SCIENTIFIC RATIONALE AND SUPPORTING INVESTIGATIONS FOR SPORTSMETRICS NEUROMUSCULAR RETRAINING PROGRAM

The purpose of this chapter is to present the scientific rationale, supporting data, and specific strategies for the implementation of a neuromuscular knee ligament injury prevention–training program, Sportsmetrics. Although many knee ligament injury prevention–training programs have been published,* few have presented scientific justification that the training effectively improved neuromuscular deficiencies and reduced the incidence of noncontact anterior cruciate ligament (ACL) injuries in female athletes (Table 19-1). Some programs had small sample sizes and were thus underpowered to avoid the potential for a type II statistical error.^{7,11,28,29,33,35} Most studies were not randomized, and several did not contain a control group studied concurrently with a trained group. Although some investigations cited a reduction in noncontact ACL injury rates, others failed to find a statistically significant effect.^{11,28,29,33–35}Some programs have been published even though the investigators did not follow athletes over a season or a period of time to determine whether a reduction in ACL injuries occurred as a result of preventive training. ^14,16,21

The Sportsmetrics program is effective in inducing changes in neuromuscular indices in female athletes, because studies have shown improved overall lower limb alignment on a drop-jump test,²⁴ increased hamstrings strength, ^13,24,36 increased knee flexion angles on landing,^13,31 and reduced deleterious abduction/adduction moments and ground reaction forces.¹³ Sportsmetrics also significantly reduces the risk of noncontact ACL injuries in female athletes participating in basketball, soccer, and volleyball.¹²

A pilot laboratory study was conducted at the authors’ institution using 11 high school female volleyball players to determine the effect of Sportsmetrics training on landing mechanics and lower extremity strength.¹³ The mean age of the female subjects was 15 ± 0.6 years, and they had participated in organized volleyball for an average of 2 ± 1 years before the study was initiated. A control group of 9 male subjects was selected and matched to the females according to height, weight, and age. The Sportsmetrics training program, described in detail later in this chapter, was performed 3 times a week (2-hr sessions) for 6 weeks. The athletes were taken through a series of tests before and after the training program. These tests included isokinetic muscle testing at 360°/sec and force analysis testing with a two-camera, video-based, optoelectronic digitizer for measuring motion and a multicomponent force plate for measuring ground reaction force. The subjects performed 10 jumps on the force plate that simulated volleyball jumping and landing maneuvers.

After 6 weeks of training, peak landing forces from a volleyball block jump decreased 22% (P = .006), or an average of 456N (103lb); all but 1 of the female subjects demonstrated a decrease in these forces (Fig. 19-1). Knee adduction and abduction moments, which induce a lateral or medial torque to the knee joint, decreased approximately 50% (Fig. 19-2). These moments were significant predictors of peak landing forces. The importance of this finding is that decreased abduction or abduction moments may lessen the risk of lift-off of the medial or lateral femoral condyle, improve tibiofemoral contact stabilizing forces,²⁰ and reduce the risk of knee ligament injury.

FIGURE 19-1 Bar graph shows decrease in peak landing forces with training in female subjects before and after training and relative to age- and weight-matched athletic male subjects. *P < .01.

(From Hewett, T. E.; Stroupe, A. L.; Nance, T. A.; Noyes, F. R.: Plyometric training in female athletes. Decreased impact forces and increased hamstring torques. Am J Sports Med 24:765–773, 1996.)

FIGURE 19-2 Bar graph shows peak knee adduction and abduction moment data at landing before and after training. The female subjects were grouped according to the dominant moment (adduction or abduction) and all the female subjects grouped together (all). *P < .05 compared with untrained females.

(From Hewett, T. E.; Stroupe, A. L.; Nance, T. A.; Noyes, F. R.: Plyometric training in female athletes. Decreased impact forces and increased hamstring torques. Am J Sports Med 24:765–773, 1996.)

Female athletes demonstrated lower landing forces than male athletes, and lower adduction and abduction moments after training compared with pretraining values. External knee extension moments (which are balanced by an internal flexion, hamstring muscle) of male athletes were three times higher than those of female athletes. The training did not significantly alter these extension moments.

After training, hamstring-to-quadriceps muscle peak torque ratios increased 26% on the nondominant side and 13% on the dominant side, correcting side-to-side imbalances in the female athletes. In addition, hamstring muscle power increased 44% on the dominant side and 21% on the nondominant side. Whereas peak torque ratios of male athletes were significantly greater than those of the female athletes before training, the ratios were similar between genders after training.

A second study was conducted in a group of 62 high school female athletes to determine whether Sportsmetrics training altered lower limb alignment on a drop-jump task and isokinetic lower limb muscle strength.²⁴ This investigation is described in detail in Chapter 16, Lower Limb Neuromuscular Control and Strength in Prepubescent and Adolescent Male and Female Athletes. Before training, 80% of the female athletes had a valgus overall lower limb alignment on landing from a drop-jump. After training, 34% of the females demonstrated this alignment (P < .0001). Significant increases were also noted after training in knee flexion peak torque in both the dominant and the nondominant limbs (P < .0001).

In order to determine whether Sportsmetrics training reduced the incidence of noncontact ACL injuries in female athletes, a controlled, prospective investigation was conducted in 1263 high school athletes.¹² One group of 366 females underwent 6 weeks of Sportsmetrics training and a second group of 463 females was not trained. Included in the study was a group of 434 untrained male athletes. All athletes were followed throughout a single soccer, volleyball, or basketball season. Weekly reports submitted by athletic trainers included the number of practice and competition exposures and mechanism of injury. All ACL injuries were confirmed by arthroscopy, and medial collateral ligament (MCL) injuries were confirmed by manual valgus testing.

The total number of athlete-exposures were 23,138 for the untrained group, 17,222 for the trained group, and 21,390 for the male control group. There were 14 serious knee ligament injuries, which were sustained in 10 of 463 untrained female athletes (8 noncontact), 2 of 366 trained female athletes (0 noncontact), and 2 of 434 male athletes (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 = .02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = .05) and 4.8 times higher than male athletes (P = .03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (Fig. 19-3; P = .86).

FIGURE 19-3 Serious knee injuries per 1000 player-exposures in soccer and basketball players.

(From Hewett, T. E.; Stroupe, A. L.; Nance, T. A.; Noyes, F. R.: Plyometric training in female athletes. Decreased impact forces and increased hamstring torques. Am J Sports Med 24:765–773, 1996.)

The risk factors that have been hypothesized to increase the potential for an ACL injury are discussed in Chapter 15, Risk Factors for Anterior Cruciate Ligament Injuries in the Female Athlete. The final position of the knee joint on landing, pivoting, and cutting is influenced by the center of gravity of the upper body and the trunk over the lower extremity. Equally important are trunk-hip adduction or abduction, foot-ankle pronation-supination, and foot separation distance. These effects add together to produce either a varus or a valgus moment about the knee joint that must be balanced by the lower limb musculature. If the athlete is off-balance, or contacts another player, a loss of trunk and lower limb control and position may occur and the knee joint may go into a hyperextended or valgus position. Although there are many potential mechanisms for ACL injury, it has been postulated that excessive valgus moments about the knee joint with subsequent high anterior tibial shear forces may be one of the most common to occur in females.^8,15,18 Excessive valgus loading may result in decreased tibiofemoral contact, or condylar lift-off,²⁰ and a reduction in the normal joint contact geometry that contributes to knee joint stability. This position, coupled with a highly activated quadriceps muscle that produces maximum anterior shear forces with the knee joint at low flexion angles (0°–30°),^5,10,26 and a relatively inactive hamstrings musculature, could potentially lead to ACL rupture. The function of the hamstrings is dependent on the angle of knee flexion and degrees of external tibial rotation.²⁵ The mechanical advantage of these muscles increases as the knee is flexed. At 0° of extension, the flexion force is only 49% of that generated at 90° of flexion. Withrow and coworkers³⁷ measured the relative strain in the anteromedial region of the ACL in cadaver knees during a simulated jump landing maneuver. Increased hamstring muscle forces during the knee flexion phase significantly reduced the peak relative strain in the ACL by greater than 70% compared with the baseline condition (P = .005). The authors concluded that it may be possible to limit ACL strain by accentuating hip flexion during knee flexion phase of jump landings because this increases the tension in the active hamstring muscles.

