Many sports, such as netball, basketball, and volleyball, are typified by a variety of jump-landing tasks that are often critical to success and winning performance. Typically, high ground reaction forces (GRFs) are generated by athletes in these sports given the dynamic and explosive nature of jump landings in training and competition (12,36,48). When jump-landing impact forces are expressed relative to body weight (BW), they have been reported to be as high as 5.7–8.9 BW (12,36,44) during specific sporting movements. As a result, athletes are exposed to high external and internal forces, which are considered potentially injurious for the lower extremities (24,44,46).
GRFs produced during jumping and landing are an accurate representation of impact intensity as there is an association between impact force and compressive strain on the bones and surrounding musculature (51). If the impact force surpasses the force produced by the involved musculature, then all exceeding GRFs will be diverted by the bones and ligamentous tissue, which amplifies the expected risk of ligament ruptures (21). This injury mechanism is particularly prevalent among athletic female populations (21,24,40). The inability for female athletes to correctly attenuate high jump-landing impact forces through muscle contraction has been linked to incorrect landing technique (12,43), insufficient muscular strength (18,21,35), a lack of balance (25,41), and deficiencies in neuromuscular control (20).
To physically condition the body to effectively attenuate impact force during competition, it is essential to systematically progress jump-landing intensity throughout training. This can be achieved by gradually increasing the stress imposed on the body in an effort to develop a high jump-landing impact tolerance. This systematic increase in stimulus is important for continual adaptation and a prerequisite for injury prevention and athletic improvement (30).
Given the previous information, the need for an appropriately designed jump-landing program integrating correct landing principles and progressive conditioning of the lower limb is apparent. This article first presents ideal fundamental jump-landing and feedback mechanics before introducing a systematic progression model for the development of jump-landing proficiency. The model incorporates recommended design methods and targeted training components for effective program implementation.
FUNDAMENTAL JUMP-LANDING AND FEEDBACK MECHANICS
When implementing any type of jump-landing training, it is imperative that the strength and conditioning professional emphasizes proper technique (40). It is proposed by Myer et al. (40) that throughout an effective jump-landing sequence, the chest is encouraged to be over the knees with shoulders and hips aligned. The vertical jump should have minimal forward/back or side-to-side movement, and the landing should display adequate flexion of the hips, knees, and ankles (Figure 1) as this helps to attenuate impact forces. In addition, the knees should be positioned above the feet with no excessive adduction or abduction as equal distribution of force across both the medial and lateral compartments of the knee may reduce the impact stress (23). With respect to foot placement, a forefoot to heel ground contact pattern is advocated with the feet landing parallel as this helps to diffuse impact forces more evenly throughout the feet (29). In the case of a single-leg landing, the foot should be positioned under the body's center of mass (COM). Adhering to these fundamental jump-landing mechanics may help to reduce both the rate and magnitude of GRF during impact.
Receiving feedback is an essential part of modifying movement patterns as it is a key component of acquiring new motor programs (12). Herman et al. (18) examined the use of strength training and feedback on lower body biomechanics during a jump task. They concluded that with the exclusion of proper instruction on technique, athletes may not effectively integrate the benefits of their increased strength into their movement patterns. The use of video feedback and expert feedback has been shown to significantly reduce vertical ground reaction force (VGRF) (−25.8%) for all video feedback conditions (43). Researchers exploring the effects of verbal feedback on volleyball spike jump–landing technique reported that a single session of augmented feedback significantly reduced VGRF by −23% (12). Similar conclusions were drawn from McNair et al. (37) demonstrating that precise kinematic instruction (feedback on knee flexion angle at initial ground contact) can mediate decreases in landing GRF by −13%.
Consistent landing technique feedback is critical during each phase of this proposed training model to ensure that fundamental movement patterns are maintained during potentially unsafe jump-landing sequences. Furthermore, it is suggested to cease all jump landings if the desired technique diminishes to ensure that the incorrect behavior is not learned. A set of suggested jump-landing kinematics for effective feedback delivery throughout training can be observed in Figure 1. It is also recommended that the strength and conditioning coach uses a camera or other electronic devices for video recording purposes to reinforce verbal feedback to the athlete, as this will be invaluable and likely enable a more rapid progression through the phases.
