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Intensity rankings of plyometric exercises using joint power absorption
... 1 The efficacy of plyometrics in rehabilitation programs used to stress bodily tissue to facilitate a healing response has been established, and plays a critical role when recommencing sport specific activity. 2 An important consideration in a conditioning program is the timing of introduction of an exercise, such as a plyometric exercise, with respect to the ability of the tissue to cope with imposed loading. 2 Plyometric exercises like all resistance exercises, are subject to the training principles of mode, frequency, volume, progression, recovery and intensity. 3 Understanding the amount of stress an exercise places upon specific bodily tissues is of value to clinicians when formulating strength and conditioning programs. ...
... 2 An important consideration in a conditioning program is the timing of introduction of an exercise, such as a plyometric exercise, with respect to the ability of the tissue to cope with imposed loading. 2 Plyometric exercises like all resistance exercises, are subject to the training principles of mode, frequency, volume, progression, recovery and intensity. 3 Understanding the amount of stress an exercise places upon specific bodily tissues is of value to clinicians when formulating strength and conditioning programs. ...
... 3 Understanding the amount of stress an exercise places upon specific bodily tissues is of value to clinicians when formulating strength and conditioning programs. [1][2][3][4] In order to optimise the transfer of training effect of a prescribed exercise, a selected exercise should be as similar to the desired performance task as possible. 4 The principle of transfer of training effect is demonstrated by Singh & Singh,5 where horizontal jump-landing tasks were more effective in improving sprint performance than vertical jumps, in a male student population. ...
Horizontal jumps have been used to assess pathological landing mechanics and as a plyometric conditioning exercise. Investigations have yet to clarify what and how varying jump characteristics influence landing mechanics. A search of Medline, CINAHL, Embase, Scopus and SPORTDiscus was conducted. Included articles were original published research articles, which reported 3D kinetic or kinematic measurements on landing, from bilateral horizontal jumps in healthy adult populations. Nine articles met inclusion criteria and demonstrated a satisfactory to low risk of bias. Kinematic and kinetic landing data for bilateral horizontal jumps were extracted and analysed. The addition of a subsequent jump on landing reduced peak vertical ground reaction force (GRF), and addition of a heading task reduced landing hip and knee joint flexion. Greater magnitude jumps increased knee joint flexion. Horizontal jump tasks which restricted arm swing produced less peak vertical GRF. Bilateral horizontal jumps described as having higher peak vertical trajectories appeared to be associated with reduced hip flexion on landing. These findings highlight the importance of considering jump characteristics when designing bilateral horizontal jump tasks. Further research on landing performance following bilateral horizontal jumps is required to strengthen findings and should include measures of flight trajectory.
... However, an important distinction lies in the velocity at which one falls and the direction of landing relative to that of the takeoff, with rapid landings below the takeoff point being more eccentrically stressful. A surplus of scientific publications investigating GCT classifications, reactive strength index, kinetic forces, and joint power absorption now bring into question the traditional classifications of plyometric training and provide more advanced analysis on the specific stress from different exercises (24,42). For instance, analysis of lower-body jump exercises revealed that jumping movements in the forward direction have ;19-24% greater summed, ankle, knee, and hip joint peak power than the box drop and jump up exercises, although classified as low compared to moderate intensity via subjective ratings (42). ...
... A surplus of scientific publications investigating GCT classifications, reactive strength index, kinetic forces, and joint power absorption now bring into question the traditional classifications of plyometric training and provide more advanced analysis on the specific stress from different exercises (24,42). For instance, analysis of lower-body jump exercises revealed that jumping movements in the forward direction have ;19-24% greater summed, ankle, knee, and hip joint peak power than the box drop and jump up exercises, although classified as low compared to moderate intensity via subjective ratings (42). Moreover, specific joint analysis reveals that intensity rankings differ by joint contribution, with forward jumps being classified as high intensity for the ankle, but low for the hip (42). ...
... For instance, analysis of lower-body jump exercises revealed that jumping movements in the forward direction have ;19-24% greater summed, ankle, knee, and hip joint peak power than the box drop and jump up exercises, although classified as low compared to moderate intensity via subjective ratings (42). Moreover, specific joint analysis reveals that intensity rankings differ by joint contribution, with forward jumps being classified as high intensity for the ankle, but low for the hip (42). ...
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 XX(X): 000-000, 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.
... Moreover, the intensity rating of PJT may differ as a function of the drill type and the measuring method. For example, a drop jump (DJ) can be rated as more intense compared with a box jump if ground reaction forces or muscle damage markers are considered (12,41). However, when EMG is used as an intensity marker, the box jump is more intense (12,41). ...
... For example, a drop jump (DJ) can be rated as more intense compared with a box jump if ground reaction forces or muscle damage markers are considered (12,41). However, when EMG is used as an intensity marker, the box jump is more intense (12,41). In addition, controversy exists with regard to the intensity of identical drills under different conditions. ...
... As for the current study, it is speculative to discuss potential mechanisms responsible for the larger performance improvements in PJT-100 compared with PJT-80 or PJT-65. Therefore, future studies are needed to elucidate the potential neuromuscular and biomechanical mechanisms (e.g., propulsive force, motor unit recruitment, and joint power) responsible for intensity-specific improvements in PJT (41). More specifically, the use of inverse dynamics could help to disentangle specific moments in the ankle, knee, and hip joints during jumping at different intensities. ...
An 8-week single-blind randomized controlled trial was conducted to compare the effects of separate programs of equal volume, but different intensity, plyometric jump training (PJT), on physical fitness in healthy adults. Thirty-eight physically active males (mean age: 21.8 ± 2.5 years) participated. Subjects were randomly assigned to one of 3 PJT groups or a control (CON, n = 9) according to their jump performance. Plyometric jump training was conducted at maximal (PJT-100, n = 10), high (PJT-80, n = 9), or moderate (PJT-65, n = 10) intensity within each group. Baseline and follow-up tests were performed for the assessment of countermovement jump (CMJ) height, CMJ height with arm swing (CMJA), and drop jump height from a 20-cm drop box (DJ20), linear speed (30 m), and change-of-direction speed (CODS) (the Illinois CODS test). Results revealed significant group × time interactions for CMJ, CMJA, DJ20, 30-m sprint, and CODS (all p < 0.001; d = 0.39–0.76). Post hoc analyses showed significant improvements in all 5 fitness measures for PJT-100 (all p < 0.01, Δ3.7–13.5%, d = 0.26–1.4). For PJT-80, 3 of 5 fitness tests demonstrated significant change (CMJ: p < 0.001, Δ5.9%, d = 0.33; CMJA: p < 0.001, Δ7.0%, d = 0.43; CODS: p < 0.001, Δ3.9%, d = 0.9), and for PJT-65, only 1 test was significant (CMJ: p < 0.05, Δ2.8%, d = 0.15). No significant changes were observed in CON. Except for similar gains in DJ20 and 30-m sprint in PJT-100 and PJT-80, gains in physical fitness were, in general, greater (p < 0.05) after PJT-100 vs. PJT-80 vs. PJT-65 vs. CON. Therefore, maximal PJT intensity may induce larger physical fitness gains, although high and moderate intensities may also be useful, but to a lesser extent.
