Bulletproof Soccer Knees

TAGS: Soccer Knees, needs analysis, genu valgum, concussions, biomechanical analysis, bioenergetics analysis, ACL tear, training athletes, Bryan Mann, soccer, sports, training

I have been working with soccer on the Division I level since 1999, so you can say that my strength and conditioning career with soccer now has a learner's permit.

With any sport, a needs analysis needs to be performed, and this consists of several things: 1) a biomechanical analysis, 2) a bioenergetics analysis, and 3) an analysis of the individual athlete.

Biomechanical Analysis

First addressed will be the biomechanical analysis. The biomechanical analysis is composed of the movements, planes of movement, muscles involved, common injuries of the sport, and the causative factors of the injuries.

For soccer, the movements will be done with the lower body in all three planes: sagittal, frontal and transverse. Knowing this, the lower body must be trained in these planes. In turn, if it’s going to be done in the sport, it needs to be trained in the weight room. It needs to be trained so that force and power can be improved in that plane, increasing the performance of the athlete in that plane. If force is improved in only one plane, it doesn’t necessarily translate to the other planes. For instance, if an athlete only works in the sagittal plane, then he may become much faster in a sprint, but he will remain the same or become slower in his agility drills. This would be a travesty, especially since change of direction is necessary for the sport. Therefore, if it is demanded in the sport, it must be demanded in the weight room.

The muscles involved are what initiates changes of direction, sprinting, kicking, jumping, pushing when battling for the ball, and diving (in regards to goalies). Fortunately, the muscles for these different actions are much the same—hip abductors, hip adductors, hip flexors, hip extensors, knee flexors, and knee extensors. All of these muscles groups must be trained.

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What are the most common injuries and most common devastating injuries in soccer? Well, ankle sprains, quad strains, hamstring strains, and concussions are among the most common injuries in soccer, with shoulder sprains being common amongst goalies. The most common devastating injury for soccer, however, has long been the anterior cruciate ligament (ACL) tear. Now comes the causative factors. For quad and hamstring strains, the strain is coming from either a lack of proper hydration or from a lack of eccentric strength. See, a strain occurs when the muscle isn't strong enough to slow down the lower leg, resulting in a small muscle tear. Rolling an ankle is also quite common. Therefore, working on improvement of the proprioceptors and working on ankle strengthening for dorsiflexion, plantarflexion, inversion, and eversion is necessary to prevent these injuries. Many coaches love to do proprioceptive work on unstable surfaces to increase the challenge, but I am not a fan of this. Research has shown that proprioceptive training in healthy, trained individuals actually causes the reactions of the muscle spindles to be slower rather than faster. While it is true that the unstable surfaces have a positive impact in rehabilitation, it does not seem to translate in regards to healthy populations. Think about this: in how many circumstances is the surface of the sport unstable? I have only seen a few, and they involve torrential downpours. The surface is stable, but the environment is chaotic. Therefore, I like to do things that involve creating chaotic and unstable environments on a stable surface.

For some injuries, there is more than meets the eye in terms of causative factors. Concussions, for instance, occur as a result of headers. The ball is coming towards the athlete's head at a very high speed, increasing in acceleration. The impact causes the head to rattle around—causing impacts on the brain that lead to a contusion or, in the brain's case, a concussion. Yet, recent research has shown that if the flexors of the neck are strengthened, the neck will become strong enough to prevent the head from whipping back and causing the brain to rattle around. So, while neck training is seen as crucial for football, it’s an important exercise that is too often overlooked in soccer.

ACL tears are another injury that has complicated causes. When I started out in strength and conditioning, I looked at the ACL and thought, "if I strengthen the muscles around the knee, I will reduce ACL tears on the soccer team." The result? We were still consistent with the 9.75% incidence rate of ACL tears. While not excessive, we were well within the norms. However, I still thought this was unacceptable. Upon further investigation, I found that one of the major causative factors of ACL tears (specifically in female athletes) had to do with the Q angle. The Q angle is the angle that exists between the pelvis and the femur. Excessive Q angles lead to what’s called genu valgum, or what’s more commonly known as knock knees.

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With the femur coming angled in such a way, there is a great amount of medial stress placed on the knee. More importantly, there is innately less structural support. The best example of this is from Dr. Aaron Gray of the University of Missouri Sports Medicine during a talk on ACL injuries and soccer at the ACSM Central States meeting in Columbia, MO.

He took two straws. One was a normal, straight straw, and the other had a bend in it (resembling the genu valgum).  He placed a finger from each hand on the tips of one of the straws and pushed in. With the straight straw, nothing happened. 