The time in which an ACL rupture occurs was recently estimated to range from 17 to 50 msec after initial ground contact.¹⁷ It is evident that there is not enough time for an athlete, upon sensing a knee injury about to occur, to alter the body or lower extremity position to prevent the injury. In order to have a significant impact on reducing the incident rate of this injury, a training program must teach athletes to control the upper body, trunk, and lower body position; lower the center of gravity by increasing hip and knee flexion during activities; and develop muscular strength and techniques to land with decreased ground reaction forces. In addition, athletes should be taught to pre-position the body and lower extremity prior to initial ground contact in order to obtain the position of greatest knee joint stability and stiffness. The program should consist of a dynamic warm-up, plyometric jump training, strengthening exercises, aerobic conditioning, agility, and risk awareness training.⁹

SPORTS INJURY TEST

The authors developed a sports injury test (SIT) in order to obtain a profile of each athlete before and after Sportsmetrics training. The SIT measures (1) knee and ankle position on landing and take-off from a drop-jump during a video test (described in detail in Chapter 16, Lower Limb Neuromuscular Control and Strength in Prepubescent and Adolescent Male and Female Athletes), (2) lower limb symmetry^1,23 and a general assessment of lower limb control on single-leg hop tasks (Fig. 19-4), (3) isokinetic lower extremity muscle strength, (4) hamstring flexibility, and (5) vertical jump height. Athletes participating in sports-specific Sportsmetrics training programs, discussed later in this chapter, also undergo a 10-yard dash, a 20-yard dash, a T-drill run, and a 1-mile run. A history is collected for each athlete regarding prior injuries to the knees and ankles. The SIT is completed just prior to the initiation of training and within 1 week of completion of training.

FIGURE 19-4 Single hop for distance video screening allows a qualitative assessment of an athlete’s ability to control the upper and lower extremities upon landing, which may be rated as either good (A), fair (B), or complete failure, fall to ground (C).

SPORTSMETRICS NEUROMUSCULAR TRAINING PROGRAM COMPONENTS

The essential elements of the Sportsmetrics neuromuscular training program are a dynamic warm-up, plyometric jump training, strengthening, and flexibility. It is recommended that this training program be conducted either during the off-season or just prior to the beginning of the athlete’s sport season. The training is conducted 3 times a week on alternating days for 6 weeks.

As is described later, sports-specific speed and agility components may be incorporated into the training program if desired by an athlete or team. Sports-specific programs have been developed for soccer (Sportsmetrics Soccer), basketball (Sportsmetrics Basketball), and tennis (Sportsmetrics Tennis) players. A maintenance-training program (Sportsmetrics Warm-up for Injury Prevention and Performance [WIPP]) may be performed upon completion of the 6 weeks of formal Sportsmetrics to continue to instill the skills and techniques learned during the athlete’s sports season. For athletes who have already suffered an injury or had ACL reconstruction, Sportsmetrics Return to Play is recommended as end-stage rehabilitation training.

Training may be accomplished either in classes led by an instructor who has completed certification training from the authors’ foundation or from an instructional step-by-step videotape series. Athletes who do not train with a certified instructor are encouraged to perform the training either in front of a mirror or with a partner so that mistakes in technique, form, and body alignment may be detected and corrected. A list of certified instructors and sites is available at http://www.sportsmetrics.net.

Dynamic Warm-up

The purpose of the dynamic warm-up is to prepare the body for activity with functional-based activities that incorporate sports-specific motions. The goals are to raise core body temperature; increase heart rate; increase blood flow to the muscles; and improve flexibility, balance, and coordination. Upon completion of this warm-up, the athlete will be physically prepared for training. All of the exercises should be performed across the width of a court or field or for approximately 20 to 30 seconds.

1 Toe walk. The athlete walks up on the toes with the legs straight. The heel of the foot should not touch the ground and the hips should remain neutral throughout.

2 Heel walk. The athlete walks on the heels with the legs straight. The toes should not touch the ground, the knees should not lock, and the hips should remain neutral.

3 Straight leg march. The athlete walks with both legs straight, alternating lifting up each leg as high as possible without compromising form. The knees are kept straight and posture is erect; the body should not lean backward. The arms are swung in opposition.

4 Leg cradle (Fig. 19-5). The athlete walks forward, keeping the entire body straight and neutrally aligned. One leg is lifted in front of the body, bending at the knee. The knee is rotated outward and the foot inward. The foot is held with both hands, standing on one leg, and held in this position for 3 seconds. The foot is placed back down and the exercise is repeated with the opposite leg.

5 Dog and bush (hip rotator) walk (Fig. 19-6). The athlete is instructed to pretend that there is an obstacle directly in front of her or him. The athlete faces forward and keeps the shoulders and hips square. One leg is extended at the hip and the knee kept softly bent. The leg is externally rotated out at the hip and the knee is bent to approximately 90°. The leg is rotated and brought up and over the obstacle and then placed back on the ground. The exercise is repeated with the opposite leg.

6 High knee skip. The athlete begins to skip. One knee is driven up in the air as high as possible, while the other leg hops off the ground. As the athlete lands, the exercise is immediately repeated on the opposite side. The opposite arm of the high knee is swung up in the air to help gain height.

7 High knees. The athlete begins to jog forward. With each step, the knees are driven up as high as possible using short, choppy steps. The athlete remains facing forward, keeping the shoulders and hips square throughout the exercise.

8 Glut kicks. The athlete begins to jog forward. Each step, the athlete kicks the feet back as if trying to reach the gluts with the heel, using short, choppy steps. The athlete remains facing forward, keeping the shoulder and hips square throughout the exercise.

9 Stride out. The athlete begins jogging forward with an exaggerated running form. The knees are driven as high as possible and the feet are kicked back, as if trying to make a large complete circle with the legs. The athlete should stay up on the balls of his or her feet throughout the exercise.

10 All-out sprint. The athlete sprints forward as fast as possible while keeping proper technique and running form.

FIGURE 19-5 A–C, Leg cradle.

FIGURE 19-6 A–D, Dog and bush walk.

Plyometrics/Jump Training

In reference to ACL injury prevention–training programs, Griffin and associates⁹ stated, “The rationale to include plyometric exercises is based on evidence that the stretch-shortening cycle activates neural, muscular, and elastic components and, therefore, should enhance joint stability (dynamic stiffening).” Plyometrics help develop muscle control and strength considered critical to reduce the risk of knee ligament injuries. These exercises are well known to increase muscular power, vertical jump height, acceleration speed, and running speed.^3,4,32 However, if done improperly, these exercises would not be expected to have a beneficial effect in reducing the risk of a noncontact ACL injury. Therefore, the philosophy of the plyometric and jump-training component in the Sportsmetrics program is to place a major emphasis on correct jumping and techniques throughout the 6 weeks of training. Specific drills and instruction are used to teach the athlete to pre-position the entire body safely when accelerating or decelerating on landing. The selection and progression of the exercises entail neuromuscular retraining and proceed from simple jumping drills (to instill correct form) to multidirectional, single-foot hops and plyometrics with an emphasis on quick turnover (to add movements that mimic sports-specific motions). The jump training is divided into three 2-week phases. Each 2-week phase has a different training focus and the exercises change correspondingly (Table 19-2).

