Cardio-boxing is a combination of the traditional training movements of a boxer—including sparring, shadow boxing, and blows delivered to a boxing bag—structured so as to be performed in sequences, similar to those of aerobics classes, that have a primarily aerobic training effect. Cardio-boxing also developed its own offshoot, cardio kickboxing, where martial arts movements involving blows delivered with the feet are incorporated into the training routine.

The rise of aerobics as a significant health and fitness regimen began in North America in the early 1980s. In its earliest incarnations, popularized by television versions such as the Twenty Minute Workout, aerobics was an outgrowth of calisthenics, with traditional stretching and resistance exercises performed in rapid succession, usually to music. Aerobics, through both the pace and the duration of the activity, utilizes the aerobic energy system to provide muscle energy; its exercises assist in the maintenance of cardiovascular (cardio) and cardiorespiratory health. Aerobics can be performed by a solo participant, at the participant's own pace, or in group settings.

Aerobics did not develop as an exclusively female activity, although a majority of aerobics adherents are women; it is seen as a user-friendly, non-competitive athletic alternative for people seeking the benefits of fitness, who may never have participated in other more structured, competitive sports.

Over time, some aerobics enthusiasts sought out a more vigorous, total body fitness experience than that provided by regular aerobics classes. This desire led to the development and refinement of a number of aerobics variants. High impact aerobics, with an emphasis on the longer duration (sessions of one hour or more) of the fitness activity, combined with the introduction of adjustable portable platforms into the aerobics routines, to require more intense, increased resistance jumping and stepping exercises. High impact aerobics gained a measure of popularity for people who wanted a more demanding cardio workout; this variant also proved to result in a higher injury rate. It was in this context that cardio-boxing rose to prominence as a training and fitness program.

Organized boxing requires an athlete to compete in matches, referred to as bouts, which are divided into segments known as rounds, which may number from four to 12 in the bout, depending upon the level of competition. Each round is typically two to three minutes in length, with a one-minute rest interval. Each round is generally a period of high energy, punctuated with periods of very intense activity, usually through exchanges of punches between the competitors. Boxing, for this reason, places significant demands on both the body's anaerobic system for shorter energy sequences required in each round, and on the aerobic system to both provide the energy to carry the boxer through the entire competition as well as to facilitate recovery between rounds, primarily through the reduction of the heart rate to a normal level. Effective boxing training mimics these stresses upon the body; cardio-boxing training routines are an application of these training principles.

The equipment required for cardio-boxing is geared to flexible, unencumbered movement. Shoes are preferably ones that provide maximum stability, given the physical movements required. Some cardio-boxers do not wear shoes, given the martial arts influence. The participants' clothing should permit ease of movement. Additionally, many boxers tape their hands, using a flexible wrap that is supportive of the entire hand from the knuckle to above the wrist; the tape will stabilize the wrist on contact when punches are delivered to the training bag, and also protect against the wrist being bent upon contact, a mechanism that exposes the wrist and the conjunction of the wrist, ulnar, and radial bones (bones of the forearm) to sprain or fracture. Other necessary items include boxing gloves and a boxing bag (typically a heavy bag, one that is stable, weighing 75-100 lb [34-45 kg]).

While cardio-boxing routines themselves may be effectively employed as a warm up for other athletic activities, the athlete should engage in a period of stretching and loosening of the muscles prior to cardio-boxing, especially if the routine will involve blows delivered to a bag or other resistance device. Particular attention should be paid in this warm up to the hands, wrists, arms, and shoulders.

As cardio-boxing is an application of boxing principles, the exercise routine includes both upper body and footwork components. There are many variations of cardio-boxing workouts, and individual preferences will create useful modifications; all involve the athlete assuming a fighting stance, the crouched athletic position adopted by boxers, with arms raised and fists positioned to both defend against and to deliver a blow. As blows are delivered, alternating left and right hands to the full extension of the athlete's arms, there is a corresponding weight shift from each foot, so as to maintain balance. The quicker that the blows are delivered, the greater resistance to the fist, arm, and shoulder. Cardio-boxing fighting stance routines can be performed with a bag, or by shadow boxing, which emphasizes the movements without the resistance of striking an object.

The basic punches of boxing include the jab, the punch delivered straight from the shoulder; the hook, the punch made with a combination of a hip and shoulder turn and corresponding blow; the uppercut, a punch delivered with the fist moving forward and upward to the target. In cardio-boxing, all these punches can be thrown in various sequences and combinations to maximize training effect.

For many athletes engaged in cardio-boxing, a heart monitor is a useful training tool. The monitor will provide an accurate count as to the athlete's heart rate, and can provide instantaneous feedback. Heart rate is a useful, although not complete, predictor of how hard the body is working. The chief purpose of the heart monitor is to provide a guideline to the athlete as to whether the heart rate is approaching a critical range. In general terms, if a cardio-boxer determined that the workout had elevated the heart rate to what the athlete believed to near the maximum for an extended period, the athlete would consider reducing the intensity level; conversely, when the heart rate records a level of below 50% of maximum, the athlete might use that reading as a signal that the workout intensity could be increased.

The kickboxing variation of cardio-boxing places greater emphasis on the legs and feet to deliver blows as part of the training sequence. As with various types of martial arts, the kick is delivered using a full rotation and extension of the body into the target. Strong leg muscles and coordination are required to be effective.

SEE ALSO Boxing strength and training exercises; Calisthenics; Exercise, intermittent.