AIS - Nutrition - Resources - Peak Performance, chapter 14

Peak Performance

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Peak Performance

Peak Performance: training and nutritional strategies for sport
J. Hawley and L. Burke.
Sydney: Allen & Unwin, 1998.

Chapter 14: Eating for recovery Peak Performance

Eating for recovery

'I like to get replenishment in the first half hour after my race with high carbohydrate drinks and foods. Especially when I have a busy program with more than one race each night. I have to fit in swim downs, massage, drug tests, the next race, coaches, the media. It can be frantic. I have my own supplies organised—a sports drink, bananas, or something sweet.'

Michael Klim, sprint swimmer, 1998 World Champion for 100 metre butterfly and 200 metre freestyle, and world-record holder in 100 metre butterfly

'My team has discovered that it's important to ingest a small amount of carbohydrates, usually by eating a bowl of cereal, immediately following the race. This is quite a change from the traditional approach in cycling, in which riders were told not to eat anything until many hours after . . . supposedly to allow their bodies to recuperate before ingesting. In fact, they were losing four hours of precious glycogen storage time.'

Greg LeMond, three-time winner of the Tour de France, on eating after a day's stage

The finish line has been crossed, the final whistle blown, the winning shot played, or the last set in the training session completed. Should these have involved a medal-winning performance, a premiership cup or the athlete's retirement, then this chapter may not be necessary. But for the vast majority of athletes, even if the immediate schedule reads 'rest', it is likely that another workout or competition event is looming on the horizon. Therefore, recovery is an important item on the athlete's agenda. As outlined in Chapter 2, recovery is the desirable process of adaptation to physiological stress. In the training situation, with correct planning of the workload and the recovery time, adaptation allows the body to become fitter, stronger or faster. In the competition scenario, however, there may be less control over the work to recovery ratio. A simpler but more realistic goal may be to face the next opponent, or the next round or stage in a competition, in the best shape possible.

Recovery encompasses a complex range of processes which include:

refuelling the muscles and liver of their expended energy;
replacing the fluid and electrolytes lost in sweat;
allowing the immune system to handle the damage and destruction caused by the exercise bout; and
manufacturing new proteins, red blood cells and other cellular components.

In other words, although an athlete may appear to be 'resting', a lot of activity is occurring within the body. The traditional approach to recovery is a passive one—'let it happen'. Other athletes take an even less effective route—the 'make it even harder approach'. This might involve activities such as drinking excessive alcohol, further heat exposure via sun or saunas despite already being overheated, or failing to get sufficient rest or sleep. Such activities hamper recovery processes and/or add to the damage that must be repaired.

The best approach is a proactive recovery. In dietary terms, this means providing the body with all the nutrients it needs, in a speedy and practical manner, so that refuelling, rehydration, repair and regeneration processes are all optimised. Where specific recovery processes have been identified and studied, clear nutritional guidelines can be stated. This is the case for rehydration and refuelling. Unfortunately, the post-exercise workings of the immune system, protein metabolism, anti-oxidant defence and many other issues relating to recovery remain unclear. This chapter will outline the guidelines that can be made with a good degree of certainty, and include a safety margin for ideas that are intuitively sensible. Future research will help to fill in the gaps.

REFUELLING

The muscle biopsy technique, introduced into sports science research in the 1960s, has made possible a large number of studies of muscle glycogen storage. Thanks to this technique, a number of factors that promote speedy resynthesis of the carbohydrate stores in a depleted muscle have been identified (see Table 14.1). Not surprisingly, athletes have been less willing to submit to having needles poked into their livers, so there have been few direct studies of the 'ins and outs' of liver glycogen storage in humans. However, it is known that the liver can deplete and restore its fuel levels quickly—it can empty after a few hours of heavy exercise, or after 10–12 hours without food (eg overnight). But it can also rapidly refuel within two to four hours after a high-carbohydrate meal. After exercise, the body gives priority to the recovery of muscle glycogen stores over liver stores. In fact, if the athlete does not eat carbohydrate immediately after exercise, the liver will work hard to convert compounds such as lactate and amino acids into glucose, and promote a low rate of muscle glycogen recovery. However, muscle refuelling is best achieved by supplying the body with carbohydrate-rich foods and drinks.

TABLE 14.1

Factors affecting muscle glycogen recovery

Factors which enhance the rate of recovery

Depleted stores—the lower the stores the faster the rate of recovery.
Immediate intake of carbohydrate after exercise. Adequate amounts of carbohydrate:

—1–1.5g CHO/kg BM within 30 minutes after exercise
—7–10g CHO/kg BM per 24 hours.

Focus on carbohydrate-rich foods with a high glycaemic index.

Factors which have minimal or no effect on the rate of recovery

Gentle exercise during recovery.
Spacing of meals and snacks (provided the total amount of carbohydrate is adequate).
Other food at meals (eg fat- or protein-rich foods) provided that the total amount of carbohydrate is adequate.

Factors which slow the rate of recovery

Damage to the muscle (contact injury or delayed-onset muscle soreness caused by eccentric exercise).
Delay in intake of carbohydrate after exercise.
Inadequate amounts of carbohydrate.
Reliance on carbohydrate-rich foods with a low glycaemic index.
High-intensity exercise during recovery.

