CrossFit is a branded fitness regimen created by Greg Glassman.^[1] It is a registered trademark of CrossFit, Inc.,^[2] which was founded by Glassman and Lauren Jenai in 2000.^[3][4][5]

CrossFit is promoted as both a physical exercise philosophy and a competitive fitness sport, incorporating elements from high-intensity interval training, Olympic weightlifting, plyometrics, powerlifting, gymnastics, girevoy sport, calisthenics, strongman, and other exercises. It is practiced by members of over 13,000^[6] affiliated gyms,^[7] roughly half of which are located in the United States,^[8] and by individuals who complete daily workouts (otherwise known as "WODs" or "workouts of the day").^[9][10] CrossFit has been criticized for allegedly causing people to suffer from unnecessary injuries^[11] and exertional rhabdomyolysis, a possible life-threatening breakdown of muscle from extreme exertion.^[12][13][14]

Greg Glassman and Lauren Jenai founded CrossFit, Inc. in 2000.^[15][16] The company was conceived a few years earlier, in 1996, as Cross-Fit.^[17] The original CrossFit gym is in Santa Cruz, California, and the first affiliated gym was CrossFit North in Seattle, Washington; there were 13 by 2005, and today there are more than 13,000.^[6] Coaches associated with CrossFit include Louie Simmons, John Welbourn, Bob Harper, and Mike Burgener.^[18]

Glassman obtained complete control over the company after a divorce with Jenai. Jenai tried to sell her share in the company to an outside party after the divorce settlement, but Glassman bought it with a $16 million loan from Summit Partners.^[19]

CrossFit is a strength and conditioning program consisting mainly of a mix of aerobic exercise, calisthenics (body weight exercises), and Olympic weightlifting.^[20] CrossFit, Inc. describes its strength and conditioning program as "constantly varied functional movements executed at high intensity across broad time and modal domains,"^[21] with the stated goal of improving fitness, which it defines as "work capacity across broad time and modal domains."^[22] Hour-long classes at affiliated gyms, or "boxes", typically include a warm-up, a skill development segment, the high-intensity "workout of the day" (or WOD), and a period of individual or group stretching. Some gyms also often have a strength-focused movement prior to the WOD. Performance on each WOD is often scored and/or ranked to encourage competition and to track individual progress. Some affiliates offer additional classes, such as Olympic weightlifting, which are not centered around a WOD.^[23]

CrossFit gyms use equipment from multiple disciplines, including barbells, dumbbells, gymnastics rings, rope climbs, pull-up bars, jump ropes, kettlebells, medicine balls, plyo boxes,^[24] resistance bands, rowing machines, and various mats. CrossFit is focused on "constantly varied, high-intensity, functional movement,"^[25] drawing on categories and exercises such as calisthenics,^[26] Olympic-style weightlifting, powerlifting, Strongman-type events, plyometrics, body weight exercises, indoor rowing, aerobic exercise, running, and swimming.^[27]

CrossFit programming is decentralized, but its general methodology is used by thousands of private affiliated gyms, fire departments, law-enforcement agencies, and military organizations, including the Royal Danish Life Guards,^{[28][29][30][31]} as well as by some U.S. and Canadian high-school physical-education teachers, high-school and college sports teams, and the Miami Marlins.^[15][32][33]

"CrossFit is not a specialized fitness program, but a deliberate attempt to optimize physical competence in each of 10 recognized fitness domains," says founder Greg Glassman in the Foundations document. Those domains are cardiovascular and respiratory endurance, stamina, strength, flexibility, power, speed, coordination, agility, balance, and accuracy.^[34]

A 2014 statistical analysis showed that 50% of CrossFit participants were male and 50% were female.^[35] CrossFit's growing interest internationally has created a spike in Olympic weightlifting interest in the United States.^[36][37]

CrossFit, Inc. licenses the CrossFit name to gyms for an annual fee and certifies trainers.^[38] Besides the standard two-day^[39] "Level 1 Trainer Course",^[40] specialty seminars include gymnastics, Olympic weightlifting, powerlifting, strongman, running and endurance, rowing, kettlebells, mobility and recovery, CrossFit Kids, CrossFit Football, and self-defense and striking. Other specialized adaptations include programs for pregnant women, seniors, and military special operations candidates.^[41] Affiliates develop their own programming, pricing, and instructional methods. Many athletes and trainers see themselves as part of a contrarian, insurgent movement that questions conventional fitness wisdom.^[42] In addition to performing prescribed workouts, they follow CrossFit's nutrition recommendations, adopting a paleo and/or zone diet.^[43]