TABLE 19-2 Sportsmetrics Neuromuscular Training Program: Jump-Training Component

Phase 1, termed the technique development phase, aims to teach the athlete proper form and technique for eight different jumps. Four basic techniques are stressed: correct posture and body alignment throughout the jump (spine erect, shoulders back, chest over knees), jumping straight up with no excessive side-to-side or forward-backward movement, soft landings including toe-to-midfoot rocking and bent knees, and instant recoil preparation for the next jump. The athletes are taught these techniques through verbal queues from instructors such as “on your toes,” “straight as an arrow,” “light as a feather,” “shock absorber,” and “recoil like a spring.” Constant feedback is offered by instructors, and mirrors are used in the training sessions to provide direct visual feedback as frequently as possible. Throughout each session, exercises are increased by duration or repetition. If the athlete becomes fatigued and cannot perform the jumps with the proper technique, she or he is encouraged to stop and rest. Approximately 30 seconds of recovery time is allowed between each exercise.

Phase 2, called the fundamentals phase, continues to emphasize proper technique and quality jumping form. Six jumps from phase 1 are continued, but these are performed for longer periods of time. In addition, three new jumps of increased difficulty are incorporated. Phase 3, the performance phase, increases the quantity and speed of the jumps to develop a truly plyometric exercise routine. The athlete is encouraged to complete as many jumps as possible with proper form and to concentrate on the height achieved in each jump.

1 Wall jump (wk 1–6). Also known as ankle bounces, this jump is performed with the knees slightly bent and both arms raised overhead (Fig. 19-7A). From this position, the athlete bounces up and down off his or her toes (see Fig. 19-7B). The knees should be soft and the hips, knees, and ankles in neutral alignment. This jump is performed first to prepare the athlete mentally and physically for plyometric training. This also provides the trainer an opportunity to observe and begin positive feedback and instruction.

FIGURE 19-7 A and B, Wall jump.

Mistakes to correct include slouched posture, too much knee flexion, and eyes watching the feet with the head down. The athlete should be told to keep the eyes and head focused up, bend the knees slightly, and maintain neutral alignment.

2 Tuck jump (wk 1–6). The athlete begins in an upright neutral stance with the feet shoulder-width apart (Fig. 19-8A). The athlete jumps up, bending the knees together to bring the thighs up toward the chest as high as possible (see Fig. 19-8B).

FIGURE 19-8 A and B, Tuck jump.

Mistakes to correct include lowering the chest to the knees rather than lifting the knees to the chest, bringing the knees together during take-off or landing, double-bouncing between jumps, and producing a loud landing with a lack of muscle control. The athlete should be told to lift the knees up to the chest, control and keep the landing quiet, land on the balls of the feet, keep the knees bent when landing in order to go immediately into the next jump, keep the knees and ankles at shoulder/hip width at all times, keep the back straight, shoulders back, and keep the head/eyes up with each jump.

3 Squat jump (wk 1–6). The athlete begins in a fully crouched position as deep as comfortable (Fig. 19-9A). The knees and feet are directed forward and are in alignment with the hips. The upper body is upright with the chest open. The hands touch or reach toward the ground on the outside of the heels. The athlete jumps up, reaching as high as possible (see Fig. 19-9B), and then returns to the crouched position with hands reaching back toward the heels (see Fig. 19-9C).

FIGURE 19-9 A–C, Squat jump.

Mistakes to correct include landing with body/knees forward and/or off-balance, bringing the knees together during take-off or landing, and producing a loud landing with a lack of muscle control. The athlete should be told to keep the hands reaching back toward the heels (not forward), keep the knees tracking under the hips on take-off and landing, maintain the knees and ankles at shoulder/hip width at all times, keep the back straight and the shoulders back, and keep the head/eyes up with each jump.

4 Barrier jump side-to-side (wk 1–2). A cone or barrier approximately 6 to 8 inches in height is used. The athlete stands in a modified squat position (Fig. 19-10A). The athlete then jumps from one side of the barrier to the other side with the feet kept together (see Fig. 19-10B), and lands in the same amount of knee flexion as the starting position (see Fig. 19-10C).

FIGURE 19-10 A–C, Barrier jump side-to-side.

Mistakes to correct include landing or taking off with stiff, straight, or wobbly knees; jumping side-to-side quickly without bringing the entire body over the barrier; double-bouncing on landing and take-off; and not landing with the feet together. The athlete should be told to bend the knees up to clear the barrier, land quietly on the balls of the feet and rock back to the heels, control the landing to be able to immediately take off again, keep the back straight with the shoulders back, keep head/eyes up with each jump, keep the knees tracking under the hips and toes pointed forward on take-off and landing, and keep the feet parallel to each other.

5 Barrier jump forward-backward (wk 1–2). A cone or barrier approximately 6 to 8 inches in height is used. The athlete stands facing the barrier in a modified squat position (Fig. 19-11A). The athlete jumps forward and backward with the feet kept together (see Fig. 19-11B), and lands in the same amount of knee flexion as the starting position (see Fig. 19-11C).

FIGURE 19-11 A–C, Barrier jump forward-backward.

Mistakes to correct include landing or taking off with stiff, straight, or wobbly knees; jumping forward-backward quickly without bringing the entire body over the barrier; double-bouncing on landing and take-off; and separating the feet to clear the barrier. The athlete should be told to lift the knees up to the chest to clear the barrier, land quietly on the balls of the feet and rock back to the heels, control the landing to be able to immediately take off again, keep the back straight with the shoulders back, keep the head/eyes up with each jump, and keep the knees tracking under the hips and the toes pointed forward on take-off and landing.

6 180° jump (wk 1–2). The athlete begins from an upright neutral stance with the feet shoulder-width apart (Fig. 19-12A). The athlete jumps with both feet straight up into the air and makes a 180° turn in midair (see Fig. 19-21B) before landing (see Fig. 19-12C). The landing is held for two seconds, and then the direction is reversed and the jump repeated.

FIGURE 19-12 A–C, 180° jump.

Mistakes to correct include over- or underrotating; not turning the body 180°; not rotating the body as a unit; landing loud, straight, stiff-legged, with staggered feet or one foot landing before the other; always jumping in the same direction (in a circle); rotating back and forth with minimal height during jump; and separating the feet beyond the desired “feet shoulder-/hip-width” distance.

The athlete should be told to jump straight up and rotate the body as a unit from the head to the toes; land with soft, slightly flexed knees; always jump in opposing directions (one jump over the right shoulder, the next over the left); keep the knees tracking under the hips on take-off and landing; maintain knees and ankles at shoulder/hip width at all times; keep the back straight with the shoulders back, and keep the head/eyes up with each jump.

7 Broad jump (wk 1–2). The athlete starts from an upright neutral stance (Fig. 19-13A) and jumps forward as far as possible (see Fig. 19-13B), taking off with both feet. The athlete lands on both feet, remains in a deep crouch position (see Fig. 19-13C) for 5 seconds, and then repeats the jump.

FIGURE 19-13 A–C, Broad jump.

Mistakes to correct include not holding or sticking the landing, pointing the knees inward during landing and take-off, and landing in a straight-legged or upright position. The athlete should be told to track the knees over the heels and under the hips on take-off and landing, land with a soft toe ball-heel rock with the knees flexed, and hold the landing for 5 seconds.

8 Bounding in place (wk 1–2). The athlete begins this jump on a single leg, with the opposite leg bent behind. Staying in one place, the leg positions are alternated by driving the back leg forward and upward. The rhythm and height are progressively increased throughout the exercise (Fig. 19-14).

FIGURE 19-14 A–C, Bounding in place.

