Knowledge of results during vertical jump testing: an effective method to increase the performance but not the consistency of vertical jumps

The Battle of the Equations: A Systematic Review of Jump Height Calculations Using Force Platforms

Vertical jump height measures our ability to oppose gravity and lower body neuromuscular function in athletes and various clinical populations. Vertical jump tests are principally simple, time-efficient, and extensively used for assessing athletes and generally in sport science research. Using the force platform for jump height estimates is increasingly popular owing to technological advancements and its relative ease of use in diverse settings. However, ground reaction force data can be analyzed in multiple ways to estimate jump height, leading to distinct outcome values from the same jump. In the literature, four equations have been commonly described for estimating jump height using the force platform, where jump height can vary by up to ∼ 15 cm when these equations are used on the same jump. There are advantages and disadvantages to each of the equations according to the intended use. Considerations of (i) the jump type, (ii) the reason for testing, and (iii) the definition of jump height should ideally determine which equation to apply. The different jump height equations can lead to confusion and inappropriate comparisons of jump heights. Considering the popularity of reporting jump height results, both in the literature and in practice, there is a significant need to understand how the different mathematical approaches influence jump height. This review aims to investigate how different equations affect the assessment of jump height using force platforms across various jump types, such as countermovement jumps, squat jumps, drop jumps, and loaded jumps.

Effects of adding dual-task or sport-specific task constrains to jump-landing tests on biomechanical parameters related to injury risk factors in team sports: a systematic review

Background

Jumping and landing tests are frequently used as a tool to assess muscle function. However, they are performed in a controlled and predictable environment. The physical tests commonly used as part of the criteria for return to sport after injury are often performed with little or no cognitive load and low coordinative demand compared to game-specific actions. The aim of this systematic review was to examine the influence of performing a dual task (DT) or sport-specific task constrains during jump-landing tests on biomechanical variables related to lower limb injury risk in team sports.

Methods

This systematic review followed the specific methodological guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The search was conducted in the databases Medline (PubMed), Web of Science, Cochrane Plus, and SportDiscus for studies published from 2013 until June 30, 2023. To be eligible, studies had to include: (1) kinematic and/or kinetic assessment of injury risk factors in the lower extremity; (2) a comparison between a simple jump or landing test and a DT jump or landing test which included cognitive information. The risk of bias in the selected articles was analyzed using the recommendations of the Cochrane Collaboration.

Results

Of the 656 records identified, 13 met the established criteria. Additionally, two more articles were manually included after screening references from the included articles and previous related systematic reviews. Regarding the Risk of bias assessment, 12 studies did not surpass a score of 3 points (out of a total of 7). Only three studies exceeded a score of 3 points, with one article achieving a total score of 6. From the included studies, comparative conditions included actions influenced by the inclusion of a sports ball (n = 6), performing tasks in virtual environments or with virtual feedback (n = 2), participation in cognitive tasks (n = 6), and tasks involving dual processes (n = 7). The execution of decision-making (DM) during the jump-landing action resulted in biomechanical changes such as lower peak angles of hip flexion and knee flexion, along with increased vertical ground reaction force, knee abduction, and tibial internal rotation. Regarding limitations, discrepancies arise in defining what constitutes DT. As a result, it is possible that not all studies included in this review fit all conceptual definitions of DT. The inclusion of DT or constraints in jump-landing tests significantly alters biomechanical variables related to lower extremity injury risk in team sports. In future research, it would be beneficial to incorporate tasks into jumping tests that simulate the specific cognitive demands of team sports. This systematic review was registered in PROSPERO (registration number: CRD42023462102) and this research received no external funding.

Presence of an Overhead Goal Does Not Improve the Effectiveness of Jump Training

ABSTRACT

Akbaş, A, Marszałek, W, and Król, H. Presence of an overhead goal does not improve the effectiveness of jump training. J Strength Cond Res 37(4): e280-e288, 2023-This study investigated the effectiveness of jump training with and without an overhead goal (OG) on a modified countermovement jump (CMJ) tested in a similar manner, with and without OG. Fifty-two men divided into 3 groups-trained with OG, trained without OG, and untrained-were examined: before the commencement of training; after 2, 4, and 6 weeks of training; and 2 weeks after the discontinuation of training. Each session consisted of 50 modified CMJ and was performed 3 times per week. Countermovement jump height, mean power, peak power, countermovement depth, and take-off phase time were quantified, and the statistical level was set at p < 0.05. Although the results showed the beneficial effect of OG on jump height ( p < 0.01), the training with OG did not bring significantly better results than training without OG. In addition, the group trained without OG improved after 2 weeks in both testing conditions (with and without OG), whereas the group trained with OG improved after 2 weeks when tested with OG and only after 6 weeks when tested without OG. We believe the use of OG in jump training may be detrimental when the OG is withdrawn from the testing procedure because of its strong motivational and feedback features. Consequently, athletes in disciplines which require them to jump toward an object located over their head during a game, e.g., a ball or crossbar, should be tested with the presence of OG. Despite this, OG is still an important factor in maximizing jump performance.