JUMP-LANDING PROGRESSION MODEL
The majority of studies investigating interventions aimed at improving jump-landing performance and injury prevention use a variety of training methods, for example, strength and plyometric training (6,14,23,39). It is therefore difficult to decipher the degree of influence certain programs have on the training outcomes. It would seem that a combination of training strategies has the most advantageous effect on landing mechanics, impact force dissipation, and physical conditioning of the lower body. The most promising training components seem to be teaching fundamental exercise techniques and landing principles with the appropriate feedback; improving balance and stability with specific focus surrounding the ankle and hip joint; increasing muscular strength, with particular emphasis on the muscles of the posterior chain; and heightening neural drive and neuromuscular control through plyometric-type exercises.
The ultimate goal of a jump-landing program is to not only improve performance but also prevent injury. For this to occur, the program must systematically progress in intensity, so that the body can appropriately adapt to the given training stimulus. The most influential barriers that impede the advancement of jump-landing performance are injury and training plateaus; however, the correct application of progressive overload can potentially reduce the effects of these barriers (30). In this regard, we propose a model that addresses this progression and the integration of various training methods. The model is a derivative of that proposed by Kritz et al. (33) where athletes are loaded according to their ability to perform an exercise and as such athletes are progressed through assisted, BW, resisted, eccentric, and plyometric exercises.
This model incorporates 4 phases, which increase in load intensity and movement complexity (Figure 2). The 4 phases focus on specific outcomes and include (a) technique and general strength, (b) eccentric strength, stability, and alignment, (c) stretch-shorten cycle (SSC) propulsive power and landing, and (d) sport-specific jump landing. It needs to be acknowledged that each phase has a focus and builds upon the previous, but the focus is not exclusive to that phase.
With respect to the proposed model, the reader needs to be cognizant that some examples are given for each of the training modalities used in each phase. There are, however, a myriad of exercises and combinations that can be used. The menu is only limited by the imagination and experience of the strength and conditioning coach. Each program should be specifically tailored in regard to the athlete's particular weaknesses, sport movements, and positional demands. The aim of this model is to provide a framework to guide exercise prescription and progression for a flexible decision-making approach to meet the athlete's requirements.
PHASE 1: TECHNIQUE AND GENERAL STRENGTH
This first stage should focus on exercises and techniques aimed at developing competent movement patterns and general strength. In this phase, exercises are chosen that aim at optimizing movement efficiency, laying the foundation for more complex and explosive movement patterns typical of the latter phases. Optimal movement has been described as pain-free motion involving correct posture, muscle coordination, and joint alignment (4). Typically, fundamental movement patterns, such as squats, lunges, push, pull, bend, and twist patterns, form the basis of much of the training.
This type of movement education is typically linked to “strength endurance” training and is progressed through an assisted, BW, or resisted paradigm (Figure 3). For example, the athlete is asked to perform a BW squat with good technique [Kritz et al. (32)], and if the athlete cannot perform an acceptable squat, then it is recommended that the athlete performs assisted squat training until squat technique is perfected. Thereafter, this athlete will progress to BW squat training and when ready resisted squat training.
Females have a tendency to adopt an erect trunk position during landing (27), which can subsequently reduce flexion of the knee (2). It is speculated that this upright positioning of the trunk is because of weak gluteal and hamstring muscles, given their function as hip extensors and trunk stabilizers (5). It is also documented that female athletes are inclined to use their quadriceps muscles to a greater extent to stabilize during landing while underusing their hamstring muscles (21,23,26). Particularly for the knee, the co-activation of the hamstrings and quadriceps may provide injury protection during landing by resisting anterior and lateral tibial translation along with transverse tibial rotations (9). Greater activation of the hamstring muscles allows the knee to produce increased flexion, which creates a better position to absorb impact forces (21). By strengthening these muscles (Figure 4), and mimicking suggested landing mechanics, the body has a considerable mechanical advantage by simulating a safer landing position (38).