Mistakes to correct are simply alternating the knees or jogging in place, and landing loudly or with wobbly knees. The athlete should be told to use the arms as a countermovement to progress to increase height and power, drive the knees upward, and land with soft knees and a toe-ball-heel rock landing pattern.

9 Jump, jump, jump, vertical jump (wk 3–4). The athlete performs three broad jumps, with each take-off and landing in a deep crouch position. Then, the athlete finishes with a maximum vertical jump and returns to the deep crouch position and holds the position for 5 seconds.

Mistakes to correct include pointing the knees inward during landing and take-off, and carrying the body forward rather than up on the vertical jump. The athlete should be told to keep the knees over the heels and under the hips on take-off and landing, land with the toe-ball-heel rock with the knees flexed, and go straight up on the vertical jump.

10 Barrier hop side-to-side (wk 3–4). Using the same cone or barrier from phase 1, the athlete performs a single-leg hop rather than a double-leg jump side-to-side over the barrier (Fig. 19-15).

FIGURE 19-15 A–C, Barrier hop side-to-side.

Mistakes to correct are landing or taking off with stiff, straight, or wobbly knees; hopping side-to-side quickly without bringing the entire body over the barrier; and double-bouncing on landing. The athlete should be told to bend the knee to clear the barrier; land quietly on the ball of the foot and rock back to the heel; control the landing to be able to immediately take off again; keep the back straight, shoulders back, and head/eyes up with each hop; keep the knee tracking under the hips; and keep the toes pointed forward on take-off and landing.

11 Barrier hop forward-backward (wk 3–4). Using the same cone or barrier from phase 1, the athlete performs a single-leg hop rather than a double-leg jump forward and backward over the barrier (Fig. 19-16).

FIGURE 19-16 A–C, Barrier hop forward-backward.

Mistakes to correct are landing or taking off with stiff, straight, or wobbly knees; hopping forward-backward quickly without bringing the entire body over the barrier; and double-bouncing on landing. The athlete should be told to bend the knee to clear the barrier; land quietly on the ball of the foot and rock back to the heel; control the landing to be able to immediately take off again; keep the back straight, shoulders back, and head/eyes up with each hop; keep the knee tracking under the hips; and keep the toes pointed forward on take-off and landing.

12 Scissor jump (wk 3–4). The athlete begins in a long lunge position with the front knee bent directly over the ankle (Fig. 19-17A). The athlete pushes off the front leg, jumps straight up in the air (see Fig. 19-17B), lands with the opposite leg bent in front (see Fig. 19-17C), and then alternates legs.

FIGURE 19-17 A–C, Scissor jump.

Mistakes to correct are landing with wobbly knees or knees extended past the front ankle, jumping up to alternate legs with minimal height, legs not switching directly under body, simply switching legs without power, landing loudly, landing with a straight or stiff leg, landing with staggered feet, or landing one foot before the other. The athlete should be told to push off with power from the front leg, obtain maximum height on the leg switch, land in control with the legs bent and the front knee directly over the ankle, keep the back straight, shoulders back, and head/eyes up with each jump, and keep the toes pointed forward with each take-off and landing.

13 Single-leg hop (wk 3–4). This hop is performed just like the broad jump, except the athlete starts and lands on the same leg. The athlete lands in a deep crouched position, which is held for 5 seconds, and then repeats the hop on the opposite leg (Fig. 19-18).

FIGURE 19-18 A–C, Single-leg hop.

Mistakes to correct include landing with a wobbly knee, landing upright with the knee straight, and landing in deep knee flexion but standing up immediately. The athlete should be told to keep the knees over the heels and under the hips on take-off and landing, land with the toe-ball-heel rock and the knees and ankles flexed, and hold the landing for 5 seconds (more important than distance).

14 Bounding for distance (wk 3–4). The athlete begins bounding in place and progresses forward, increasing the distance with each step while keeping the knees high.

Mistakes to correct include performing alternating knee lifts or a high knee jog, landing loudly or with wobbly knees, and keeping the knee low instead of lifting up. The athlete should be told to use the arms as a countermovement to progress and increase height and power, and drive the knee upward and forward.

15 Jump up, jump down, 180°, vertical (wk 5–6). This is a double-foot jump onto a 6 to 8-inch box or stacked mat. The athlete lands in a deep crouched position and immediately performs a double-foot jump down (a depth jump) off the box or mat. The athlete lands again in a deep crouched position and immediately performs a 180° jump. Upon landing, the athlete jumps right into a maximum vertical jump, landing once again in the deep crouched position, which is held for 5 seconds.

Mistakes to correct are landing each jump in an upright straight or stiff-legged stance or landing with one foot. The athlete should be told to land every jump in a deep crouch with the knees and ankles flexed, and to have the feet land at the same time.

16 Mattress jump side-to-side (wk 5–6). The cone or barrier is placed on a cushioned surface approximately 2 to 3 inches deep. The athlete performs a double-foot jump side to side (Fig. 19-19).

FIGURE 19-19 A–C, Mattress jump side-to-side.

Mistakes to correct are landing with wobbly knees or knees pointed inward, double-bouncing on landing, landing with feet staggered, or landing with one foot in front of the other. The athlete should be told to land and take-off with both feet together, control the landing to be able to immediately take-off back over the barrier, and keep the feet parallel to each other.

17 Mattress jump forward-backward (wk 5–6). The cone or barrier is placed on a cushioned surface approximately 2 to 3 inches deep. The athlete performs a double-foot jump forward and backward (Fig. 19-20).

FIGURE 19-20 A–C, Mattress jump forward-backward.

Mistakes to correct include landing with wobbly knees or knees pointed inward, double-bouncing on landing, landing with the feet staggered, or landing with one foot in front of the other. The athlete should be told to land and take-off with both feet together, control the landing to be able to immediately take-off back over the barrier, and to keep the feet parallel to each other.

18 Hop, hop, hop, stick (wk 5–6). The athlete performs three single-leg hops for distance, holding and sticking the final landing for 5 seconds.

Mistakes to correct include landing with wobbly knees or knees pointed inward, landing upright with poor knee and ankle flexion, and landing in deep knee flexion but immediately standing up. The athlete should be told to keep the knees over the heels and under the hips on take-off and landing, land with a toe-ball-heel rock and keep the knees flexed, and to hold the landing for 5 seconds (more important than distance).

19 Jump into bounding (wk 5–6). The athlete jumps forward off both feet, landing on one leg with the other bent behind and immediately begins bounding for distance.

Mistakes to correct are performing alternating knee lifts or a simple high knee jog, landing loudly or with wobbly knees, and keeping the knees low instead of lifting high. The athlete should be told to land with control off the jump and immediately begin bounding, use the arms as a countermovement to progress and increase height and power, and to drive the knees upward and forward as if going for an approach vertical jump.

Strength Training

A combination of strength-training options is used to focus on the development of core strength and the improvement of overall muscular efficiency. Either isokinetic equipment or free weights may be used by the athlete, based on the available equipment. The lower extremity muscle groups targeted are the quadriceps, hamstrings, gluteals, and gastrocnemius. The athlete begins with 12 to 15 repetitions for each muscle group. When the athlete can perform 15 repetitions, the amount of weight is increased. The upper body muscle groups include the deltoids, pectorals, triceps, latissimus dorsi/low back, and abdominals. Ten to 12 repetitions are recommended initially, and when the athlete can perform 12 repetitions, the amount of weight is increased. Athletes are encouraged to use 70% of their 1 repetition maximum upon initiation of strength training. The overload principle is stressed.

For athletes who do not have access to isokinetic equipment or free weights, exercises for strength training using body weights and a Theraband may be used, as described later.

