Agility is a context-specific ability, reliant on both physical and technical qualities (7). During an elite squash match, each athlete must perform frequent lunging and squatting movement patterns with variable execution and recovery (4,6,19). Effective court coverage relies on rapid and forceful change of direction, and the lunge is a specialized movement component, critical to the movement repertoire of the squash athlete (3,9). The lunge patterns performed during squash competition vary greatly in their direction, amplitude, velocity, mechanics, and kinematics (6). The extreme high-velocity lunge performed during world-standard squash is best characterized as an explosive bound or “jump lunge.” This movement differs markedly from the traditional lunge pattern and requires the athlete to leap into unilateral hip extension before playing a shot (Figure 1).
The jump lunge demonstrates specialist agility, underpinned by mechanically efficient, coordinated, and controlled movement. Movement into and out of the jump lunge represents a movement sequence that depends on rapid force production to maximize velocity (21). Effective application of impulse is critical to success; therefore, conditioning must emphasize maximum strength and explosive training to enable the trained athlete to continue to make physiological gains (11,12).
Biomechanical analysis of a traditional “walk forward lunge (WFL)” and the “jump forward lunge (JFL)” demonstrates that the quadriceps, hamstrings, and gastrocnemius remain active throughout each stage of each movement and all 3 muscle groups perform eccentric, concentric, and isometric contractions (8). This underlines the requirement for program design to be based around multi-joint and structural compound exercises, such as the squat and deadlift.
Examination of the force characteristics between lunge techniques of trained athletes lunging with maximal exertion demonstrates that the JFL consistently elicits higher muscle activation, and so program planning must also ensure that exercise progression develops specific movement dynamics. Contrary to common belief, the JFL does not elicit prolonged eccentric hamstring contraction. Electromyography data presented by Jonhagen et al. (8) demonstrate that eccentric activity occurs during the approach phase of the lunge, but even at maximal exertion, the time spent in eccentric hamstring contraction is short (18 ± 8%) relative to the whole movement.
Hamstring muscle activation during approach is determined by the force/time characteristics of the movement, and analysis demonstrates that in the WFL, eccentric contraction is quickly followed by hamstring lengthening. This contrasts with the pattern of muscular contraction found in the hamstring in the JFL where stability in stance requires a higher degree of muscular control and underlines the need for good form and posture. In the JFL, increased force correlates with increased eccentric activation but instead of lengthening, the hamstrings then utilize an isometric contraction to control the higher forces absorbed at foot strike. Analysis of muscle activation for both the WFL and the JFL demonstrates that at all speeds eccentric contraction predominately occurs in the gastrocnemius (61 ± 3% during approach and 63 ± 12% during recovery) (8).
Jumping into the lunge changes the kinematics of the movement and requires the athlete to control force while using a greater range of motion at the hip, knee, and ankle. During this movement, the length of the hamstrings is influenced more by the angle at the hip than the angle at the knee (5). In squash, world-class performance relies on the ability of the athlete to combine explosive lunging with dynamic trunk flexion to support shot execution. In these “jump lunges,” the athlete leads the movement with an extended knee before striking the floor with the heel and rolling onto a full foot contact. Frequently in these movements, on striking the floor with the heel, the athlete then immediately flexes at the hip to lower the trunk into a position approaching horizontal to play the shot (Figure 1B). After playing the ball, the athlete is then required to rapidly recover into a ready position for the next movement sequence. The development of sport-specific explosive ability therefore necessitates an integrated training program to underpin dynamic correspondence for explosive exercise progression (16).
STRENGTH DEVELOPMENT FOR FUNCTIONAL TRANSFER
In squash, the loser of the rally will usually cover more distance than the winner (18). During performance, fatigue will induce changes in lower limb muscle activation and muscle co-activation ratios that threaten to compromise multi-joint coordination (13). Strength and conditioning coaches must therefore prioritize functional loading, to ensure that physiological capacity is developed in synergy with motor competence, to support technical performance (2).
Examination of lunge forces and technique reveals that more experienced squash players learn the ability to suppress impact loading forces following coordination of high initial impact force. Kinematic analysis of the technique of developing players demonstrates that in comparison, junior players tend to land with a slightly straighter leg, causing foot placement to produce a flat foot strike in advance of knee flexion (20). Performance enhancement therefore necessitates coaching that emphasizes motor control as the athlete learns to exert and absorb greater force (10). Exercise progression must be underpinned by safe and effective movement competence, and the Y Balance Test offers a validated movement screening protocol to objectively assess dynamic balance (14).
THE EXPLOSIVE LUNGE DEVELOPMENT EXERCISE CONTINUUM
The explosive lunge development exercise continuum (Figure 2) presents an evidence-based model for functional exercise progression that has been demonstrated to be effective in the support and development of world-class squash performance.
