For this episode of MythBusters, we called on two STACK experts to convey the truth and reveal the fallacies concerning one of the most commonly injured joints for an athlete: the knee.

The experts:
Justin Robinson, MA,RD,CSSD,CSCS, director of strength and conditioning, Rehab United Physical Therapy and Sports Performance Center (San Diego, Calif.)
Sean Hill, MPT, FAFS, CSCS, co-owner, Rehab United Physical Therapy and Sports Performance Center

Myth: Tears only occur in the anterior cruciate ligament (ACL)
Fact: “Though ACL injuries are really common right now,” says Hill, “it’s not the only one.” Thanks to the media, ACL injuries are the most talked about [injury] in sports, but the knee consists of other functioning parts that can get tweaked or pulled. “Other ligament injuries, like the MCL and meniscus tears, are very common, too,” Hill explains.

Robinson and Hill warn that any pain in the knee area needs to be monitored.

Myth: Knee injuries only happen in “meat stick” contact sports
Fact: “Believe it or not, ACL tears most commonly happen in non-contact sports,” Hill claims. Obviously in football or even baseball, there is a stronger likelihood of getting taken out at the knee due to direct contact; but it’s important to know that there are many other source factors for injury. “These sources affect all athletes and can come from lack of body control, tightness or flexibility limitations throughout the body,” states Hill.

Myth: Fancy new field turf is safer than old-fashioned grass
Fact: “If there was a perfect surface, everyone would use it,” Hill says. Most athletes prefer natural grass, but field conditions can differ and are therefore a factor in a player’s safety. “Field turf provides a very predictable, fast surface that many players prefer. However, your cleats can get caught in synthetic turf; there’s no divot. The body ends up giving instead of the field.” When playing on a synthetic field, Hill recommends rounded, molded cleats versus blade cleats to allow pivoting similar to how a cleat can divot on natural grass.

Basically, a natural grass surface chunks up when cleats dig in, providing a divot so the field gives when an athlete cuts. However, in sharp cuts on field turfs, the joint is going to give rather than the field, leading to potential knee injuries.

Myth: Athletes of both genders suffer the same amount of knee injuries
Fact: Studies show that female athletes suffer knee injuries at about a 9:1 ratio compared to their male counterparts. The common assumption is that female athletes’ knees are made of bubble gum and paper maché, but that is also incorrect. “One theory is that the female pelvis is wider and creates a different angle at the knee than the male,” Hill says. “The problem with that theory is the body hasn’t changed in the last 10 years to see such a drastic spike in female knee injuries.”

Hill reasons that the intensity of sports, especially involving females, has dramatically increased in recent years. “Not only has the intensity increased, but so has the volume,” he says. “Those two factors placed on a young athlete during his or her developmental stages can lead to more injures.”

Myth: Knee injuries are caused by the knee
Fact: “The knee is actually a pretty dumb joint,” Hill says. “It relies on the hip and ankle to tell it what to do, so if people are always going after the knee as the source of the problem, most of the time they’re mistaken.”

Both Robinson and Hill emphasize that the knee is part of a chain, and if deficiencies exist above or below the knee, they can lead to problems with the knee. “It’s pretty fun to take somebody who has chronic knee pain, for instance, and just do a more thorough assessment of his foot mechanics and hip mechanics and quickly fix the problem.”

Myth: Build up those quads to avoid knee injuries
Fact: “A big myth in physical therapy today is hearing that an athlete’s quad-to-hamstring ratio plays a factor in knee injuries,” Hill says.

As our experts explain, a muscle, such as the quad, does not contract separately during a functional motion; it requires help from other muscles. “At Rehab United we preach ‘train motion patterns’ so an athlete doesn’t miss muscles that are important to his sport-specific motions,” Robinson says.

Myth: All knee injuries can be treated the same
Fact: “At RU Performance Center, we’re always trying to prove the principle that the knee should properly function in relation to the foot, hip and trunk, and if it’s not working, then it’s my job to strategize on how to make it work,” Hill says.

Hill and Robinson avoid “cookie-cutter” exercises, because every athlete is built differently and each sport possesses its own rigorous demands. “We believe sport is chaos,” Hill says. “You have to take your athletes through chaos when appropriate. Sport is very unpredictable, so if your training is [comprised of] predictable exercises, you’re not quite taking it to that next level to be the best.”

Myth: The knee and its surrounding joints should only move in one fixed direction
Fact: According to Hill, “The body moves in three planes at all times unless an athlete consciously tells it not to.” The three planes include: sagittal (forward-backward), frontal (side-to-side) and transverse (rotation). “Any given joint in the body, even if it’s designed to be more biased for one of those three planes, will actually go through all three during an exercise, practice or game,” Hill notes.

Myth: Injury-prevention drills take too much time
Fact: Yes, practice time is limited each day, but in less than 10 minutes an athlete can adequately prep the body for practice or a game and reduce the potential for injury. Hill provides an example that might, unfortunately, sound familiar: “When you sit in class all day, your hips and joints become tight. If all you do is jog a few laps around the track, then pull your heels to your butt to stretch the quads, and then go out and sprint, you’re not preparing the body for the demands of your sport.”

To combat senseless injuries, Robinson and Hill suggest a general warm-up to increase fluid in the joints, followed by a specific warm-up to mimic the motions to be used in practice or the game.

Myth: Diet does not affect injury-prevention training
Fact: Long-time readers of STACK know the importance of nutrition while training; but just in case you forgot, here’s a reminder. “If your body is not well fueled, it’s going to accelerate fatigue, which can cause a lapse in your technique or judgment on the field,” Robinson warns. “For example, if you’re fatigued from improper nutrition, your muscles will be too tired to control that knee drive into the grass or turf, and then all of a sudden a tear or injury occurs.”

In addition, Robinson and Hill claim that for every pound an athlete is overweight, that’s three to four more pounds pressing on the joints. “It may not be a single jump or landing that will cause injury, but over the course of a game or practice the excess weight is putting extra force on the joints that can lead to knee issues,” Hill says.

Check back on May 25th for some dynamic warm-up drills from Hill and Robinson to help prevent knee injuries.