1 Mini-squats with Theraband. The athlete stands on the center of a strip of TheraBand with the feet shoulder-width apart (Fig. 19-21A). While gripping each end of the band, the athlete pulls both hands up to waist level to make the band taut. The athlete squats down into a modified 70° bend at the hips and knees, lowering the body against the resistance of the band (see Fig. 19-21B). The knees are kept over the ankles. The athlete rises back up, pushing through the heels to the starting position. This exercise is done for 30 seconds during weeks 1 to 3 and for 60 seconds during weeks 4 to 6.

FIGURE 19-21 A and B, Mini-squat with TheraBand.

Mistakes to correct are body weight and/or knees shifting forward, slouched posture, and maintaining too much slack in the band. The athlete should be told to wiggle the toes throughout the movement, and to keep the back straight, the head up, and the knees centered over the ankles.

2 Walking lunges forward. This exercise is similar to the lunges performed during the dynamic warm-up, but uses a larger range of motion and slower movements. While keeping the entire body facing forward, the athlete steps out with one leg as far as possible. Bending the knees, the athlete lowers the back leg toward the ground stopping just before the knee touches the ground. The front knee should stay directly over the ankle. The athlete lifts the body up to standing by initiating the lift-up with the front leg. The back leg is brought alongside the front leg, pause, repeat with the opposite leg. This exercise is done for 30 seconds during weeks 1 to 3 and for 60 seconds in weeks 4 to 6.

Mistakes to correct are bending the knee past the front toe, wobbly knees or lack of upper body control, moving fast, and pushing off from the back leg for leverage. The athlete should be told to maintain an upright posture, lift with the gluteal and quadriceps muscles on the front leg, and move slowly and deliberately.

3 Prone hamstrings with partner resistance. The athlete lies flat on the stomach, tightening the abdominals and gluteus muscles to press the hips into the floor. A partner places even, downward pressure on the lower calf as the athlete resists, bending at the knee so the heel comes toward the gluteus muscles without raising the hips off the floor. The athlete continues to bend and straighten the leg with control as the partner applies even, downward pressure. This exercise is repeated on each leg for 30 seconds during weeks 1 to 3 and for 60 seconds during weeks 4 to 6.

Mistakes to correct including lifting the upper body, lifting the working hip off the ground, and the partner not resisting to create eccentric contractions. The athlete should be told to keep the hips pressed into the ground, keep the upper body relaxed, and move the leg through the full range of motion.

4 Supine hamstring bridge. While lying flat on the back, the athlete bends one knee and places the heel of the foot as close to the gluteus as possible. The other leg is extended straight up into the air (Fig. 19-22A). Pushing through the heel that is on the ground, the athlete performs small lifts, raising the gluteus off the ground and taking the extended leg higher in the air with each push (see Fig. 19-22B). The abdominals should be tight and the upper back in neutral. The arms should be relaxed above the head. This exercise is repeated on each leg for 30 seconds during phase I.

FIGURE 19-22 A and B, Supine hamstrings bridge.

Mistakes to correct include simply swinging the leg in the air back and forth, not raising the gluteus off the ground into a bridge position, bending the leg in the air, pushing up through the toe instead of the heel, and holding the body up off the ground with the arms or hands. The athlete should be told to press the heel into the ground, keep the abdominals tight and the lower back neutral, lift the leg in the air straight up and push the foot up toward the ceiling, keep the heel close to the gluteus, and raise and lower the leg slowly and under control.

5 Bridge with alternating-leg hamstring glide. This exercise is similar to the supine hamstring bridge; however, instead of extending one leg directly up from the hip, the athlete places both heels as close as possible to the gluteus. The athlete slides one leg to near full extension, keeping the heel on the ground. The leg is returned to the starting position and repeated. This exercise is repeated on each leg for 30 seconds in phase II.

Mistakes to correct are not lifting and holding the hips off the ground, not moving the leg through the full range of motion, and locking the knee. The athlete should be told to relax the shoulders and keep the head on the ground, move in a slow and controlled pattern, and keep the abdominals tight.

6 Bridge with double-leg hamstring glide. This exercise is similar to the alternating-leg hamstring glide. The athlete begins with both heels as close to the gluteus as possible. Both legs are slid to near full extension and then back up to the starting position. This exercise is repeated for 30 seconds in phase III.

Mistakes to correct include not lifting and holding the hips off the ground, not moving the legs to near extension, and locking the knee. The athlete should be told to relax the shoulders and keep the head on the ground, move in a slow and controlled pattern, and keep the abdominals tight.

7 Arm swing with TheraBand. The athlete stands on the center of a strip of TheraBand with the feet shoulder-width apart. While gripping each end of the band, the athlete pulls up to waist level so the band is taut and the elbows are at a 90° angle (Fig. 19-23A). The arms are kept at a 90° angle (see Fig. 19-23B) while alternately swung from the hip to the ear, mimicking a running pattern (see Fig. 19-23C). This exercise is done for 30 seconds during weeks 1 to 3 and for 60 seconds during weeks 4 to 6.

FIGURE 19-23 A–C, Arm swing with TheraBand.

Mistakes to correct include not keeping the arms in a 90° angle through the full range of motion, locking the knees, and twisting the torso. The athlete should be told to keep the head up and shoulders back, maintain an upright neutral spine, and keep the abdominals tight.

8 Superman (alternating arms/legs). The athlete lies face down and places the forehead on top of the back of one hand. The other arm is extended out on the ground. The abdominal muscles are tightened and the upper body is raised to lift the extended arm. At the same time, from the hip and gluteals, the leg opposite from the extended arm is raised. The toes and fingers on the lifted leg and arm are extended. The abdominals remained tightened. This exercise is done for 30 seconds during weeks 1 to 3 and for 60 seconds during weeks 4 to 6.

Mistakes to correct are lifting the head up, overly arching the back, and lifting the leg to the side. The athlete should be told to keep the spine as neutral as possible, focusing the eyes on the mat/ground directly below; lift from the trunk; lift the leg and arm only to the point of tension in the lower back; and keep the abdominals tight.

9 Abdominals (Russian twists). The athlete lies on the ground, bends the knees, and places the heels on the floor. The athlete bends at the hips, not the waist, to bring the upper body to a 45° angle and holds this position. Moving the trunk as a unit, the athlete rotates the upper body side-to-side allowing the hands to touch the ground next to the hip with each rotation (Fig. 19-24). This exercise is done 1 day each week for 30 seconds in phase I, 60 seconds in phase II, and 90 seconds in phase III.

FIGURE 19-24 A–C, Abdominals (Russian twists).

Mistakes to correct are slouched posture, rounded shoulders, and twisting only the shoulders and not the torso. The athlete should be told to keep the back straight and shoulders relaxed, keep the upper body at a 45° angle, and to move the trunk as a unit, making sure that both hands are touching the ground with each rotation.

10 Abdominals (plank). The athlete lies face down and places the elbows under the shoulders with the forearms on the floor (Fig. 19-25A). The legs are placed a hip-distance apart and the toes curled under. The athlete lifts the body up onto the elbows and toes (see Fig. 19-25B). A neutral posture is maintained. The position is held with tight abdominals. This exercise is done 1 day each week for 30 seconds in phase I, 60 seconds in phase II, and 90 seconds in phase III.

FIGURE 19-25 A and B, Abdominals (plank).

Mistakes to correct include maintaining a slouched or arched midsection, placing the head down with chin resting on chest, and keeping the elbows and/or toes too close together. The athlete should be told to make sure to maintain a neutral posture, keep the neck and shoulders relaxed, keep the body in a straight line parallel to the ground, maintain head in a neutral position, and keep the abdominals tight at all times.

11 Abdominals (bicycle kicks). The athlete lies on the back with the knees bent into the chest, placing the fingertips on the back of the head. The upper body is raised off the ground until the shoulders no longer touch the ground and holds this position. The legs are moved in a cyclic motion, bringing the heels into the gluteus and extending the legs out as close to the floor as possible (Fig. 19-26). This exercise is performed 1 day each week for 30 seconds in phase I, 60 seconds in phase II, and 90 seconds in phase III.

