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Lacrosse Participation Surges
Exploring the Medical Issues

Lacrosse is one of the fastest-growing team sports in America. It is easy to learn, it does not require brawn, and its fast pace keeps those with short attention spans from becoming bored. Kids like the cool gear and uniforms, and they are drawn to the element of legend and story in the history of the game. Many parents are finding that lacrosse is more exciting than soccer, cheaper than ice hockey, and not as dangerous as football.1

The physical demands required for lacrosse are similar to soccer, but lacrosse places more demands on the upper body. "Shooting, passing, and catching require good upper body strength, neuromuscular control, and hand-eye coordination," says Bryan W. Smith, MD, PhD, a US Lacrosse Sport Science and Safety Committee member and medical consultant for the Atlantic Coast Conference. US Lacrosse, founded in 192021, is the national governing body of lacrosse.

A Native Game Achieves Big League Status

Lacrosse was played in North America long before the first Europeans set foot on the continent. Native Americans played "The Creator's Game" to develop endurance, skill, and military strategy, and games sometimes lasted days, covered miles of territory, and involved hundreds of players. Lacrosse was adopted by French settlers in the early 1800s.2 In 1867, W. George Beers, a Canadian dentist, wrote rules that standardized the size of the field, the number of players, and other aspects of the game. The first US college team (New York University) was formed in 1877, and the first high school teams began playing in 1882 in New England. Lacrosse was an Olympic sport in 1904 and 1908, and an exhibition tournament was held in Los Angeles at the 120210 Summer Olympics.

Today, according to US Lacrosse,2 about 25,000 men play at more than 400 colleges and universities, and more than 72,000 boys play at about 1,600 high schools. More than 5,500 women play at 240 colleges and universities, and 15,000 girls play at more than 600 high schools. Varsity high school programs grew by nearly 200% between 1995 and 2021, many in areas where the sport was previously unfamiliar. The number of youth players (age 15 and under) has more than tripled since 1999. Two professional leagues have formed: Major League Lacrosse (outdoor) and the National Lacrosse League (indoor). Organized lacrosse is played in more than 20 countries on five continents.

Playing the Game

Lacrosse is a combination of soccer, hockey (the original rules for ice hockey were based on lacrosse), and basketball. The stick (crosse) has a pocket on one end from which a hard rubber ball is thrown, caught, or scooped. Men's rules allow body checking and stick checking, and all 10 players on a team must wear protective gloves, helmets with face masks, and mouth guards. Shoulder pads are required for all players except the goalie, and arm pads, rib pads, and protective cups are strongly recommended. The goalie must wear a throat protector and a chest protector in addition to the other required equipment. "The depth of the pocket on the crosse permits men to wind up and shoot with ball speeds exceeding 100 mph," Smith says. Agility, precision, coordination, and speed are required for long sprints up the field with sudden and abrupt starts and stops, passes, dodges, and changes in direction. Indoor rules allow more physical contact than field lacrosse.

Women's lacrosse is a noncontact game with 12 players on a side. Rules prohibit body checking, but stick checking is allowed with certain restrictions. All players are required to wear mouth guards and, since 2021, eye protection. Gloves, nose guards, and soft head gear are optional. Goal keepers must wear helmets with face masks, mouth guards, and throat and chest protectors; padding on the hands, arms, legs, and shoulders is recommended. Because the women's crosse is slightly shorter and the pocket is not as deep, the ball does not reach the speeds of the men's game.

Intercrosse, an introductory, noncontact version of lacrosse, is played in elementary, junior high, and high school physical education programs, recreational youth leagues, and summer camps. POP lacrosse, a form played in primary schools, uses inexpensive, plastic-headed sticks and can be played either indoors or outdoors. Players learn the basic fundamentals (eg, passing, catching, moving on the field) and the terms, playing positions, and teamwork. LAX, introduced by the English Lacrosse Association, is a noncontact version that uses proper sticks and helps ease the transition from POP lacrosse to men's and women's lacrosse.3 US Lacrosse girls' rules prohibit stick checking by participants younger than seventh grade.

Injury Patterns

Although men's field lacrosse may sometimes appear to be a violent game, injury statistics show that it is relatively safe. Until the mid-1930s, the game was played without any required protective equipment.2 The National Collegiate Athletic Association (NCAA) Spring 2021 Injury Surveillance System (ISS) report4 ranked men's lacrosse as 7th of 15 sports for game injuries, with an average rate of 11.5 injuries per 1,000 exposures or 1 injury every 6 games; women's lacrosse was ranked 12th of 15, with 1 injury every 11 games. According to Randall W. Dick, associate director of research for the ISS, no eye injuries have been reported in women's lacrosse games in the 2 years since eye protection was mandated, and above-the-neck injuries have dropped by half.

