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Differences in Inter-Limb Asymmetries During the CMJ AS compared to the CMJ NAS.

Differences in Inter-Limb Asymmetries During the CMJ AS compared to the CMJ NAS.

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The purpose of the present study was to establish the intrasession and intersession reliability of variables obtained from a force plate that was used to quantitate lower extremity inter-limb asymmetry during the bilateral countermovement jump (CMJ). Secondarily, a comparison was performed to determine the influence of the jump protocol CMJ with or...

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... outlined in Table 4, there was a significant condition [CMJ AS versus CMJ NAS] effect, with CMJ AS demonstrating a significant decrease, with a small effect, in lower-limb differences in the total net impulse over first 100-ms epoch of the concentric phase (ConcImp-100) (p = 0.048; d = 0.40. Additionally, there was a significant decrease, all with small to medium effects, in lower-limb differences during the CMJ NAS in the eccentric rate of force development from minimum force at the start of the active braking phase to zero velocity at the end of the eccentric phase (EccBrakRFD) (p = 0.019; d = 0.40), EccBrakRFD-100 (p = 0.019; d = 0.45), eccentric rate of force development from maximum negative velocity to zero velocity at the end of the eccentric phase (EccDecRFD) (p = 0.036; d = 0.46), and force exerted at peak power (F@PP) (p = 0.029; d = 0.32). ...