The continuum dictates that explosive training is preceded by strength training with exercise selection and loading determined by individual needs analysis. During general preparation, low speed-high force exercise predominates, whereas during specific preparation and competition phases, increased emphasis is placed on high speed-high force movements. Exercises on the continuum increase in velocity (low to high: left to right) with the corresponding increase in musculoskeletal stress indicated by progression through colored zones, from green through amber to red. The green zone contains low speed-high force program components used to enhance muscle force production and develop movement-specific strength. Exercises in the amber zone emphasize mechanical specificity to train peak power, rate of force development, and acceleration. The red zone contains exercises for speed strength training that use ballistic muscular actions to promote successful performance adaptation. Exercises from the red zone must be used selectively and programming requires careful periodization, integrated planning, and qualified supervision (17).
The following section presents 4 lunge pattern exercises from the explosive lunge development continuum to exemplify how exercise selection supports program design to enhance sport-specific movement mechanics, force production, and velocity. Used within a periodized program, the featured exercises target the neuromuscular factors involved in strength production to effect performance adaptation to develop explosive lunge performance (Figs. 3–6).
TRADITIONAL (WALK FORWARD) DYNAMIC LUNGE
The traditional gym-based WFL (Figure 3) requires the athlete to maintain an upright trunk, and the knee of the lead leg is flexed on contact with the floor. This exercise can provide relatively high external loading at moderate movement velocities. Requiring the athlete to drive up and out of the lunge as explosively as possible increases the sport specificity of the movement in relation to perceptual and decision-making factors, velocity, and neuromuscular recruitment (15). The moderate movement velocity, flexed knee on ground contact, and upright trunk mean that for squash, this exercise is best suited to the general preparation phase of training.
EXTENDED DYNAMIC FORWARD LUNGE
When the squash player is challenged to perform an extended dynamic forward lunge over an increased distance, the coach should instruct the athlete to extend the knee of the lead leg toward ground contact (Figure 4A–C). This exercise targets both the amplitude and the mechanics of sport-specific movement dynamics to develop high-velocity lunging ability for squash. Unlike the traditional WFL, progression requires that external loading on the bar is reduced and amplitude and velocity of movement are increased.
REAR FOOT ELEVATED SPLIT DEADLIFT
In this exercise, the ascent of the rear foot elevated split deadlift (Figure 5A–C) is executed by extending the knee of the lead leg before extending at the hip. To descend, this sequence is then reversed in a smooth controlled movement. The athlete should maintain a flat back with shoulders retracted throughout the movement. The benefit of this exercise is that it provides loading in an extremely relevant position in relation to trunk forward lean and disassociation at the hip. Coaches should recognize, however, that the relatively low velocity of the movement and the position of partial hip and knee extension attained at the top of the exercise may also threaten to limit functional transfer. This example underlines the need for coaches to integrate a balance of exercises in program design to ensure that each of the neuromuscular factors involved in strength production is targeted.
EXPLOSIVE FORWARD BOUND TO REBOUND
The forward bound to rebound (Figure 6A–C) provides an extremely specific stimulus for training to improve high-velocity lunging in squash. The athlete is instructed to leap as far as they can from one foot to the other, before rebounding back toward the start position. Coaching emphasizes active pre-activation around the ankle, knee, and hip to brace the landing and thus enable the athlete to rebound back toward the start position as quickly as possible. Contact time at the extent of the movement should be minimized. This exercise exemplifies the performance of sport-specific power and explosive ability, demonstrating high velocity—high force movement, augmented by strength development. Explosive rebound to rebound repetitions can be used to successfully promote performance adaptation through an overload application that conditions the athlete, to mitigate fatigue-induced reductions in performance (13,21).
Squash players who, according to the Long Term Athlete Development model (1), are still within the Train to Train stage must learn to perfect coordination of strength and movement to control impact landing (6). Programming to develop the JFL must therefore be supported by a range of reduced force exercises. The same exercises are used by the elite squash player to compliment high-force work undertaken to help improve JFL performance. Rather than having a strength or power emphasis, these “assistance” exercises provide the athlete with either a stability or range of motion (mobility) challenge to elicit a positive impact on the overall performance of explosive lunging movements. Examples of relevant assistance exercises are provided in Table 1.
When working to develop the ability of the squash athlete to perform high-velocity lunges, the strength and conditioning coach must take a strategic, need-based approach underpinned by a clear understanding of the direction, amplitude, velocity, mechanics, and kinematics of the lunges performed during competition. Maturation, movement competence, training age, and phase of training should all be considered when selecting exercises to support and develop explosive lunge movements. The explosive lunge development continuum (Figure 2) presents an evidence-based model for functional exercise progression, which in careful combination with assistance exercises enables the strength and conditioning coach to select relevant exercises, to support performance progression to attain and sustain world-class performance.
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