Why Female Athletes Suffer More Knee Injuries (cont.)

by CoachZ on January 2, 2009

Study Affirms Differences Between Sexes – At Least When It Comes To Knees

ScienceDaily (Mar. 2, 2001) — San Francisco – Knee injuries are a common hazard for athletes – especially those who play basketball, volleyball, soccer or other sports where knees are subjected to turning, twisting and jerking. 

But a University of Michigan Health System study, presented today at the annual meeting of the American Academy of Orthopaedic Surgeons here, shows that female athletes may be at an even greater risk for a certain type of knee injury than their male counterparts due to the differences in the muscle structure around the knee. [The Cleveland Clinic study focused more on fatigue and landing reaction when tired...above. Comments and bold type added.]

“Knee muscles are capable of protecting ligaments and preventing injury,” says Edward M. Wojtys M.D., professor of orthopaedic surgery, U-M Medical School, and Director of Sports Medicine at UMHS.

“Female athletes are two to eight times more likely to tear their anterior cruciate ligament because they may not able to achieve the same muscle stiffness across the knee joint.” [emphasis added]

Wojtys calls the U-M study “one piece of the puzzle” in determining the differences between female and male athletes and, consequently, providing for the training and conditioning needs of female athletes in a safe and effective way.

[Training needs to be different…”safe and effective.” added]

Injury to the anterior cruciate ligament – the ligament behind the kneecap that connects the thigh bone to the shin bone and is responsible for knee stability – is common in athletes. The U-M study measured the muscle protection, or rotational knee stiffness, present in size- and sport-matched young males and females, to determine if females are more susceptible to anterior cruciate ligament injury.

In addition to gender differences, the study looked at whether the types of sports the athletes played made a difference in knee stiffness. [emphasis added]

In the study, researchers examined 24 NCAA Division I athletes – 12 males and 12 females – who compete in basketball, volleyball and soccer [added]. All three are “pivot” sports that, because of turning, twisting and jerking, put players at high risk for injury to the anterior cruciate ligament. Another 28 collegiate athletes – 14 males and 14 females – who participated in the “non-pivot” sports of cycling, running and crew also were examined.

Male-female pairs were matched for age, height, weight, body mass index, shoe size and activity level – making them all but equal except for gender.

Researchers used a device specifically designed for this study to measure the rotational motion of the knee [added] when it was bent at 30 degrees and 60 degrees, both when the muscles were relaxed and when the muscles were contracted, or tensed. Knee stiffness, a gauge of joint stability and resistance to injury, was measured as a function of muscle contraction.

In both the pivoting and non-pivoting sports, males were shown to produce more knee stiffness and therefore, better protection against anterior cruciate ligament injury. [emphasis added]

Results showed that, when an athlete’s muscles went from a relaxed to a tensed state, knee stiffness increased by 258 percent for male athletes in pivoting sports and 171 percent for female athletes involved in pivoting sports. Male athletes in non-pivoting sports had an increase of 207 percent versus 198 percent for their female counterparts.

Wojtys expected the higher knee stiffness for males in pivoting sports compared to males in non-pivoting sports.

“The thought is, if you play jumping, turning, twisting sports, that you should be better prepared to protect your knee against rotational forces,” Wojtys says. [emphasis added]

That’s why the measurements for the females involved in non-pivoting sports were surprising when compared to females in the pivoting sports.

Females in non-pivoting sports had an increase in knee stiffness of 198 percent – 27 percent higher than the females in pivoting sports. “Women who played jumping, turning, twisting sports actually had the poorest ability to protect themselves against rotational strains,” Wojtys says. Wojtys says that male and female athletes are generally trained the same way. [READ THAT AGAIN!] But based on his recent research and that of other researchers, that could be a big mistake. [EXACTLY!]

“We may need to train female athletes differently,” Wojtys says. “The long term scenario is to try to find rehabilitation and training tools that will specifically help female athletes because they seem to be more susceptible to this type of injury.”[YES! YES! YES! emphasis added]


Co-authors on the study were James Ashton-Miller, Ph.D., distinguished research scientist, U-M Department of Engineering; Laura J. Huston, M.S., senior health science research associate, U-M Section of Orthopaedic Surgery; James P. Boylan, B.S.; and Harold J. Schock, B.S.




Adapted from materials provided by University Of Michigan Health System.
University Of Michigan Health System (2001, March 2). Study Affirms Differences Between Sexes – At Least When It Comes To Knees.
Coach Z:
My apologies to the authors for the editorial comment but it has been 8 years since this article; and, it has been much longer than that since we recognized that there is a real problem with female soccer athletes and the ACL. Recognizing this fact, many still train female athletes, particularly at the youth through collegiate levels, LIKE THEIR MALE COUNTERPARTS!
While it seems, at least at the US Regional and National Team levels, there is a concerted effort and indeed a real movement toward gender specific training, many youth, secondary, and collegiate coaches are still training female athletes like their male counterparts. This seems to be particularly true with male coaches training female athletes. Sorry guys! That being said, once again, there does seem to be movement to break the inertia of the last quarter of a century. Unfortunately for many female soccer athletes, this shift in philosophy, driven by sports medicine and kinesiology, comes too late, the damage has been done.
Tomorrow we will discuss ACL surgery, the effect surgery has generally and specifically, and the increased incidence of other competition-related injuries after ACL surgery.
An aside: Please do not get discouraged or quit playing as a result of this series. Or worse yet, pull your daughter out of competitive play because of what you’ve read here. Patience! There is light at the end of the tunnel and we will get there soon enough. There is method to my madness, or so they say, so please have patience and read on. The point I am making is an important one, and one that should already be apparent to most. We will get there.
And by all means: PLAY ON!  

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