Characteristics of the Sport of Swimming
Swimming requires a serious commitment to training. Typically, 6-12 sessions are undertaken each week, with the distance covered in each session ranging dramatically. Sprinters during a taper phase may only cover 1000-2000 metres compared to distance swimmers who can travel up to 10 kilometres per session. Elite swimmers typically train twice a day but during heavy training camps can train 3 sessions a day. This can mean time spent in the water can be more than 6 hours. In addition, swimmers usually complete 2-3 weight training sessions per week and may undertake some land-based aerobic training such as running or cycling. Training commitments of sub elite swimmers can still be large and it is not uncommon for swimmers in their early teens to be training 10 times per week.
Olympic swimming events last from 20 seconds to 15 minutes. Swimming is therefore a highly anaerobic sport, with aerobic metabolism becoming more important as the race distance increases. Although each event may be brief, swim meets are usually held over 3 to 7 days, with swimmers typically competing in heats in the mornings and semi finals and finals in the evening. In minor competitions, swimmers may enter a large number of events and be required to swim 2 or 3 times per session with 20 minutes to several hours between events.
Swimmers tend to be tall with pronounced upper body muscle development. Low body fat is an advantage, since swimmers need to move their body weight through water. However, some body fat in the right distribution may enhance flotation.
It is not uncommon for swimmers in their teens to have similar training commitments to elite swimmers. For male adolescence this is a period of heavy growth and muscular development, requiring high-energy support. The addition of an intense training program means male swimmers can have trouble eating enough kilojoules to meet energy needs. Adolescence for females brings hormonal changes, which promote an increase in body fat. Despite heavy training loads, many female swimmers can struggle to maintain low body fat levels. Long training hours restrict a swimmer's lifestyle. This can either reduce the opportunities to eat in a busy daily schedule or raise the importance of eating for comfort or entertainment. Access to food can also be an issue when at swimming carnivals, and for athletes travelling to compete.
Common Nutrition Issues
Strenuous daily training requires a high-energy, high-carbohydrate diet. Swimmers who fail to meet their carbohydrate requirement will fail to recover adequately between training sessions resulting in fatigue, loss of body weight and poor performance. Additional energy requirements for growth may compound the problem, especially during the teenage years when training and school commitments can make it hard to access suitable volumes of food. Swimmers with high-energy requirements need to increase the number of snacks during the day and make use of energy-dense foods. It is good to have nutritious carbohydrate-rich snacks on hand to eat straight after training to start the refueling process. This is especially important for swimmers who travel long distances from their pool to work or home and have to wait until the next meal can be consumed.
Fluid Needs in Training
High-intensity exercise in the steamy environment of a heated indoor pool, or outdoors in the sun, can lead to moderate sweat losses, which are not obvious when the swimmer is already wet. Smart swimmers bring drink bottles to the pool deck and drink during rest periods or between sets. Sports drinks provide an additional fuel supply for long training sessions. In a fluid balance study undertaken on the Australian Swimming Team in Atlanta in 1995, we measured average sweat losses of ~125 ml per kilometre in training or about 600 ml per workout. These swimmers were provided with both water and sports drink at the session and managed an average intake that perfectly matched their losses (125 ml per km). Of course, some swimmers were better at matching losses than others. And during anaerobic threshold sets, sweat losses increased to 170 ml/km.
An iron imbalance may occur in swimmers undertaking heavy training who fail to consume sufficient iron. Female swimmers on weight loss diets are particularly at risk. Iron levels should be checked regularly when in heavy training. Iron-rich foods such as lean red meat and breakfast cereals fortified with iron should be included regularly in the diet. Iron-rich plant foods such as wholegrain cereals, spinach and legumes should be combined with animal iron sources (e.g. wholegrain pasta with bolognese sauce) and vitamin C sources (e.g. glass of orange juice consumed with breakfast cereal) to improve iron absorption. A sports dietitian will be able to provide specific dietary help.
Swimmers often worry about getting sick during periods of heavy training. Many nutritional supplements and strategies have been suggested to keep the swimmer from catching coughs and colds. To date, the most important strategy emerging from immune studies of athletes is to keep well fuelled during training sessions. Sports drink during the workout and a recovery snack afterwards help to reduce the stress on the immune system.
Muscle glycogen stores can be filled by 24 hours of a high-carbohydrate diet and rest. Swimmers who are undertaking a long taper may need to reduce total energy intake to match their reduced workload; otherwise unwanted gains in body fat will occur. Fluid levels and carbohydrate stores need to be replenished between events and between heats and semi-finals/finals. Drink a carbohydrate-containing fluid such as sports drink, fruit juice or soft drink when there is only a short interval between races. Snacks such as yoghurt, fruit, cereal bars or sandwiches are suitable for longer gaps between races, or for recovery at the end of a session. Between day heats and evening final sessions, most swimmers eat a high-carbohydrate lunch and have a nap. On waking, a carbohydrate-rich snack is eaten before returning to the pool.