Weight categories have been employed for centuries as a method of equalizing competition in a number of different sports. In sports where the physical strength of the combatants was understood to be crucial to their ultimate success, weight categories recognized the fundamental principle that, all things being equal, in strength sports the larger athlete was likely to be the stronger athlete. Stated in the alternative, where two athletes possess equal technical skill in a strength-oriented sport, the larger athlete is more likely to overpower the smaller athlete.
Weight categories are fundamental to the organization of competition in the individual sports of boxing, wrestling, and weightlifting. Each of these sports requires the athlete to build a dynamic, powerful body that possesses explosive power capabilities, all of which are integrated into a physical structure with a strong aerobic foundation. The only prominent team sport where weight divisions are employed is in rowing, which is divided into lightweight and heavyweight competitions.
Boxing is perhaps the best known of the sports in which weight divisions define the extent of the competition. The definition of each weight class varies slightly between those used at the Olympic Games and the common professional weight designations and some amateur competitions. The same weight categories are used with different weight limits for women's boxing. Boxers compete in divisions that range from the straw weight division for men up to 105 lb (46 kg), through the heavyweight division for men over 200 lb (91 kg). Throughout the history of professional boxing, certain weight divisions have garnered greater degrees of public attention and acclaim, particularly the heavyweight and the welterweight divisions (140-147 lb, or 66.6 kg limit).
In all sports where there are weight categories, the limits provided are not merely guidelines; they are inflexible limits. An inability on the part of the athlete to "make the weight" will disqualify the athlete from competition. Strategies have often been devised by athletes to assist in meeting a particular weight category standard, many of which compromise both the ability of the athlete to compete at the optimal level, in addition to placing significant adverse stresses on the function of many bodily systems.
There are two general approaches with respect to how an athlete should achieve and maintain a competitive weight standard. The first is the development of a training program in which the athlete seeks to develop maximum strength and fitness while at all times maintaining the target weight for competition. The second strategy is to develop maximum strength and fitness without a primary concern for the weight limit, with a concerted weight loss effort immediately prior to competition to come under the standard. The second strategy is premised on the theory that the athlete can bring a level of strength to competition that would otherwise only be attainable at a higher weight.
The number of times during a competition that an athlete will be tested for compliance with the weight category limits varies from sport to sport. In amateur boxing and wrestling, in which the competitions may span a number of bouts over a period of several days, the athlete will be weighed at the beginning of the competition and then prior to each succeeding match. Once the athlete has achieved a desired weight, it must be maintained throughout the competition.
All weight category sports place significant demands on the body during both competition and in training with respect to sufficient caloric intake, proper nutrition, and hydration. Whatever strategy is employed concerning the achievement of the requisite weight standard, sports scientists and nutritionists generally recommend that the athlete maintain a year-round weight that never exceeds the competitive weight limit by more than 10%. The management of weight targets is another aspect of how the athlete will plan the training for a competitive season, a process known as the periodization of training. In these sports, weight management is as important to athletic success as the development of sport-specific technique, for without making the proper weight, there is no competition.
There are no additional risks to an athlete who maintains competitive weight year-round. Athletes who must dramatically cut weight before competition create potential physical and psychological risks that must be carefully considered. Weight cutting strategies should first be implemented in the dietary choices made in training, where nutrition-rich, and relatively low-calorie, low-fat foods will reduce the accumulation of excess weight. The body's ability to repair itself during the rest intervals between workouts is founded on its nutritional intake; when athletes are monitoring their weight, they must seek maximum nutritional return for reduced caloric value.
When the athlete seeks to lose weight through a "crash" diet in the period leading up to competition, nutrients that are not stored in the body, including the water-soluble vitamin B complex and vitamin C, may not be present in sufficient quantities to perform their respective maintenance and repair functions. Vitamin C, as an example, is essential to the production of collagen, a building block of bone, ligaments, and tendons.
When the athlete must lose 5 lb (2.2 kg) or more on the eve of competition, it is common to dehydrate to make the desired weight. The sudden loss of fluids, which must be maintained through the entire competition, will likely impair the performance of the athlete. The loss of significant quantities of body fluid will directly impact blood volume, which limits the ability of the cardiovascular system to function at peak efficiency. When the athlete competes in successive bouts at reduced fluid levels, the risk of a heat-related illness triggered by dehydration is significant, as the body's thermoregulatory system will not be able to cool itself as efficiently through perspiration.
Peak athletic performance will require a complete commitment to the employment of competitive strategies and the execution of demanding physical maneuvers. The additional stress imposed on the competitor to make weight or be disqualified may serve as a significant distraction to the efforts of the athlete to maintain competitive focus prior to the event.
The most common dehydration techniques used in weight category sport are the use of "sweat boxes," or similar artificial heating of the athlete to induce perspiration, and taking diuretics. The use of diuretics is a time-honored practice in sports such as boxing; these are substances that stimulate the increased production of urine by the kidneys. Many diuretics are prohibited in international competitions that are regulated by the World Anti-Doping Agency (WADA), although this ban is aimed more at the use of diuretics as a steroid-masking agent than for their use by athletes to achieve a weight. Diuretic use for any purpose will lead to disqualification.
In some youth sports, weight categories are a means of ensuring safety for all participants; American football for players below high school age is an example.