Applying augmented feedback in basketball training facilitates improvements in jumping performance

Augmented feedback, which is feedback about movement characteristics provided by an external source, can facilitate performance improvements. Results from recent studies, in which information about the jumping height were presented, indicated increased jumping performance due to augmented feedback. In the present study we aimed to utilize augmented feedback about the jumping height in regular basketball training. Therefore, augmented feedback was implemented and part of the training regime, and information about the jumping height was displayed while subjects performed catch and shoot exercises with the basketball. 18 subjects (9 with augmented feedback, 9 without augmented feedback) practiced for 3 weeks (9 training sessions). The subjects receiving augmented feedback, but not subjects in the control group, displayed increased jumping heights of countermovement-jumps and drop-jumps after the training. The ground contact times of countermovement-jumps and drop-jumps were not significantly changed after training. The number of successful hits, indicating ball performance, did also not change after training. Thus augmented feedback had no detrimental effect on sport-specific performance. The unchanged ground contact times of drop-jumps in combination with increased jumping heights indicate increased efficiency of stretch shortening cycle contractions. According to the positive effect of augmented feedback on jumping performance and the simplicity with which it was integrated into the training regime we recommend this method for regular basketball training.HighlightsAugmented feedback about the jumping height in basketball training facilitated jumping height of countermovement-jumps and drop-jumps.The ground contact times were not altered, suggesting increased efficiency of the stretch-shortening cycle during jumping.According to the positive effect and its simple implementation augmented feedback is recommended for regular basketball training.

Kinetic and Kinematic Assessment of the Band-Assisted Countermovement Jump

ABSTRACT

Fernandes, JFT, Arede, J, Clarke, H, Garcia-Ramos, A, Perez-Castilla, A, Norris, JP, Wilkins, CA, and Dingley, AF. Kinetic and kinematic assessment of the band-assisted countermovement jump. J Strength Cond Res XX(X): 000-000, 2022-This study sought to elucidate kinetic and kinematic differences between unloaded and band-assisted countermovement jumps (CMJs). In a randomized order, 20 healthy subjects (mass 84.5 ± 18.6 kg) completed 3 repetitions of CMJs across 3 conditions: unloaded (at body mass), low, and moderate band (8.4 ± 1.9 and 13.3 ± 3.3 kg body weight reduction, respectively). For all repetitions, a force platform and linear position transducer were used to record and calculate kinetic and kinematic data. Body weight was significantly different between the unloaded, low, and moderate band conditions (p < 0.05). Peak velocity, absolute peak, and mean force and movement duration displayed a trend that was mostly related to the condition (i.e., unloaded > low > moderate) (p < 0.05). The opposing trend (i.e., moderate > low > unloaded) was generally observed for relative peak and mean force, reactive strength index modified, and flight time (p < 0.05). No differences were observed for mean velocity, movement duration, and absolute and relative landing forces (p > 0.05). The use of band assistance during CMJs can alter force, time, and velocity variables. Practitioners should be aware of the potential positive and negative effects of band assistance during CMJs.

Do Primary School Children Benefit from Drop-Jump Training with Different Schedules of Augmented Feedback about the Jump Height?

In children, the training of jumps leads to improved jumping and running performance. Augmented feedback about the jump height is known to facilitate performance improvements in adults. In the present study, the impact of augmented feedback on jumping performance was investigated in 4th grade primary school children executing drop-jump training for 8 weeks (24 sessions, 3 times/week). Ten children (eight males, two females, aged 9.6 ± 0.3 years), received feedback for 8 weeks, and 11 children (nine males, two females, aged 9.5 ± 0.2 years) received feedback only during the last 4 weeks. Drop-jumps training was integrated in physical education classes. Drop-jump and countermovement-jump heights were improved after 24 training sessions (p < 0.01 for both types of jumps in both groups). Ground contact times of drop-jumps were quite long (>200 ms) and not altered by training, and the reactive strength index of drop-jumps was between 0.75 and 1.5 in most children. Augmented feedback did not facilitate jumping performance like in previous studies with adult participants. In contrast, withholding augmented feedback during the first 4 weeks of training was associated with a reduction in jumping performance (p < 0.01 for drop-jumps, p < 0.05 for countermovement-jumps). Finally, improvements did not transfer to functional motor tasks containing jumps. According to the costs and outcomes we do not recommend drop-jump training with augmented feedback about the jump height for 4th grade physical education classes.