THE MUSCLE BIOPSY

For subjects who have taken part in sports science studies, a muscle biopsy scar is something like a badge of honour or courage. Certainly, it is an invasive process and not many athletes like the sight of needles. However, in skilled hands, a muscle biopsy is a safe and relatively painless procedure, and has assisted scientists towards greater understanding of exercise metabolism. Today it is just one of a number of techniques used to study fuel usage and exercise performance. But in the 1960s when exercise scientists began to experiment with muscle biopsies, it allowed great leaps in 'proof' or support for certain exercise science theories. Muscle glycogen levels were one of the first factors to be measured and manipulated by different diets and training programs. Once it became possible to monitor changes in muscle fuel levels before and after exercise, scientists were able to correlate endurance capacity with the size of glycogen stores, and fatigue with fuel depletion. Today, many features of the muscle can be measured from tiny muscle samples.

Before a muscle biopsy is performed, a small amount of local anaesthetic is injected just under the skin. Once the area is numb, a scalpel is used to make a small incision in the skin and underlying muscle fascia (muscle sheath). The size of the biopsy needle is determined by the amount of muscle that is needed—tiny samples from 10 to 100 mg are typical—but is generally thinner than a ball-point pen. The biopsy needle is hollow, with a small 'window' at its end, and another smaller cylinder that slots inside it. This second cylinder has a sharp end or blade. Once positioned through the muscle fascia and into the muscle belly, a syringe can be attached to the outer end of the needle and some suction applied. This causes a small amount of muscle to be drawn into the window of the needle, which can be sliced off by dropping the inner cylinder with blade. With a relaxed subject and an experienced doctor, the sensation can vary from no feeling at all, to a deep pressure inside the muscle. Some exercise scientists have even been known to perform biopsies on themselves!

Scientists take samples from the major muscle groups involved in various exercise types—for example, from the vastus lateralis (quadriceps) of cyclists, from the gastrocnemius (calf) of runners, and from the deltoid muscles of swimmers. Some studies have required a muscle sample to be taken within seconds of finishing exercise or in the middle of a race. This requires expertise and good cooperation from the subject. Studies often program a series of biopsies to be taken to monitor changes in the muscle content of some compound over a short time period—for example, before and after exercise, or before and after recovery. Where possible, each sample should be taken from different sites—for instance, in opposite legs or through a new incision at least 3 cm from the first one. This is because the biopsy itself causes temporary damage to the muscle and can interfere with the storage of the compound that is being monitored at that site. A muscle biopsy generally leaves the subject feeling a deep bruise for 24–48 hours, and leaves a small scar which fades with time. However, as part of a well-conducted study it may also leave behind a new piece of information about the science of exercise.

Refuelling and the amount of dietary carbohydrate

The most important dietary factor affecting muscle glycogen refuelling is the amount of carbohydrate consumed. There is a direct relationship between the quantity of dietary carbohydrate consumed and post-exercise glycogen storage, at least until the muscle storage capacity has been reached. The daily upper limit for conversion of dietary carbohydrate into muscle glycogen appears to be 7–10 g of carbohydrate for each kg of body mass (BM)—or around 500–700 g of carbohydrate per day. This amount will vary between athletes according to the size of their muscle mass and other factors. However, when the aim is to maximise muscle glycogen storage, these are the carbohydrate intake targets to reach.

Refuelling and timing of dietary carbohydrate

Eating immediately after exercise also promotes speedy refuelling. The results of several studies have led to guidelines that the athlete should consume carbohydrate-rich foods and drinks, providing at least 1 g of carbohydrate for each kg BM (50–150 g of carbohydrate for most athletes) within 30 minutes of the completion of their exercise session. Since it is often difficult or unappealing to eat large meals after exercise, many athletes prefer to have a post-exercise snack and then ease back into a meal routine a couple of hours later.

One study by Dr John Ivy from the University of Texas has suggested that muscle glycogen storage is slightly enhanced during the first couple of hours of recovery, because exercise has left the muscle more sensitive and with a greater capacity to take up blood glucose. After a couple of hours these benefits dissipate, and glycogen storage slows to more typical rates. While this finding has received much publicity, the more important message is that unless or until carbohydrate is consumed, muscle refuelling is very slow. Optimal refuelling is important when the first exercise session has substantially depleted glycogen stores and the recovery period until the next session is short (eg less than 4–12 hours). Therefore, when minutes count, it makes sense to provide the muscle with an early supply of carbohydrate and promote glycogen storage at full capacity.

Over the day, it is not important whether carbohydrate is eaten as a series of small snacks, or as 'three square meals', provided that carbohydrate intake targets are met. Studies have shown that glycogen storage over 24 hours of recovery was similar when a high-carbohydrate diet was consumed as two huge meals or as seven smaller meals, or when four high-carbohydrate meals were redistributed into sixteen hourly snacks. The frequency of eating affects blood glucose and insulin profiles over the day, and each of these affect glycogen storage. So there may be some influence on muscle glycogen storage when it is working below its full capacity. However, if sufficient carbohydrate is consumed, this doesn't appear to be an issue. Whether the athlete prefers to 'nibble' their way through the day, or 'gorge' on a few larger meals, is a matter of individual preference and timetabling within a busy day.

