Is CrossFit an effective training program for Warfighters?

From the Field

Is CrossFit effective for Warfighters?


Training program CrossFit


CrossFit is an extreme exercise program designed to promote functional fitness. There are no published data on CrossFit-related injuries and no comparisons of injury rates with other demanding physical sports, which are leading causes of Warfighter injury. The program requires modifications for use by unfit and beginning exercisers.


CrossFit is an extreme exercise program that includes dietary recommendations and diverse exercises. CrossFit’s objective is to optimize performance in multiple domains: cardiovascular endurance, stamina, strength, flexibility, power, speed, coordination, agility, balance, and accuracy. CrossFit is not sport specific, but it is designed to improve core strength and functional fitness through the use of Olympic weightlifting methods, kettlebells, gymnastics rings, pull-up bars, and a wide variety of calisthenics. A typical workout may include running, rowing, rope climbs, jumping up onto and off of boxes, flipping tractor tires, carrying heavy operational gear, and bouncing medicine balls against the floor or wall. CrossFit advocates eating lean meats and vegetables, nuts and seeds, some fruit, little starch, and no sugar.

Myths and Claims

Devotees swear by the method, while many sports medicine physicians and athletic trainers anecdotally report high injury rates.


CrossFit has gained immense popularity among military and law enforcement personnel; it has replaced or is used to augment traditional military physical training in many units. The U.S. Army conducted a recent CrossFit study wherein 14 men and women received initial and post-study physical assessments of their ability to perform a variety of functional movements. They then participated in CrossFit training for six weeks. Although most participants increased their power output and work capacity, the methodology of this study was weak: small sample size, no comparison training method or control group, and no injury or adverse data. Importantly, the results were not peer reviewed or published in the open scientific literature.

The issue of injury remains unresolved. There are no reliable published data on CrossFit-related injuries and no comparisons of injury rates with other demanding physical sports such as running and basketball, which are leading sources of military training injuries.


CrossFit is an extreme exercise program and is likely to be unsuitable for beginners and unfit users. The recommended types of activities, exercise intensity, and duration may exceed the capacity of some individuals and cause (at least) soreness and (at worst) injury. All extreme exercise programs carry a risk of injury and muscle damage.

Individuals who select this program should start slowly, be aware of their physical limits, and proceed cautiously when increasing time, repetitions, and intensity. Modifications to the difficult body-weight exercises (push-ups and pull-ups) should be considered. Such precautions will help prevent injury. Refer to the Navy Seal Fitness Guide, Building the Soldier Athlete, and the Air Force Fitness Program for specific training guidelines. Warfighters should be cautioned to see a health care provider if they experience muscle soreness, weakness, restrictions in normal range of motion, and/or cola-colored urine.

Mission and heavy-training nutrition requirements of Warfighters may not be met using CrossFit dietary guidelines. For example, under certain trainig and mission conditions, Warfighters require more nutrients for fuel. Refer to the Warfighter Nutrition Guide for specific dietary guidelines to sustain the Warfighter.

Summary for Military Relevance

In 2006, Lt Gen James F. Amos, USMC, the 31st and current Assistant Commandant of the Marine Corps, described “functional fitness” as "the ability to perform a broad array of natural or realistic physical work that involves all tasks associated with performance in combat." He emphasized that operational and combat demands vary regarding load and duration, which in turn affect intensity of physical exertion. Traditional training methods do not adequately prepare Warfighters. He further noted that functional fitness involves "multiple planes and joints" in the performance of real-life combat tasks. Therefore, the Marine Corps should incorporate elements of functional-fitness training in their daily conditioning regimen.

CrossFit may be effective for achieving functional fitness, but it also poses a risk of injury for many potential users. The importance of military-personnel fitness is unquestionable, but the viability of CrossFit as a method to achieve high levels of functional fitness is still unresolved. CrossFit should be implemented with caution, and beginners, unfit, and/or injured individuals should start it under the guidance of an experienced trainer.


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