Association of the load-velocity relationship variables with 2000-m rowing ergometer performance

AbstractThis study aimed to compare the maximal mechanical variables derived from the load-velocity (L-V) relationship and 2000-meter rowing ergometer performance between rowers of different age categories, and to identify the L-V relationship variables more closely related to 2000-meter rowing ergometer performance. Nineteen competitive rowers (15 males and four females) aged between 15 and 25 years were evaluated during the national 2000-meter rowing ergometer competition organised by the Chilean Rowing Federation. Thereafter, the L-V relationship variables (load-axis intercept [L₀], velocity-axis intercept [v₀], and area under the L-V relationship line [A_line]) were determined on separate occasions during the squat jump and prone bench pull exercises. Rowers were classified according to their chronological age for comparative purposes (under 16 years [U16] vs. over 16 years [O16]). L₀ and A_line were always higher for O16 than for U16 (p ≤ 0.046; ES range = 0.99 to 1.79), while v₀ was generally comparable for both age categories (p ≥ 0.038; ES range = 0.07 to 1.03). Furthermore, the O16 revealed a greater performance (i.e., shorter total time) during the 2000-meter rowing ergometer competition (p = 0.011; ES = -1.31). In general, significant correlations were obtained between rowing performance and the L-V relationship variables obtained during the squat jump (r or ρ range = -0.294 to -0.922) and prone bench pull (r or ρ range = -0.322 to -0.928). These results support the L-V relationship as a sensitive procedure to evaluate the maximal mechanical capacities of lower- and upper-body muscles in competitive rowers.

Influence of Coaching Condition on the Magnitude and Reliability of Drop Jump Height in Men and Women

This study examined the effect of different coaching conditions on the magnitude and reliability of drop jump height in men and women. Nineteen collegiate sport sciences students (10 men) performed two sets of 10 drop jumps under four different coaching conditions: neutral, augmented feedback, external focus of attention, and a combination of augmented feedback and external focus of attention. The augmented feedback condition revealed a significantly higher jump height than the neutral condition (p = .002), while no significant differences were observed for the remaining conditions (p ≥ .38). The external focus of attention condition was more reliable than the neutral and augmented feedback conditions (coefficient of variationratio ≥ 1.15), while no differences were observed between the remaining conditions. These results suggest that both the magnitude and reliability of the drop jump height performance are influenced by the coaching condition.

Influence of countermovement depth on the countermovement jump-derived reactive strength index modified

This study aimed to investigate the effect of countermovement depth on the magnitude of the countermovement jump (CMJ) derived reactive strength index modified (RSI_mod), and to compare the RSI_mod between the CMJ performed with a self-preferred knee flexion angle (CMJ_pref) and the CMJ performed from a pre-determined knee flexion angle (CMJ_refer) with the countermovement depth more similar to the CMJ_pref. Sixteen subjects (11 males and 5 females; age 25.1 ± 6.3 years, body mass 69.7 ± 10.2 kg, body height 172.9 ± 8.1 m) randomly performed in a single session the CMJ_pref and CMJs from five pre-determined knee flexion angles (60°, 75°, 90°, 105°, and 120°). Our results showed that lower knee flexion angles were generally associated with greater RSI_mod values with the CMJ performed at 60° showing the greatest RSI_mod (P ≤ 0.049; effect size [ES] range = 0.19-0.63). The greatest RSI_mod for the CMJ performed at 60° was caused by the proportionally lower values of the time to take-off (ES range = 0.65-1.91) compared to the decrease observed in jump height (ES range = 0.11-0.25). The RSI_mod was higher for the CMJ_pref compared to the CMJ_refer (P < 0.001; ES = 0.34) due to a higher jump height (P = 0.021; ES = 0.14) and reduced time to take-off (P < 0.001; ES = 0.85). These results indicate that practitioners should be careful when interpreting an individual's changes in RSI_mod when the countermovement depth is not similar across the testing sessions. However, since the use of pre-determined knee flexion angles negatively impacts the RSI_mod, we encourage practitioners to use the CMJ_pref but only compare the RSI_mod when CMJs are performed using consistent countermovement depths.Highlights The magnitude of the countermovement jump-reactive reactive strength index modified is influenced by the knee flexion angle instruction.The magnitude of the countermovement jump-reactive reactive strength index tended to progressively increase with lower amounts of knee flexion.The magnitude of the countermovement jump-reactive reactive strength index is lower when an external reference is used to control the depth of the countermovement.