Acute kinematic and kinetic augmentation in horizontal jump performance using haltere type handheld loading

Kinetic Analysis, Potentiation, and Fatigue During Vertical and Horizontal Plyometric Training: An In-Depth Investigation Into Session Volume

Despite previous support for plyometric training, optimal dosing strategies remain unclear.

PURPOSE

To investigate vertical and horizontal jump kinetic performance following a low-volume plyometric stimulus with progressively increased session jump volume.

METHODS

Sixteen academy rugby players (20.0 [2.0] y; 103.0 [17.6] kg; 184.3 [5.5] cm) volunteered for this study. Vertical and horizontal jump sessions were conducted 1 week apart and consisted of a 40-jump low-volume plyometric stimulus using 4 exercises, after which volume was progressively increased to 200 jumps, using countermovement jump (CMJ) for vertical sessions and horizontal broad jump (HBJ) for horizontal sessions. Jump performance was assessed via force-plate analysis at baseline (PRE-0), following the low-volume plyometric stimulus (P-40), and every subsequent 10 jumps until the end of the session (P-50, P-60, P-70, ... P-200).

RESULTS

The low-volume stimulus was effective in potentiating HBJ (2% to 5%) but not CMJ (0% to -7%) performance (P < .001). The HBJ performance enhancements were maintained throughout the entire high-volume session, while CMJ realized small but significant decrements (-5% to -7%) in jump height P-50 to P-80 before recovering to presession values. Moreover, increases in eccentric impulse (5% to 24%; P < .001) in both sessions were associated with decreased or maintained concentric impulse, indicating a breakdown in performance-augmenting mechanisms and less effective power transfer concentrically after moderate volumes.

CONCLUSION

Practitioners should consider kinetic differences between HBJ and CMJ with increasing volume to better inform and understand session dosing strategies.

Loaded Plyometrics and Short Sprints with Change-of-Direction Training Enhance Jumping, Sprinting, Agility, and Balance Performance of Male Soccer Players

This project investigated effects of 8 weeks of biweekly loaded combined plyometric and short sprint with change-of-direction training an in-season regimen of young soccer players. An experimental (n = 17, age: 16.5 ± 0.5 years, body mass: 64.5 ± 5.2 kg, height: 1.73 ± 0.07 m,) and control group (n = 17, age: 16.7 ± 0.5 years, body mass: 65.6 ± 4.8 kg, height: 1.74 ± 0.07 m) were tested pre- and post-intervention for squat-jump (SJ), countermovement-jump (CMJ), and five-jump test (5JT), 10 m and 30 m sprint performance, change-of-direction ability, and dynamic balance performance. The experimental group (EG) outperformed the control group (CG) over 8 weeks in jumping (p < 0.001; d = 0.98–1.17), 10 m sprinting (p < 0.001; d = 0.94), change-of-direction ability (p < 0.001; d = 1.24), and dynamic balance performance (p < 0.001; d = 0.53–0.74). We conclude that adding biweekly loaded plyometric with short sprints and change-of-direction training to habitual training improves athleticism of young soccer players. Therefore, loaded plyometric with short sprints and change-of-direction training should be implemented as a part of research-informed soccer training.

Acute Effects of Handheld Loading on Standing Broad Jump in Youth Athletes

The study aimed to investigate the acute effects of handheld loading on standing broad jump (SBJ) performance and biomechanics. Fifteen youth male athletes (mean age: 14.7 ± 0.9 years; body mass: 59.3 ± 8.0 kg; height: 1.73 ± 0.07 m) volunteered to participate in the study. Participants were assigned to perform SBJ with and without 4 kg dumbbells in a random order. Kinematic and kinetic data were collected using 10 infrared high-speed motion-capture cameras at a 250 Hz sampling rate and two force platforms at a 1000 Hz sampling rate. A paired t-test was applied to all variables to determine the significance between loading and unloading SBJs. Horizontal distance (p < 0.001), take-off distance (p = 0.001), landing distance (p < 0.001), horizontal velocity of center of mass (CoM; p < 0.001), push time (p < 0.001), vertical impulse (p = 0.003), and peak horizontal and vertical ground reaction force (GRF; p < 0.001, p = 0.017) were significantly greater in loading SBJ than in unloading SBJ. The take-off vertical velocity of CoM (p = 0.001), take-off angle (p < 0.001), peak knee and hip velocity (p < 0.001, p = 0.007), peak ankle and hip moment (p = 0.006, p = 0.011), and peak hip power (p = 0.014) were significantly greater in unloading SBJ than in loading SBJ. Conclusions: Acute enhancement in SBJ performance was observed with handheld loading. The present findings contribute to the understanding of biomechanical differences in SBJ performance with handheld loading and are highly applicable to strength and conditioning training for athletes.