While landing, balance is achieved primarily through the ankle and/or hip (14). Stability is maintained through the ankle when the body is static or when there is limited disturbance as seen during the end recovery phase of a landing, because of the joint's small range of motion (28). The ankle achieves this stability mainly in the anterior-posterior plane. Therefore, with regard to balance training, basic stability exercises are initially static with limited movement. The objective of this is to develop the ability to activate the stabilizer muscles and concentrate on proprioceptive information being received to maintain stability; therefore, this section has been termed “proprioception.” Static balance exercises can be manipulated by opening and closing eyes, changing the arm position, and progressing from stable ground to unstable surfaces (Figure 5) (50). The use of unstable surfaces aids the development of synergistic muscle recruitment and activation patterns (22,41). It needs to be acknowledged that strength and balance training does not necessarily need to be viewed in isolation. For example, exercises, such as single-leg squats, split squats, and lunges, will also challenge balance ability.
Plyometric training during phase 1 has been termed “long response” in that the propulsion and landing are typified by adequate hip, knee, and ankle flexion and also alignment upon impact. That is, the propulsive and landing phases are deeper than other phases, reducing particularly the landing forces (i.e., soft landings), which become a greater focus in phase 2. Plyometric exercises should initially be performed bilaterally with a progression to single-leg landings once correct landing mechanics are regularly demonstrated (Figure 1). It is also advocated that all landings are held for 3–5 seconds to assist in the development of perfect landing technique.
Box jump exercises are effective during this phase as they develop basic jump-landing ability in a controlled environment. Jumping onto a box effectively develops jumping actions without the accentuated landing impact caused by gravity through reducing the descent to the ground. Jumping onto a box also allows the athlete to comfortably simulate a deep squat position during landing, which is the position they will be encouraged to replicate during eccentric landings in phase 2. These types of jump landings can be progressed within this phase by increasing the height of the box as this challenges the force required to perform the jump. Increasing the height also increases the depth of the squat position during landing as more hip flexion is required to get the feet onto the higher box.
Progression to phase 2 is recommended once the athlete demonstrates adequate strength endurance during squatting and lunging patterns at an appropriate load in addition to demonstrating satisfactory single-leg balance. It is also important that perfect technique during jump-landing tasks (Figure 1) is displayed as competent performance in this phase is critical to the development of jump-landing ability in the latter stages of this progressive model.
PHASE 2: ECCENTRIC STRENGTH, STABILITY, AND ALIGNMENT
The emphasis of phase 2 is to develop eccentric leg strength along with enhancing balance, stability, and control of joint alignment. The landing component is the primary focus throughout this phase with exercises and drills projected toward improving the body's ability to land controlled and aligned.
During jump landing, the most prominent forces are present when the involved musculature is contracting eccentrically (8). Therefore, the body must possess adequate levels of eccentric strength to control the body's movements and accomplish safe jump-landing form (18). Consequently, the strength-training emphasis during phase 2 should move toward developing “eccentric strength.” Exercising muscles with an eccentric muscle contraction focus has been shown to promote greater gains in overall strength and muscle hypertrophy because of the larger loads that the muscle can control in comparison with concentric training (47). Therefore, an increase in muscle mass is an adaptation that may occur throughout this phase.
In terms of specific exercises, the emphasis should continue to progress squatting ability in addition to exercises that focus on single-leg strength development (Figure 6). Incorporating single-leg exercises will help to develop the athlete's ability to express strength in an unstable environment and eccentrically loading the lower extremities in a safe manner. In the absence of specific eccentric machines, the strength and conditioning professional is encouraged to be creative in designing or using eccentric overload exercises. Instances of this could be using “two up one down–type exercises” where athletes push concentrically with 2 limbs and eccentrically lower with one. In addition, the exercises displayed in Figure 4 are also suitable as they effectively stimulate the eccentric action of the muscles involved in jump-landing performance.
Balance training drills in phase 2 should transition toward more dynamic stabilizing exercises, however, they should still be performed in a stationary position, and therefore have been labeled as “dynamically static.” With the focus being stability and alignment, effective balance drills should allow the athlete to maneuver their COM while continuing to stabilize on their stance leg (Figure 7), as this is consistent with successful landing performance.
Exercises such as swings as seen in Figure 8 challenge functional ankle stability and strengthen the gluteal muscles. Cueing the torso to be strong and tall is important given the reduced base of support, which increases the required stability to perform competent movement. The swing exercise can progress to swinging movements while on toes as this effectively decreases the base of support and creates a higher COM, which challenges the ability to stabilize to a greater extent.
