n = 10). Players performance in the vertical and horizontal countermovement jump with arms, 5 multiple bounds test (MB5), 20-cm drop jump reactive strength index (RSI20), maximal kicking velocity (MKV), sprint, change of direction speed (CODS), Yo-Yo intermittent recovery level 1 test (Yo-Yo IR1), and balance was measured. No significant or meaningful changes in the CG, apart from small change in the Yo-Yo IR1, were observed while all training programs resulted in meaningful changes in explosive, endurance, and balance performance. However, only VHG showed a statistically significant (p ⩽ 0.05) increase in all performance test and most meaningful training effect difference with the CG across tests. Although no significant differences in performance changes were observed between experimental groups, the VHG program was more effective compared with VG (i.e., jumps, MKV, sprint, CODS, and balance performance) and HG (i.e., sprint, CODS, and balance performance) to small effect. The study demonstrated that vertical, horizontal, and combined vertical and horizontal jumps induced meaningful improvement in explosive actions, balance, and intermittent endurance capacity. However, combining vertical and horizontal drills seems more advantageous to induce greater performance improvements.

Temporal and kinetic analysis of unilateral jumping in the vertical, horizontal, and lateral directions

Abstract The aims of this study were to: (1) assess the reliability of various kinetic and temporal variables for unilateral vertical, horizontal, and lateral countermovement jumps; (2) determine whether there are differences in vertical ground reaction force production between the three types of jumps; (3) quantify the magnitude of asymmetry between limbs for variables that were established as reliable in a healthy population and whether asymmetries were consistent across jumps of different direction; and (4) establish the best kinetic predictor(s) of jump performance in the vertical, horizontal, and lateral planes of motion. Thirty team sport athletes performed three trials of the various countermovement jumps on both legs on two separate occasions. Eccentric and concentric peak force and concentric peak power were the only variables with acceptable reliability (coefficient of variation = 3.3–15.1%; intra-class correlation coefficient = 0.70–0.96). Eccentric and concentric peak vertical ground reaction force (14–16%) and concentric peak power (45–51%) were significantly (P < 0.01) greater in the vertical countermovement jump than in the horizontal countermovement jump and lateral countermovement jump, but no significant difference was found between the latter two jumps. No significant leg asymmetries (–2.1% to 9.3%) were found in any of the kinetic variables but significant differences were observed in jump height and distance. The best single predictors of vertical countermovement jump, horizontal countermovement jump, and lateral countermovement jump performance were concentric peak vertical power/body weight (79%), horizontal concentric peak power/body weight (42.6%), and eccentric peak vertical ground reaction force/body weight (14.9%) respectively. These findings are discussed in relation to monitoring and developing direction-specific jump performance.

The effect of maturation on adaptations to strength training and detraining in 11–15-year-olds

To investigate how maturity status modifies the effects of strength training and detraining on performance, we subjected 33 young men to 8 weeks of strength training twice per week followed by 8 weeks without training. Changes in performance tests were analyzed in three maturity groups based on years from/to age of predicted peak height velocity (PHV): pre‐PHV (−1.7 ± 0.4 years; n = 10), mid‐PHV (−0.2 ± 0.4 years; n = 11), and post‐PHV (1.0 ± 0.4 years; n = 12). Mean training effects on one repetition maximum strength (3.6–10.0%), maximum explosive power (11–20%), jump length (6.5–7.4%), and sprint times (−2.1% to −4.7%) ranged from small to large, with generally greater changes in mid‐ and post‐PHV groups. Changes in force–velocity relationships reflected generally greater increases in strength at faster velocities. In the detraining period, the pre‐PHV group showed greatest loss of strength and power, the post‐PHV group showed some loss of sprint performance, but all groups maintained or improved jump length. Strength training was thus generally less effective before the growth spurt. Maintenance programs are needed for most aspects of explosive performance following strength training before the growth spurt and for sprint speed after the growth spurt.