... Another joint kinetic measure that has been used within the literature is (negative) joint power 17,33,36 and reliability for this measure has been assessed 17 (r=0.85). As is the case with V-GRFp, when used to quantify mechanical output of common plyometric exercises, these variables present a different order of 'stress' to that of Potach and Chu's 29 traditional intensity continuum. ...
... This concurs with previous studies which show that the depth jump is not inherently intense and the classic intensity continuum needs revision. 11 These discrepancies cannot be solely attributed to the independent joint assessment, as two studies 17,36 have summed (negative) joint powers (summing values for the ankle, knee and hip to obtain a global value) and the divergence with traditional descriptors remained. ...
... Recent studies have increased our understanding of GRF derivatives and how they depict the order of intensity or 'stress' of common plyometric exercises. 10,11,17,19,33,36 These studies for the most part highlight that kinetic measures are repeatable and are able to detect differences between exercises, but this doesn't mean they are necessarily meaningful descriptors of 'stress'. When considering the biological effect of a plyometric exercise, coaches are reminded that mechanical output will vary greatly between joints. ...
... Tra questi, le massime forze di reazione del terreno (GRF), [6][7][8] il tasso di sviluppo della forza (RFD), 7,8 il tempo per la stabilizzazione, 9 il tempo per lo stacco da terra e quello di volo del salto, 8 l'elettromiografia di superficie (SEMG), 10,11 l'impulso 7,11 e l'assorbimento della potenza articolare. 12 Il risultato di questi studi ha variato e in certi casi si è rivelato contraddittorio. Inoltre, i metodi citati presentano una fortissima dipendenza da tecnologia e competenza tecnica. ...
... This methods include peak ground reaction forces (GRf), 6-8 rate of force development (RfD), 7, 8 time to stabilization, 9 time to takeoff and flight time, 8 surface electromyography (SEMG), 10, 11 impulse, 7, 11 joint power absorption. 12 The result of these studies was varying and in some special cases was contradictory. Also, the mentioned methods absolutely have a strong dependence on technology and technical expertise. ...
... In most previous studies conducted for quantifying of plyometrics the intensity of BJ had a moderate intensity, but DJ intensity was variable between moderate to high depend on box heights. 6,8,9,12,24 Only EMG data form Ebben et al. study ranked DJ in lowest intensity than other plyometrics. 10 High intensity of single-leg vertical jump and PJ in the present study potentially related to high eccentric force of this jumps that may allow better utilization of the muscle spindles, resulting in more forceful concentric contractions of these muscle groups. 1 Khodaei et al. that used of Borg RPE for ranking and equitizing plyometric training modes include assisted, resisted and common plyometrics demonstrated squat jump and cone jump have "light" intensity and Single-leg Vertical Jump have "high" intensity. ...
Background: The purpose of this study was to evaluating and quantifying plyometric exercises intensity using Ratings Of Perceived Exertion (RPE) Scale. Methods. Twenty athletes volunteered to perform 9 plyometric exercises with 10 repetitions. The resting intervals between each plyometric exercises set three minutes. During resting intervals, participants filled the Borg RPE questionnaire. Testing protocol performed in two trials with 48-hour-interval. Average values of each plyometric exercise in two trials analyzed by a 1-way repeated measures Analysis of Variance (ANOVA). Results. The results were revealed a significant main effect for all plyometrics. The Post-Hoc Test result indicated that the skipping had the "very light" intensity and significantly lower intensity than all plyometrics. The Cone hops and the squat jump had the "light" intensity and significantly had lower intensity than all plyometrics except the skipping. The tuck jump, the barrier jump, the box jump, and the depth jump had the "moderate" intensity and significantly lower intensity than the single leg vertical jump and the pike jump. The single leg vertical jump and the pike jump also had the "high" intensity and significantly higher intensity than all plyometrics. Conclusions: The results of present study indicated that individual responses to plyometric exercises with the RPE scale as a physiological assessing method more similar to responses of biomechanical assessing methods used in previous studies. This method is a low-cost and practical method that applicable in large groups and various plyometric exercises.
... 5 Previous research has used lower-limb peak power absorption, joint (ankle, knee, hip) peak power absorption, knee joint reaction forces, ground reaction forces (GRFs), and the rate of eccentric GRF development to quantify the intensity of plyometric exercises. 8,9 A limitation of these metrics is that they provide little insight into individual muscle function during an exercise, as it is not possible to differentiate the actions of individual muscles from GRFs and net joint moments alone. 10 It is plausible that different exercises demand differential loads on the gastrocnemius and soleus because of their anatomical and functional differences. ...
... The ankle bounce and hurdle jumps were executed perpendicular to the series of force plates with feet contacting different force platforms so that GRFs for each limb could be independently collected. 8 The hurdles were arranged so that the force plates captured GRFs between the second and third hurdle jumps. ...
Objectives
Plyometric exercises are used to prevent and rehabilitate plantarflexor injuries among runners. To facilitate exercise programming, this study compared plantarflexor musculotendon output during running to plyometric exercises in distance runners.
Design
Experimental study with cross-over design.
Method
Fourteen trained distance runners performed running, ankle bouncing, A-skips, bounding, and hurdle jumps. Three-dimensional motion capture and force plate data were collected and computational simulations used to calculate gastrocnemius lateralis and soleus musculotendon peak forces, strain, power generation and absorption, and total positive and negative work. Percentage difference scores and standardised mean differences (SMD) were used to compare variables between plyometrics and running. Musculotendon units were classified as energy generators or absorbers according to their net mechanical work.