For the plyometric training component, a progression to accentuated landings begins, thus termed “eccentric response.” It is recommended that drop and stick exercises are initially used in this phase. Drop and stick exercises are performed with the athlete starting in a standing position and then quickly dropping into an athletic squat stance. A progression from this point is to drop into a lunge position and then finally a single-leg squat position.
Exercises in this phase can be further advanced by performing drop landings off a box. Drop-landing exercises are particularly important as they allow the body to adapt to high impact forces in a controlled manner (44). Advancing drop landings within this phase can be achieved by increasing box drop height and also jumping distance. Increasing the box height will allow athletes to experience greater impact forces because of the effect of gravity and an associated increase in impact velocity (38). In the same respect, larger jumping distances yield greater propulsive forces upon takeoff (15), which effectively increases both vertical and horizontal COM velocities during landing. This in turn increases the magnitude of the landing forces. In addition, the proportion of unilateral landings should increase to challenge the need to stabilize and balance.
Progression to phase 3 is recommended once the athlete exhibits acceptable eccentric control during squatting at an appropriate load. Furthermore, athletes must demonstrate an ability to maintain balance during exercises that challenge dynamic stability in addition to performing correct landing mechanics during single-leg drop landings. This would validate that the required physical ability is present to safely advance the training phase.
PHASE 3: STRETCH-SHORTEN CYCLE PROPULSIVE POWER AND LANDING ABILITY
Phase 3 of this progression model should focus on exercises and techniques aimed at developing propulsive power and landing ability. The impact forces experienced during jump landings are inherently larger and have more degrees of freedom than the previous drop-landing program in phase 2. For example, because the landing is preceded by a jump, there is likely to be greater horizontal and/or lateral momentum to arrest or control when jumping for distance.
The focus for the strength-training component throughout phase 3 is to increase “relative strength.” A typical adaptation of consistent high-intensity strength training is the growth and proliferation of myofibril muscle filaments; however, increases in strength can also be achieved by increasing neural activation, which limit changes in muscle size (16). The objective is to develop neural strength without increasing muscle size to increase strength per kilogram of body mass. It is recommended that developing relative strength is achieved by increasing maximum strength while minimizing changes in body mass; however, it can also be developed by maintaining strength and reducing body mass. In particular, reducing body mass by decreasing body fat is advocated as this increases the athlete's functional body mass.
Given the association between decreased strength and increased injury prevalence (21), it is important that maximum neural strength is continually increased in an effort to attenuate the increased impact forces experienced during the advancement of exercises performed throughout this phase. In addition, most sports necessitate athletes to possess certain amounts of strength endurance and power; therefore, maximal relative strength is an optimal quality to develop given the strong correlation between both strength endurance and muscular power.
As intimated previously, there is likely to be greater horizontal and/or lateral momentum to arrest or control during this phase because of the inclusion of the propulsive jump phase; so, the strength training needs to become multiplanar in focus. Exercises that strengthen the musculature in the vertical, horizontal, and lateral planes are fundamental to this phase (Figure 9).
The location of the upper body's COM has been shown to affect the final position of the knee during landing (6), particularly during single-leg landings. When landing is projected from a mediolateral direction or when landing from a perturbed jump, balance is maintained predominately through the hip joint (28). This is evidently because of the hip joint's larger ranges of motion, which is achieved in both the medial-lateral and anterior-posterior planes (1). This type of balance is termed “dynamic” as the body endeavors to stabilize while simultaneously performing movement.
It is recommended that balance training exercises during phase 3 challenge stability in a dynamic fashion. That is, a landing will be preceded by a pre-movement, such as a lateral jump. This can be progressed by jumping onto an unstable surface (Figure 10). To continue the progression of swing drills, the strength and conditioning coach should add a jump and land with each swing repetition. These exercises are designed to develop functional stability while also continuing to improve technique in both landing and takeoff positions.