Refuelling and type of carbohydrate foods and drinks

The choice of carbohydrate foods and drinks in the recovery diet is probably also more of a practical concern than direct physiological importance. Studies have found no difference in the rates of refuelling between liquid and solid forms of carbohydrate. However, there are confusing results from studies of carbohydrate food types, largely because researchers have looked at carbohydrate foods according to the 'simple' and 'complex' classification—a system that is unhelpful and somewhat misleading (Chapter 10).

Research involving the Australian Institute of Sport and Professor Mark Hargreaves has investigated the glycaemic index (GI) of carbohydrate-rich foods and recovery. One study compared post-exercise recovery on a high-carbohydrate diet composed of foods with high GI, with a diet of an equal amount of carbohydrate provided by foods of low GI. The high GI diet produced significantly greater glycogen storage during 24 hours of recovery from prolonged cycling (106 mmol/kg) compared with the low GI diet (71 mmol/kg). However, this does not provide a major change to sports nutrition education, because in real life athletes don't eat diets composed only of low GI carbohydrate-rich foods such as lentils, legumes, oatmeal and sweetened dairy foods. Although recovery nutrition guidelines can include an encouragement to focus on foods of higher GI, this is largely a reinforcement of typical eating patterns.

Since the major hurdle for most athletes is to consume sufficient carbohydrate—particularly immediately after exercise—the 'best' foods and drinks are those that lend themselves to these goals. Practical issues such as taste and appeal to the athlete are important factors to consider, especially when the athlete is hot and exhausted after exercise. Portability and ease of 'eating on the run' also need to be considered in a busy lifestyle. Athletes may favour 'compact' carbohydrate-rich foods and carbohydrate drinks, rather than bulky high-fibre food choices, in order to meet high carbohydrate intakes without feeling uncomfortably full.

Other nutrients and overall nutritional needs

It has been suggested that other nutrients eaten with carbohydrate-rich foods or meals could alter the rate of glycogen refuelling, primarily by changing blood glucose and insulin responses to meals. One study has reported that protein added to a post-exercise carbohydrate drink stimulates glycogen storage. However, subsequent research from the Australian Institute of Sport, using real foods, has shown that the protein and fat content of meals does not affect glycogen storage during 24 hours of recovery from prolonged exercise when adequate carbohydrate is consumed. The problem with eating large amounts of protein and fat in post-exercise meals, or recovery diets in general, is that most athletes will not have the stomach capacity or energy budget to consume their carbohydrate goals as well. Therefore, the advice to athletes is to focus on carbohydrate needs first, and look after other nutritional needs or concerns accordingly.

There may be other reasons for including protein and other nutrients such as vitamins and minerals in snacks and meals eaten immediately after exercise. These nutrients are important in other recovery processes—for example, repair and rebuilding activities and immune responses—and an immediate intake may be useful in promoting these activities. This issue is still awaiting research. In the long term, eating patterns must balance carbohydrate recovery goals with many other nutritional concerns. Choosing carbohydrate-rich foods that are also good sources of other nutrients can help to achieve a number of everyday nutrition goals simultaneously. In tricky situations, particularly during or immediately post-exercise, the practical aspect of meeting a carbohydrate need may be the first priority, and the nutrient content of carbohydrate foods or drinks may be of less importance. However, in the bigger picture of the everyday training diet, or competition seasons lasting over weeks and months, the focus on nutritious carbohydrate-rich foods and drinks makes good sense. With a little creativity, the athlete can find foods that are both practical and nutritious.

The panel on the following pages provides guidelines to eating for post-exercise refuelling which take all these factors into account.

GUIDELINES FOR PROMOTING POST-EXERCISE REFUELLING

Consume a high-carbohydrate meal or snack within 30 minutes of completing a strenuous exercise session. Be organised to have suitable food and drinks available—at the exercise venue if necessary.
Aim for an intake of typically 1.0–1.5 g of carbohydrate per kg BM (typically, 50–150 g of carbohydrate) immediately after exercise, and repeat after two hours or until normal meal patterns are resumed (see the panel on the following pages).
A daily carbohydrate intake of 7–10 g per kg BM (typically 400–700 g) is required to optimise muscle glycogen storage.
When carbohydrate needs are high, and appetite is suppressed or gastric comfort is a problem, focus on compact forms of carbohydrate—low-fibre forms of carbohydrate foods, sugar-rich foods and special sports supplements such as sports bars.
Carbohydrate-containing fluids are also low in bulk and may be appealing to athletes who are fatigued and dehydrated. These include sports drinks, soft drinks and fruit juices, commercial liquid meal supplements, milk shakes and fruit smoothies.
Low glycaemic index (GI) carbohydrate foods such as lentils and legumes may be less suitable for speedy glycogen recovery and should not be the principal carbohydrate source in recovery meals. This is generally not a problem, as typical Western diets are generally based on carbohydrate-rich foods of moderate and high GI.
Small, frequent meals may assist the athlete to achieve high carbohydrate intakes without the discomfort of overeating. However, organise your routine of meals and snacks to suit your individual preferences, timetable and appetite/comfort. As long as enough carbohydrate is consumed, it doesn't appear to matter how you space it over the day.
When gastric comfort or total energy requirements limit total food intake, high-fat foods and excessive amounts of protein foods should not be consumed at the expense of carbohydrate foods. Focus on high-carbohydrate foods and meal choices first.
Nutritious carbohydrate-rich foods and drinks may provide protein and other nutrients (vitamins and minerals) that are important in other post-exercise recovery processes. These will be important in the overall diet. Future research may show that intake early after exercise could enhance other activities of repair and rebuilding.
Muscle damage interferes with glycogen storage—this may be partially offset by increasing carbohydrate intake during the first 24 hours of recovery. Carbohydrate needs may also be increased if exercise is undertaken during the recovery period.