Implementation and Efficacy of Plyometric Training: Bridging the Gap Between Practice and Research

ABSTRACT

Watkins, CM, Storey, A, McGuigan, M, and Gill, ND. Implementation and efficacy of plyometric training: Bridging the gap between practice and research. J Strength Cond Res 35(5): 1244-1255, 2021-Plyometric training is an effective method for improving speed and acceleration. However, a gap seems to exist between research recommendations and practitioner's actual programs. Some reports suggest as many as 400 jumps per session, while anecdotally some strength and conditioning coaches are using as few as 15-40 jumps even with elite athletes. Thus, the purposes of this study were to obtain a clearer understanding of the practitioner's perspective on plyometric training strategies as compared to literary recommendations and to compare any trends across competition level or sport categories. An integrative mixed-methods model was used. Globally, 61 strength and conditioning practitioners completed an anonymous online survey, containing 5 sections: 1. Sport and coaching background information, 2. Plyometric training focus, 3. Periodization strategy, 4. Plyometric program details, and 5. Efficacy of plyometrics for sport performance. Questions included yes/no, multiple choice, Likert scale, percentage-based, and open-ended questions. The majority (70.5%) of respondents reported regularly implementing plyometric training and overwhelmingly (96.7%) reported positive athlete feedback surrounding its perceived efficacy. Findings confirmed that many practitioners regularly use significantly lower session volumes than previous literary recommendations (p < 0.05). In addition, significant differences were noted in many program details across competition level and sport category including volume periodization, exercise choice, and plyometric intensity. Practitioners may want to reflect on these reported group differences when building training programs best suited for their athletes. Meanwhile, future research should consider these reported perspectives when formulating interventions in attempts of bridging the gap between practice and theory.

Effects of Unloaded vs. Ankle-Loaded Plyometric Training on the Physical Fitness of U-17 Male Soccer Players

The aim of this study was to compare the impact of two differing plyometric training programs (loaded plyometrics (with 2.5% of body mass placed above the ankle joint) vs. unloaded plyometrics), performed biweekly for 10 weeks, on the physical fitness of elite junior male soccer players. Participants aged 16.0 ± 0.5 years were randomly assigned between unloaded plyometrics (UP; n = 12), loaded plyometrics (LP; n = 14) and control (C; n = 12) groups. Two-way analyses of performance (group x time) were assessed by 40-m sprint times; 9–3–6–3–9 m sprints with 180° turns (S180°); 9–3–6–3–9 m sprints with backward and forward running (SBF); and 4 × 5 m sprints (S4 × 5 m); four jump tests; measures of static and dynamic balance; repeated change of direction tests and the Yo-Yo intermittent recovery test. Both LP and UP enhanced sprinting performance relative to C (p < 0.05) but performance increased more in LP relative to UP (p < 0.05) in all sprints except 40 m. Change of direction times were also significantly shortened by LP relative to UP (p < 0.05) and C (p < 0.01) in all tests, with no significant differences between UP and C. Jumps heights increased similarly in both LP and UP relative to C (p < 0.05), with no significance between LP and UP. LP and UP also enhanced repeated change of direction scores relative to C (p < 0.01) with greater changes in LP than in UP (p < 0.01). Finally, LP enhanced some balance scores relative to UP (p < 0.05) and C (p < 0.05). We conclude that the introduction of 10 weeks of in-season loaded plyometrics into the regimen of U17 male soccer players yields gains in several physical performance scores relative to either unloaded plyometrics or the control training regimen.

Acute kinematics and kinetics changes to wearable resistance during change of direction among soccer players

This study determined the acute changes in kinematics and kinetics when an additional load equivalent to 5% body mass was attached to the torso during change of direction (COD). In this within-subject repeated measures study, 14 male soccer players (age: 18.29 ± 0.32 years) volunteered to participate. Subjects performed COD under two conditions in randomized order: (1) no WR, and (2) with WR. No significant differences between the loaded and unloaded conditions in actual COD angle, approach speed, braking time, propulsive time, contact time, COD completion time (all p > 0.05, ES = 0.05-0.11), and all measured kinematic parameters (all p > 0.05, ES = 0-0.18). Nonetheless, ankle plantar/dorsi flexion ROM had possibly small increase in the loaded condition (ES = 0.24). Kinetics analysis has shown that the loaded condition was likely to have small increase in relative peak vertical propulsive ground reaction force (GRF, p = 0.11, ES = 0.41), and possible small increases in relative peak braking GRF (vertical: p = 0.21, ES = 0.42; total: p = 0.22, ES = 0.38), relative peak total propulsive GRF (p = 0.24, ES = 0.26), and relative braking impulse (horizontal, vertical, and total; p = 0.27-0.41, ES = 0.26-0.28). WR did not significantly change the acute movement techniques, meanwhile induced small increases in important kinetic stimuli for potential adaptation in COD.