FIGURE 19-26 A–C, Abdominals (bicycle kicks).

Mistakes to correct include not keeping the upper body off the ground, rotating the upper body, and cycling the legs close to body. The athlete should be told to keep the chest open and lift from the waist, keep the elbows open and upper body stationary, and fully bend and straighten the legs close to the ground.

12 Hip flexor TheraBand kicking. The athlete places one end of a piece of TheraBand around the ankle, with the other end around the ankle of a partner or anchored to a stationary object. With the athlete’s back to the partner or stationary object, the athlete steps forward to produce moderate tension in the band while the leg with the TheraBand around it is in approximately 15° of hip extension (Fig. 19-27A). Then, the athlete drives the knee that is back up and forward with maximal effort against the resistance of the band until the thigh is parallel with the ground (see Fig. 19-27B). The leg is returned to a slightly extended position after each exertion. This exercise consists of two sets of 10 repetitions, with 30 seconds rest between each set. A third set is performed of 20 repetitions in phase I, 30 repetitions in phase II, and 40 repetitions in phase III.

FIGURE 19-27 A and B, Hip flexor TheraBand kicking.

Mistakes to correct include swinging the leg up and back, hiking the hip, and moving the torso. The athlete should be told to keep head and neck straight, look straight down, keep shoulders and hips square, keep the upper body stationary, and always return the working leg to a slightly extended position before kicking forward again.

13 Steamboats (hip flexion). The athlete places a resistance band around the thighs, halfway between the hips and the knees. The exercise is begun with the feet shoulder-width apart and one knee is bent slightly so that the foot is off the ground. The athlete balances on the one leg and begins kicking forward and backward on the bent leg at the hip. The upper body is kept still and does not sway. This exercise is done for 30 seconds on each leg during weeks 1 to 3 and for 60 seconds during weeks 4 to 6. It may replace hip flexor TheraBand kicking.

Mistakes to correct include flexing or extending at the knee, simply bending and straightening the knee and not moving at the hip, swaying the upper body back and forth with kicking movements, and not kicking forward or backward enough to feel resistance of the band. The athlete should be told to keep the back straight, the shoulders back, and the head/eyes up, maintain slight bend in both knees at all times, keep the upper body stationary, kick the leg back and forth through full range of motion, keep the hips level at all times, and do not hike the hip with motion.

14 Hip abductor TheraBand kicking. The athlete places one end of a piece of TheraBand around the ankle with the other end around the ankle of a partner or anchored to a stationary object. The athlete stands in line with the partner or stationary object so that the leg with the resistance is farthest away from the partner or object (Fig. 19-28A). The athlete steps sideways to produce moderate tension in the band, kicks the outside leg out sideways against the resistance of the band (see Fig. 19-28), and returns to the starting position. This exercise consists of two sets of 10 repetitions, with 30 seconds rest between sets. A third set is performed of 20 repetitions in phase I, 30 repetitions in phase II, and 40 repetitions in phase III. This activity is performed 2 days a week.

FIGURE 19-28 A and B, Hip abductor TheraBand kicking.

Mistakes to correct are swinging the leg out and back without control, and leaning the upper body to the side while kicking. The athlete should be told to keep the head and neck straight, look straight ahead, keep shoulders and hips square, keep upper body stationary, and keep movements slow and controlled.

15 Lateral walking with TheraBand. The athlete places a resistance band around the thighs, halfway between the hips and the knees. The exercise is begun with the feet shoulder-width apart. The athlete steps out to the side approximately 2 to 3 feet. Slowly and under control, the athlete follows with the other foot to regain the “feet shoulder-width apart” position. Once finished, the athlete reverses directions so that the opposite foot leads the exercise. This exercise is done for 30 seconds during weeks 1 to 3 and for 60 seconds during weeks 4 to 6. It may replace hip abduction TheraBand kicking.

Mistakes to correct include allowing the feet to come together between steps, allowing the leg that follows to “snap” back to the starting position, walking with the knees locked in the straight position, bending forward at the waist, rounding the shoulders, and looking down at the feet/ground. The athlete should be told to keep the back straight, the shoulders back, and the head/eyes up, keep the steps to a distance that allows for leg control throughout the activity, keep motion slow and under control at all times, and make sure that all motion is coming from the hips and legs.

Flexibility

Passive stretching is done at the conclusion of training, with each stretch held for 20 to 30 seconds and repeated twice on each side. Stretching is considered essential to achieve maximum muscle length to allow muscles to work with power through a complete range of motion. The major muscle groups targeted are the hamstrings, iliotibial band, quadriceps, hip flexor, gastrocnemius, soleus, deltoid, triceps, biceps, pectoralis, and latissimus dorsi.

1 Hamstrings. While seated, the athlete extends the right leg fully and bends the left leg, placing the inside of the foot along the left calf (Fig. 19-29A). The back is kept straight and the chest is brought toward the knee. The athlete reaches with both hands toward the toes (see Fig. 19-29B). The hands are placed on the floor alongside the legs or hold on to the toes. Switch the side and repeat.

FIGURE 19-29 A and B, Hamstrings stretch.

Mistakes to correct are rounding the shoulders when leaning into stretch, bringing the chin into the chest when stretching, allowing the knee of the leg on the ground to bend, and bouncing into the stretch. The athlete should be told to keep the back straight when leaning forward into the stretch, bend forward at the waist, and keep the shoulders back and head up for the duration of the stretch.

2 Iliotibial band. While seated, the athlete bends the right knee and places the right foot flat on the floor. The left foot and ankle are placed on the right thigh just above the knee. Both hands are placed on the floor behind the hips and the chest is pressed toward the knee and foot. The upper torso, neck, and shoulders remain neutral and open and the upper back is not rounded (Fig. 19-30). This stretch may be performed while lying on the back to support the spine and neck.

3 Quadriceps. While standing, the athlete grabs the foot or ankle and lifts it up behind the body. The lower leg and foot are gently pulled up, directly behind the upper leg, with no twisting inward or outward (Fig. 19-31). The stretch is held for 20 seconds, released, and repeated on the same side. Then, the opposite side is stretched with the same sequence.

FIGURE 19-30 A and B, Iliotibial band stretch.

FIGURE 19-31 A and B, Quadriceps stretch.

Mistakes to correct include allowing the foot to rest on the buttocks, pulling the leg and/or foot inward or outward, and locking the knee of the leg being used for balance. The athlete should be told to pull straight up on the foot and leg, and to keep the back straight, shoulders back, and head/eyes up.

4 Hip flexor. The athlete stands with the feet in a lunge position and the front knee slightly bent. The athlete pushes up on the rear toe. The hips are pressed forward while the buttocks are tightened until a stretch is felt in the front of the hip. The upper torso remains upright and centered directly over the hips (Fig. 19-32).

FIGURE 19-32 Hip flexor stretch.

Mistakes to correct include leaning the upper body forward, not pressing the hips forward, and bouncing into the stretch. The athlete should be told to keep the upper body upright and centered directly over the hips, press or rock the hips forward to initiate stretch, and keep the back straight, shoulders back, and head/eyes up.

5 Gastrocnemius. The athlete stands in a long lunge position with the front knee slightly bent, but not extended past the ankle. The hands are placed on the front of the thigh and the body is leaned forward while keeping the back leg straight. The rear heel is pressed down (Fig. 19-33). This stretch may also be done by placing both hands against a wall and leaning forward. The stretch is held for 20 seconds, released, and repeated.

FIGURE 19-33 Gastrocnemius stretch.