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... Similar to strength, a wide variety of jumping tasks can assess inter-limb asymmetries. For example, countermovement jumps (CMJ) (7,34), drop jumps (45) and a variety of horizontal hopping (continuous unilateral jumping) tasks (13,16) have all been previously employed, each of which has shown acceptable reliability data both bilaterally and unilaterally (ICC = 0.68-0.99; CV = 2.82-9.18) in a number of studies (9,13,14,16). ...
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The aim of this brief narrative review is to summarize the present evidence, provide recommendations for data analysis, and appropriate training methods to reduce strength and power asymmetries within athlete populations. Present evidence shows that a strong interest in the assessment of asymmetry exists. Despite the perceived associated relationship between asymmetry and injury and performance, a clear link is still missing. Practitioners need to be aware of this when they decide to assess asymmetries and later design training interventions. Several bilateral and unilateral tests could be used to assess asymmetries such as isokinetic dynamometry, the isometric mid-thigh pull, squat and Nordic hamstring exercise. Based on the current evidence, future investigations require further standardization of methodology and analysis to optimize interpretation (e.g., within session and between session), adoption, and implementation of inter-limb asymmetry testing and appropriate interventions. In this review three training interventions have been proposed to reduce existing lower limb asymmetries in sport populations: traditional resistance training, flywheel resistance training, and combined training interventions, with some evidence suggesting such interventions can reduce lower limb asymmetries. Nonetheless, the number and quality of articles currently available are too limited to draw firm conclusions, therefore, further research is needed to verify whether training interventions can achieve these aims. To develop an understanding and application of interventions addressing inter-limb asymmetries within the sport, greater methodological rigor should be applied towards study design, data analysis and interpretation of future investigations as well as when appraising the current literature.
... Therefore, it is not surprising that force platforms continue to be recommended for obtaining more comprehensive information of CMJ performance [1,6]. Another potential advantage of a special type of force platforms, known as bilateral or dual force platforms, is that they discriminate the force produced by each leg during bilateral jumps [7]. The possibility to selectively assess the force exerted by each leg during bilateral jumps has allowed sport scientists to explore inter-leg asymmetries [8,9], this metric being a rich source of research due to its potential applications to improve sports performance and reduce the risk of injury [10][11][12]. ...
... The jump initiation in the CMJ is typically identified as the time point in which the vGRF falls below a given threshold (e.g., 10 N below body weight) [18,19]. In this regard, some authors have considered the total body weight (i.e., the sum of the vGRF of both force platforms) to select the same time point of jump initiation for both legs [7,16], while other authors have analysed the vGRF data of each force platform independently being possible to determine a different jump start for each leg [13]. Therefore, considering the limited reliability of inter-leg asymmetries variables reported in previous studies [13,14], it seems important to identify the procedure of analysis that allows obtaining the single-leg mechanical performance variables with the greatest consistency. ...
... The effect of the jump start detection for each leg (simultaneous or independent) when analysing the force-time signal during bilateral CMJs performed on dual force platforms was also examined in the present study. An analysis of the literature reveals that there is no consensus regarding which is the most appropriate procedure of analysis [7,13,16]. We hypothesised that the Synchronous procedure would provide a greater reliability than the Asynchronous procedure due to the lower influence for the Synchronous procedure of the distribution of the weight between the two force plates during the weighing phase. However, contrary to our hypothesis, the Synchronous procedure did not provide any variable with a greater reliability than the Asynchronous procedure. ...
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... The participants were positioned on the plate in an upright hip wide stand and the hands holding on the hips to prevent any acceleration impulse during the movement. Starting on command, the participants were asked to bend their knees and hips to a personal choice (Heishman et al., 2019). Reaching the individual deepest position, the participants were asked to jump as explosive and high as possible. ...
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... Similarly, asymmetry in the pattern of movement is presented as a factor in increasing the risk of injury. Measuring asymmetry and explosiveness is also useful for assessing and directing an athlete returning to the training process after a rehabilitation process [22]. Asymmetry can be explained as the continuity of overload on one side of the body or muscle imbalance that occurs if it is not adequately compensated. ...
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... Athletes' CMJ's performance to measure lower body explosive power is well researched (Eagles et al. 2015). Previous studies have highlighted inter-limb asymmetry when athletes return from lower limb injury from soccer (Hart et al. 2019), basketball (Heishman et al. 2019) and youth elite team-sports athletes (Fort-Vanmeerhaeghe et al. 2020). A CMJ performance on force platforms is regarded as the benchmark for test accuracy to measure lower-body power (Requena et al. 2012). ...
... at RTP compared with baseline, which indicates a good rehabilitation outcome as asymmetry is usually present after lower limb injuries. Studies have shown that asymmetry is relevant and does exist when players RTP(Fort-Vanmeerhaeghe et al. 2020;Hart et al. 2019;Heishman et al. 2019). Recently ...
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... The participant was asked to get into an upright hip-wide standing position on the plate. On command, the participant was asked to make a downward movement while bending their knees and hips to a position of personal choice (Heishman et al. 2019). After reaching the individual deepest position, the participant was instructed to jump as explosively and as high as possible. ...
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... In fact, the forwards decreased their jump height between the beginning and the middle of the season, despite it increased between the middle and the end of the season. Despite the fact that these data are controversial with respect to those of the SJ and CMJa, it can be hypothesized that the inclusion of an arm swing while performing a countermovement jump is able to elicit different results [31][32][33]. In fact, an arm swing generates an additive lower-extremity independent effect in the CMJ, increasing the jump height [33], while the CMJa isolates lower-extremity force production. ...
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... Since most players have some degree of interlimb asymmetry, a cut-off value of 85% for the limb asymmetry index had been established [66]. Besides the so-called Four Functional Hop Test [1], both CMJ NAS and CMJ AS provide reliable information of interlimb asymmetries; however, experts should use a single protocol consistently during testing [66]. ...
... Since most players have some degree of interlimb asymmetry, a cut-off value of 85% for the limb asymmetry index had been established [66]. Besides the so-called Four Functional Hop Test [1], both CMJ NAS and CMJ AS provide reliable information of interlimb asymmetries; however, experts should use a single protocol consistently during testing [66]. To show the differences between legs, sports experts categorize legs as dominant and non-dominant. ...
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We conducted a review to collect the validated basketball-specific physical field tests and to provide practical advice for their appropriate selection and application. A comprehensive electronic literature search was performed via three electronic databases (PubMed, GoogleScholar, and SportDiscuss). Results of 93 studies provided recommendations for seven test packages and eighteen individual tests that have already been validated for basketball players. Although there is a lack of standardized, widely, and systematically used test protocols for testing the fitness levels of basketball players, standardized, normative data from NBA Combine Testing and other basketball-specific tests have the potential to help coaches compare their players with elite basketball players. Our review indicated that agility and reactive agility are fundamental skills in basketball; however, linear sprinting ability should not be considered a determining factor of success for basketball players. Finally, the countermovement jump test can help experts monitor fatigue, loss of explosive force, and interlimb asymmetries. In general, we found that identifying and developing a talented player is a complex task and requires experts from different fields, including trainers, coaches, performance- and movement analyzers, and physiotherapists. We found that during the testing of basketball players, experts always have to normalize their data with anthropometric measures for valid results. Most importantly, although experts always need to define an aim of testing and should follow the protocol of the chosen test, they also have to be open to making adjustments if the actual circumstances require it.
... The countermovement jump (CMJ) is a ballistic exercise commonly performed on a force platform to comprehensively assess lower-body neuromuscular function [1,2]. The CMJ has been also used to measure single-leg performance and detect inter-limb asymmetries [3][4][5]. The assessment of inter-limb asymmetries is justified by the influence that CMJ-based asymmetry may have on athletic performance [6,7] and injury risk [4]. ...
... The assessment of inter-limb asymmetries is justified by the influence that CMJ-based asymmetry may have on athletic performance [6,7] and injury risk [4]. Both unilateral and bilateral CMJs have been used to detect inter-limb asymmetries [3][4][5][6]8]. During unilateral CMJs athletes jump from a monopodial stance with the tested leg placed on a single force platform, while during the bilateral CMJ a bipodal stance is used with each leg positioned on an individual force platform [5]. ...
... Both unilateral and bilateral CMJs have been used to detect inter-limb asymmetries [3][4][5][6]8]. During unilateral CMJs athletes jump from a monopodial stance with the tested leg placed on a single force platform, while during the bilateral CMJ a bipodal stance is used with each leg positioned on an individual force platform [5]. Although it is reasonable to believe that the inter-limb asymmetries measured during bilateral and unilateral CMJs should be closely related, research has shown that impulse asymmetries observed during bilateral and unilateral CMJs are unrelated [3]. ...
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... Some variables were estimated within an acceptable error range (±10%), while others presented only tolerable (±20%) errors. Those error thresholds were defined based on the suggestions in [47][48][49][50]. Some metrics presented larger errors as this is due to the fact that accelerometers are good at measuring acceleration but poor at estimating position, because of problems when integrating data, therefore inevitably introducing errors when estimating the velocity and position curves from an acceleration signal [51]. ...
... However, a similar indication is not provided in the sport field for sport performance devices. Nevertheless, previous literature has suggested that test reliability standards should ultimately be judged by the individual researcher or practitioner based in accordance with their intended use, and that the most reliable variables may not necessarily be the most efficacious in athlete monitoring and performance testing regimens [49,50]. Therefore, based on the previous indications, this investigation considers the validity criteria of 20% error threshold as tolerable and 10% error as acceptable for consumer-level technology. ...
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