Results
Both plantarflexors behaved as net energy generators during running. Plantarflexor peak force and power generation and absorption were lower in the A-skip and ankle bounce compared to running. Soleus behaved as a net energy absorber during hurdle jumps, with greater total negative work (16.5%; SMD 0.92) and higher peak strain (0.3%; SMD 0.28) during hurdle jumps than running. Gastrocnemius lateralis behaved as a net energy absorber during bounding, with greater total negative work (63.8%; SMD 0.81) and peak strain (0.4%; SMD 0.77) during bounding than running.
Conclusions
The ankle bounce and A-skip may be appropriate exercises when runners desire lower plantarflexor loads than running. Hurdle jumps elicited high soleus loads but low gastrocnemius lateralis loads, highlighting the disparate function of the plantarflexors. Bounding demanded high plantarflexor musculotendon output and may be suitable when eccentric overload is desired.
... Hence, plyometric exercises can offer exercise intensities ranging from submaximal to supramaximal. Based upon information from numerous studies that have used ground reaction forces, RFD ECC , GCT, impulse, and integrated electromyography to quantify the intensity of a variety of plyometric exercises [81][82][83][84][85][86][87][88][89][90][91], the progression of plyometric exercises can be aligned with an athlete's relative back squat strength [92,93]. Figures 2 and 3 present a theoretical model of how ECC exercise intensity may be progressed for athletes within the different categorization of lower body strength levels. ...
... Hence, plyometric exercises can offer exercise intensities ranging from submaximal to supramaximal. Based upon information from numerous studies that have used ground reaction forces, RFDECC, GCT, impulse, and integrated electromyography to quantify the intensity of a variety of plyometric exercises [81][82][83][84][85][86][87][88][89][90][91], the progression of plyometric exercises can be aligned with an athlete's relative back squat strength [92,93]. Figures 2 and 3 present a theoretical model of how ECC exercise intensity may be progressed for athletes within the different categorization of lower body strength levels. ...
The purpose of this review is to provide strength and conditioning practitioners with recommendations on how best to implement tempo eccentric training (TEMPO), flywheel inertial training (FIT), accentuated eccentric loading (AEL), and plyometric training (PT) into resistance training programs that seek to improve an athlete’s hypertrophy, strength, and power output. Based on the existing literature, TEMPO may be best implemented with weaker athletes to benefit positional strength and hypertrophy due to the time under tension. FIT may provide an effective hypertrophy, strength, and power stimulus for untrained and weaker individuals; however, stronger individuals may not receive the same eccentric (ECC) overload stimulus. Although AEL may be implemented throughout the training year to benefit hypertrophy, strength, and power output, this strategy is better suited for stronger individuals. When weaker and stronger individuals are exposed to PT, they are exposed to an ECC overload stimulus as a result of increases in the ECC force and ECC rate of force development. In conclusion, when choosing to utilize ECC training methods, the practitioner must integrate these methods into a holistic training program that is designed to improve the athlete’s performance capacity.
... Recent interest of the plyometric literature has been focused on disbanding from the subjective classification of plyometric-type movements in favor of a kinetic-based (e.g. forcetime, power) approach for assessing the intensity and specificity of various plyometric exercises (Jensen and Ebben, 2007;Ebben et al., 2011;Jidovtseff et al., 2014;Van Lieshout et al., 2014). ...
... The squat jump condition (SJ) emphasized the concentric phase, as it required subjects to squat and jump as high as possible in a single, fluent motion. Two depth jump conditions were performed from a height of 0.35 m (Van Lieshout et al., 2014). For the depth jump conditions, subjects were asked to 'step forward' off the box onto a force platform, followed by a subsequent vertical jump with verbal cues to jump 'as high as possible' (DJH) or 'as quick as possible' (DJT). ...
Plyometric training is a popular method utilized by strength and conditioning professionals to improve aspects of functional strength. The purpose of this study was to explore the influence of extrinsic verbal cueing on the specificity of jumping movements. Thirteen participants (age: 23.4 ± 1.9 yr, body height: 170.3 ± 15.1 cm, body mass: 70.3 ± 23.8 kg,) performed four types of jumps: a depth jump “as quickly as possible” (DJT), a depth jump “as high as possible” (DJH), a countermovement jump (CMJ), and a squat jump (SJ). Dependent measures, which included measurement of strength and power, were acquired using a force platform. From the results, differences in body-weight normalized peak force (BW) (DJH: 4.3, DJT: 5.6, CMJ: 2.5, SJ: 2.2), time in upward propulsion (s) (DJH: 0.34, DJT: 0.20, CMJ: 0.40, SJ: 0.51), and mean acceleration (m·s-2) (DJH: 26.7, DJT: 36.2, CMJ: 19.8, SJ: 17.3) were observed across all comparisons (p = 0.001 - 0.033). Differences in the body-weight normalized propulsive impulse (BW·s) (DJH: 0.55, DJT: 0.52, CMJ: 0.39, SJ: 0.39) and propulsive power (kW) (DJH: 13.7, DJT: 16.5, CMJ: 11.5, SJ: 12.1) were observed across all comparisons (p = 0.001 - 0.050) except between the CMJ and SJ (p = 0.128 - 0.929). The results highlight key kinetic differences influencing the specificity of plyometric movements and suggest that verbal cues may be used to emphasize the development of reactive strength (e.g. DJT) or high-velocity concentric power (e.g. DJH).
... However, it continues to be the subject of research in different disciplines. Indeed, its effect on ankle sprain and joint power absorption in orthopedics (Ismail, Ibrahim, Youssef & Shorbagy 2010;Van Lieshout, Anderson, Shelburne & Davidson, 2014); In the field of physiotherapy and rehabilitation, the effect of athletes on injuries (Chmielewski, Myer, Kauffman & Tillman, 2006) and the effect of plyometric training on the human body in many other areas are investigated. ...
Plyometric training is a training method that includes a stretch-shortening cycle and is designed with exercises that require explosiveness. Sports science has studied this training method for many years, and a great deal of research has been done at var ious levels. This study aims to evaluate the research articles on plyometric training in the field of sports sciences with bibliometric data and to reach specific norm values within the study's limitations. The study was carried out with a bibliometric analysis design, one of the quantitative research methods, and the Web of Science database was used as a data collection tool. The database related to the study; was included in the category of sports sciences; 358 research articles scanned in any of the SSCI, ESCI, or SCI-Expanded indexes were had. Statistical analyzes of the study were performed with the programming language R (ver. 4.2.2), and the biblioshiny function was used. The findings of this study revealed that the most influential researcher on the subject is Rodrigo Ramirez Campillo, and the journal that most accepts plyometric training research is the Journal of Strength and Conditioning Research. However, there is a need to examine the effects of plyometric training on agility, change of direction, and sprint performance, to conduct more research on children and youth and to address the issue from different perspectives, especially on football players. As a result, the findings may be necessary for researchers and field experts who will research the subject of plyometric training. Furthermore, the study's findings can offer an idea to the researchers studying the topic.