Mistakes to correct are allowing the back heel to rise off the ground, bouncing into the stretch, allowing the knee of the back leg to bend, and not maintaining upper body posture. The athlete should be told to keep the back straight, the shoulders back, and head/eyes up; keep the back leg straight; and keep the heel on the ground at all times.

6 Soleus. The athlete stands with one foot forward and one foot back, in a short lunge position. Both knees are bent and the athlete is instructed to sit the hips down into the back heel, with the majority of body weight on the back leg (Fig. 19-34). The heel is kept on the floor. This stretch may be performed by placing both hands against a wall for balance.

7 Deltoid. While either standing or sitting, the athlete brings the left arm across the body, placing the elbow in close to the chest. The palm of the hand faces the rear. The arm is clasped at the elbow and gently pressed into and across the body (Fig. 19-35). Both shoulders stay relaxed and low. The head, neck, and spine all remain neutral.

8 Triceps, latissimus dorsi. While either standing or sitting, the athlete extends the right arm above the head. The elbow is bent behind the head while the palm of the hand is brought toward the center of the upper back. The elbow is grasped with the left hand and gently pressed down and back (Fig. 19-36).

9 Pectoralis, biceps. While standing, the athlete clasps the hands behind the back. With the shoulders and neck relaxed, the elbows are extended, the chest opened, and the hands lifted up. The posture should remain upright and neutral and the knees slightly flexed (Fig. 19-37).

10 Low back. The athlete kneels on the floor with the hands close to the buttocks. The athlete bends forward with the arms fully extended reaching out onto the floor. The head is lowered between the arms with the forehead close to or resting on the floor. The hands are gradually moved out farther from the body without rising up from the heels (Fig. 19-38).

FIGURE 19-34 Soleus stretch.

FIGURE 19-35 Deltoid stretch.

FIGURE 19-36 A and B, Triceps, latissimus dorsi stretch.

FIGURE 19-37 Pectoralis, biceps stretch.

FIGURE 19-38 Low back stretch.

SPORTSMETRICS TRAINING PROGRAM OPTIONS

Sports-Specific Training

Sportsmetrics Soccer and Basketball

Soccer and basketball represent two of the highest-risk sports for noncontact ACL injuries in female athletes. Sports-specific training programs were designed for these activities that allow all training to be conducted on the field or court. These programs incorporate strength training, cardiovascular conditioning, and agility drills that mirror the typical demands of the sports. Seventeen of the jumps from Sportsmetrics are included in the training.

These programs should be performed in the athlete’s off or preparatory season at least 3 days/week. No equipment other than a basketball or soccer ball for each athlete is required. As in Sportsmetrics training, emphasis is placed on the athlete performing every exercise or drill with proper technique, body alignment, and form. If an athlete exhibits compromised form, the exercise should be stopped by the instructor. The athlete should then perform one more repetition of the task, focusing on correcting obvious deficiencies.

Sportsmetrics Soccer includes the components of Sportsmetrics in addition to agility drills and three different cardiovascular workouts that are both aerobic and anaerobic (Table 19-4). Each cardiovascular workout has a slightly different combination of short bursts of hard running and longer-distance/lower-intensity movements. The intensity of each running maneuver is monitored using a Rating of Perceived Exertion (RPE) scale from 1 to 10, with a rating of 1 indicating the lightest intensity and a rating of 10 designating an all-out maximum effort.

TABLE 19-4 Sportsmetrics Soccer Training Program

Sportsmetrics Basketball was designed to address fundamental strength, coordination, agility, and aerobic fitness (Table 19-5). The dynamic warm-up, jump/plyometric drills, and stretches are essentially the same as the original Sportsmetrics program with the addition of a basketball whenever possible to enhance balance, postural/body control, and trunk strength. The strength exercises are functional body weight exercises emphasizing total body conditioning. Agility drills and cardiovascular workouts, based upon basketball movement patterns and drills, round out the training.

TABLE 19-5 Sportsmetrics Basketball Training Program

Sportsmetrics Tennis

Although not considered a high-risk sport for noncontact ACL injuries, tennis carries the risk of other lower extremity injuries and overuse syndromes. A recent review of the literature regarding tennis injuries found that the lower extremity was the most common area injured.³⁰ The concepts developed in traditional Sportsmetrics of decreased landing forces, increased knee and hip flexion angles during activity, improvement in balance and posture, and increased strength and agility may be effective in reducing the risk of other lower extremity injuries during tennis. Emphasis is placed on the athlete performing every exercise or drill with proper technique, body alignment, and form. The program incorporates strength training, cardiovascular conditioning, and skill/agility drills that match the demands of the sport (Table 19-6). Performed three times a week for 6 weeks, the training may be conducted during season or off-season. All training is performed on the court, and the authors recommend the use of clay courts if possible.

TABLE 19-6 Sportsmetrics Tennis Training Program

The foundation of the program duplicates traditional Sportsmetrics, because the athletes begin with dynamic warm-up exercises and jump training. The program strives to teach athletes to control the upper body, trunk, and lower body position; lower their center of gravity by increasing hip and knee flexion; and develop muscular strength and techniques to land with decreased ground reaction forces. In addition, athletes are taught to pre-position the body and lower extremity prior to initial ground contact in order to obtain the position of greatest knee joint stability and stiffness.

In addition to the jumps from the traditional Sportsmetrics program, the athletes perform level surface box (four-square) hops over barriers in a variety of patterns of increasing difficulty each week (Fig. 19-39). The patterns involve right-left, forward-backward, and diagonal directions to simulate the constant change of direction required during competitive tennis. While maintaining proper body position and knee flexion angles, the athletes are encouraged to perform as many hops as possible in 20 to 25 seconds.

FIGURE 19-39 Barrier four-square hop patterns. The red triangles designate barriers.

After jump training, the players are taken through a series of rigorous speed, agility, footwork, and skill drills. The drills emphasize body posture, knee and hip flexion position, and balance techniques taught in the jump-training element of the program. Some of the tasks include use of a resistance belt during groundstroke and approach shot training, net zigzag that includes nine sharp cuts around cones placed between the baseline and the net, short sprints, and a cross-shadow drill which stresses balance and appropriate footwork along the baseline. In addition, muscle strengthening exercises include backward lunges, medicine ball tossing, single-leg toe-raises, wall-sits, seated press-ups, and wall push-ups. Athletes perform a variety of upper body free weight strength exercises. Free weights are added to the lunges and single-leg toe raises during the 3rd week of training to increase the difficulty of these tasks. A variety of abdominal exercises round out the program, starting with 100 repetitions the 1st week and working up to 250 repetitions the last week of training.

Sportsmetrics Speed and Conditioning Program

The Sportsmetrics Speed and Conditioning Program incorporates complex conditioning in addition to the other components of Sportsmetrics. The conditioning program encompasses a series of vigorous speed and agility drills comprising quick feet, sharp cuts, straight sprints, backward running, and unpredicted agility patterns (Table 19-7). With each drill, athletes concentrate on correct running form, body posture, and proper technique associated with cutting, pivoting, and decelerating. The entire program may be performed on a court or field with minimal equipment. It should be conducted in the athlete’s off or preparatory season, 3 days a week for 6 weeks. A few examples of the speed and agility training drills are listed later. The four-square hops shown in Figure 19-39 are included in the training (termed dot drill). This program is under prospective investigation to determine its effectiveness on both improving performance and reducing the rate of ACL noncontact injuries.

1 Quick feet. The athlete begins this drill at the end of a straight line, lined up parallel to the line. Moving down the line, to the left, the athlete steps the left foot forward and diagonally over the line followed quickly by the right foot. As soon as the right foot crosses the line, the athlete steps the left foot backward and diagonally (back over the line), again followed quickly by the right foot. This pattern is continued along the length of the line for 30 seconds. At the end of the first 30 seconds, the athlete proceeds back to the starting position, moving to the right, leading with the right foot and following with the left for 30 seconds.