CARBOHYDRATE RECOVERY SNACKS AND MEALS

Each of the following selections provides approximately 50 g of carbohydrate. Eat one to three of these portions to ensure speedy recovery after a heavy exercise session, and repeat this pattern after two hours or until normal eating patterns have been resumed.

650–800 ml of sports drink
800 ml of cordial
500 ml of fruit juice, soft drink or flavoured mineral water
250 ml of carbohydrate loader drink
60 g packet of jelly beans or jube sweets
3 medium pieces of fruit
1 round of jam or honey sandwiches (thick-sliced bread and plenty of jam/honey)
3 muesli bars
1 large Mars bar or chocolate bar (70 g)
2 breakfast bars
3 rice cakes with jam or honey
2 crumpets or English muffins with Vegemite
Cup of thick vegetable soup with large bread roll
Jaffle/toasted sandwich with banana filling (using whole banana)
One sports bar (check the label to see total carbohydrate content)
115 g (1 large or 2 small) cake-style muffin, fruit bun or scones
330 g (1 cup) of creamed rice
300 g (large) baked potato with salsa filling
120 g (1–2 large) pancakes with 30 g syrup

50 g carbohydrate snacks which also contain at least 10 g of protein:

250–350 ml of liquid meal supplement
250–350 ml of milk shake or fruit smoothie
Some sports bars (check labels to see carbohydrate and protein content)
2 x 200 g cartons of fruit-flavoured yoghurt
Bowl of breakfast cereal with milk
200 g carton of fruit-flavoured yoghurt or fromage frais topped with 1 cup of breakfast cereal
250 g tin of baked beans or spaghetti on 2 slices of toast or in jaffle/toasted sandwich
1 round of sandwiches, including cheese/meat/chicken in filling, plus 1 piece of fruit
1.5 cups of fruit salad with 1/2 carton of fruit-flavoured yoghurt or frozen yoghurt
Carton of fruit-flavoured yoghurt and a muesli bar
2 crumpets or English muffins with thick spread of peanut butter
250 g (large) baked potato with cottage cheese or grated cheese filling
200 g thick-crust pizza
1 cup fruit crumble with 1/3 cup custard

Source: NUTTAB 1995, Australian Department of Community Services and Health.

REHYDRATION

Despite consuming fluid during exercise, most athletes will become mildly to moderately dehydrated. Studies show that most athletes typically replace between 30% and 70% of their sweat losses when they train or compete. More importantly, studies also report that even when the session is over and drinks are freely available, athletes do not fully replace their fluid losses. There can be a time lag of up to 24 hours before body fluid levels are competely restored. And in cases of severe fluid losses, or a sudden change to a hot or high-altitude environment, athletes may carry a fluid deficit from one day and one training session to the next. This is clearly not conducive to optimal recovery or peak performance in future exercise sessions. Ideally, an athlete should aim to fully restore fluid losses between exercise sessions. Difficulties arise when the fluid deficit is moderate to high (2–5% of BM or greater) and when the recovery interval is less than six to eight hours.

One aspect of post-exercise rehydration is to ensure that the athlete consumes an adequate intake of fluid. However, there is an additional challenge. During recovery, the athlete will continue to lose fluid—partly due to continued sweating, but mostly through urination. The athlete will need to plan their fluid intake to account for physiological issues, such as overcoming inadequate thirst responses and minimising urine production, as well as practical difficulties such as poor opportunities to drink.

Making athletes drink—is thirst sufficient?

Thirst is not a sensitive and reliable indicator of dehydration. Most people are already mildly dehydrated (2% of BM) before they even feel thirsty. And then when they drink, thirst shuts off before fluid needs are fully replaced. In addition, there appears to be considerable individual variability in the reaction to thirst—some people are 'big drinkers' when they are dehydrated, while others are reluctant to drink much at all.