... A 30 cm box height was used, and each athlete performed 3 drop jump attempts (DJ30) following previously established norms [5,20,35,36]. To reduce possible errors in the RSI measurement and reduce the effects of PB2.0 movement during jumping [28], the belt was fixed on the subjects with double-sided tape between L3 and L4 ( Figure 1). ...
This study aims to verify the validity of the Push Band 2.0 (PB2.0) device on the reactive strength index (RSI) measurement, using a force plate (FP) and an optical sensor device, OptoJump (OPT), as a reference. Twenty trained athletes performed 60 drop jump trials with a height box of 30 cm. A randomized repeated measures study was conducted during a single session using the PB2.0, the OPT, and the plate force manually synchronized to obtain RSI data for each jump. Validity was analyzed by contrasting three measures: the intra-class correlation coefficient (ICC), the Bland-Altman test, and R2 coefficient of determination. Bland-Altman analysis showed that RSI and FP for PB2.0 (media = −0.047; IC 93.34%) of all data were within the confidence interval, indicating a statistically reliable result. The RSI measured by the OPT and PB2.0 also provided similar values (media = −0.047). These data are identical to other validity measures (ICC and linear correlation) but differ in the R2 values. The explained variation of PB2.0 measures attained only 29.3% of the FP (R2 = 0.293) and 29.5% (R2 = 0.295) of the OPT assessment, showing a very low determination coefficient. The results of this study point to caution in the use of PB2.0 when measuring RSI in scientific research .
... Se ha sugerido, que la progresión en el proceso de readaptación inicie con ejercicios de baja intensidad como "saltos hacia el cajón" en donde se enfatiza la fase de impulso y se minimiza la fase de aterrizaje, para posteriormente progresar a ejercicios de mayor intensidad como "saltos desde el cajón" en donde se enfatiza la fase de aterrizaje 33 ; Van Lieshout et al. 60 determinaron que los ejercicios como "saltos hacia la caja" y "saltos desde la caja" generan menos carga articular en cadera, la rodilla y el tobillo que otros tipos de ejercicios como el salto en contra-movimiento, salto vertical con flexión de rodillas y salto vertical con caída previa. Una vez readaptadas las fases de impulso y aterrizaje, se sugiere iniciar la readaptación del gesto pliométrico con ejercicios como el "salto caja a caja" 33 . ...
... While this review has primarily focused on monitoring and adjusting intensity within the weight room using traditional resistance training exercises (e.g., squats, presses, and pulls), it should be noted that other forms of resistance training such as weightlifting movements [131][132][133][134][135][136][137], eccentric training methods [138][139][140][141][142][143][144], isometric training [145][146][147], plyometric training [148][149][150][151][152], and loaded jumps [153][154][155] may require different monitoring methods due to unique loading methods (e.g., eccentric, isometric, etc.) or coordinative complexity (e.g., weightlifting movements and jump variations). In addition, practitioners should consider the fact that novice athletes may lack consistency in the weight room due to modifications of their strength, technique, and effort. ...
Linear loading, the two-for-two rule, percent of one repetition maximum (1RM), RM zones, rate of perceived exertion (RPE), repetitions in reserve, set-repetition best, autoregulatory progressive resistance exercise (APRE), and velocity-based training (VBT) are all methods of adjusting resistance training intensity. Each method has advantages and disadvantages that strength and conditioning practitioners should be aware of when measuring and monitoring strength characteristics. The linear loading and 2-for-2 methods may be beneficial for novice athletes; however, they may be limited in their capacity to provide athletes with variation and detrimental if used exclusively for long periods of time. The percent of 1RM and RM zone methods may provide athletes with more variation and greater potential for strength–power adaptations; however, they fail to account for daily changes in athlete’s performance capabilities. An athlete’s daily readiness can be addressed to various extents by both subjective (e.g., RPE, repetitions in reserve, set-repetition best, and APRE) and objective (e.g., VBT) load adjustment methods. Future resistance training monitoring may aim to include a combination of measures that quantify outcome (e.g., velocity, load, time, etc.) with process (e.g., variability, coordination, efficiency, etc.) relevant to the stage of learning or the task being performed. Load adjustment and monitoring methods should be used to supplement and guide the practitioner, quantify what the practitioner ‘sees’, and provide longitudinal data to assist in reviewing athlete development and providing baselines for the rate of expected development in resistance training when an athlete returns to sport from injury or large training load reductions.
... Biomechanical performance variables are defined in this paper as quantifiable performance measures collected using biomechanical equipment such as force platforms and motion capture technology. Although there are many methods to assess biomechanical performance during direction changes and jumping (Jensen & Ebben, 2007;McLellan et al., 2011;Van Lieshout et al., 2014), the effects of specific shoe designs on these performance variables have not been investigated. ...
The objective of this research was to determine if three alternative shoe closures improve biomechanical performance measures compared to a standard lace closure in agility-based movements. NCAA Division 1 and club-level male athletes recruited from lacrosse, soccer, tennis, and rugby performed four court-based movements: Lateral Skater Jump Repeats (LSJ), Countermovement Jump Repeats (CMJ), Triangle Drop Step Drill (TDS), and Anterior-Posterior Drill (AP). Each athlete performed the movements in four shoe upper closures: Standard Closure, Lace Replacement, Y Wrap, and Tri Panel. Movement completion time, Ground contact time, peak eccentric rate of force development (RFD), peak concentric GRF, peak concentric COM power, eccentric work, and concentric work were measured. The Y Wrap configuration the Tri Panel configuration delivered improvements between 3 and 9% over the Standard Closure depending on the movement tested and variable of interest. The Lace Replacement had mixed results with some improvements and some declines in performance. This study allowed for the mechanical properties of the shoe bottom package to remain consistent across designs to examine if alternative upper configurations could enhance performance. We hypothesise that improved containment and possibly increased proprioception—due to the wrapping fit of the configurations influences these changes in performance. These findings suggest that the design and construction shoe upper is essential to consider in athletic shoe design.
... To increase leg muscle explosive power it is very important for researchers to pay attention to the energy system used. The basic principle in the training program is to know the main energy system used to carry out an activity [5]. The energy system used is anaerobic which means without using oxygen, in other words the activity carried out is less than or equal to 90 seconds. ...
