As soccer continues to grow in popularity, injuries to soccer players are likely to increase as well, says the Hospital for Special Surgery, New York. Certain injuries fall into gender-based patterns and new research at the facility suggests some underlying causes that could help lead to better treatment, or even prevention for present and future soccer stars, according to a statement issued by the hospital.

Data presented at this year’s American Orthopaedic Society for Sports Medicine meeting explores the differences in soccer kick dynamics based on gender. With the use of video motion analysis at the Leon Root Motion Analysis Laboratory at Hospital for Special Surgery, researchers were able to examine the dynamics of the kicking motion, says the statement.

Robert Brophy, MD, lead investigator and former resident and fellow at Hospital for Special Surgery, said in the statement that prior to this kick study, little motion analysis had been conducted to show what was going on during the soccer kick. He said it is knosn that female soccer players face a greater risk of ACL injury and patellofemoral problems, and male players are more at risk for sports hernia. The hospital used motion analysis to determine if the two types of players have different alignment and muscle activation that might correlate to the injury patterns, the statement says.

During motion analysis, the kick is looked at in two different ways simultaneously, according to the statement. The activity of each of the muscles involved is measured based on electrical impulse. Sherry Backus, PT, DPT, MA, advanced clinician at the motion analysis lab and co-author on the paper said in the statement that you also need to know what the body is doing when you are taking the readings—is it kicking? Standing?

Backus said that to record what the body is doing while the muscles are working, the researchers attach bright surface markers to different parts of the body, and around the room there are eight to 10 cameras that are trained on the markers, recording what the body is doing. The researchers merge the images from all of the cameras and create a 3-D picture of the person going through the kicking motion. From there the researchers can match up, frame by frame, the electrical signals from the muscles with what the person is doing, she said in the statement.

The researchers found that male and female players do differ in both of these areas. Male players have more activation in the hip flexors of their kicking leg and in their hip abductors of the supporting leg compared to women. Brophy, now an assistant professor in the department of orthopaedic surgery at Washington University in St Louis and head team physician for the St Louis Athletica professional women’s soccer club said that the hip abductor may be protective against ACL injury and he notes that it is interesting that its activation was markedly diminished in women.  In addition, the knee of the supporting leg in female players assumes a more knock-kneed, or valgus, position, putting more stress on the outside of the knee joint, the statement said. These two differences, low activation of the hip abductor and the knee position, could be a factor in the increased ACL injuries seen in female soccer players, the researchers found.

Female players also do not activate their medial quad muscles in their standing leg, one way male players could be protecting their patellofemoral joint from injury, according to the statement. The hip flexor activation, however, in their kicking leg could correlate to the pattern of sports hernia seen in male soccer players. With more than 18 million people playing soccer in the United States, according to the latest FIFA (Fédération Internationale de Football Association) survey, understanding the body mechanics specific to the sport could potentially prevent a large number of injuries from occurring, say the researchers.

Brophy said that it is a logical extension to think about how the researcher’s data could be connected to injury patterns. The researchers found that the role of muscle activation and leg alignment in injury warrants further investigation, he said.

Riley J. Williams, MD, senior author and orthopedic surgeon in the Sports Medicine and Shoulder Service at Hospital for Special Surgery, said that in investigating the dynamics of kicking, the researchers hopes are to help soccer players reduce their injury risk and to assess the impact of a specific injury on a player’s return to play. Further, that by understanding the mechanics of a soccer kick, the long-term goal would be to recommend small changes in training, coaching, or strengthening that could protect female and male athletes from the most common injuries, said Williams, who is also the head team physician for the New York Red Bulls soccer club.

For the most part, Hospital for Special Surgery uses motion analysis in a clinical setting to analyze children who don’t walk normally, according to the statement. Clinicians and doctors identify, before surgery, which muscle is pulling a joint. The analysis allows the doctors to look closely at where motions are coming from so the surgical plan is strategic.

As motion analysis technology has improved, Hospital for Special Surgery researchers say motion analysis can now be used to look at and analyze faster and more complex movements like the soccer kick.

[Source: Hospital for Special Surgery]