What is on offer to drink makes a difference to how much fluid a dehydrated athlete will consume. Factors such as the taste, general palatability and temperature of a fluid can all influence the volume that is drunk. It is hard to know each person's individual preference, but a sweet taste appears to be attractive to most. A small amount of salt (sodium) also enhances the palatability of drinks offered to people who are dehydrated after exercise. Sports drink companies spend millions of dollars to find a taste profile that is appealing, and it appears to be money well spent. A study from the Exercise Research Laboratory of Professor Carl Gisolfi at the University of Iowa measured voluntary fluid consumption in dehydrated athletes after they had sweated 2% of BM by cycling in the heat. On two occasions, these cyclists were observed during three hours of recovery, while they rested, and were given free access to fluids. When the choice was water, subjects drank enough to replace 63% of their sweat losses. However, on the other occasion when sports drink was offered, total fluid consumption was significantly greater—replacing 79% of sweat losses. Interestingly, on neither occasion did the athletes fully meet their fluid needs. It is a paradox that advertisements for many sports drinks promote them as 'thirst quenchers'. In fact, the ideal sports drink should probably be the opposite! It should keep the athlete thirsty so that they want to keep drinking. Better rehydration for the athlete; better sales and profits for the company.

The temperature of a drink also seems to be an important factor in encouraging intake. When an athlete is hot and sweaty, a cool drink is more welcoming than luke-warm or hot fluids. However, sometimes the perception of palatability and actual intake may not always go hand in hand. Studies suggest that while very cold water (0°C) might be rated as the most pleasurable drink, it is hard to quaff in large quantities. Therefore, cool drinks (10–15°C) are likely to promote greater intake.

Rehydration and urine losses

Urine is produced to help eliminate the body's waste products, and to keep body water and electrolyte concentrations in balance. An obligatory urine loss occurs over the day for this first purpose. When athletes sweat, they lose water and a small amount of electrolytes—principally sodium. Exercise dehydration produces a reduction in total body water and blood volume, and a mild increase in blood concentration and sodium content.

Consuming large amounts of plain water after exercise causes dilution of blood contents, before the entire blood volume has been restored. In order to preserve blood concentrations within healthy limits, the body shuts off thirst to stop the athlete drinking, and produces urine to reduce the dilution. In effect, the athlete can produce large amounts of dilute urine, even though they are still dehydrated. However, by consuming some sodium in the rehydration fluids, volume and concentration can be restored in better harmony, without the need for excessive urine production.

Professor Ron Maughan, an exercise physiologist from Aberdeen in Scotland, recently conducted a series of elegant rehydration studies. In his trials, athletes exercised to dehydrate by approximately 2% of BM and were then required to consume a specified quantity of fluids of varying compositions. Urine production and the restoration of blood volume and contents were monitored over six hours of recovery. Figure 14.1 shows the effect of the sodium concentration of various drinks on urine production and fluid balance. Low-sodium drinks (those containing either no or small amounts of sodium—25 mmol/L) produced significantly greater urine losses than drinks with higher sodium concentrations (those containing 50 and 100 mmol/L sodium). By the end of the recovery period, the difference in total urine production amounted to approximately 800 millilitres. With the low-sodium drinks, subjects were still dehydrated despite having consumed volumes equal to 150% of their fluid deficits. Studies from other laboratories have confirmed that until sodium losses are replaced, even forced intake of large volumes of water will not restore fluid balance after dehydration. Instead it will merely result in more urine production. This can be confusing for the athlete who thinks it is a sign of overhydration. And it can interfere with sleep patterns if the athlete has to continually get up in the night!

FIGURE 14.1

Effects of adding sodium (salt) to rehydration drinks. These measurements were taken six hours into recovery after subjects had dehydrated (about 1.3 litres) and then consumed large volumes (about two litres) of various drinks

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Source:

Maughan, R.J. and Leiper, J.B. 'Sodium intake and post-exercise rehydration in man', European Journal of Applied Physiology, 71: 311–19, 1995.

Some fluids exacerbate urine losses in other ways. Caffeine and alcohol exert a diuretic effect on the body—that is, they increase urine production. A study from Professor Ed Coyle's laboratory at the University of Texas compared the efficiency of rehydrating after exercise with a sports drink (containing a small amount of sodium), water (no sodium) or a diet cola (no sodium, plus caffeine). Subjects were made to consume a volume of these drinks equal to their fluid deficit (2.5% of BM), and were monitored over two hours of recovery. The diet cola resulted in increased urine losses and a retention level of only 54% of fluid lost, while the sports drink (73% retention) was slightly superior to water (65% retention), probably due to its higher sodium content.

Professor Maughan has also studied post-exercise rehydration with alcoholic beverages of 1–4% alcohol content and showed increased urine losses with the higher alcohol drink. This confirms the experience of many athletes who have found themselves making frequent visits to the bathroom while 'recovering' their fluid losses at a local hotel. While it is sometimes said that alcohol and caffeine drinks 'dehydrate' the athlete, this is not strictly true. When consumed, they add fluid to the system and improve hydration levels. However, the increase in urine losses compared to other drinks means that they are less efficient and effective as recovery fluids. When the situation calls for speedy rehydration, better fluids can be found.

A recipe for fluid replacement

When fluid deficits are greater than 1.5–2 litres, the athlete should consider both a plan of drinking and a considered choice of fluids. The 'ideal' will depend on the athlete and the situation. It appears sensible to actively replace sodium losses when the fluid deficit is significant and the time for rehydration is short. Common examples are when the athlete has dehydrated to 'make weight' before competition and there is only an hour or two between the weigh-in and the event, or where an athlete has just finished one event (eg a singles match in a tennis tournament) and the next session is scheduled within hours (eg a doubles match).