... Biomechanical performance variables are defined in this paper as quantifiable performance measures collected using biomechanical equipment such as force platforms and motion capture technology. Although there are many methods to assess biomechanical performance during direction changes and jumping (Jensen et al. 2007;McLellan et al. 2011;Van Lieshout et al. 2014), the effects of specific shoe designs on these performance variables have not been investigated. ...
The objective of this research was to determine if three alternative shoe upper closures improve biomechanical performance measures relative to a standard lace closure in court-based movements. NCAA Division 1 and club-level male athletes recruited from lacrosse, soccer, tennis, and rugby performed four court-based movements: Lateral Skater Jump repeats (LSJ), Countermovement Jump repeats (CMJ), Triangle Drop Step drill (TDS), and Anterior-Posterior drill (AP). Each athlete performed the movements in four shoe upper closures: Standard Closure, Lace Replacement, Y Wrap, and Tri Strap. Ground contact time, peak eccentric rate of force development (RFD), peak concentric GRF, peak concentric COM power, eccentric work, concentric work, and movement completion time were measured. Tri Strap saw improvements in four of seven biomechanical variables during CMJ and LSJ and one variable during TDS. Lace Replacement delivered improvements in one performance measure during CMJ, LSJ, and AP, and two variables in TDS. Y Wrap improved performance in three performance measures during LSJ and impaired performance in two measures during CMJ and three measures during AP. Tri Strap provided the most consistent performance improvements across all movements. This study allowed for the mechanical properties of the shoe lower to remain consistent across designs to examine if an alternative shoe upper closure could enhance performance. Our results indicate that increased proprioception and/or mechanical properties due to the alternative closures, especially Tri Strap, improves athlete performance, which concludes that the design of the shoe upper is an essential consideration in shoe design.
... Based on the newest concept of plyometric, the exercise intensity is high because there were more than 200 foot works in every meeting [8]. Meanwhile based on the intensity level of joints absorbance towards power, this exercise program was considered low [19]. As fast as possible As fast as possible Frecuency ...
... Biomechanical performance variables are defined in this paper as quantifiable performance measures collected using biomechanical equipment such as force platforms and motion capture technology. Although there are many methods to assess biomechanical performance during direction changes and jumping (Jensen & Ebben, 2007;McLellan et al., 2011;Van Lieshout et al., 2014), the effects of specific shoe designs on these performance variables have not been investigated. ...
... Specifically, the plyometric exercises chosen, the athletic population being trained, the other methods of training that are being used, the season that the athlete is currently in, and the training adaptations sought may drastically modify how plyometric exercises may be implemented. Several studies [162][163][164][165][166][167][168] have sought to identify the intensity of different plyometric exercises by using a variety of ECC (e.g., rate of force development, joint power absorption, joint reaction forces), CON (e.g., peak force, time to takeoff, muscle activation), and landing variables (e.g., impulse, time to stabilization, rate of force development). As displayed in Figure 5, these exercises may fall within an intensity spectrum, which may allow for the intentional prescription of low, moderate, and high intensity exercises. ...
The purpose of this review was to provide a physiological rationale for the use of eccentric resistance training and to provide an overview of the most commonly prescribed eccentric training methods. Based on the existing literature, there is a strong physiological rationale for the incorporation of eccentric training into a training program for an individual seeking to maximize muscle size, strength, and power. Specific adaptations may include an increase in muscle cross-sectional area, force output, and fiber shortening velocities, all of which have the potential to benefit power production characteristics. Tempo eccentric training, flywheel inertial training, accentuated eccentric loading, and plyometric training are commonly implemented in applied contexts. These methods tend to involve different force absorption characteristics and thus, overload the muscle or musculotendinous unit in different ways during lengthening actions. For this reason, they may produce different magnitudes of improvement in hypertrophy, strength, and power. The constraints to which they are implemented can have a marked effect on the characteristics of force absorption and therefore, could affect the nature of the adaptive response. However, the versatility of the constraints when prescribing these methods mean that they can be effectively implemented to induce these adaptations within a variety of populations.
... However, the examples presented in Figs 3, 4 and 5 are not the only possible applications of the technique. A similar approach could be used to monitor the changing load distribution beneath athletes performing a range of other training activities 24 or simply during standing. The device also has potential applications in physiotherapy for monitoring improvements during the rehabilitation of injured athletes or in elderly patients who may have suffered a fall. ...
Frustrated total internal reflection (FTIR) imaging was used to perform remote optical measurements of the forces/pressures exerted beneath shoes and feet during a number of different training activities including countermovement jumps, jogging and drop jumps. A single camera was used to simultaneously image two acrylic, FTIR waveguide imaging elements from below, at frame rates up to 200 frames per second. The images obtained using the camera were converted into pressure/force maps using a previously developed theory which combines the mechanics of contact of soft objects and the scattering of evanescent waves. The forces obtained from the optical measurements were shown to be in good agreement with measurements obtained from load cells placed beneath the FTIR imaging elements. The ability to produce accurate spatial maps of the force/pressure distribution beneath soft contacting objects such as feet and shoe outsoles at high frame rates has numerous potential applications in sports sciences and medicine.
... For example, a depth jump could be considered one of the more advanced plyometric exercises, requiring athletes to have adequate neuromuscular control and strength (59). This could be replaced by coaches in the MID phase by a less demanding exercise such as a box jump, which can reduce forces exerted on the involved joints (90). Such manipulation of training variables, incorporating changes to volume, intensity, and modality, could contribute to a reduced adaptive response. ...
Recent debate on the trainability of youths has focused on the existence of periods of accelerated adaptation to training. Accordingly, the purpose of this meta-analysis was to identify the age- and maturation-related pattern of adaptive responses to plyometric training in youth athletes. Thirty effect sizes were calculated from the data of 21 sources with studies qualifying based on the following criteria: (a) Healthy male athletes who were engaged in organised sport; (b) Groups of participants with a mean age between 10 and 18 years; (c) Plyometric-training intervention duration between 4 and 16 weeks. Standardised mean differences showed plyometric training to be moderately effective in increasing countermovement jump (CMJ) height (ES = 0.73 95% confidence interval: 0.47-0.99) across PRE-, MID-, and POST-peak height velocity groups. Adaptive responses were of greater magnitude between the mean ages of 10 and 12.99 years (PRE) (ES = 0.91 95% confidence interval: 0.47-1.36) and 16 and 18 years (POST) (ES = 1.02 [0.52-1.53]). The magnitude of adaptation to plyometric training between the mean ages of 13 and 15.99 years (MID) was lower (ES = 0.47 [0.16-0.77]), despite greater training exposure. Power performance as measured by CMJ may be mediated by biological maturation. Coaches could manipulate training volume and modality during periods of lowered response in order to maximise performance. Copyright (C) 2016 by the National Strength & Conditioning Association.