CrossFit makes use of a virtual community Internet model.^[44][45] The company says this de-centralized approach shares some common features with open source software projects and allows best practices to emerge from a variety of approaches,^[46] a contention that is disputed by some competitors and former affiliates.^[34]

The "CrossFit Games", directed by Dave Castro, have been held every summer since 2007. Athletes at the Games compete in workouts they learn about only hours beforehand, sometimes including surprise elements that are not part of the typical CrossFit regimen. Past examples include a rough-water swim, a softball throw, and a pegboard climb.^[47] The Games are styled as a venue for determining the "Fittest on Earth," where competitors should be "ready for anything."^[48]

In 2011, the Games adopted an online qualification format, facilitating participation by athletes worldwide. During the five-week-long "CrossFit Open", one new workout is released each week. Athletes have several days to complete the workout and submit their scores online, with either a video or validation by a CrossFit affiliate. Since the Open is available to any level of athlete, many affiliates encourage member participation and the number of worldwide participants can be in the hundreds of thousands.^[49]

From 2011 to 2018, the top CrossFit Open performers for individuals and teams in each region advance to the regional events, held over the following two months around the world. Each regional event qualifies a specified number of its top finishers to send to the Games. The Games include divisions for individuals of each gender, co-ed teams, and a number of Masters and Teenage age groups.^[50] Since 2019, regionals were discontinued and individual athletes qualify by either being the national champion in the Open, finishing in the top 20 worldwide in the Open, winning a CrossFit-sanctioned event, or by invitation.^[51]

In order to become a certified CrossFit coach, one must go through a series of four training levels. To open a CrossFit affiliated gym, it only requires a coach to be certified to level one.^[52]

Level One (CF-L1) is the introduction level, where participants attend a group weekend class, talk about the basic methodology and fundamentals of CrossFit, and learn how to conduct their own classes. They go over techniques and how to adjust them for those who cannot perform them. After completing the Level One training course, one should be confident in conducting a class, scale workouts accordingly for athletes, and hold CrossFit to its standards.^[53] In the second level, training goes deeper into the mechanics of the movements and how to be leaders and communicate with other students. In the Level Two course, participants learn about athletic capacity and are evaluated as a trainer in groups.^[54] In order to earn the Level Three certificate, a coach one must complete 1,500 hours of active fitness coaching and become CPR certified. To earn the Level Four certificate, the highest level currently recognized by CrossFit, Inc., the coach must record several years as a Level Three and pass a test.^[55]

The risk of injury associated with CrossFit training has been a controversial question since the program's popularity began to climb in the early 2000s.^[56] Critics have accused CrossFit, Inc. of using dangerous movements and inappropriate levels of intensity, and allowing underqualified individuals to become CrossFit Trainers.^{[57][58][59][60]}

In response to these criticisms, CrossFit, Inc. claims, “CrossFit is relatively safe even when performed with poor technique, but it is safer and more effective when performed with good technique.”^[61] CrossFit, Inc. also claims risk for injury can be reduced by properly scaling and modifying workouts, a concept taught on its website and at the CrossFit Level 1 Trainer Course.^[62][63]

CrossFit, Inc. supports this position by citing three academic surveys of CrossFit participants. These surveys calculated injury rates between 2.4 and 3.1 injuries per 1000 hours of training, which CrossFit argues is consistent with or below injury rates found in "general fitness training."^[64]

A study published in the Journal of Strength and Conditioning Research entitled "Crossfit-based high intensity power training improves maximal aerobic fitness and body composition" followed 54 participants for 10 weeks of CrossFit training. The study said that "...a notable percentage of our subjects (16%) did not complete the training program and return for follow-up testing." The authors said "This may call into question the risk-benefit ratio for such extreme training programs..."^[65] In 2014, CrossFit, Inc. filed a lawsuit against the National Strength and Conditioning Association for publishing this study, alleging that the data were false and were "intended to scare participants away from CrossFit."^[66] The NSCA denies CrossFit, Inc.'s allegations^[66] but has issued an erratum acknowledging that the injury data were incorrect.^[67] In September 2016, the District Court ruled in favor of CrossFit Inc.'s claims that the injury data were found to be false, but not that the NSCA was commercially motivated or that the publishing of the study was defamatory as the NSCA no longer stood behind the study.^[68] In February 2017, CrossFit filed for sanctions against the NSCA after one of the NSCA's witnesses admitted to falsifying statements during deposition.^[69] In May 2017, the Court issued 17 issues sanctions against the NSCA, writing that the organization did have a commercial motive to falsify the data, had published the false data knowingly to disparage CrossFit, and had misled the public with their erratum.^[69] CrossFit was awarded $74,000 in legal fees and allowed to continue investigating the NSCA. If the neutral-party analysis of the NSCA servers turns up any further misconduct, CrossFit may file an amended complaint for further sanctioning and compensation for lost revenue.^[70]