With regard to the plyometric training, this phase should involve a wide variety of movements that are dynamic in nature with an overriding objective of enhancing the SSC and landing ability of athletes (44). Movements and ground contact times are typically quicker during this phase as opposed to the 2 preceding phases; therefore, this component has been termed “short response.” Essentially, this phase emphasizes development of neuromuscular control, particularly aiming to stabilize the working joints through unconscious activation of the surrounding musculature (46). Unconscious muscle recruitment, co-activation, and coordination have been found to be critical factors involved in successful jumping landing in females (20).
Researchers have reported that after a growth spurt, adolescent females do not seem to develop the neuromuscular system at the same rate as the musculoskeletal system (19). This is suggested to reduce the amount of neuromuscular control of the knee during landing, causing landing techniques which are associated with injury. Various studies using plyometric-type training have been able to correct this imbalance in neuromuscular control (6,17,34,39,42). The strength and conditioning coach needs to be aware of this reduced control throughout the neuromuscular system during periods of rapid growth, thus paying particular focus toward the development of phases 1 and 2. The importance of developing phase 3 is amplified as the impact forces during landing occur too rapidly to be modified by a reaction response from the neuromuscular system (13). To effectively prevent unwarranted injury during jump landing, it is essential to pre-activate the involved musculature before ground contact (20,46).
Muscle activation strategies and their subsequent effect after plyometric training were explored by Chimera et al. (7). This study observed significantly different muscle activation patterns from the adductor muscles with pre-activation occurring earlier, in conjunction with greater activation magnitude before landing. Furthermore, significant increases in adductor and abductor muscle co-activation were found, suggesting that the muscles were working in concert to balance joint forces during jump-landing propulsive exercises.
Plyometric exercises in this phase should demand quicker propulsive actions and stiffer more abrupt landings. For example, the athlete could perform continuous hop and stick exercises with a focus on jumping and landing execution. This can be progressed into the athlete performing submaximal triple or quintuple bounding sequences with the strength and conditioning coach observing their single-leg propulsive and landing ability (alignment and stability) when there are increasing motor control demands associated with increased horizontal and vertical momentum. Short response movements are more aggressive in nature and are an appropriate prerequisite for the sport-specific exercises within phase 4.
The ability to perform the jump-landing movements with good technique (Figure 1) drives progression through this phase. If faulty technique is observed during the propulsive phase, the athlete could benefit from further phase 1 training or a less intense plyometric exercise. If faulty technique is observed during the landing phase, then further phase 2 training may be prescribed. To advance to phase 4, it is recommended that the athlete possesses adequate muscular strength during resistance exercises with a multiplanar focus. It is also advocated that the athlete demonstrates the ability to stabilize from a moving position. Furthermore, it is advised that fundamental jump-landing mechanics along with control and posture are maintained during exercises using multiple jump-landing efforts. Athletes who can repeatedly perform short response jump-landing activities successfully will demonstrate the capability to effectively train these movements in a sport-specific context.
PHASE 4: SPORT-SPECIFIC JUMP-LANDING ABILITY
The objective of this final phase is to develop propulsive power production and landing ability specific to the sport or activity the athlete is engaged in. This is in an effort to optimize the transfer of conditioning activities to the performance demands of the sport.
The focus for the strength-training component during this phase is similar to phase 3 of increasing relative strength but also consequently developing “muscular power.” The overall aim is to increase strength per kilogram of BW in addition to increasing the speed at which the load moves during exercises. The amount of jump-landing training the athlete performs during sport-specific training and competition is high velocity in nature and therefore will preserve or develop the athlete's velocity capability. Therefore, if force-producing capabilities of the muscles increase during this phase, the net effect will be enhanced power through increasing the load lifted at the same velocity. The athletes, however, should also be instructed to increase the movement speed of exercises in comparison with phase 3. Increasing relative strength needs to be the continual aim during this phase, as it is quite likely that the athlete's resistance training volume will be reduced given the training requirements of the sport during competition. This is assuming that this phase of training is implemented adjunct to in-season competition. As with all phases, exercise selection should complement the nature of jump-landing actions and should be specific to the athlete's particular weaknesses. However, if an athlete has developed the required level of relative strength for their specific sport, position, and/or movement requirements, as ascertained by the strength and conditioning coach, it is suggested that resistance training could progress to fast explosive movements, such as Olympic-style weightlifting derivatives. Weightlifting exercises, such as power cleans and snatches, are an effective means of developing power (31,49). The movement patterns used in these types of exercises are similar to movement witnessed in jumping-landing patterns (3). In addition, the skill and muscle coordination required to execute these exercises may help to foster neuromuscular adaptations that are transferred to sports performance (50). Another effective set of exercises that can be used to develop muscular power for jump-landing proficiency are resisted jump squat variations (10). Jump squats involve the exact action of jump landing in addition to providing similar neuromuscular benefits as weightlifting exercises (11).