If a meal or snack is eaten during this time, it is useful to include high-sodium foods or to add a little salt to what is consumed. Bread, breakfast cereals and pretzels are examples of carbohydrate-rich foods with a signficant salt content. Alternatively, salt may be provided in the sauces, fillings or dressings added to carbohydrate-rich foods. Commercial oral rehydration solutions provide a ready-made fluid and salt replacement alternative when solid food cannot be eaten. Typically they have a sodium concentration of 50–90 mmol/L (2–5 g or a teaspoon of salt per litre) which is specifically designed to maximise rehydration in clinical settings such as following gastrointestinal upsets. However, they taste quite salty—beyond the usual taste preferences of most people—and the athlete needs to be encouraged to drink a set amount of such drinks rather than leave it to voluntary intake. Sports drinks contain smaller amounts of sodium (10–25 mmol/L) and may promote more efficient rehydration than plain water. However, additional sodium intake from food sources may be necessary over the next hours to correct the final body fluid/sodium balance. In most situations in Westernised countries, people consume sodium far in excess of their requirements. Therefore, with time and food intake, balance will be restored.

The most important issue for most athletes is to drink fluid in sufficient quantities—in excess of their fluid deficit and their thirst. Setting targets of intake and keeping a supply of fluids on hand are practical strategies that will assist in this goal. The panel on the following pages summarises guidelines for post-exercise rehydration.

GUIDELINES FOR PROMOTING POST-EXERCISE REHYDRATION

Drink to a plan rather than relying on thirst or opportunity. The 'hit or miss' approach may be acceptable when fluid deficits are one litre or less, but when fluid losses are greater, there will be more 'miss' than 'hit'.
Monitor changes in body mass from pre- to post-exercise to evaluate the success of drinking strategies during exercise, and the residual fluid deficit that must now be replaced. A loss of one kilogram equals a fluid deficit of one litre.
Remember that you will continue to lose fluid during recovery via urine losses and ongoing sweating, and that these losses must also be replaced. Typically you will need to consume about 1.5 times the volume of your post-exercise fluid deficit over the subsequent two to four hours to fully restore fluid balance.
Ensure that an adequate supply of palatable drinks is available. This may be difficult when you are at a remote competition venue, or travelling in a country where bottled water must be consumed instead of the local water supply.
In situations where you need to encourage fluid intake, try a flavoured drink rather than plain water. Most people prefer sweet-tasting drinks.
Keep drinks at a refreshing temperature to encourage greater intake. Cool drinks (eg 10–15°C) are preferred in most situations. Very cold fluids (0–5°C) may seem ideal when the environment or the athlete is hot; however, it is often challenging to drink them quickly.
Carbohydrate-containing drinks are also useful in assisting with refuelling goals—you can tackle a number of recovery goals simultaneously.
Replace sodium losses to help maximise the retention of ingested fluids by minimising urine losses. Options include sports drinks, commercial oral rehydration solutions, salty foods, or salt added to post-exercise meals. This is particularly important when fluid deficits are greater than 2–3% of BM or 2 litres. A high-sodium beverage such as an oral rehydration solution (50–90 mmol/L or 2–5 g of salt per litre), or salt added to post-exercise meals, may be the best way to guarantee efficient and rapid rehydration after significant fluid loss.
Caffeine-containing fluids (eg cola drinks) and alcohol are not ideal rehydration beverages since they may increase urine losses.
Where possible, avoid post-exercise activities that exacerbate sweat losses—for example, long exposure to hot spas, saunas or the sun.

A FEW WORDS ABOUT ALCOHOL AND RECOVERY

It is hard to imagine the end of a Grand Prix race or a premiership final without champagne spraying from the victory dais. Alcohol and sport are closely linked—sponsorship money plays a big part in making many sports possible. And while there is no necessity to include alcohol in an athlete's diet, neither is there any reason to exclude it totally. One of the unfortunate ways that alcohol has been linked to sport is in the post-event (or post-training) drinking binge. Whereas once every now and again there may be a special celebration that warrants the inconvenience of a sore head the next morning, some athletes repeat this pattern at frightening frequency and with frightening ferocity, and to a level that affects their heath, other people and their performance—in both the short term and the long term.

In some sports, but notably team sports, the tradition is to 'relax' and 'celebrate' or 'commiserate' the outcome by drinking alcohol together. This is often undertaken when the athlete is dehydrated and hasn't eaten for a number of hours, thus potentiating the absorption and effects of the alcohol. Often good sense goes out the window after a couple of drinks, and in a spirit of camaraderie or even competition, the athlete may overindulge considerably. There are many rationalisations about its benefits ('team bonding') and acceptability ('everybody else is doing it'), and minimisation of the disadvantages ('I can run it off the next day').