In May 2019, CrossFit, Inc. contacted the Orthopaedic Journal of Sports Medicine with a demand for the retraction of another paper, published in the journal earlier that month.^[11] The paper states that CrossFit participants “are more likely to be injured and to seek medical treatment compared with participants in traditional weightlifting”, a finding that CrossFit, Inc. claimed to be based on scientific errors and material from retracted or mis-represented studies.^[71]

The relationship between CrossFit and exertional rhabdomyolysis has been a subject of controversy for the company. Some medical professionals have asserted that both the CrossFit methodology and the environment created by CrossFit trainers put athletes at high risk for developing rhabdomyolysis.^[12][13][14]

A man successfully sued his uncertified CrossFit trainers and was awarded US$300,000 in damages,^[72] after he suffered from rhabdomyolysis after performing a CrossFit workout on December 11, 2005, at Manassas World Gym in Manassas, Virginia, under the said trainers' supervision.^[73] CrossFit, Inc. was not listed as a defendant in the lawsuit.^[72]

CrossFit, Inc. does not dispute that its methodology has the potential to cause rhabdomyolysis.^[74] The company states that exertional rhabdomyolysis can be found in a wide variety of sports and training populations and argues that its critics have conflated CrossFit's high awareness of rhabdomyolysis with high risk.^[14][75] One CrossFit spokesman stated that "ESPN's report on the 53 deaths in US triathlons from 2007 to 2013 should have put the issue to rest."^[75]

Since May 2005, CrossFit, Inc. has published several articles about rhabdomyolysis in the company's CrossFit Journal.^{[76][77][78][79]} Three of the articles are included in the CrossFit Manual provided to all prospective trainers.^[80]

CrossFit, Inc. has also been criticized for having a "cavalier"^[81] attitude towards rhabdomyolysis by promoting a character known as "Uncle Rhabdo" (a cartoon clown dying in a dramatic fashion—hooked up to a dialysis machine, with his kidneys and intestines falling on the floor).^[77] In response to this criticism, Greg Glassman stated "We introduced (Uncle) Rhabdo because we're honest and believe that full disclosure of risk is the only ethical thing to do."^[75]

CrossFit, Inc. has been variously criticized and praised for its unorthodox approach to social media.^[82][83][84] This approach has included publishing articles and tweets about non-fitness topics (including politics, philosophy, and poetry)^[85][86] as well as directly interacting with other social media users and critics of the company's program.^[1]

On 4 June 2014, CrossFit uploaded a "parody video to their Facebook page" of Jesus, featuring concepts such as the "Holy Trinity of exercise".^[87] Yasmine Hafiz wrote in The Huffington Post that some "viewers are outraged at the disrespectful use of a Christian symbol", with one user asking "on what planet is it comical or encouraged to mock someones belief?"^[88][87]

In June 2018, CrossFit fired its chief knowledge officer, Russell Berger, after Berger disparaged the LGBT community on Twitter. Berger's tweet followed a CrossFit location in Indianapolis being forced to shut down after an employee boycott of the location being closed for a day in honor of LGBT Pride Month. Berger wrote on Twitter "As someone who personally believes celebrating "pride" is a sin, I'd like to personally encourage #CrossFitInfiltrate for standing by their convictions and refusing to host an @indypride workout. The intolerance of the LGBTQ ideology toward any alternative views is mind-blowing." The tweet triggered angry responses denouncing Berger as a bigot and pressuring CEO Glassman for him to be fired; Berger was first placed on unpaid leave, but was later fired by Glassman, who publicly condemned Berger in an interview, stating "He [Berger] needs to take a big dose of 'shut the fuck up' and hide out for a while. It's sad."^[89]

In May 2019, CrossFit shuttered its Facebook and Instagram accounts, which had 3.1 million and 2.8 million followers respectively.^[90][91] On the company's homepage, the announcement stated that CrossFit was concerned about user privacy and security in the wake of "well-known public complaints about the social-media company that may adversely impact the security and privacy of our global CrossFit community." The company also cited theft of intellectual property and Facebook's collusion with "food and beverage industry interests" as reasons for deactivating its social media accounts.^[92]