Exercises and drills throughout this phase should use unanticipated cutting actions and perturbed movements, as this helps to integrate safe levels of sport-specific landing technique. Adaptations from this specific form of stimulus have been shown to reduce injury prevalence and improve performance during multidirectional sporting activities (23). Specifically for balance and stability training, the ultimate aim during phase 4 is to advance the athletes' ability to maintain steadiness and regain stability while resisting external forces. This type of balance training has been termed “perturbed dynamic.” An example of this is getting an athlete to catch a medicine ball while standing with one leg. This phase can also incorporate moving swings that use the same initial swing movement process from phase 3; however, they are overloaded by jumping and landing diagonally, laterally, horizontally, or backward after every swing. The preceding swings can also integrate jumping with ball in hand in addition to perturbed or disrupted flight. This final progression of exercises allows the body to attempt to stabilize in a sport-specific dynamic fashion.
Phase 4 plyometric training concentrates on jumps that are “sport specific.” Intramuscle and intermuscle activation patterns are sensitive to specific landing movements (45); therefore, it is important to stimulate the musculature with jump-landing activities related to actual performance. An example of this is a depth jump exercise in which an athlete descends from a height to the ground, thus overloading the eccentric phase and performing a concentric action such as a maximum vertical jump immediately after the landing. This is an effective modality of training as it allows the body to simulate similar loading stimulus experienced during competition.
Once the appropriate jump-landing technique (Figure 1) has been demonstrated during multiple drop jump–landing tasks, the plyometric component can introduce unanticipated landing drills to enhance the pre-activation of muscles, thus increasing the ability to dynamically stabilize during unplanned landings. This is an important aspect to develop as many competition sporting actions involve reactive unexpected jump landings. These can be effectively administrated using verbal and/or visual directional prompt drills (Figure 11) or perturbing the athlete. Reducing the reaction time for the athlete to perform the directional demand will help to progress this type of activity.
The final progression among the plyometric components is to introduce game-related drills and exercise situations that demand multidirectional, unanticipated perturbed jump landings. Examples of these situations are repetitive rebound blocks in volleyball, 3-step jump shot at goal in handball, and/or receiving a pass that necessitates a jump and reacting to the movement of the ball as seen in netball (Figure 12).
During this final phase, the advancement to unpredictable game-simulated movements requires the integration of all training components to be performed to a high standard. It is therefore critical that each phase of this proposed model is progressed only after the appropriate level of strength, balance, and jump-landing proficiency is continually demonstrated to the satisfaction of the strength and conditioning coach. Decisions surrounding the advancement of an athlete through each phase is at the discretion of the strength and conditioning coach; however, it must be reiterated that demonstrating competent movement during a particular phase is the critical factor required for successful progression.
It is evident that an effective jump-landing program involves various components, which address the diverse demands of landing that is implicit during competition. Identified strategies targeted toward perfecting landing technique, improving balance, and increasing strength and plyometric ability may accumulatively enhance jump-landing performance and reduce injury prevalence. Additionally, to optimize athlete compliance, program design should focus on performance and injury prevention simultaneously. Most importantly, training regimes must systematically progress task-specific intensity at an individualized rate for optimal adaptation, hence the development of this 4-phase program. Decisions surrounding the most appropriate method to maximize training efficiency are dependent on the intended aim of the training phase and the particular conditioning response the strength and conditioning coach is envisioning. The proposed model provides a framework to assist strength and conditioning professionals in making sound decisions concerning individualized jump-landing training. Within each of these phases, there is still much research to be performed in terms of improving practice. Future research may want to direct their attention to quantifying the GRFs associated with various jump-landing tasks, which can be tabled into a program that progressively overloads the athlete. This would be invaluable to the strength and conditioning coach in terms of exercise prescription.
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