Fuel for Swimming

Swimming requires a serious commitment to training. Typically, 6-12 sessions are

undertaken each week, with the distance covered in each session ranging from 1000-

2000 metres of quality work for a sprinter in taper phase to 10 kilometres for a distance

swimmer in the base phase of training. At the elite level workloads can involve 2-3 daily

sessions adding up to 6 hours of training per day. In addition, swimmers may undertake

some land-based aerobic training such as running or cycling as well as weight training

sessions. Training commitments are usually smaller at the club or school level.

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 finals

in the evening. In minor carnivals, swimmers may enter a large number of events and

be required to swim 2 or 3 times in one day 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.

Many top swimmers are in their teens. Male adolescence is a period of heavy growth

and muscular development, requiring high-energy support. For males, 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 traveling to

compete.

Strenuous daily training requires a high-energy, high-carbohydrate diet. Swimmers who

fail to consume enough carbohydrate 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. 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.

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.

Grant was a young up and coming swimmer who began to struggle with fatigue after

making the jump to training with an elite squad. As Grant's training sessions increased

to 12 per week, his times began to drop off and he struggled to maintain weight. A

sports dietitian examined Grant's diet and found additional carbohydrate was needed to

cover Grant's extra training needs. In particular, more carbohydrate was needed for

Grant to replenish muscle glycogen stores between sessions. At 80 kg, a daily intake of

600-800 g of carbohydrate each day was required. Although Grant loved to eat high

carbohydrate foods such as bread, cereal, fruit, potato, rice and pasta, he struggled to

consume sufficient quantities each day of these bulky foods. Grant's dilemma was

solved by increasing the number of meals consumed and making use of portable, easy to-

eat snacks. With some planning and preparation Grant made sure he always had

access to quick easy-to eat high-carbohydrate snacks such as smoothies, liquid meal

supplements, cereal bars, sports drink, yoghurt, fruit and bread. He started having

carbohydrate-rich foods and drinks immediately after each training session so that

muscle glycogen storage was activated as quickly as possible. Grant's intake was

increased to 800-900 g of carbohydrate and 21,000-23,000 kilojoules each day. Within

three weeks Grant had regained some weight and was feeling a new energy at training.