TABLE 19-7 Sportsmetrics Speed and Conditioning Training Program

Mistakes to correct include overlapping the feet while traveling along the line, rotating the upper body, leading with the wrong foot, taking very wide steps, bending forward at the waist, rounding the shoulders, and looking down at the feet/ground. The athlete should be told to keep the toes and knees pointed forward; keep the back straight, shoulders back, and head/eyes up; make the steps short and choppy, with feet not going wider than shoulder width; and keep speed under control until proper pattern is achieved.

2 Ladder drill 1. A 15-foot ladder is placed along a sideline. The athlete begins at the left end of the ladder and steps the right foot forward and diagonally over the ladder into the first square followed quickly by the left foot (Fig. 19-40). As soon as the left foot crosses the ladder, the right foot steps backward and diagonally (back over the ladder), again followed quickly by the left foot. This pattern is continued along the 15-foot distance until the right end of the ladder is reached. Then, the same pattern is repeated leading with the left foot back to the starting point. The athlete should travel back and forth along the distance of the ladder for 30 seconds. The athlete should be told to keep the feet shoulder-width apart at all times; make all steps quick, short, and choppy; keep the knees slightly bent and relaxed; keep the back straight and the head up with eyes forward; and try not to land on any portion of the ladder.

3 Ladder drill 2. A 15-foot agility ladder is placed flat on the floor. The athlete begins the drill at the bottom of the ladder, with the feet outside of the first ladder “square” (Fig. 19-41). The right foot steps forward into the first ladder “square” followed quickly by the left foot. As soon as the left foot touches down in the ladder “square,” the right foot steps forward and laterally (to the outside right of the ladder) so that it is parallel to the ladder and in line with the ladder’s rung. Once the right foot touches down outside of the ladder, the left foot steps forward and laterally (to the outside left of the ladder) so that it is parallel to the ladder and in line with the rung. Once the left foot is down, the right foot steps forward and laterally into the next ladder “square,” followed immediately by the left foot. This pattern is continued along the length of the ladder in order to move in and out of each of the ladder “squares.” Upon reaching the end of the ladder, the same pattern described previously is followed, but the footwork moves backward in order to return to the starting position.

FIGURE 19-40 Ladder drill 1.

FIGURE 19-41 Ladder drill 2.

The athlete should be told to make all steps quick, short, and choppy; keep the knees slightly bent and relaxed; keep the back straight and head up with eyes forward; and try not to land on any portion of the ladder

4 T-drill. A T-shaped course is created with three cones and a start/finish marker as shown in Figure 19-42. The first cone is placed 30 feet in front of the start/finish marker. The other two cones are placed so that each is exactly 15 feet from (and in line with) the first cone. This forms a 30-foot line that is perpendicular to the line formed by the start/finish marker and the first cone. The athlete begins at the base of the “T” and sprints forward to the cone straight ahead. Upon reaching the cone, the athlete immediately shuffles left toward the cone to the left making sure that the feet do not cross at any point during the shuffle. The athlete taps the top of the cone. Then, the athlete shuffles right, making sure that the feet do not cross at any time. The athlete moves past the middle cone and shuffles to the cone located on the far right. The athlete taps the top of that cone and then shuffles left back toward the center cone. Once the center cone is reached, the athlete taps the top of the middle cone and immediately runs backward to the start/finish marker. Two repetitions of the course are completed, with at least 15 seconds rest between each repetition. A stopwatch is used to record the time of each repetition.

FIGURE 19-42 T-drill.

The athlete should be told to keep the head and neck straight, look straight ahead, keep the shoulders and hips square, do not round shoulders forward, make sure the back is straight, lean slightly forward for the duration of the activity, and make sure that the feet do not cross at any point during shuffle activities.

5 Beanbag game. A square course is created with flat markers placed on each corner of a 40- x 40-foot area on a gym floor (Fig. 19-43). Eight beanbags are placed in the center of the square. The athletes are divided into four groups (each group should contain the same number of athletes, if possible). Each group lines up behind one of the flat markers that will be their “home-base,” and faces the beanbags. On the command “GO,” one athlete from each team sprints to the center of the square and retrieves one of the beanbags for their team. Each athlete then sprints back to their home-base and places the beanbag on the flat marker so that the entire beanbag is on the marker. As soon as the beanbag is completely on the marker, the next team member leaves home-base and sprints to retrieve another beanbag. This teammate has the choice of going to the center of the square for a beanbag or running to the home-base of an opposing team to retrieve their beanbag. After retrieving each beanbag, the team member must return the beanbag to their home-base so that it is resting entirely on the marker before their next teammate can take off. The object of the game is for one team to get three beanbags resting on their home base, and yell “BEANBAG,” before anyone else. The first team to do this wins and receives a point. The game is played for 5 minutes in phase I, 7 minutes in phase II, and 9 minutes in phase III.

6 Forward/backward sprints. Starting on the baseline of a standard basketball court, the athlete sprints forward until the opposite baseline is reached (approximately 94 ft) and then immediately runs backward at ¾ speed to the starting baseline. The athlete completes 5 repetitions in phase I, 6 repetitions in phase II, and 7 repetitions in phase III, with 15 seconds rest between each repetition.

FIGURE 19-43 Beanbag game.

The athlete should be told to keep the head and neck straight, look straight ahead, keep the shoulders and hips square, do not round the shoulders forward, keep the back straight, lean slightly forward for the duration of the activity, and decelerate each sprint with a bent knee.

7 Shuttle sprints. Five cones are placed in a zigzag pattern within an 18- × 48-foot area (Fig. 19-44). Beginning to the left of the first cone, the athlete sprints across to the next cone in the pattern. Upon approaching the second cone, the athlete decelerates the sprint with choppy steps in order to allow for tapping the top of the cone once it is reached. As soon as the second cone is tapped, the athlete immediately accelerates across to the next cone and repeats the decelerate/tap/accelerate sequence until the last cone in the pattern is reached. Once the last cone is reached, the athlete rounds the cone and runs through the pattern again back to the start/finish line. One repetition involves running up and back the course. The athlete completes 2 repetitions with at least 15 seconds rest between each repetition. A stopwatch is used to time each repetition.

FIGURE 19-44 Shuttle sprints.

The athlete should be told to keep the head and neck straight, look straight ahead, keep the shoulders and hips square, do not round the shoulders forward, keep the back straight, lean slightly forward for the duration of the activity, decelerate each sprint with a bent knee, and stay tight to the cones throughout the activity.

8 Reaction agility drill 1. During this drill, the athlete reacts to verbal cues given by an instructor who stands on the baseline. The athlete starts in the center of the court with the back facing the instructor (Fig. 19-45) and runs backward toward the instructor. The instructor commands the athlete to turn left or right, upon which time the athlete shuffles left or right. The instructor then commands the athlete to run backward diagonally toward the closest sideline, then sprint straight forward. The final command instructs the athlete to go to the left, center, or right of the cones. The length of each command is based on the instructor and space available. The drill is performed twice with 30 seconds rest.

9 Reaction agility drill 2. The athlete stands in the center of the court facing the instructor who is standing on the baseline. The instructor uses hand motions to indicate the direction the athlete should move toward. For example, if the instructor points straight forward, the athlete will backpedal away from the instructor. If the instructor points to the right, the athlete will side shuffle to the left. If the instructor points diagonally to the right, the athlete will backpedal diagonally to the left. The length of each command is based on the instructor and space available. The drill is performed twice for 30 seconds, with 30 seconds rest between repetitions. As athletes progress, the time for this drill is increased to 45 seconds.

FIGURE 19-45 Reaction agility drill.

STRATEGIES FOR IMPLEMENTATION OF NEUROMUSCULAR TRAINING