... This is important, as it is has been established that performing drop jumps from higher drop heights (40-60 cm) places greater stress on the joints of lower extremities, which contributes to an increased demand on the neuromuscular system for successful performance and therefore could influence the reliability the results of the test. 11,16,23 Establishing the reliability of a variety of drop heights could strengthen the application of the drop-jump profile used to analyze elite athletes' reactive strength capabilities. ...
Purpose:
To evaluate the reliability of the Reactive Strength Index (RSI) and jump-height (JH) performance from multiple drop heights in an elite population.
Methods:
Thirteen professional basketball players (mean±SD age 25.8±3.5 y, height 1.96±0.07 m, mass 94.8±8.2 kg) completed 3 maximal drop-jump attempts onto a jump mat at 4 randomly assigned box heights and 3 countermovement-jump trials.
Results:
No statistical difference was observed between 3 trials for both the RSI and JH variable at all the tested drop heights. The RSI for drop-jump heights from 20 cm resulted in a coefficient of variation (CV)=3.1% and an intraclass correlation (ICC α)=.96, 40 cm resulted in a CV=3.0% and an ICC α=.95, and 50 cm resulted in a CV=2.1% and an ICC α=.99. The JH variable at the 40-cm drop-jump height resulted in the highest reliability CV=2.8% and an ICC α=.98.
Conclusion:
When assessing the RSI the 20-, 40-, and 50-cm drop heights are recommended with this population. When assessing large groups it appears that only 1 trial is required when assessing the RSI variable from the 20, 40-, and 50-cm drop heights.
The quantification of mechanical power can provide valuable insight into athlete performance because it is the mechanical principle of the rate at which the athlete does work or transfers energy to complete a
movement task. Estimates of power are usually limited by the capabilities of measurement systems, resulting in the use of simplified power models. This review provides a systematic overview of the studies on mechanical power in sports, discussing the application and estimation of mechanical power, the consequences
of simplifications, and the terminology. The mechanical power balance consists of five parts, where joint power is equal to the sum of kinetic power, gravitational power, environmental power, and frictional power. Structuring literature based on these power components shows that simplifications in models are done on four levels, single vs multibody models, instantaneous power (IN) versus change in energy (EN), the dimensions of a model (1D, 2D, 3D), and neglecting parts of the mechanical power balance. Quantifying the consequences of simplification of power models has only been done for running,
and shows differences ranging from 10% up to 250% compared to joint power models. Furthermore, inconsistency and imprecision were found in the determination of joint power, resulting from inverse
dynamics methods, incorporation of translational joint powers, partitioning in negative and positive work, and power flow between segments. Most inconsistency in terminology was found in the definition and application of ‘external’ and ‘internal’ work and power. Sport research would benefit from structuring the research on mechanical power in sports and quantifying the result of simplifications in mechanical power estimations.
El entrenamiento pliométrico (EPLI) es una herramienta utilizada para mejorar las acciones explosivas en muchos deportes; no obstante, este tipo de entrenamiento no genera el mismo efecto en todos los deportes. El objetivo del estudio fue evaluar el efecto del entrenamiento pliométrico sobre la fuerza explosiva (FE) en los deportes colectivos. En el análisis final, se incluyeron 31 estudios que generaron 50 Tamaños de Efecto (TE). Bajo un modelo de efectos aleatorios, se encontró que el EPLI es efectivo para mejorar la FE (TE=0.98; p=0.00; CI95%=0.77 a 1.20; n=50; Q=174.51; I²=71.95) en deportes de conjunto. Los resultados orientan que para mejorar la FE en este tipo de deportes se debe utilizar el entrenamiento pliométrico sin combinarlo con otro tipo de ejercicios durante al menos diez semanas. Además, este tipo de entrenamiento produce mejorías en la altura de salto, tanto en el periodo preparatorio como en el competitivo, independientemente del tipo de protocolo que se utilice. Se propone realizar estudios confirmatorios con los resultados de este metaanálisis en los que se incluyan otros deportes y se estudie más el tema en mujeres, así como la combinación del EPLI con otro tipo de ejercicios o entrenamientos.
Reactive strength exercises are characterized by muscle actions in the stretch-shortening cycle (SSC) which is why reactive strength training is a specific form of SSC training. During the SSC, the pre-activated muscle is lengthened in the braking or plyometric phase (i.e., eccentric phase) followed by an immediate muscle shortening in the push off or myometric phase (i.e., concentric phase). However, it is to be assumed that 95% of sport-related movements are conducted in the SSC. Reactive strength training represents an effective mode of exercise to improve in particular throwing and jumping performances. It contributes positively to improved agility, speed of action, and other performance indicators in handball. Furthermore, reactive strength training supports positively the prevention of sport-related injuries, e.g., knee and ankle injuries, and helps to regain pre-injury performance level in athletes. A systematic and progressive training approach is presented during all stages of long-term athlete development to induce adaptive changes following reactive strength training and to increase the likelihood of transferring a talented young player into an elite athlete. The specific training variables of reactive strength training, such as exercise selection, training frequency, exercise order, training load and repetitions, and training volume as well as the technical correctness and movement quality of the exercise, have to be systematically controlled and gradually adjusted according to the development of the athletes.
Plyometric exercise was initially utilized to enhance sport performance and is more recently being used in the rehabilitation of injured athletes to help in the preparation for a return to sport participation. The identifying feature of plyometric exercise is a lengthening of the muscle-tendon unit followed directly by shortening (stretch-shortening cycle). Numerous plyometric exercises with varied difficulty and demand on the musculoskeletal system can be implemented in rehabilitation. Plyometric exercises are initiated at a lower intensity and progressed to more difficult, higher intensity levels. The progression to higher-intensity plyometric exercise is thought to resolve postinjury neuromuscular impairments and to prepare the musculoskeletal system for rapid movements and high forces that may be similar to the demands imposed during sport participation, thus assisting the athlete with a return to full function. While there is a large body of scientific literature that supports the use of plyometric exercise to enhance athletic performance, evidence is sparse regarding the effectiveness of plyometric exercise in promoting a quick and safe return to sport after injury. This review will describe the mechanisms involved in plyometric exercise, discuss the considerations for implementing plyometric exercise into rehabilitation protocols, examine the evidence supporting the use of plyometric exercises, and make recommendations for future research.
