Bettering the Odds

ACL injuries are not like the weather—there is something you can do about them. Here’s a look at the recent studies on the subject and how to develop your own ACL injury-prevention program.

By Vern Gambetta

Vern Gambetta, MA, is the President of Gambetta Sports Training Systems in Sarasota, Fla., and the former Director of Conditioning for the Chicago White Sox. He is a frequent contributor to Training & Conditioning and can be reached at

Training & Conditioning, 13.5, July/August 2003,

For readers of this magazine it’s no secret: Female athletes tear their anterior cruciate ligaments more often than males. But the rest of the world has recently also taken notice of this phenomenon, and it is getting a lot of attention.

From the Pittsburgh Post-Gazette to WBAL-TV in Baltimore to National Public Radio’s “Only A Game,” mainstream media outlets are picking up the story. At the recent American College of Sports Medicine (ACSM) Convention in San Francisco, the issue of ACL injury prevention was the hottest topic discussed. Just the other day, one of the young female basketball players I work with made the statement, “girl basketball players are more likely to hurt their knees.”

What are the facts? Females are up to eight times more likely to injure their ACLs than males. An estimated one in 3,000 Americans will sustain an ACL injury per year, with high school and collegiate women athletes experiencing more than 30,000 serious knee injuries per year. A typical ACL surgery costs $25,000. High schools and colleges spend an estimated $100 million per year on ACL reconstruction surgery for female athletes.

The good news is that all this national attention has produced an increased focus on prevention tactics. From small studies to large-scale NCAA-funded research, clear guidelines are emerging on how to prevent these crushing injuries. For this article, I’ve reviewed the studies completed in the last few years and provide suggestions on developing ACL-injury-prevention programs for your own teams.

There are many theories about why women suffer more ACL injuries than men. These include:
• Femoral-notch width differences
• Size of the ACL
• Vulnerability during a certain phase of the menstrual cycle
• Greater joint laxity in women
• Landing mechanics
• Quad dominance
• Inability to recruit the hamstrings
• Wider pelvis
• Larger “Q” angle
• Greater hip varus
• Knee valgus and foot pronation
• Bracing and footwear

Since it is impossible to change the anatomical structure of the body or significantly alter biochemistry, the logical approach is to work on aspects that can be changed through training: strength, balance, proprioception, power, agility, and sport-specific fitness.

There is no question that the knee is vulnerable regardless of gender. It is not designed for some of the movements we ask from it on a consistent basis. We need to assist the knee joint by involving the entire kinetic chain to better reduce force. We need to get away from focusing on the knee and look at the knee as one link in the kinetic chain.

A very important, yet often ignored, fact is that 70 percent of knee injuries, regardless of gender, are non-contact. The typical mechanisms of these non-contact injuries are planting and cutting, straight-knee landing (no flexion on landing), hard one-step stops with the knee hyperextended, pivoting, and rapid deceleration. These are all movements inherent in sports that often occur with high force and at high speed. They usually happen too quickly for the athlete to consciously think about them. But these movements can be trained to be more efficient as part of a comprehensive prevention program, which is what some of the recent studies have looked at.

Tim Hewett, PhD, Director of the Sports Medicine Research Institute and Human Performance Laboratory at Children’s Hospital Research Foundation in Cincinnati, has pioneered research to identify some of the biomechanical factors that put female athletes at greater risk. Based on this research, he designed a prevention program that emphasized proper landing techniques and plyometric training. In one of Hewett’s studies, there were two non-contact ACL tears among 366 women who participated in a six-week training program. In the non-training group of 463 women, there were 10 ACL injuries.

In another smaller study conducted by Hewett, he used a program that included weight training, jumping, and neuromuscular training to teach athletes correct landing positions. Peak landing forces were reduced 22 percent, and peak jump height increased 10 percent.

The Santa Monica Orthopedic and Sports Medicine Research Foundation, under the direction of Bert Mandelbaum, MD, focused on improving biomechanics of female high school soccer players. The program was implemented as part of warmups for each practice session. During the 2000 season, 1,041 girls participated in the training, and two tore their ACLs, while a control group of 1,902 girls suffered 32 ACL tears. In 2001, 844 girls participated in the training, with four tearing their ACLs, while the control group of 1,092 had 35 ACL injuries. The NCAA is currently providing a similar program to its member institutions as part of its own study.