The Effects of Interday Rest on Adaptation to 6 Weeks of Plyometric Training in Young Soccer Players

Abstract Ramírez-Campillo, R, Meylan, CMP, Álvarez-Lepín, C, Henriquez-Olguín, C, Martinez, C, Andrade, DC, Castro-Sepúlveda, M, Burgos, C, Baez, EI, and Izquierdo, M. The effects of interday rest on adaptation to 6 weeks of plyometric training in young soccer players. J Strength Cond Res 29(4): 972–979, 2015—The purpose of this study was to determine the effects of short-term plyometric training interposed with 24 or 48 hours of rest between training sessions on explosive and endurance adaptations in young soccer players. A total of 166 players, between 10 and 17 years of age, were randomly divided into 3 groups: a control group (CG; n = 55) and 2 plyometric training groups with 24 hours (PT24; n = 54) and 48 hours (PT48; n = 57) of rest between training sessions. Before and after intervention, players were measured in squat jump, countermovement jump, 20 (RSI20) cm drop jump reactive strength index, broad long jump, 20-m sprint time, 10 × 5-m agility time, 20-m multistage shuttle run test, and sit-and-reach test. The plyometric training program was applied during 6 weeks, 2 sessions per week, with a load from 140 to 260 jumps per session, replacing some soccer-specific drills. After intervention, the CG did not show significant performance changes. PT24 and PT48 groups showed a small-to-moderate significant improvement in all performance tests (p < 0.001), with no differences between treatments. Although it has been recommended that plyometric drills should not be conducted on consecutive days, the study shows that plyometric training applied twice weekly on consecutive or nonconsecutive days results in similar explosive and endurance adaptations in young male soccer players.The purpose of this study was to determine the effects of short-term plyometric training interposed with 24 or 48 hours of rest between training sessions on explosive and endurance adaptations in young soccer players. A total of 166 players, between 10 and 17 years of age, were randomly divided into 3 groups: a control group (CG; n = 55) and 2 plyometric training groups with 24 hours (PT24; n = 54) and 48 hours (PT48; n = 57) of rest between training sessions. Before and after intervention, players were measured in squat jump, countermovement jump, 20 (RSI20) cm drop jump reactive strength index, broad long jump, 20-m sprint time, 10 × 5-m agility time, 20-m multistage shuttle run test, and sit-and-reach test. The plyometric training program was applied during 6 weeks, 2 sessions per week, with a load from 140 to 260 jumps per session, replacing some soccer-specific drills. After intervention, the CG did not show significant performance changes. PT24 and PT48 groups showed a small-to-moderate significant improvement in all performance tests (p < 0.001), with no differences between treatments. Although it has been recommended that plyometric drills should not be conducted on consecutive days, the study shows that plyometric training applied twice weekly on consecutive or nonconsecutive days results in similar explosive and endurance adaptations in young male soccer players.

The reliability of jump kinematics and kinetics in children of different maturity status.

Abstract Meylan, CMP, Cronin, JB, Oliver, JL, Hughes, MG, McMaster, DT. The reliability of jump kinematics and kinetics in children of different maturity status. J Strength Cond Res 26(4): 1015–1026, 2012—The purpose of this study was to determine the reliability of eccentric (ECC) and concentric (CON) kinematic and kinetic variables thought to be critical to jump performance during bilateral vertical countermovement jump (VCMJ) and horizontal countermovement jump (HCMJ) across children of different maturity status. Forty-two athletic male and female participants between 9 and 16 years of age were divided into 3 maturity groups according to peak height velocity (PHV) offset (Post-PHV, At-PHV, and Pre-PHV) and percent of predicted adult stature. All the participants performed 3 VCMJ and HCMJ trials and the kinematics, and kinetics of these jumps were measured via a force plate over 3 testing sessions. In both jumps, vertical CON mean and peak power and jump height or distance were the most reliable measures across all groups (change in the mean [CM] = −5.4 to 6.2%; coefficient of variation [CV] = 2.1–9.4%; Intraclass correlation coefficient [ICC] = 0.82–0.98), whereas vertical ECC mean power was the only ECC variable with acceptable reliability for both jumps (CM = −0.7 to 10.1%; CV = 5.2–15.6%; ICC = 0.74–0.97). A less mature state was “likely” to “very likely” to reduce the reliability of the HCMJ ECC kinetics and kinematics. These findings suggested that movement variability is associated with the ECC phase of CMJs, especially in Pre-PHV during the HCMJ. Vertical CON mean and peak power and ECC mean power were deemed reliable and appropriate to be used in children as indicators of jump and stretch-shortening cycle performance.

