Wednesday, February 16, 2011

Similar Injury Risk on Turf and Grass

More and more clubs, schools communities are installing artificial turf for their soccer fields. The benefits are obvious in terms of maintenance and year-round use. However, one question that keeps coming up is “are these fields safe for the players?” The concern is that players are at risk of knee and ankle injuries by playing on the “plastic stuff”. But is this really the case? Over the past few years, Scandinavian clubs have installed many artificial turf fields as a way to combat damage caused by weather and use. As a result, teams routinely train and play matches on both grass and turf. From a research perspective, these areas make for excellent “laboratories” to study the incidence and risks of injury on artificial turf. They provide a great opportunity to answer questions about safety. Researchers from Norway and Sweden have taken advantage of this. They have recently published three long-term studies of acute injuries on turf and grass. All three suggest that the injury risk of playing on artificial turf is no greater than playing on natural grass.

The three studies examined acute injuries over periods of 4-5 years. They all included hundreds of players and thousands of hours of matches and training. The medical staffs of teams and tournaments associated with each study recorded the injuries as well as their type, location and severity and fed the data into a database. The researchers then calculated injury rates and made comparisons between the two surfaces (artificial turf and natural grass).

Because different teams and players spend varying amounts of time playing on each surface, the number of injuries sustained is normalized by the amount of time spent playing on each surface. For example, the rate of concussions might be expressed as 7.6 per 1000 hours of play (7.6/1000hr). As a comparison, 1 injury recoded in a 90 min 11v11 match equals an injury rate or incidence of 30/1000hr.

The first study focused on male players in the Norwegian professional league (Tippeligaen) and examined injuries sustained during training and matches played on turf and grass. On artificial turf, the injury incidence was 17.0 injuries per 1000 hours of play compared to 17.6 on grass. Specific injuries were also not significantly different between the two surfaces. For example, the incidence of knee sprains suffered during training on turf and grass were 0.2 and 0.3 / 1000 hr. There was a slight tendency for match-related knee and ankle sprains to be greater on turf than grass. But the authors noted that the small difference was not cause for alarm.

The second study focused on male and female professionals playing for one of 25 elite club teams in northern Europe. As in the first study, both match- and training-related injuries were recorded. The researchers found that on either surface, men suffered about 22.0/1000 hrs of play while the women suffered closer to 13.0. However, the injury rates did not differ between turf and grass. As for specific injuries, the men were slightly less likely to suffer a quadriceps strain during matches played on turf and slightly more likely to sprain an ankle. Other injures such as concussions, MCL tears and fractures were very similar on the two surfaces. This was the case for both women and men and both training and match injuries.

The last study focused on male and female youth players (U13-U19) participating in the Norway Cup over a four year period (a total of 7848 matches). During this tournament matches are played on both turf and grass. The overall injury rates were similar on the turf and grass surfaces (34.2 versus 39.7 / 1000 hr). In this group of athletes, the incidence of ankle injuries was significantly reduced on turf by almost 50%. Injuries to the back and shoulder however were increased. Other injuries such as knee and head were similar between the surfaces.

From these studies, two concepts emerge. The first is that playing or training on artificial turf does not raise the risk of acute injury. The second is that the studies differ slightly in their specific findings. For example, one study finds a slightly elevated risk of ankle injuries on turf and anther finds a slightly reduced risk. Why the conflicting results? There are several reasons that studies often report results that are at odds with one another. These include factors such as the type and number of subjects that were studied, the way the data were collected and analyzed, and how various injuries were defined or categorized. The challenge is using multiple studies to arrive at a consensus. Reflecting on previous research is also helpful. For these three studies, ankle injury risk either increased, decreased or did not differ between surfaces. When these studies are considered as a whole and when similar, previous studies are taken into account, it seems reasonable to conclude that the risk of ankle injury is not appreciably increased nor decreased when playing on artificial turf.

There are a few drawbacks to all three studies. Most notably is that no overuse injuries were recorded. As mentioned here (LINK), playing on artificial turf does not seem to be associated with significant increases in the risk of chronic pain, the authors of that study suggest that turf may slightly elevate the incidence of low back pain. Players often complain that playing on turf is more physically demanding than playing on grass and they often feel more “tired” after training of on turf. If those perceptions are real, then the risk of chronic injury might be increased. The emphasis here is on “might be”. To answer that question, additional studies that focus on long-term issues are needed.

While these three studies found some subtle differences in the risk of specific injuries between turf and grass, the overall message is fairly clear. Playing matches or training on artificial turf does not raise the risk of suffering an acute injury. Players are no more likely to suffer a head, knee or ankle injury when playing on turf that they are when playing on grass.

References:

Bjørneboe J, Bahr R, Andersen TE (2010) Risk of injury on third generation artificial turf in Norwegian professional football. British Journal of Sports Medicine, 44: 794-798.

Ekstrand J, Hägglund M, Fuler CW (2010) Comparison of injuries sustained on artificial turf and grass by male and female elite football players. Scandinavian Journal of Medicine and Science in Sports, DOI: 10.1111/j.1600-0838.2010.01118.x

Soligard T, Bahr R, Andersen TE (2010) Injury risk on artificial turf and grass in youth tournament football. Scandinavian Journal of Medicine and Science in Sports, DOI: 10.1111/j.1600-0838.2010.01174.x