Nutrition (from USA Swimming's website)
Fueling Your Stroke
Six 200’s descending on five minutes. Twenty-five 50’s on :58. Whatever your “favorite,”
every set during every workout and dry land session requires energy.
Nutrients are the “chemicals” that supply the body with energy. Carbohydrate, protein and
fat supply energy in the form of calories. These are your “Energy-Yielding Nutrients.”
Vitamins, Minerals and Water don’t supply energy in the form of calories, but their presence
is required in order for the body to access the energy provided by carbohydrate, protein and
During exercise, the body gets its energy primarily from carbohydrate and fat. It likes to save
protein for other things (building and repairing muscle tissue, hormones and red blood cells, and
supporting the immune system). The only time the body uses protein as an energy
source during exercise is when carbohydrate and fat are not present in sufficient quantities.
This happens when the total caloric intake is too low over a period of months, and or the
bout of exercise is so long that the body’s accessible sources of carbohydrate and protein
become exhausted. Neither of these scenarios is desirable for swimmers.
Think about money. When you have lots of it, you don’t mind paying full price for things. But
when money is scarce, or there is just too much you have to buy, you look for bargains.
You’re not being cheap, just thrifty. Simplified to some extent, your body knows how to shop.
Now instead of dollars, think of your currency as oxygen. When swimming is “easy,” say
during warm-up or your easiest sets, there is plenty of oxygen available to support the
exercise. The body perceives itself as “rich” and doesn’t mind splurging on fat (1 gram of fat
costs 9 units of oxygen). In fact, it automatically does so because it knows it might need
carbohydrate at a later time.
When exercise is hard (we’re talking tough sets, definitely your hardest sets), oxygen is not
plentiful. In fact, the body needs every bit it can get to support the exercise, but even that is
often not enough, and the body is forced to derive energy in ways that do not require oxygen
(i.e. anaerobic metabolism). In this situation, the body perceives itself as very “poor” and
becomes very thrifty with its “purchase” if fuel. Since carbohydrate costs less than fat (1
gram of carbohydrate costs 4 units of oxygen), the body chooses to rely primarily on carbohydrate
for its energy.
Keep in mind that this entire fuel burning process is never a case of “all or none.” In other
words, the body is always using some combination of carbohydrate and fat, but the
intensity of the exercise dictates which fuel source will be the dominant one. When
swimming is easiest, fat is the primary fuel source. When swimming is toughest,
carbohydrate is the primary fuel source. When swimming is about 50% of maximum effort,
carbohydrate and fat contribute about equally. Let’s face it – the majority of workouts are hard.
The typical swim workout, it’s pretty safe to say that the primary fuel source is carbohydrates.
Eat Colorful Foods!
What are the first three foods that come to mind when we say “carbohydrate?”
Each of these is excellent. One of the most overlooked sources of carbohydrate is fruit.
Fresh, canned, frozen, dried or juiced. No matter how you look at it, fruit is an excellent source of
carbohydrate. Not only does fruit provide carbohydrate in the form of natural sugars (versus
refined sugar), the bright colors of fruits indicate that they are also excellent sources of
vitamins and minerals, including a sub-group called anti-oxidants.
You might recall that exercise is the stimulus that leads to training adaptations. And that
adaptations to training occur ONLY is you give the body the right kinds of fuels during
periods of rest. Well, one of the side effects of exercise is the generation of “free radicals.”
Free radicals are molecules that can actually cause damage to muscle tissue above and beyond the
damage caused by exercise. The damage caused by exercise is normal. It serves as part of the
stimulus for training adaptation to take place. But damage caused by free radicals is NOT a
desired part of the training process. Damage caused by free radicals (aka “scavengers”)
circulating in the bloodstream after workout can continue well into the recovery period. This
is when the body is supposed to be adapting!
Anti-oxidants “absorb” free radicals, neutralizing their effect in the body before their damage
to muscle tissue can amount to much. A diet consistently rich in fruits (and other colorful
foods, such as VEGETABLES) is apt to keep the body consistently supplied with antioxidants,
which will assist the body in keeping free radical formation to a minimum. This a
good reason to eat lots of colorful foods during the recovery time between workouts.
Colorful foods include, but are not limited to: apples, strawberries, blueberries, bananas,
watermelon, raspberries, grapes, mango, papaya, apricots, red peppers, broccoli, corn, squash,
carrots, peas,green beans, oranges, kiwis and tomatoes.
Colorful foods DO NOT include: Skittles, Jelly Beans, M&Ms, Mike& Ikes, Fruit Loops,
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 kilometer 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 yogurt, 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.