The purpose of this study was to quantify the vertical ground reaction forces (VGRFs) developed during the performance of popular bilateral plyometric movements. Fourteen power-oriented track and field men of collegiate and national level randomly performed 3 trials of 9 different bilateral plyometric exercises in a single testing session. Three depth drop (DD) and 3 depth jump (DJ) conditions from 30, 60, and 90 cm heights (DD30, DD60, and DD90 and DJ30, DJ60, and DJ90) were tested, in addition to vertical jump (VJ), standing long jump (SLJ), and 2 consecutive jump (2CJ) conditions. Peak impact VGRFs were normalized to body weight. Additionally, all conditions were compared against the VJ in an intensity index. The SLJ condition resulted in a significantly higher peak VGRF than the 2CJ condition (p < or = 0.05). 90DD, 90DJ, 60DD, and SLJ had a significantly greater peak VGRF (5.39, 4.93, 4.30, and 4.22 times body weight, respectively) than the VJ condition (3.34 times body weight). The 30DJ condition had an insignificantly smaller peak VGRF (2.78 times body weight) when compared with the VJ. Practitioners may use these findings to more effectively progress athletes in these movements based on their intensities.
To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.
In the standard inverse dynamic method, joint moments are assessed from ground reaction force data and position data, where segmental accelerations are calculated by numerical differentiation of position data after low-pass filtering. This method falls short in analyzing the impact phase, e.g. landing after a jump, by underestimating the contribution of the segmental accelerations to the joint moment assessment. This study tried to improve the inverse dynamics method for the assessment of knee moment by evaluating different cutoff frequencies in low-pass filtering of position data on the calculation of knee moment. Next to this, the effect of an inclusion of direct measurement of segmental acceleration using accelerometers to the inverse dynamics was evaluated. Evidence was obtained that during impact, the contribution of the ground reaction force to the sagittal knee moment was neutralized by the moments generated by very high segmental accelerations. Because the accelerometer-based method did not result in the expected improvement of the knee moment assessment during activities with high impacts, it is proposed to filter the ground reaction force with the same cutoff frequency as the calculated accelerations. When this precaution is not taken, the impact peaks in the moments can be considered as artifacts. On the basis of these findings, we recommend in the search to biomechanical explanations of chronic overuse injuries, like jumper's knee, not to consider the relation with impact peak force and impact peak moment.
Because the intensity of plyometric exercises usually is based simply upon anecdotal recommendations rather than empirical evidence, this study sought to quantify a variety of these exercises based on forces placed upon the knee. Six National Collegiate Athletic Association Division I athletes who routinely trained with plyometric exercises performed depth jumps from 46 and 61 cm, a pike jump, tuck jump, single-leg jump, countermovement jump, squat jump, and a squat jump holding dumbbells equal to 30% of 1 repetition maximum (RM). Ground reaction forces obtained via an AMTI force plate and video analysis of markers placed on the left hip, knee, lateral malleolus, and fifth metatarsal were used to estimate rate of eccentric force development (E-RFD), peak ground reaction forces (GRF), ground reaction forces relative to body weight (GRF/BW), knee joint reaction forces (K-JRF), and knee joint reaction forces relative to body weight (K-JRF/BW) for each plyometric exercise. One-way repeated measures analysis of variance indicated that E-RFD, K-JRF, and K-JRF/BW were different across the conditions (p < 0.05), but peak GRF and GRF/BW were not (p > 0.05). Results indicate that there are quantitative differences between plyometric exercises in the rate of force development during landing and the forces placed on the knee, though peak GRF forces associated with landing may not differ.
Abstract The present study aimed to quantify the intensity of lower extremity plyometric exercises by determining joint mechanical output. Ten men (age, 27.3 ± 4.1 years; height, 173.6 ± 5.4 cm; weight, 69.4 ± 6.0 kg; 1-repetition maximum [1RM] load in back squat 118.5 ± 12.0 kg) performed the following seven plyometric exercises: two-foot ankle hop, repeated squat jump, double-leg hop, depth jumps from 30 and 60 cm, and single-leg and double-leg tuck jumps. Mechanical output variables (torque, angular impulse, power, and work) at the lower limb joints were determined using inverse-dynamics analysis. For all measured variables, ANOVA revealed significant main effects of exercise type for all joints (P < 0.05) along with significant interactions between joint and exercise (P < 0.01), indicating that the influence of exercise type on mechanical output varied among joints. Paired comparisons revealed that there were marked differences in mechanical output at the ankle and hip joints; most of the variables at the ankle joint were greatest for two-foot ankle hop and tuck jumps, while most hip joint variables were greatest for repeated squat jump or double-leg hop. The present results indicate the necessity for determining mechanical output for each joint when evaluating the intensity of plyometric exercises.
The ability to develop force quickly is a requisite ability in most sports. The reactive strength index (RSI) has been developed as a measure of explosive strength and is derived by evaluating jump height divided by ground contact time during the depth jump (DJ). At present, the RSI is typically used to evaluate DJ performance, because it is the only plyometric exercise with an identifiable ground contact time. The purpose of this study was to introduce a modification of the RSI (RSImod) that can be used to evaluate the explosive power of any vertical plyometric exercise. This study will also assess the reliability of the RSImod, evaluate the RSImod of a variety of plyometric exercises, and examine gender differences. Twenty-six men and 23 women served as subjects. Subjects performed 3 repetitions for each of 5 plyometric exercises including the countermovement jump (CMJ), tuck jump, single-leg jump, squat jump, and dumbbell CMJ. Data were analyzed using a 2-way analysis of variance to evaluate differences in RSImod between the plyometric exercise and the interaction between plyometric exercise RSImod and gender. The analysis of RSImod revealed significant main effects for plyometric exercise type (p <or= 0.001) but not for the interaction between plyometric exercise type and gender (p > 0.05). Results of pairwise comparisons indicate that the RSImod is statistically different between all plyometric exercises studied. Intraclass correlation coefficients indicate that RSImod is highly reliable for all of the exercises studied. The RSImod offers a highly reliable method of assessing the explosiveness developed during a variety of plyometric exercises.
