Resistance exercise is that which focuses on the development of musculoskeletal strength. This type of exercise includes weight training or strength training, as a resistance program seeks the enhancement of muscle strength, endurance, and power. A well-rounded and well-balanced athlete will incorporate resistance exercises, aerobic conditioning, and flexibility exercises into an overall training program. Resistance exercise commonly, although not exclusively, utilizes weight training to generate the forces necessary to create resistance against which the working muscles can act; weightlifting, as a competitive sport, is distinct from resistance exercise.
The essence of resistance exercise is the principle of overload. The progressive increase of the load (or the resistance) applied to a muscle, will cause the muscle to become fatigued. Through the combination of overloading during workouts and the repair initiated by the body on its muscle fibers when at rest, the muscles grow stronger. Resistance training, in addition to being an essential component of total fitness, is a specific contributor to stronger and denser bones. A body with a greater percentage of lean muscle mass will consume greater amounts of energy at rest, as muscles place greater demands on the body's metabolism than do fat cells.
Resistance exercise training can be started at almost any age, although considerable caution must be taken with young athletes (persons under the age of 18 years). As the bodies of these persons are not yet mature, the growth plates present on the long bones of the juvenile athlete are not yet ossified, or hardened into their final adult form. Overly vigorous resistance training can place unhealthy levels of stress on these structures, causing the bone to either grow incompletely or to become vulnerable to later bone damage. Any resistance exercise training program must be accompanied by a comprehensive stretching and flexibility routine, both as a part of the warm up/cool down aspect to a particular workout, as well as those stretching exercises conducted on a daily basis.
Resistance training, especially those exercises involving free weights, will emphasize a complete range of motion to obtain the maximum resistance benefit. The more flexible the joints of the athlete, the greater the range of motion is achieved. The types of stretches that are central to yoga and Pilates are a very effective counterbalance to the stresses placed on the body in resistance exercise training. Conversely, when the range of motion in the athlete is more limited, the desired form necessary to execute the particular routine may be absent, which will both limit the effectiveness of the exercise and increase the risk of musculoskeletal injury.
Successful resistance exercise depend upon a number of factors, including the level of fitness of the athlete at the beginning of the program. When a person is new to resistance training, or otherwise does not possess a moderate level of general fitness, the resistance program must be advanced gradually. Also, the warm up should involve both stretching and flexibility exercises as well as a light aerobic workout, such as an easy run or a short session on a treadmill, elliptical machine, or other stationary trainer.
Resistance training will ultimately require the involvement of all muscle groups. For this reason, the workout should begin with the larger muscle groups, such as the back and chest muscles, and
Like any form of training, resistance exercises develop greater muscular strength, endurance, and power by virtue of their progressive nature. The training progression is accomplished through increases in both training intensity and training volume. The variables in any resistance program are the amount of resistance (often the weight to be lifted), the number of repetitions, and the rest period between exercise; increasing resistance or repetitions, or decreasing rest, will contribute to the overall intensity and volume.
As all resistance training is anaerobic in nature, the efficient production of muscle energy is important to training success. Adenosine triphosphate (ATP) is the ultimate fuel used to generate energy in working muscles; ATP functions in an energy cycle with phosphocreatine (creatine phosphate). Persons engaged in serious resistance training often consume creatine supplements to assist in this energy process.
While resistance training most often involves the use of weights to provide the necessary resistance, other training aids can be effective. Sprinters use either parachutes or similar devices to create additional drag on their bodies to increase the resistance to their leg muscles; the blocking sleds used for many years in American football by linemen to simulate line play against an opposing team are a similar device.