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Preventing ACL Injuries in Soccer

ACL injuries can be devastating to a soccer players competitive season. For this reason, reputable medical institutions like the Cincinnati Sportsmedicine Foundation and Santa Monica Orthopedics have designed and published ACL prevention protocols. These programs focus on preventing injuries and enhancing athletic performance. The concentration of these programs is placed on stretching, strengthening, plyometrics, and agilities. The following article will discuss important concepts in preventing ACL injuries, and make recommendations for implementing prevention into your teams training.

Posted by: KSherry
By Brian Goodstein MS, ATC, CSCS, CES, EMT

ACL injuries can be devastating to a soccer players competitive season. For this reason, reputable medical institutions like the Cincinnati Sportsmedicine Foundation and Santa Monica Orthopedics have designed and published ACL prevention protocols. These programs focus on preventing injuries and enhancing athletic performance. The concentration of these programs is placed on stretching, strengthening, plyometrics, and agilities. The following article will discuss important concepts in preventing ACL injuries, and make recommendations for implementing prevention into your teams training.


The ACL can be ruptured via contact and non-contact mechanisms. Understanding the mechanism and possible contributors is an important factor in preventing these injuries. Typically non- contact ACL injuries occur during deceleration, landing, and sudden directional change on a planted foot. The ACL can also be torn when a valgus force is delivered to an already planted leg, or by landing on an opponents foot with fully extended leg, causing hyperextension.


Although most contact injuries cannot be prevented, we can prevent the non-contact type by training athletes to have more neuromuscular control of the knee. Functional knee stability is established by muscle power and recruitment pattern between the quadriceps and hamstring muscles. Soccer mechanics emphasize repetitive kicking motions. Kicking primarily contracts the hip flexors, knee extensors, and abductors. Because of this, soccer players are notorious for having larger quads and tight, weak hamstrings. There should be a 3:2 ratio in strength between the quadricep to hamstring. Numbers favoring the quads over hamstrings may predispose an athlete to a non contact ACL injury.



Implementing Prevention Into Your Teams Training

Soccer is a very dynamic sport! There are many athletic components to train to prepare for the demands of competition. Players must be able to stop and change directions, jump and land properly, sprint at top speed, ward other players of with their bodies, and have the ability to perform at a high level for 90 minutes. Take the time to assess the needs of each one of your players. Some of your athletes may be predisposed to ACL injuries because of inflexibility, instability, improper bio-mechanics, or history of previous injury. From your assessments, implement individual and team pre-hab exercises into your weekly training routine.


ACL prevention protocols will differ depending on gender, level of athlete, and pre, in, or post-season training. Like most strength and conditioning programs your prevention protocols should be periodized based on the soccer season. In Major League Soccer (MLS) we have a 6-8 week pre-season, followed by a 7 month regular season. The pre-season is an ideal time to evaluate the needs of your athletes. Sportmetrics recommends implementing 6 weeks of stretching, strengthening, and plyometrics at a frequency of 3 times per week.


Since the MLS season is so long, you should continue prevention by implementing a maintenance program into your teams training. A typical week features one game on Saturdays. Most coaches in our league conduct a 90 minute practice Monday through Thursday and taper Friday. Try to incorporate dynamic flexibility, speed, and agility drills into practice each day. On Mondays and Wednesdays incorporate a 30-45 minute weight training and plyometrics session. Exercises can be performed before or after practice. I recommend picking 10-12 exercises that concentrates on total body strengthening and maintaining explosive power. Perform exercises in a curcuit training manner for 2 sets of 10-15 at 60-80% max. On Tuesdays and Thursdays prevention can be implemented into your post practice by performing sport specific agilities, core strengthening, and static stretching sessions. Obviously this will need to be adjusted with the mid-week game, but should be used as a general guideline for an in-season prevention program.

Stretching and Flexibility
During the pre-season evaluate your players flexibility. The purpose of stretching is to achieve maximum muscle length in order to balance muscle strength and flexibility. Static stretching for the calf, quad, hamstring, hip flexor, adductors, and abductors, is recommened for 3 x 30 seconds. Important flexibility tests to perform are the deep squat (look for asymmetry and limitations in the calf, quad, or lower back) supine single leg raise (look to see if the leg can make a 90 degree angle at the hip) and the Thomas Test (to assess hip flexor flexibility).


Warm Up
The warm up is one of the most important parts of a soccer players prevention program. Incorporate dynamic stretching movements that challenge propioception and the neuromuscular system. Movements should include: walking pulling the knee to chest, heel to rear, cradle walk, jogging, back pedaling, lateral shuffling, carioca, skipping, leg kicks, round house kicks, high knees, high heels, forward and backward shuffling, hip changeovers, drop steps, accelerating forward and backward, and lateral shuffling changing directions. These movements should be performed for approximately 10 minutes and be mastered over a 20 yard area.


Balance and coordination are basic to soccer, and fundamental to every ACL rehab protocol. Caraffa et al in Italy prospectively followed 600 male soccer players over three seasons. Half of the athletes were placed in a proprioceptive training program consisting of 20 minutes per day for a minimum of 6 weeks of balance training with and without various types of balance boards. The authors found a sevenfold reduction of ACL injuries in the proprioception group when compared with the controls.


Test your athletes balance. Can they keep balance on 1 foot for at least 30 seconds with and without eyes closed? Have your athletes stand 1 footed on a wobble board that challenges both medial-lateral and anterior-posterior balance. Use the same board and have your athlete perform a squat. Look to see in which plane your athletes are stronger or have a deficit in. Try to incorporate balance drills in your warm-ups and cool-downs. The best proprioceptive exercise for a soccer player is one legged kicking with a partner. This can be progressed to kicking on a balance boards, mini disc cushions, and altering the type of kick (laces, instep, volleys, and 2 touch).