The effect of three different start thresholds on the kinematics and kinetics of a countermovement jump.

Meylan, CMP, Nosaka, K, and Green, J, Cronin, JB. The effect of three different start thresholds on the kinematics and kinetics of a countermovement jump. J Strength Cond Res 25(4): 1164-1167, 2011-Force plates are used to quantify kinematic and kinetic variables of countermovement jump (CMJ). The jump is initiated by an unloading phase resulting in the force-time curve to drop below body weight (BW). However, there is no consensus in the literature to determine the start of the analysis of the jump (i.e., start threshold). To determine the effects and reliability of 3 different start thresholds on the kinematics and kinetics of a CMJ, 10 soccer players performed 3 CMJs for maximal jump height 30 seconds apart. Initiation of the jump movement was defined as the point where the force-time curve dropped below a threshold of 2.5, 5, or 10% BW. Significant differences were found in all variables except eccentric and concentric peak force and force at zero velocity between 2.5 and 10%, and 5 and 10% thresholds. Similar results were found for the 2.5 and 5% threshold variables except that no significant difference was found in the concentric ground contact time. The different thresholds did not appear to influence the variability of the measurement and only concentric time to peak power was found to have high variability. These data suggest that the use of any of the start thresholds can be used to determine the starting point of a CMJ considering their reliability. However, the 2.5% BW threshold is preferable because most of the force-time signal can be considered for analysis, and significant differences in eccentric and concentric kinematic and kinetic variables were found when a higher threshold was used.

VARIABILITY AND INFLUENCE OF ECCENTRIC KINEMATICS ON UNILATERAL VERTICAL, HORIZONTAL, AND LATERAL COUNTERMOVEMENT JUMP PERFORMANCE

Meylan, CMP, Nosaka, K, Green, JP, and Cronin, JB. Variability and influence of eccentric kinematics on unilateral vertical, horizontal, and lateral countermovement jump performance. J Strength Cond Res 24(3): 840-845, 2010-The purposes of this study were to determine the (a) magnitude of variability associated with certain eccentric variables (eccentric peak velocity, displacement, and ground contact time) during unilateral countermovement jump performance (vertical [VCMJ], horizontal [HCMJ], and lateral [LCMJ]); (b) differences between limbs as well as between jumps; and (c) relationship between jump performance and the eccentric variables of interest. The jumping ability in 3 directions (VCMJ, HCMJ, and LCMJ) of 30 field sport athletes were assessed. The variability (coefficient of variation [CV]) of the eccentric variables was the lowest for the VCMJ (CV = 8.5-10.6%) and the highest for the HCMJ (CV = 11.7%-13.5%). No difference was found between limbs in the variables of interest. Significant statistical differences (p < 0.05) across the different jumps were found in the eccentric variables (9.1-29.4%). No significant correlations between the eccentric variables and jump performance were found for the VCMJ; however, significant correlations were found between jump length and eccentric displacement or eccentric peak velocity in both HCMJ (r = −0.60 and 0.57) and LCMJ (r = −0.54 and 0.37), respectively. It appears that in the absence of instruction and standardization of the countermovement, eccentric phase kinematics remains relatively stable over trials. In terms of the between jump analysis, it appears that the eccentric phase kinematics are relatively unique to each jump and directionally specific and therefore may need to be trained accordingly.