The global success of soccer as a worldwide attraction actively involves an estimated 270 million people or 4% of the world’s population (4).

The increases in participation, with some countries such as Canada reporting a mean rate of increase in excess of 27% from 1998 to 2008 (7), draws attention to the importance of this sport’s specific injury pattern and the effective methods of injury prevention.

The rules of soccer (football) were officially codified by Great Britain in 1863. In 1869, Princeton and Rutgers played the first American intercollegiate football game played by “soccer” rules.

The enactment of Title IX in 1972 within the National Collegiate Athletic Association (NCAA) formed the initial American catalyst of soccer growth with the direct effect on the creation of female soccer programs. More recently, the 1991 U.S. women’s soccer team World Cup victory in China was a second stimulus for growth.

The World Cup of Soccer was held in the United States for men and women in 1994 and 1999, respectively. This local spectacle of sport propelled and elevated the caliber of play of soccer in the United States, which culminated in strong World Cup men’s performances in 2002 and Olympic Gold Medal performances for women’s soccer in 1996, 2004, and 2008.

The U.S. Soccer Federation is the governing body of soccer in the United States. The professional first divisions for men’s and women’s soccer in the United States are Major Soccer League (MSL) and Women’s Professional Soccer (WPS), respectively. Currently, the MSL is composed of 16 teams, and the WPS is composed of 7 teams.

Soccer is classified as a high- to moderate-intensity contact/collision sport by the American Academy of Pediatrics.

The 26th Bethesda Conference classifies soccer as a low-static, high-dynamic sport.

Soccer demands change of direction or cutting maneuvers followed by deceleration and jumping with major muscle movement and proprioception through the trunk and lower extremity.

The aerobic challenges of soccer infuse the endurance requirements of a distance runner with the abrupt acceleration demands of a sprinter. The average distance covered by an elite midfield male player is in the 10-km range, with the strikers, fullbacks, and center backs covering less distance. Sprinting makes up significantly 10% of the total distance (31).

The physiologic demands of soccer present unique challenges to hydration. In 2006, the U.S. Soccer Federation published its “Youth Soccer Heat Stress Guidelines” based on research conducted at the University of Connecticut (34). Several sport-specific factors expose soccer players to heat injury, including limited stoppage times with periods of intense aerobic activity, large fields with limited to no shade, and numerous games or practice sessions occurring in a day with limited attention to environmental stressors of heat and/or humidity.

As little as 2% body weight drop in young competitors in hot conditions not only generates impairments in performance but also causes a compounded reduction in the ability to dissipate heat, resulting in accelerated heat-related injury. In temperate to cool environments, research shows greater tolerance for body weight drops in these same ranges. Most experts agree that a 5% drop in body weight during or following a soccer match or practice should sideline that athlete for 24 hours to recuperate fluid losses and to identify an intrinsic etiology such as poor acclimatization, supplement usage, or illness (8,27).

It has been demonstrated that 30-60 mg of carbohydrate ingestion in the fluids before and during soccer activity can delay muscle glycogen depletion. In one study, Foster et al. (18) demonstrated that indoor soccer athletes who drank a glucose polymer enhanced work output and increased time to exhaustion when compared to controls.

The overall injury incidence in soccer varies across studies because of differences in study designs, populations, and injury definitions.

Soccer has a higher injury rate than many contact sports, including field hockey, rugby, basketball, and football (26).

Injury rates within the sport of soccer increase with participant age and correlate with the increased intensity of the match. More injuries occur during competitive games than during practice. Over a complete season, girls and boys may expect 4.0 and 3.5 injuries per season, respectively. When a correction is incorporated for exposure rates, senior athletes (age > 18) sustain 15-30 times as many injuries as youths, but when analyzing the National Electronic Injury Surveillance System, approximately 80% of these injuries affected participants younger than 24 years old (24,26,33).

Female youths can have soccer injury rates more than twice as high as male youths. Engström et al. (16) published an incidence per 1,000 player-hours of 12 for girls versus 5 for boys. Schmidt-Olson et al. (32) documented an incidence per 1,000 player-hours of 17.6 for girls versus 7.4 for boys.

Lower extremity injuries are the most common, with nonbody contact composing the majority of the injuries (16,24,26,29,32). Ankle injuries represent 16%-29% of these injuries and predominate among male players. Knee injuries occur in 16%-29% of players and occur more frequently in females (24,26,29,32).

Ankle sprain is the single leading injury in soccer and is implicated as a reinjury 56% of the time (15).

Soccer injury rates reported by the NCAA use an established Injury Surveillance System to follow male and female collegiate injuries (29).

Head injuries represent 1.2%-8% of all injuries, depending on the study. The higher head injury rates in youth soccer are thought to be attributed to underdeveloped neck muscles to absorb the impact shock, increased ball weight to head weight ratio, and, more importantly, improper head ball technique (33).

Serious anterior cruciate ligament (ACL) tear injury and concussion-type injuries follow gender differences. Women soccer players sustain more concussions than men, at a ratio of 4.3:1, and more ACL injuries, at ratios of 1.8:1 (practice) and 5.78:1 (games) (2,15,22,25).

Indoor versus outdoor soccer injury rates are similar in severity and type (14).

Soccer in the competitive ranks has migrated to artificial turf. In 2005, Fédération Internationale de Football Association (FIFA) accepted the use of third-generation artificial turf for official tournaments. Research on injury risk on third-generation artificial turf is limited but indicates small differences in injury pattern between artificial turf and natural grass (19).