However, alcohol is a drug and, in large amounts, a poison. Excessive intake causes harm to the body—depending on the frequency and the level of the dose. It impairs the physiology of body recovery processes in a number of ways, including:

vasodilation—swelling of blood vessels—and a likely increase in the fluid accumulation in damaged tissues;
increased urine losses, thus reducing the rate of rehydration (see above); and
interference with metabolic processes, such as glycogen recovery in the liver and perhaps muscle.

Most importantly, however, it interferes with good judgment and common sense. Athletes who are drunk rarely undertake the guidelines for recovery eating and drinking well—it simply isn't a priority. Alcohol may also have a small impact on the muscle's ability to store glycogen. But it has a major effect on whether the athlete cares about, and is capable of, meeting their carbohydrate intake goals. Most athletes fail to eat sufficient fuel-replacement foods when they are drinking—they drink rather than eat, or choose unsuitable high-fat takeaway foods. Carbohydrate intake is also sacrificed the next day as they sleep off their nausea and hangovers. In other words, recovery is considerably impaired and will affect the ability of the athlete to train (or compete) again the following day. Repeated occurrences of this pattern will greatly diminish the fitness and performance of the athlete. Ironically, the worst offenders are often professional team sports players who face the challenge of weekly (and sometimes, daily) competition, but appear to ignore the incentive of huge rewards and salaries for good performance.

Alcoholic binges cause the same poor compliance to matters of treating injury or muscle damage. In fact, they increase the chance of accidents and high-risk behaviour off the field. In many sports there have been an unfortunate number of fatalities and major injuries occurring from accidents and motor vehicle crashes after the game or competition, involving alcohol-impaired athletes. It would be a shame if the excitement and celebration of fantastic sporting performances couldn't be toasted! However, alcohol intake is definitely an area in which the athlete should know and respect their limits (see the following panel).

GUIDELINES FOR SENSIBLE INTAKE OF ALCOHOL AFTER SPORT

Avoid alcohol for 24–36 hours after sport or exercise that results in muscle damage or injury. Alcohol promotes vasodilation and may impair the recovery and repair processes.
Rehydrate and refuel as a first priority after intense exercise. Ban alcoholic drinks from the locker room and have appropriate drinks and snacks available instead.
Remember that alcoholic drinks (more than 4% alcohol) are not ideal rehydration beverages. Nor do they provide a significant source of carbohydrate. These 'myths' are often used as a rationalisation to approve/excuse the heavy alcohol intake of some athletes.
Once fluid and carbohydrate needs have been met, alcohol may be consumed in moderation. 'Drink-driving' education messages may provide a guide for sensible intake of alcohol.
The vasodilation caused by alcohol may increase heat loss in cold environments (eg in winter sports). Take care to stay warm in such environments.

POST-EXERCISE EATING—THE PRACTICAL CHALLENGES

In an ideal world the athlete would tackle recovery with hunger, enthusiasm, organisation and knowledge. And the ideal world would supply all the athlete's food and fluid needs within easy reach. Unfortunately, these conditions rarely coexist. Instead the athlete is faced with a number of practical challenges. Advice from a sports dietitian can provide specific ways to tackle the various obstacles. The following guidelines may provide some general ideas

PROBLEM	SOLUTION
Fatigue—the athlete is too tired and lacking motivation to obtain or prepare suitable meals and snacks.	1 Be organised and manage time well in order to have food ready to eat or requiring minimal preparation when you are most tired. Batch cook and store/freeze meals in convenient size portions. Prepare your meal before training. 2 Eat out.
Eating out requires time to find a restaurant and then wait for the meal to be ordered and prepared.	1 Pre-arrange the restaurant or catering so that a suitable menu is established and available immediately you arrive. 2 In large groups, arrange buffet-style catering for quick service and to allow athletes to choose the individual type and quantity of food they need.
Poor access to suitable foods immediately after exercise: a The athlete must travel a significant distance to their home base. b The competition or training venue does not provide (suitable) food and drinks.	1 Bring suitable foods/drinks to the venue. Portable carbohydrate-rich snacks include sandwiches, sports bars and sports drinks, liquid meal supplements, breakfast cereal, fruit, flavoured yoghurt, dried fruit and rice cakes. Have a snack, and top up later with a more substantial meal when access to a better range of foods is possible. 2 Organise 'team' snacks or meals where teams or clubs of athletes face similar problems. 3 Take over or assist the venue catering/kiosk to improve their menu.
The athlete is too tired to eat or has a reduced appetite after intense exercise.	1 Choose a snack rather than a meal, and choose foods according to the environment and your appetite. When you are hot and sweaty, foods that are cool and high in liquid content may be most appealing. These may include juices, sports drinks, fruit smoothies and milk shakes, liquid meal supplements, or flavoured/frozen yoghurt. In cold weather, a hot soup, toasted sandwiches or pizza squares may be appetising. 2 Offer food in 'bite-size' pieces rather than overbearing amounts. Fruit portions, sandwich fingers or small pizza squares may tempt a tired and timid appetite.
The athlete's attention is demanded by other post-event activities—coaches' post-mortems, media interviews, drug tests, equipment handling, watching other events, etc.	1 Look after first things first! 2 Choose foods and drinks that are portable and can travel along to other post-event activities.
The post-competition tradition is to celebrate or commiserate the results.	Look after first and important things first, and don't worry about what everyone else is doing. Stick to your recovery goals and then join in (sensibly) later.