Plyometric exercises are frequently used in strength and conditioning and rehabilitation programs because the landing phase of these exercises requires dynamic stabilization. This study examined the differences in landing stability of a variety of plyometric exercises by assessing time to stabilization (TTS), its reliability, and sex differences therein. Forty-nine men and women performed a variety of plyometric exercises thought to represent a continuum of difficulty of dynamic stabilization during landing. Plyometric exercises included line hops, cone hops, squat jumps, tuck jumps, countermovement jumps, dumbbell countermovement jumps, and single leg countermovement jumps, each performed for 3 repetitions on a force platform. A 2-way mixed analysis of covariance with repeated measures for plyometric exercise type was used to evaluate the main effects for plyometric exercise type and the interaction between plyometric exercise type and sex for TTS. Subject jumping ability was evaluated as a covariate. Results revealed significant main effects for plyometric exercise type (p < or = 0.001) and for the interaction between plyometric exercise type and sex (p = 0.002). Bonferroni adjusted post hoc analysis demonstrated differences in TTS between a number of plyometric exercises for men and women. Reliability analysis revealed intraclass correlation coefficients ranging from 0.51 to 0.86 with no significant difference between trials (p > 0.05). Practitioners who use plyometrics to train dynamic stability should create programs that progress the intensity of the exercises based on the results of this study. This study also demonstrated that TTS is moderately to highly reliable for a variety of jumping conditions for both men and women.
In the literature, athletes preparing for explosive activities are recommended to include drop jumping in their training programs. For the execution of drop jumps, different techniques and different dropping heights can be used. This study was designed to investigate for the performance of bounce drop jumps the influence of dropping height on the biomechanics of the jumps. Six subjects executed bounce drop jumps from heights of 20 cm (designated here as DJ20), 40 cm (designated here as DJ40), and 60 cm (designated here as DJ60). During jumping, they were filmed, and ground reaction forces were recorded. The results of a biomechanical analysis show no difference between DJ20 and DJ40 in mechanical output about the joints during the push-off phase. Peak values of moment and power output about the ankles during the push-off phase were found to be smaller in DJ60 than in DJ40 (DJ20 = DJ60). The amplitude of joint reaction forces increased with dropping height. During DJ60, the net joint reaction forces showed a sharp peak on the instant that the heels came down on the ground. Based on the results, researchers are advised to limit dropping height to 20 or 40 cm when investigating training effects of the execution of bounce drop jumps.
This study investigated the mechanical consequences of differences in dynamic frontal plane alignment of the support limb and the influence of anticipatory muscle activation at the hip and ankle on reducing the potential for non-contact ACL injury during single-limb landing. A frontal plane, three-link passive dynamic model was used to estimate an ACL non-contact injury threshold. This threshold was defined as the maximum axial force that the knee could sustain before the joint opened 8 degrees either medially or laterally, which was deemed sufficient to cause injury. The limb alignment and hip and ankle muscle contractions were varied to determine their effects on the ACL injury threshold. Valgus or varus alignment reduced the injury threshold compared to neutral alignment, but increasing the anticipatory contraction of hip abduction and adduction muscle groups increased the injury threshold. Increasing anticipatory ankle inversion/eversion muscle contraction had no effect. This study provides a mechanical rationale for the conclusion that a neutral limb alignment (compared to valgus or varus) during landing and increasing hip muscle contraction (abductors/adductors) prior to landing can reduce the possibility of ACL rupture through a valgus or varus opening mechanism.
Plyometric exercise was initially utilized to enhance sport performance and is more recently being used in the rehabilitation of injured athletes to help in the preparation for a return to sport participation. The identifying feature of plyometric exercise is a lengthening of the muscle-tendon unit followed directly by shortening (stretch-shortening cycle). Numerous plyometric exercises with varied difficulty and demand on the musculoskeletal system can be implemented in rehabilitation. Plyometric exercises are initiated at a lower intensity and progressed to more difficult, higher intensity levels. The progression to higher-intensity plyometric exercise is thought to resolve postinjury neuromuscular impairments and to prepare the musculoskeletal system for rapid movements and high forces that may be similar to the demands imposed during sport participation, thus assisting the athlete with a return to full function. While there is a large body of scientific literature that supports the use of plyometric exercise to enhance athletic performance, evidence is sparse regarding the effectiveness of plyometric exercise in promoting a quick and safe return to sport after injury. This review will describe the mechanisms involved in plyometric exercise, discuss the considerations for implementing plyometric exercise into rehabilitation protocols, examine the evidence supporting the use of plyometric exercises, and make recommendations for future research.
The purpose of this study was to investigate the motor unit activation of the quadriceps (Q), hamstring (H), and gastrocnemius (G) muscle groups during a variety of plyometric exercises to further understand the nature of these exercises. Twenty-three athletes volunteered to perform randomly ordered plyometric exercises, thought to cover a continuum of intensity levels, including two-foot ankle hops; 15-cm cone hops; tuck, pike, and box jumps; one- and two-leg vertical jump and reach; squat jumps with approximately 30% of their 1RM squat load; and 30- and 61-cm depth jumps. Integrated electromyographic data were analyzed for each exercise using a one-way repeated-measures ANOVA. Results revealed significant main effects for the Q when all subjects are analyzed, as well as for separate analysis of men, women, subjects with vertical jumps greater than 50 cm, and those with vertical jumps less than or equal to 50 cm (p < or = 0.05). Significant main effects were also found for the G muscle group in the analysis of all subjects, as well as for men and subjects with vertical jumps greater than 50 cm (p < or = 0.05). No significant main effects were found for the H muscle group. Pairwise comparisons revealed a variety of differences among plyometric exercises. In some cases, plyometrics previously reported to be of high intensity, such as the depth jump, yielded relatively little motor unit recruitment compared with exercises typically thought to be of low intensity. Results can assist the practitioner in creating plyometric programs based on the nature of the motor unit recruitment.
Plyometric Training.
- Potach D.H.
- Chu D.A.
Potach, D.H., Chu, D.A., 2000. Plyometric Training. Essentials of Strength Training and Conditioning. Human Kinetics, Champaign, IL, pp. 413-456.
Dynamic Stabilization During the Landing Phase of Plyometric Exercises.
- Petushek E.
- Garceau L.
- VanderZanden T.
- Wurm B.
- Feldmann C.
- Ebben W.
Petushek, E., Garceau, L., VanderZanden, T., Wurm, B., Feldmann, C., Ebben, W., 2010. Dynamic Stabilization During the Landing Phase of Plyometric Exercises. 28 International Conference on Biomechanics in Sports.