Effects of shank mass manipulation on sprinting techniques

The purpose of this study was to determine the effects of shank mass manipulation on the sprinting technique in maximal-speed sprinting. Sixteen well-trained male athletes sprinted with and without an additional 15% of shank mass attached to the shank centre of mass. Kinematic data were collected using a 12-camera motion analysis system and analysed using linear regression analyses with categorical variables and paired t-tests. The sprinting speed (p < 0.01), knee flexion angle at landing (p = 0.028), and maximum hip flexion angular velocity (p = 0.029) decreased; contact time (p < 0.01) increased; and step length, step frequency, and other analysed technique measures of maximal-speed sprinting were unchanged (p ≥ 0.12) with shank mass manipulation, compare with no manipulation. The relationships of sprinting speed with critical linear and angular kinematics at landing, take-off and swing in maximal-speed sprinting were not affected by the shank mass manipulation. These results suggest that 15% shank mass manipulation does not change the sprinting technique of well-trained male athletes in maximal-speed sprinting. This supports the use of shank mass manipulation as a training method for well-trained sprinters; however, a change in correlations between sprinting speed and technique measures should be considered during such training.

Effects of Unloaded vs. Loaded Plyometrics on Speed and Power Performance of Elite Young Soccer Players

The purpose of this study was to investigate the effects of loaded and unloaded plyometric training strategies on speed and power performance of elite young soccer players. Twenty-three under-17 male soccer players (age: 15.9 ± 1.2 years, height: 178.3 ± 8.1 cm, body-mass (BM): 68.1 ± 9.3 kg) from the same club took part in this study. The athletes were pair-matched in two training groups: loaded vertical and horizontal jumps using an haltere type handheld with a load of 8% of the athletes' body mass (LJ; n = 12) and unloaded vertical and horizontal plyometrics (UJ; n = 11). Sprinting speeds at 5-, 10-, and 20-m, mean propulsive power (MPP) relative to the players' BM in the jump squat exercise, and performance in the squat jump (SJ) and countermovement jump (CMJ) were assessed pre- and post-training period. During the experimental period, soccer players performed 12 plyometric training sessions across a 6-week preseason period. Magnitude based inferences and standardized differences were used for statistical analysis. A very likely increase in the vertical jumps was observed for the LJ group (99/01/00 and 98/02/00 for SJ and CMJ, respectively). In the UJ group a likely increase was observed for both vertical jumps (83/16/01 and 90/10/00, for SJ and CMJ, respectively). An almost certainly decrease in the sprinting velocities along the 20-m course were found in the LJ group (00/00/100 for all split distances tested). Meanwhile, in the UJ likely to very likely decreases were observed for all sprinting velocities tested (03/18/79, 01/13/86, and 00/04/96, for velocities in 5-, 10-, and 20-m, respectively). No meaningful differences were observed for the MPP in either training group (11/85/04 and 37/55/08 for LJ and UJ, respectively). In summary, under-17 professional soccer players increased jumping ability after a 6-week preseason training program, using loaded or unloaded jumps. Despite these positive adaptations, both plyometric strategies failed to produce worthwhile improvements in maximal speed and power performances, which is possible related to the interference of concurrent training effects. New training strategies should be developed to ensure adequate balance between power and endurance loads throughout short (and high-volume) soccer preseasons.

Acute kinematic and kinetic adaptations to wearable resistance during vertical jumping

One variation of vertical jump (VJ) training is resisted or weighted jump training, where wearable resistance (WR) enables jumping to be overloaded in a movement specific manner. A two-way analysis of variance with Bonferroni post hoc contrasts was used to determine the acute changes in VJ performance with differing load magnitudes and load placements. Kinematic and kinetic data were quantified using a force plate and contact mat. Twenty sport active subjects (age: 27.8 ± 3.8 years; body mass (BM): 70.2 ± 12.2 kg; height: 1.74 ± 0.78 m) volunteered to participate in the study. Subjects performed the counter movement jump (CMJ), drop jump (DJ) and pogo jump (PJ) wearing no resistance, 3% or 6% BM affixed to the upper or lower body. The main finding in terms of the landing phase was that the effect of WR was non-significant (P > .05) on peak ground reaction force. With regard to the propulsive phase the main findings were that for both the CMJ and DJ, WR resulted in a significant (P < .05) decrease in jump height (CMJ: -12% to -17%, DJ: -10% to -14%); relative peak power (CMJ: -8% to -17%, DJ: -7% to -10%); and peak velocity (CMJ: -4% to -7%, DJ: -3% to -8%); while PJ reactive strength index was significantly reduced (-15% to -21%) with all WR conditions. Consideration should be given to the inclusion of WR in sports where VJ's are important components as it may provide a novel movement specific training stimulus. Highlights WR of 3 or 6 % BM provided a means to overload the subjects in this study resulting in decreased propulsive power and velocity that lead to a reduced jump height and landing force. Specific strength exercises that closely mimic sporting performance are more likely to optimise transference, therefore WR with light loads of 3-6% body mass (BM)appear a suitable tool for movement specific overload training and maximising transference to sporting performance. Practitioners can safely load their athletes with upper or lower body WR of 3-6% BM without fear of overloading the athletesover and above the landing forces they are typically accustomed too. As a training stimulus it would seem the WR loading provides adequate overload and athletes should focus on velocity of movement to improve power output and jump height i.e. take-off velocity.