Weight Training
Your athletes should master low intensity body weight activities at high repetitions before adding external resistance.


The lunge is the most functional strengthening exercise to mimic sport specific actions. Perform lunges forward, forward diagonal, lateral, backwards diagonal, and backwards. These exercises will stretch and strengthen the hamstrings in the sagittal, frontal, and transverse planes of motion. Coaching cues: knee doesn’t go in front of toes, keep head, chest, and shoulders up and back. Challenge balance with walking lunges, unilateral resistance, and bilateral rotation (helicopter lunges).


To prevent forward translation of the tibia on the femur it is important to have strong hamstrings. Eccentric strengthening of the hamstrings can be done by Russian hamstrings (kneeling, have partner hold feet, and slowly lower the torso to the ground) Also Romanian dead lifts. Eccentric loading with hamstring curls. Hamstring curls on a physioball.Emphasis on eccentric strengthening of the hamstrings. single legged ground touches.


Evaluate the ratio between the hip adductors and abductors. I find with many of my players that their gluteus medius and piriforis become tight because of repetitive kicking. This tightness may predispose your players to ACL tears by not being able to support the plant leg of during kicking. Perform the trendelenberg tests (stand on 1 leg, and bring contralateral leg to the chest. Look for a lag or giving in of the support leg hip) with your athletes prior to the season. Strengthen lateral movements in the frontal plane. Lateral shuffling on a treadmill, lateral sumo walks with resistance cord around ankles, and lateral shuffling with Mr. Resistor cord.


Some popular tests for return to play are the single leg squat, step down, single leg forward and medial reach. Single legged squats and step downs are other functional exercises for preventing ACL injuries. Check that the angle of knee flexion is equal bilaterally. Look to see stablility and distance of a single legged reach forward and medially. Concentration on strengthening the quadriceps in the last 10-15 degrees of extension. Leg extension with a pause at top. Single legged step downs. Backwards walking on treadmill or backwards running with cord. Forward and lateral bench/box step ups


Core strength
The primary function of the core is to maintain dynamic stability of the bodies center of gravity. Soccer players must have good core strength and stability because this is where all movement originates. Stability must first be established by doing exercises like 4 way pilar bridges (holding the body in straight position) and dead bugs (lying prone with arms and legs straight up, drop opposite arm and leg and hold 6-12 inches from the ground for 10 seconds). When strengthening the core make sure to include multiplane diagonal and rotational patterns. It is also important to strengthen the lower and upper trunk extensor. So much of the soccer players mechanics is forward flexion of the trunk we neglect the extensors. Core strength should be concentrated on during every phase of conditioning. The pre-season should emphasis core stability and muscular endurance.


Coaching cues for plyometric exercises include:

- land on the balls of the feet with knees flexed and chest over knees

- emphasize landing “softly”, “light as a feather”, “recoil like a spring”

- jump straight up and avoid excessive side to side and forward and back rocking of the knees during landing


Lateral hopping movements help prepare the ACL and muscles around the knee for sudden, ofton unpredictable movements in the frontal plane.



Sport Specific Agilities
Each player on your team has specific actions they must master to excel at their position. These actions need to be trained. Reconditioning is performing actions that mimic sport specific movements that train the neuromuscular system and help the body prepare for the demands of competition. For example, running forward with the ball, making a sharp cut, and passing / shooting the ball. Receiving the ball, and turning and pivoting to go forward. Jumping up for a header or goalie to get a ball and land properly.


Emphasis teaching proper biomechanics of planting, cutting, and changing directions. Teach planting with positive angles. When you plant to change directions the hip should load, with knee bent. The pressure should be placed on the ball of the foot and the knee should not externally rotate over the toes. A good drill to teach this is lateral bounding. Bound out as far as you can and immediately load hip and return to starting position. Another good drill is a lateral cone shuffle, touching each cone with hand. This teaches loading the hips.


Mr. Resistor cord (24’rubber cord with waist belt) helps provide a resistance against lateral movement exercises. Can also be used for acceleration speed, backpedaling, and bounding.


Cone drills


Reaction time drills


Zig-zag runs help develop balance and control needed to move in multiple directions at various speeds.


Additional Contributing Factors
Hormonal and anatomical factors may predispose athletes, particularly women, to ACL injuries. Women sustain two to eight times more ACL injuries in soccer than men. Research shows an increased incidence of ACL injury in women during the ovulatory phase of the menstrual cycle. Estrogen has shown to relax soft tissue, which may diminish neuromuscular control. Other factors that may predispose a women to injury is the size of the intercondylar notch, also having a wider pelvis and greater then average q-angle. Additional anatomic factors that may contribute to ACL injury are ACL size, lower leg malalignment, abnormal extensor mechanism anatomy, knee joint laxity, and muscle flexibility. These factors cannot be prevented but trainers and coaches should be aware of them.


Environmental factors may also contribute to injuring the ACL. In one study of ACL injury mechanics, many patients reported landing or stepping on and uneven surface at the time of landing. Austrailian research found that playing on dry playing fields (caused by low rainfall) significantly raised the likelihood of ACL damage. The theory posed by this is that athletes run with slightly greater knee flexion on hard surfaces, which can put added stress on the ACL during sudden stops.


Cleat selection may be an additional contributor. Some cleats provide a higher torsional resistance than other cleat designs. Special attention should be made especially when playing on turf surfaces.


Ensure that your athletes are properly hydrated. Dehydration can cause a decrease in neuromuscular control, loss of contractile strength, and loss of speed.


Lastly, research has shown that the effect of knee braces for ACL protection is negligible.