Is P90X safe and effective?

Form the Field

Is the P90X program safe and effective?


Exercise program P90X


P90X is a commercial, 90-day, home fitness program emphasizing cross-training and varied exercises; it uses inexpensive fitness equipment - dumbbells, bands, a pull-up bar, and a yoga mat. Common household items, like a chair and towel, are needed for some of the exercises found in the videos. The program materials include 12 DVDs, a fitness guide, and a nutrition plan.

The program provides plans for three weeks (“adaptive” and “mastery” phases) of basic conditioning components with one week of “recovery”. The cardiovascular conditioning, strength, flexibility, and core strengthening components are designed to promote overall physical fitness. Although the program is intense, each segment typically includes a warm-up to prepare the body for exercise, a cool-down for recovery after completing the workout, and mild stretching within the warm up and cool-down. The various exercises include using body weight, bands, and/or dumbbells for strength, kenpõ movements (or kempo, a type of martial arts) for cardiovascular training, plyometrics for power and agility, and yoga for flexibility and balance.

P90X promotes a nutrition and optional supplement plan. The nutrition plan comprises three 30-day phases, with the first phase a low carbohydrate diet. The second phase balances carbohydrates and protein, whereas the third phase incorporates more calories and carbohydrates than the first two plans. Supplements and vitamins are marketed for use during the program to include an exercise recovery drink (optional and not included), which is recommended after each workout.

Myths and/or Claims

Testimonials assert participants will achieve a lean and muscular physique within 90 days of following their unique technique of “muscle confusion”.


“Muscle confusion” is not currently an established exercise science principle, although it can be equated in part to cross-training, non-linear strength training, and periodization. The principles of cross-training and periodization can help prevent injury and encourage balanced muscular strength and flexibility by alternating the timing, intensity and frequency with which specific muscle groups are used.

Results presented throughout the marketing materials are anecdotal. No independent research on P90X’s total program, including nutritional and supplement components, has been conducted. Likewise, neither the efficacy of the program nor documentation of fitness results has been scientifically evaluated. Testimonials used in marketing a product should not be taken as fact.

Although the dietary recommendations may be effective for reducing body fat and building lean muscle, they may not be adequate for a deployed Warfighter, or one engaged in heavy, physical, mission training. The muscle recovery drink provides 220 calories and contains a 4:1 ratio of carbohydrates to whey protein along with creatine and the amino acids L-glutamine and L-arginine.


P90X is an intense exercise program, and may be unsuitable for beginners or unfit users. The recommended types of activities, exercise intensity and duration may exceed the capacity of the individual and cause, at least, soreness, and at worst, injury. Cases of muscle damage (rhabdomyolysis) following use of this program have been documented, as has been the case with other similar types of intense exercise program.

Individuals who select this program should start it slowly, and be aware of their physical limits; they should proceed with care 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. Warfighters should be cautioned that if they experience severe muscle soreness, weakness, restrictions in normal range of motion, or cola colored urine, they should be evaluated by a physician.

Mission and heavy training nutrition requirements may not be met using the P90X dietary guidelines.  Refer to the Warfighter Nutrition Guide for specific dietary guidelines to sustain the Warfighter.

Concerns with the recovery beverage relate to the 500% of the daily value for vitamin E and the 700 mg of arginine, which could be a problem in terms of amino acid imbalance and arginine’s action as a vasodilator. Whether the amounts of carbohydrate and protein are adequate depends on the person’s size and intensity of the exercise.

Summary for Military Relevance

P90X may be effective for achieving a lean and muscular physique, but poses a risk of injury for trained, untrained and/or unfit users. The program is DVD- or guidebook-based, depending on the need. A DVD player may not be feasible under field conditions, and damage to the DVDs may limit it possible value in the field and/or deployed settings. However, the guidebook can be used. The use of scripted workouts may save leaders time in planning physical training, while being time efficient for the Warfighter.

The Marine Corps Martial Arts program has adopted a similar training method that can be done with equipment typically found in garrison and deployed environments; it has been published with graphic instructions in a small, bound book, which fits in uniform pockets. The Marine Corps philosophy of being able to train at any time without special gear and equipment eliminates excuses for not having time and/or equipment to maintain fitness.

P90X is an extreme exercise program specifically targeted for very fit individuals looking for challenging exercise regimens.  Accordingly, the program is tailored for individuals who can adjust their repetitions; individuals who are marginally fit, or fail to adjust can be predisposed to injury.  If P90X is introduced in a group setting, precautions should be taken to allow individuals to proceed at their own pace.  Although P90X clearly offers a challenging regimen that can potentially succeed in building muscle, improving flexibility and power, currently no evidence-based studies or publications exists documenting the success of P90X over other exercise programs.

The HPRC does not recommend use of this product, nor any other commercially marketed fitness program. If a Warfighter chooses to use this program, they should seek appropriate medical guidance and have a baseline fitness assessment to support intense exercise recommended by this program. Consideration should be given to the Marine Corps Martial Arts Combat Conditioning program for deployed environments.


Exercise program P90X


Plyometrics:  An explosive form training where the muscle reaches maximal strength in the shortest time possible; it include activities such as standing jumps, repetitive jumping on and off a box, hurdle hops, and multiple squat jumps.

Periodization: The process of varying training variables (repetitions/set, type of exercise, exercise intensity, length of rest periods) over a specific period of time, such as a week, month or year, to achieve well-defined gains in performance or peak for an event. It can also be used to prevent overtraining.

Rhabdomyolysis:  Breakdown of muscle fibers with release of cellular contents, in particular myoglobin, into the bloodstream. Excessive myoglobin can cause kidney damage.  Symptoms include severe muscle soreness, weakness, restricted range of motion, and/or cola colored urine.



The P90X website

Warfighter Nutrition Guide

Navy Seal Fitness Guide

Building the Soldier Athlete


Kerksick C, Harvey T, Stout J, Campbell B, Wilborn C, Kreider R, Kalman D, Ziegenfuss T, Lopez H, Landis J, Ivy JL, Antonio J. International Society of Sports Nutrition position stand: Nutrient timing. Journal of the International Society of Sports Nutrition. http://www.jissn.com/content/pdf/1550-2783-5-17.pdf.