Giuliano Cerulli, MD, and his colleagues at the Santa Maria Hospital associated with the University of Perugia in Italy looked at 900 high-level male soccer players over three seasons. There were 10 ACL injuries in the proprioceptively trained group of 600 and 70 ACL injuries in the traditionally trained group of 300. The training took 20 minutes a day and encompassed five levels of difficulty. This study underscored the value of proprioception training as a key prevention factor. It also suggested that prevention benefits men as well as women.

I designed a program for the Duke Women’s Sport Medicine Program and the Michael W. Krzyzewski Human Performance Lab Pilot Study under the Direction of Mike Huff, MA, CSCS, Coordinator of Sports Performance, and Alison Toth, MD, Coordinator of Women’s Sports Programs. The pilot study involved high school girls’ basketball teams. There were 122 players in the training group and 73 players in the control group. The training period was eight weeks, extending from preseason to the early competitive season, and involved weight training, plyometrics, and agility drills. In the training group, 8.2 percent of the athletes sustained lower-extremity injuries. The control group sustained a lower-extremity injury rate of 17.8 percent. There were no ACL injuries in either group.

I used a similar program with the girls’ basketball team at Sarasota (Fla.) High School during the 2001-02 season, but unlike the one above, continued it throughout the entire season. Weight training occurred three days a week, beginning with a one-hour program in the offseason, 30 minutes of work during the preseason and early season, and 10 minutes by the end of the season. We trained balance, agility, and flexibility and conducted plyometrics five days a week (whenever possible) through a 20 minute warmup program.

There was one ACL injury on the team. It occurred to a girl who had not gone through the off-season conditioning program and did not regularly follow the in-season program due to work commitments. Otherwise, there were no lower-extremity injuries that caused any loss of practice or game time. And the team made it all the way to the state semifinals.

The common thread through all these studies was work on improving the mechanics of movement, balance, and proprioception; plyometric training; and strength training. In summary, these studies show that almost anything that strengthens the muscles around the knee and develops proprioception significantly reduces the incidence of ACL injury. The logical conclusion is that with an even more focused, longer-term, sophisticated intervention, the possibility of prevention and performance improvement should be even greater.

While it is clear that lowering the incidence of ACL injuries is possible, what may not be clear is how to take the protocols and adapt them to your specific teams. Depending on the level of play, the sport, time factors, the athletes, and the sport coach, you’ll want to alter the program accordingly.

Let’s start by examining time factors, since this is the top concern of many sport coaches. The studies clearly show that a significant time commitment is a key factor in any ACL-injury prevention program. Twenty minutes two or three times a week is not enough. Some form of training needs to occur five days a week. However, most sport coaches will not be willing to give up a half hour of every practice strictly for injury prevention. Therefore, I suggest breaking down the training components into modules that can be completed at different time periods.

These modules should be designed to fit within a time frame compatible with the other components of training that the athlete must accomplish. The most logical place to begin is in warmup, because the warmup is a necessary component of every training session. Others might be incorporated into drills done during the heart of practice. The athlete can also be given some of the more simple modules for “homework.”

After examining all the time factors, take a look at your individual athletes. What do they do on non-training days? How active are they? What was their prior activity level and movement background before they started the sport? Athletes who have grown up playing games like capture the flag and running bases and spend weekends playing pick-up games (in any movement-oriented sport) with family and friends will be steps ahead of those whose exposure to sport comes only through the team’s games and practices.

Also look at how they condition for their sport. Are they conditioning by jogging and doing slow aerobic work that detracts from explosiveness? This predisposes the athlete to injury by making him or her less reactive to the ground.

Injury history is also a key factor. If an athlete has a history of lower extremity sprains and joint laxity, start with a more remedial program. In this case, initial stages should look more like a rehab program.

Demands of the game must also be assessed. Most of the studies have focused on female basketball and soccer players, but athletes (of both genders) in many other sports tear their ACLs. Look at how much starting and stopping occurs in the sport and in how much space. For example, there will be differences between lacrosse and basketball because lacrosse players will have more room to accelerate and build up speed.

Another factor I’ve been looking at recently is style of play. Although I’ve seen no studies on this, anecdotal evidence has shown that athletes who play out of control are more likely to tear their ACLs. You may want to chat with your sport coaches about the difference between an athlete who hustles and an athlete who plays without regard to proper body positioning and mechanics.

As mentioned earlier, all of the successful prevention programs share a few key components: mechanics of movement, proprioception, plyometrics, and strength training. They can be translated into the following five modules:

• strength/power, including basic strength, core strength, elastic/reactive strength (plyometrics);
• balance/proprioception;
• agility, including body awareness, footwork, and change of direction;
• dynamic flexibility;
• sport-specific conditioning.