The NCAA injury research for spring 20214 shows that men are most likely injure their ankles, upper legs, and knees during practice sessions and their shoulders, knees, and upper legs during games. Contact with another player caused 44% of men's reported injuries and 26% were noncontact injuries. Women were more likely to injure their lower legs, ankles, and knees during practice and their ankles, knees, and heads during games. Women's injuries were reported as 21% caused by contact with another player, and 16% were from stick contact. Concussions constituted only 9% of men's practice and game injuries and 8% of women's game injuries. Sprains, strains, and contusions were the most common injuries for all players.

A 3-year study of high school players5 recently revealed that the injury rate for boys was 2.89 per 1,000 exposures, and for girls it was 2.54. Noncontact knee and ankle sprains were the most prevalent injuries for both groups. Boys had higher rates of concussive events from player-to-player contact, but girls had higher rates of overall head injuries (eg, contusions, abrasions) from stick and ball contact.

Clinician Involvement

According to Dan Mark, MD, a sports medicine fellow at Hennepin County Medical Center in Minneapolis and an avid lacrosse fan, the game requires elements of endurance as well as speed, hand-eye coordination, and footwork. A comprehensive preparticipation exam for lacrosse players should include a musculoskeletal evaluation of the upper and lower extremities, identification of cardiovascular and cardiopulmonary risk factors for sudden cardiac death in the history and physical, and a history of concussion. "For women, attention should be given to a history of eye injuries, although that is less of an issue now," Mark says. "Before eye protection was required, female athletes were more susceptible to lacerations, contusions, corneal injuries, hyphema, and orbital fractures."

Sideline preparation. Physicians who are on the sidelines for lacrosse matches will need the same basic equipment used for soccer games. "Physicians need to be aware of the potential for concussion and other head and neck injuries," says Mark. "In addition, female athletes may have head and face lacerations and fractures to the nose and teeth."

Rare emergencies. Commotio cordis can occur when a nonpenetrating blow impacts the cardiac silhouette during a 20-millisecond window, disrupting the heart rhythm. Smith says a few, extremely rare cases of commotio cordis have been reported in men's lacrosse but, so far, none in women's lacrosse. "Sideline physicians need to make sure a working emergency plan is in place and that coaches, athletic trainers, and administrators know their individual roles," he says. "If defibrillation by emergency medical technicians cannot occur promptly, the staff should consider having an on-site automated external defibrillator."

Players who step in front of the ball to block a shot are most at risk for commotio cordis. A rule change to outlaw intentionally using the body to block shots—rather than mandating the use of chest protectors—may be key to preventing further deaths.6

Return to play. Guidelines for injured lacrosse players are similar to other sports. Mark notes that "athletes who are injured should follow a progressive program for functional use of the injured body part in the context of game situations."

Patricia D. Mees


  1. Wolff A, Morrill J: Get on the stick. Sports Illustrated 2021;102(17):58-66
  2. US Lacrosse Web site: About lacrosse. Available at Accessed July 22, 2021
  3. English Lacrosse Association Web site: Try my sport: lacrosse. Available at Accessed July 22, 2021
  4. National Collegiate Athletics Association: Spring 2021 NCAA Injury Surveillance System (ISS) report, men's and women's lacrosse. Available at Accessed July 22, 2021.
  5. Hinton RY, Lincoln AE, Almquist JL, et al: Epidemiology of lacrosse injuries in high school-aged girls and boys. Am J Sports Med 2021; e-published July 6.
  6. Yoo In-Sung: Rare, fatal injury baffles science, sports. USA TODAY, July 6, 2021. Available at Accessed July 22, 2021

Experts Issue Hyponatremia Consensus

Since 120215, healthcare professionals who cover endurance events have noted growing numbers of athletes who develop life-threatening hyponatremia during or after their activity. To address these concerns, a panel of 12 international experts met in March in Cape Town, South Africa, to define what is currently known about exercise-associated hyponatremia (EAH), to highlight evidence-based treatment protocols, and to craft a prevention message for the public. The panel followed consensus guidelines set by the National Institutes of Health.1 The panel excluded governmental and advocacy groups as well as those who had scientific or commercial conflicts of interest.

