Swimming (100 to 400 Meters)

Perhaps there is no other sport where so much time must be spent practicing to gain such incrementally small levels of improvement. Swimmers spend a considerable amount of time in the water to perfect techniques that will better overcome drag and to improve their capacity to sustain both aerobic and anaerobic energy production. In the shorter (sprint) distances where races are typically less than 2 minutes in length, the majority of energy is predominantly derived anaerobically from phosphocreatine and glycogen. Although these sprint races are short in duration, the amount of energy needed to sustain a high level of power output is tremendously high, and the majority of this energy (more than 55 percent) must come from glycogen and phosphocreatine.

The time spent training has a high energy and nutrient cost that must be considered when developing a training plan. A study of national developmental-training-camp swimmers found that the average energy (5,221 calories for males; 3,573 calories for females) and nutrient intakes were adequate, but there was a large between- swimmer variation in intake.⁵⁸ This variation, coupled with a tendency for these swimmers to consume excessive amounts of fat and insufficient amounts of carbohydrate, suggests that a large proportion of swimmers may have dietary habits that do not optimally support training and competition needs. In addition, there is evidence of poor iron status among female collegiate swimmers, which could compromise training and exercise performance.⁵⁹ The desire for higher-fat foods from meats and dairy products has been tested in male swimmers, and it was found that they tend to like the sensory appeal of fat-containing animal products, even when undergoing a high level of exercise.⁶⁰

High-level swimmers, often high school students and college-age adults, must spend a great deal of time in the pool to gain a speed improvement, which commonly translates into multiple training sessions each day. Swimmers typically practice in the early morning and late afternoon (before and after school), and they generally accept that they must get an hour or two of laps in before classes begin (often at 5 A.M.) to have a chance of improving. The problem, therefore, is ensuring that swimmers consume enough energy at the right time and in the right form to make it supportive of the training plan. Ideally, swimmers should make the time between and during practices an opportunity to consume a significant amount of high- carbohydrate foods. However, swimmers must do this in a way that ensures the stomach is empty before getting into the water. This means that the focus, during practice and swim competitions, should be on carbohydrate-containing sports beverages. Having large amounts of solid foods shortly before getting into the water causes a fluid shift away from the muscles and into the GI tract and may cause cramping.

Keeping this in mind, swimmers must consider the following nutritionally relevant factors for their sport.

Swimmers train for many hours and have an intensive training protocol. Competitive swimmers work hard and long at getting better, and all that work translates into a tremen dously high caloric need. Since swimmers often have an early-morning practice, it is important that they consume some carbohydrates immediately upon awakening to give the food or beverage enough time to leave the stomach before practice. A failure to consume at least 100 to 200 calories of carbohydrate before practice may limit the benefits the athlete could derive from practice. Fluids (apple or grape juice or a sports beverage) are good to sip on during the trip to the pool. After the morning practice, swimmers should consume some high-carbohydrate breakfast foods (cereal, toast, bagel) that should be immediately available. This will help replenish the energy consumed during practice and begin the process of storing more energy for the afternoon practice. Also, because so much energy is needed, high school swimmers should seek approval from school administrators to consume a midmorning snack of 200 to 400 calories. Swimmers who practice sprinting in the pool should be aware that phosphocreatine (a major fuel for sprints) is likely to become depleted in muscle cells, and it takes time to regenerate the phosphocreatine to get the cells ready for the next sprint. When total sprinting time meets or exceeds 2 minutes, there should be a recovery period of up to 4 minutes to allow cells time to replenish the depleted phosphocreatine. A failure to allow for this recovery period will force the swimmer to work at a lower intensity and for shorter periods on subsequent sprints. If that happens, the swimmer will be learning to sprint in a way that could adversely affect competitive times.⁶¹

Some swimmers believe body weight reduction may be necessary to improve bathing suit appearance and reduce drag. The paper-thin material used for racing suits makes it impossible for swimmers to hide their physiques. Since everyone wants to look good, swimmers may be motivated to reduce body weight. However, many swimmers could easily experience a reduction in performance if weight loss results in a loss of muscle with a secondary loss of power. If weight were lost in a way that reduces drag, there could be a performance benefit, but most weight-loss strategies backfire and hinder performance. Therefore, swimmers wishing to lose weight to either look better or go faster (or both) should do so only under the direct supervision of a qualified health professional. Also, the focus should be on fat reduction and muscle maintenance rather than weight reduction per se.

Swimmers rely heavily on glycogen and phosphocreatine, and sprinting performance is highly dependent on carbohydrate (to make stored glycogen) and phosphocreatine. With sufficient total energy intake that focuses on carbohydrates (at least 30 calories of carbohydrate per kilogram of body weight) and the inclusion of an adequate amount of protein (about 1.5 to 2.0 grams per kilogram of body weight), there is every reason to believe that athletes can store enough glycogen and make enough phosphocreatine to properly fuel their muscles. However, there is tremendous motivation for athletes to consume creatine monohydrate supplements (a precursor to phosphocreatine) to gain a competitive edge. Although creatine monohydrate supplements may improve the number of high-intensity sprints a swimmer is able to do, swimmers should be aware that regular creatine consumption is associated with an increase in weight. Since this weight increase is likely to be from water, it could reduce buoyancy and increase drag. It is likely that a greater benefit could be achieved by creating opportunities to eat so as to ensure an optimal total energy intake.

Swimmers need to consume fluid. It is difficult to imagine that, with so much water around, swimmers could be at risk for dehydration. The fact that swimmers work in a hypothermic environment (water is usually colder than air temperature) makes it easier for the excess heat generated from muscular work to be dissipated. However, there are other good reasons for swimmers to consider whether their hydration state is adequate. A poorly hydrated athlete may develop a lower blood volume that causes the heart to work harder to bring oxygen and nutrients to cells, and there is less volume in which to place metabolic by-products. Also, many competitions take place outside, where swimmers spend a great deal of time waiting for their events, and where they can easily become overheated. Excess water storage could clearly cause a problem for swimmers by increasing weight and drag, but in sufficient body water can influence performance and concentration. Therefore, a good rule of thumb is to constantly sip small amounts of water or sports beverage while avoiding strategies that could force an excess water storage (e.g., glycogen loading, glycerol, creatine).