TO IV OR NOT TO IV? THERE SHOULD BE NO QUESTION

You may have noticed dehydrated and heat-stressed athletes in the medical tents of marathons and triathlons receiving intravenous (IV) fluids to manage their medical problems. However, in recent years there has been a growing interest by athletes in using IV feedings as a recovery tool rather than a medical treatment. It has become trendy in tennis tournaments, stage cycle races and other multi-day sports events for athletes to request an IV to speed their recovery for the next day's performance. Some professional athletes and teams make their own arrangements for this. But medical directors of some races—for example, Ironman triathlon events—see healthy athletes walking into their medical tents and asking for an IV to boost their recovery.

Standard intravenous fluids provide saline (water and sodium) in various concentrations and, sometimes, a low level of glucose. In medical practice they are used to correct fluid, electrolyte and carbohydrate deficits in people who are unable to do this by eating and drinking. If someone is unconscious, asleep or has a non-functioning gut (eg has severe vomiting, diarrhoea or gastric shut-down), an IV drip provides an alternative and effective means of getting fluid and carbohydrate into the body. In rare medical cases, people may receive substantial nutrition via IV means. And the solution may also contain lipids, amino acids, vitamins, minerals and trace elements. However, this is expensive, and carries a high risk of infection and nutritional imbalances. Such nutrient-rich solutions generally have to be given via a large 'central' vein rather than a peripheral arm vein, since the concentration may cause a small vein to collapse. This is more trouble.

It might sound dramatic and state-of-the-art for an athlete to receive intravenous fluids or intravenous nutrition after prolonged intensive exercise. Many athletes claim that it makes them feel better and helps them to recover more quickly. However, most race medical directors dispute that this is anything more than a placebo. They counter that the main benefits are the novelty and attention, and being forced to lie still for one to two hours after the event. Many are reluctant to provide these services to healthy athletes, particularly if this ties up resources and attention that are required for athletes with real medical problems arising from the race.

It is possible that IV fluids may even be worse than 'low-technology' drinking. A recent study from Dr Larry Armstrong's group at the University of Connecticut in the United States showed an interesting difference in the outcome of oral and IV rehydration. Males were dehydrated by 4% of BM by two to four hours of mild exercise, then rested for a couple of hours. During this recovery period they either received no fluid, drank 1900 mls of (saline) fluid, or were infused with 1900 ml of IV saline. Then it was back to mild exercise (walking at 50% VO_2max) in the heat. Although all exercise was conducted at the same intensity, the subjects rated the experience without fluid replacement as the hardest, and reported being 'very, very thirsty'. This is hardly surprising. However, subjects reported feeling thirstier and having to work harder at the exercise following IV rehydration compared with the trial after oral rehydration. One explanation is that the sensation of drinking—having cool liquid pass from your mouth into your stomach—sends important signals to the brain about thirst. And this may impact on how you feel during subsequent exercise. So, it may not be enough to top up plasma and other body fluids. To fully benefit, all of your body needs to join in the experience. Whether this holds true for athletes working at higher intensities, and whether it affects performance, needs further investigation.

There is also the issue of fluid overload. Some athletes finish ultra-endurance events with low blood sodium levels. This is generally associated with overhydration, rather than dehydration. And in some cases the athlete appears to have a kidney malfunction which stops excess fluid from simply being urinated out. It can be dangerous—even fatal—to pour litres of fluid into such athletes.

The bottom line for someone who has just finished a marathon or ultra-distance triathlon is that there is little real need to be concerned about aggressive, abnormally-delivered recovery nutrition. Particularly when there is adequate time for rest and recovery before the next exercise session, and they are perfectly capable of eating and drinking, and absorbing the nutrients and fluid provided.

But what about the athlete who is in the middle of Wimbledon or the Tour de France? It is likely that this athlete has a lot on the line, is severely fluid- and fuel-depleted from one day's effort, and has a date to do it all again the next day. Some of the components of the secret IV formulae reportedly used by pro-cyclists are unstudied and of dubious benefit. But there is still no proof that even the basic ingredients of IV preparations are of special help in recovery. Studies need to be undertaken before we will know if IV carbohydrate promotes faster glycogen storage than dietary carbohydrate, or whether IV fluids promote superior rehydration to post-event drinking.

No doubt there is a psychological edge from using an IV during these recovery challenges. And there may also be a practical edge. It is often hard to juggle the priority of eating and sleeping during busy competition schedules. With an IV the athlete can be given a known amount of fluid and carbohydrate, and be 'consuming' these while sleeping. The last word is that if IV recovery is used, medical supervision and strict control over the conditions in which it is given are essential.

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The Department of Sports Nutrition is a program of the Australian Institute of Sport
at the Australian Sports Commission
Leverrier Cres Bruce ACT 2617
PO Box 176 Belconnen ACT 2616
Telephone: 02 6214 1109 Facsimile: 02 6214 1603

General enquires can be emailed to: aisnutrition@ausport.gov.au