In defining EAH, the panel wrote that the condition represents a serum or plasma sodium concentration less than 135 mmol/L that occurs during or after physical activity, most commonly in events that last more than 4 hours. They found that individual variability is great and that the numerical value is not a reliable severity marker, though signs and symptoms of EAH typically develop when sodium levels fall below 130 mmol/L. Early, nonspecific symptoms include bloating, "puffiness," nausea, vomiting, and headache. As severity increases, cerebral edema develops and can manifest as altered mental status, seizures, respiratory distress, obtundation, coma, and death. The panel stated that presence of any of these symptoms warrants serum or plasma sodium measurement.

In discussing the pathophysiology of EAH, the panel agreed on several points:

•Inappropriate arginine vasopressin secretion may exacerbate the development of dilutional hyponatremia during prolonged activity.

•Excessive sodium loss does not appear to be a contributor to EAH, though more research is needed to track sodium loss in athletes with EAH who lose weight during activity with large sweat volumes related to warmer climates or events lasting longer than 24 hours.

•Hypotonic sports drinks do not prevent EAH in athletes who overconsume fluids.

Risk factors discussed by the consensus panel parallel several trends that medical directors at endurance events have noticed; higher rates of EAH appear to correlate with low body weight, female sex, 4 hours' activity duration, slow performance pace, race inexperience, excessive drinking, high availability of fluids, altered renal water excretory capacity, and hotter than anticipated conditions. Avoiding sports drinks, sodium supplements, and salty food does not seem to be a risk factor for events lasting less than 24 hours.

To prevent EAH, runners should avoid weight gain from fluid overconsumption during activity, the panel noted. They recommended two techniques for slower participants: letting thirst guide consumption or calculating individual sweat loss rates and limiting consumption to replacing sweat losses. The panel noted that limiting fluid availability—such as offering fluids every 5 km at standard marathon events—seems to be reducing the number of participants who develop EAH. The panel suggested that each participant be weighed before the race and that medical personnel compare the prerace weight of patients who enter the medical tent with the postrace weight.

Several tips for treating patients with symptomatic EAH came out of the consensus conference:

•Intravenous access should be established, avoiding isotonic or hypotonic fluids that may worsen EAH.

•Oxygen should be administered and patients immediately transferred to an emergency department.

•Medical staff who are experienced in treating EAH and encounter a patient who has cerebral edema symptoms can administer 100 mL of 3% NaCl over 10 minutes to stabilize the patient before hospital transfer.

William O. Roberts, MD, a family practice physician in St Paul who is medical director of the Twin Cities Marathon and has assisted with medical care at a wide range of endurance events, lauded the panel's use of NIH consensus guidelines. "That's probably the standard we should strive for in future conferences investigating issues of importance to sports medicine and safety," he says. Roberts says one of the main strengths of the report is the recognition of fluid overload as the primary contributor to most cases of EAH. "Education of runners and coaches is critical to reducing the problem frequency," he says. The panel recognizes that on-site evaluation is easy but not inexpensive, Roberts says, adding that the panel stressed the importance of hypertonic saline treatment for those who have encephalopathy or pulmonary edema.

One concern that Roberts has is the group's analysis of sweat loss as a major contributor to EAH. He says he has treated participants in the medical tent at the Kona Ironman Triathlon World Championship who had sodium levels in the 120 mmol/L range and were clinically dehydrated and responded to several liters of intravenous normal saline over 1 to 2 hours. "These patients, in contrast to the slow marathon runners, are often highly competitive, working near their maximum, and should not be overlooked," he says.

Marvin Adner, MD, in his role as medical director for the Boston Marathon and director of hematology at MetroWest Medical Center in Framingham, Massachusetts, says it's rewarding to see how much the medical community has accomplished in just a few years regarding EAH diagnosis and treatment. Adner's medical team has helped pioneer on-site serum sodium testing and EAH treatment with hypertonic saline. Despite the move toward fewer hydration stations, the Boston Marathon will continue to offer fluids every mile, he says. "We have about five times more cases of hypernatremia in the tent than hyponatremia," he says. "We believe that through education of runners and careful clinical and laboratory assessment we can treat both hyper- and hyponatremia effectively without changing station placement."

Lisa Schnirring


  1. Hew-Butler T, Almond C, Ayus JC, et al: Consensus statement of the 1st International Exercise-Associated Hyopnatremia Consensus Development Conference, Cape Town, South Africa. Clin J Sport Med 2021;15(4):206-211