Although he pushed significantly hard, the straw held its shape. For the bent straw, however, as soon as he started to push in, the straw bent further and snapped. Well, the same thing happens when the knee under strain and is why the genu valgum is such a big factor in ACL tears. In the case of genu valgum, the hip is internally rotated, so strengthening the opposite (which are the hip external rotators) will help prevent injury. The external rotators' strongest muscle happens to be the gluteus medius, but by strengthening the entire gluteal group, you will see a result as well. How is this done? By targeting the gluteus medius and the adductors and forcing the knee into abduction and internal rotation. By forcing the knee into this position, you will actually make the body turn on the external rotators to keep the joint from collapsing.

Bioenergetics Analysis

Next comes the bioenergetics analysisWhat energy systems are used and how are they used? Soccer is a sport of intermittent sprinting interspersed with walking and jogging. The sprints are short, usually around six to eight seconds every one to four minutes (depending on the position and the game). Soccer often falls prey to the old thought that there is only aerobic and anaerobic conditioning. Unfortunately, there are multiple portions of what can be considered anaerobic. For simplicity's sake, we will look at two: those that produce lactate and those that don’t.

Lactate starts accumulating after about 30 seconds of running. Thinking of anaerobic runs in such a simple manner has made things like the 300-yard shuttle so popular in soccer. “Oh, it’s anaerobic. Let’s do 300-yard shuttles to hit that energy system.” Unfortunately, it’s not so simple. On average, we see that sprints in soccer are much shorter. Soccer is truly an alactic-aerobic sport. The alactic system is involved during pursuits to the ball or during play with the ball, as well as the aerobic energy system during recovery. Thus, the athletes need to be trained to best utilize these systems. This is not to say that the only way to condition for soccer is to run long distances and to do sprints. Nor, however, is it to say that there should be absolutely no lactate work done, only that it is not the main emphasis.

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Analysis of the Individual

The analysis of the individual athlete has two main parts: 1) what is his injury history, and 2) what is his training history. If an athlete comes in with a history of three bulging disks, it is not a good idea to do heavy back squats with him. It’s important to know what exercise can improve his sporting form and what exercises could prevent him from being on the field. His training history is a major component as well. In my experience, I usually don’t get a whole heck of a lot of time with the team (usually 30 minutes twice a week during the season and 45 minutes three times a week in the off-season). Therefore, with such a short amount of time, I don’t teach a lot of Olympic lifts. I will do pulls of various types but no full cleans or snatches. I don’t feel that I have the time to teach them and can better spend that time developing speed-strength in other means. However, if I have an athlete who comes in having done Olympic lifts for several years and enjoys doing them, then I will put those into his program.

Logistics also need to be considered. What do you have available to you? It doesn’t matter if you want to do isokinetic exercises, if you don’t have the equipment then you won't be able to do them. It would be tough to do velocity-based training with no devices to measure velocity. For example, Fred Roll, a former strength coach at the University of Kansas, took a job as the strength coach for the rugby team in Tonga. When he started in this position, however, there were no weights. Therefore, he used what he had—coconuts and sand. He filled coconuts with sand to use as weights.

Here is a sample program for soccer off-season training:

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There’s nothing special about this workout. It’s simple, basic, and effective. All the  movement planes of the lower body are emphasized. The gluteal and posterior chain have several exercises that focus on its development (which will help with knee injuries), and the basic strengthening it provides is great for the beginning weightlifter. It will not only improve strength, but it will also improve speed and power. Day One is a lower body day, Day Two is an upper body day with just a touch of posterior chain, and Day Three is a total body day.

Here is a sample program for off-season conditioning:

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The runs are all based on Max Aerobic Speed (MAS), which was determined by the 30-15 IFT by Martin Buchenit. I use this conditioning test because of all the information that can be garnered from it: heart rate max, heart rate recovery, max aerobic speed, and an estimated VO2max.  These are all important parts of conditioning. The extensive intervals are completed in 30 seconds at 105% of MAS for the work and 50% of MAS during the conditioning. The extensive run is done at 65% of MAS for whatever the time happens to be. The intensive intermittent runs are done with a 15-second sprint at 120% of max aerobic speed and a 15-second passive recovery. The 4x4 is done by running for four minutes at 90% of one's max heart rate with a three-minute passive recovery in between. Realize, though, that maximal aerobic speed and maximal velocity are two different metrics. Maximal velocity is the fastest that a person can run for a short time, and maximal aerobic speed is the fastest speed that can be sustained over an extended period of time.

In conclusion, everything involved in training athletes must be directed. The coach must begin with the end in mind and make sure that training is set up to improve the athletes' capabilities for soccer. It should also be noted that the exercises selected should lead to a high transfer of trained-ness. If at some point the exercises or conditioning are no longer causing improvement, then they should be changed.


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