Here’s how I combine modules and fit them into different parts of the season and different sections of practices:

Off-season: One hour, three to four times a week, with an emphasis on strength training and balance/proprioception work at first, followed by a gradual shift to include agility and plyometric training.

Preseason: Every day before practice, 15 to 20 minutes of work as a warmup that includes balance/proprioception, agility, and plyometric training. After practice, 20 to 30 minutes of strength training three times a week.

In-Season: Before practice, the same as preseason work. Post-practice workouts can be reduced as the season progresses. In early season, 20 minutes of strength training three times a week; in midseason, 20 minutes of strength training twice a week is recommended; during the late season and playoffs, 10 to 15 minutes of strength training twice a week.

In the sidebar titled “A Look at LEPPP,” (below) a full program is detailed. It can be used for any sport and any level of play. Here are some additional tips for designing your own program:

• Use minimal equipment to avoid equipment becoming a limiting factor.

• Drills should be easy to teach and easy to monitor.

• Training must be progressive and varied.

• Teach landing and stopping mechanics before plyometric and agility training (see “Quiet Landings” below).

• Part of your strength training should focus on force reduction work, which can be accomplished through a heavy dose of strength training that emphasizes fast eccentric muscle action performed in postures and positions similar to sport movements.

• Remember that training is cumulative. It is not any one workout or component that will ensure success but rather the sum of all workouts and the interaction of all components.

One last tip is on communication. Just as important as developing your program is educating those who will be putting their trust in the program: the sport coach, athletes, and, in some cases, parents. If you can teach the “why,” then the “how” of the whole program will be meaningful. And since compliance with the program is vital, this final point may be the most important.

Sidebar: Quiet Landings
Teaching landing and stopping mechanics is a very important component of ACL injury prevention. Mastery of these mechanics should precede actual plyometric and agility training.

Landings should be on a “full foot.” I believe it is incorrect to teach landing on the ball of the foot, or the opposite extreme, flat-footed landing. The landing should occur with the weight distributed along the midfoot to take advantage of the elasticity of the muscles and ligaments, which absorb shock.

The most effective way to teach correct foot strike is to practice landing barefoot on a forgiving surface. Start simple—just step and hold. Cueing is important to improve these movements, because words create images and images create action. My verbal cue is a “quiet landing.” A “soft landing,” implies mushy, compliant action, whereas “quiet landing” denotes a landing that has some structural integrity.

Provide task-oriented cues or instructions that elicit the desired action you are looking for. For example, if you want athletes to take a longer step, provide a target on the ground they have to hit that forces them to take longer steps.

The best way to teach good landing and stopping mechanics is with a simple balance progression. Start with static balance movements, progress to dynamic balance, and finally to ballistic balance activities. All these movements emphasize bending the ankle, knee, and hip to spread force over three joints rather than one.

A Look at LEPPP
The following details the portion of the “Lower Extremity Prevention & Performance Program”™ that I designed to be accomplished as a warmup before practice. It can vary from 15 to 20 minutes in length.

Mini-Band Routine
Side step x 20
Forward walk x 20
Carioca x 20
Monster walk x 20

Single-leg squat
Balance Shift
Step to the side
Step forward
Step back
Note: do one rep at each position, hold 10 seconds.

Jackknife x 5
Creepy crawl x 5

Combination Lunges & Reaches
Lunge A
Lunge forward and reach up
Lunge to the side and reach up
Rotational lunge and reach up
Lunge B
Lunge forward and reach out
Lunge to the side and reach out
Rotational lunge and reach out
Lunge C
Lunge forward and reach across
Lunge to the side and reach across
Rotational lunge and reach across
Note: Reaches should be both to the right and the left. Do two reps with each leg in each plane. Combinations of A,B, and C should be varied from day to day.

Crossover skip
Side step
Carioca (low and long)
Carioca (short and quick)
Backward run
High-knee skip
High-knee skip w/rotation
Note: do two reps of each exercise the length of the basketball court.

Plyometric program
Jump in place (over line)
Forward/back x 10
Side to side x 10
Rotational x 10 each side
Hop in place (over line)
Forward/back x 10
Side to side x 10
Rotational x 10 each side
Multidirectional jump
Forward/forward/side/side/opposite side/side/back/back x 2
Restart jump
Forward/forward/back x 3
Side/side/back x 3
Opposite side/side/back x 3

Rotational jump
Land facing 180 degrees opposite to start x 10 each side

Restart hop
Forward/forward/back x 3
Side/side/back x 3
Opposite side/side/back x 3

Rotational bound
Off one foot onto opposite foot x 10 each side