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Nutrition and Performance in Sport

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Christophe Hausswirth

Chapter 2. Nutrition, sport and health

Topic 9. Overload

Yann Le Meur, Amélie Fosse, Christophe Hausswirth, Axel Heulin, Véronique Rousseau, Eve Tiollier et École Lenôtre

Texte intégral

Questions and answers

Key points
Repeating training sessions several times per day can cause overreaching in high-level athletes. Although this constitutes a normal step in the training process leading to high-level sports, respecting some nutritional strategies can help the athlete to postpone the onset of overreaching.
In this respect, it is very important to:
increase daily carbohydrate intake (from 7 to 10 g.kg−1) in line with the amount of training, and make sure carbohydrate is consumed during and immediately after training;
consume iron-rich foods three to five times per week;
increase antioxidant intake;
increase the daily protein intake from 0.3 to 0.5 g.kg−1 if there is an increase in muscle pains;
plan probiotic supplementation to reduce the risk of infections.

How can an adapted diet help the athlete to better tolerate the amount of training and the stress endured daily?

1In many sports disciplines, achieving peak performance requires a very heavy training load, which greatly taxes the athlete’s psycho-emotional resources. Even if it is normal to experience fatigue when training like this, fatigue can become a problem when it exceeds the athlete’s recovery capacity. This is when overreaching appears: the athlete cannot regain their initial performance level, despite a recovery period of several days, or even several weeks. Hence some studies have investigated how modifying food intake can accelerate or delay the appearance of over-training symptoms (decrease in performance levels, muscle fatigue, sleep disorders, irritability, etc.). Here, we are going to detail the characteristics of a diet which can help the athlete to tolerate a training load that is periodically increased and challenges their recovery and adaptation capacities.

What food should the athlete favour daily when the training load is high, inducing a sensation of loss of energy?

2Carbohydrates are the athlete’s primary source of energy; this is why it is necessary to make sure the intake is sufficient to maintain muscle and liver glycogen stores. Indeed, if these are depleted, physical performance will decrease along with cognitive capacities (increased reaction time, decreased capacity of concentration, etc.). Since insufficient carbohydrate intake can lead, in the medium term, to the onset of over-training, it is necessary to adapt the carbohydrate amount provided by food every day to the amount of training.

3Various studies have shown that the level of performance of trained athletes decreased significantly when they had to repeat a performance several days in a row without adequate carbohydrate intake to balance their daily energy expenditure. Therefore, during training courses or competitions lasting several days, when the amount of training increases, starch and cereal intake must be increased during meals. In athletes with small appetites, this increase in carbohydrate intake can be provided by increasing the number of meals eaten during the day.

4Iron is a mineral used by the body to make red blood cells, it contributes to the production of haemoglobin, which carries oxygen around the body. This is why iron deficiency reduces the athlete’s performance capacity, while also increasing the risk of infections. Iron deficiency is associated with a high level of training and accelerates the appearance of general fatigue and a reduced capacity to perform exercise. Women are particularly exposed to this problem, because of the increased iron requirements caused by menstruation and, in some cases, insufficient food intake.

5To reduce the risks of deficiency, the athlete’s diet must combine foods rich in assimilable iron and sufficient vitamin C. It is important to underline that the intestine only absorbs 2 to 10% of iron contained in vegetables, versus 10 to 35% of iron from animal sources. Interestingly, increasing meat consumption preserves iron status in female athletes more efficiently than iron supplementation using commercial preparations.

Why is post-training food essential to accelerating carbohydrate replenishment and limiting the onset of chronic fatigue?

6Carbohydrate intake and its precise timing during recovery significantly influence the quality of glycogen resynthesis (which corresponds to the body’s carbohydrate store). Because of this, food management is crucial in sports requiring significant energy expenditure (team sports, endurance events, etc.), as well as in disciplines where athletes must do several trainings per day. The earlier carbohydrate is consumed after the end of exercise, the greater the amount of muscle glycogen resynthesized. Therefore, when carbohydrates are consumed immediately after exercise, the amount of glycogen measured in the muscle six hours later is greater than when the intake is timed two hours after the end of exercise.

7This is why, when athletes train twice a day, they must eat just after the end of the training period. Of course, this strategy mainly applies to high-level athletes. For those who do not train more than once a day, it is less important to consume carbohydrates immediately after exercise. Rather, these athletes should eat a meal or snack containing a larger carbohydrate portion than a normal meal or snack.

8The speed of glycogen resynthesis is strongly influenced by the carbohydrate composition of the post-exercise snack. During recovery, it remains identical after ingestion of glucose, whereas it slows down with other sugars, such as fructose, contained in fruit. Administering carbohydrates with a high glycaemic index is thus the best strategy when seeking to optimize glycogen resynthesis. Adding proteins also accelerates muscle glycogen resynthesis (see Fact sheet No. 1 Energy recovery, p. 235).

What food should the athlete favour to promote muscle recovery despite a high training load?

9In sports characterized by a high level of mechanical constraint (strength, sprints, combat sports, etc.) the accumulation of training sessions or competitions can generate significant muscle fatigue characterized by a temporary decrease in the quality of strength, explosive power or overall power, sometimes associated with intense pain. Recovery from this can exceed 24, or even 48 hours. Under these circumstances, fatigue is more due to mechanical constraints generated by sporting activity than due to depletion of the body’s energy reserve. The role of nutrition in this context is to accelerate regeneration of the various tissues damaged during training. An inappropriate diet is associated with a high level of training, presenting various risks for the athlete, from a straightforward pulled muscle or tendinitis to a muscle tear or stress fracture.

10To combat this, the protein provided by food is essential for the athlete as it favours repair of microlesions caused by exercise, as well as psychological adaptations stimulated by training. Thus, the athlete’s protein requirements are increased when expressed relative to body weight (in grams of proteins per day, per kilogram of body weight). However, when expressed as a proportion of the total energy intake, the level is equivalent to that for the general population. Therefore, athletes should keep in mind that their meals must always contain sufficient protein for their build, all the more so when their training generates significant muscle damage because of increased levels of constraint: return to training, significant bodybuilding cycle, increase in training load, etc.

11In addition, various studies reveal that the period following training is particularly favourable to protein assimilation and the instantaneous implementation of muscle regeneration mechanisms. When proteins are consumed with carbohydrates, the insulin reaction (which inhibits protein degradation and increases the assimilation of amino acids into muscles) is enhanced, and the return to a positive protein balance post-training is quicker. Immediately after the end of training or a competition, a snack containing both protein and carbohydrate should be eaten; this is a clever nutritional strategy when the level of muscle solicitation is high and when it is necessary to keep training or to repeat a performance. A complementary protein intake can be provided by a protein-enriched snack, or in the form of industrial supplements, particularly when the athlete wishes to maintain their muscle mass and the training load is particularly high. One disadvantage of foods enriched in animal proteins is that they increase the lipid and nucleic acid intake. On the contrary, supplementation based only on proteins of vegetable origin present a risk of relative lysine and sulphur amino acid deficiency. Very often, in a sports environment, complementary protein is provided by industrial preparations of total proteins, protein hydrolysate, or amino acid combinations. The composition of these preparations of essential amino acids must be studied carefully: indeed, they must respect a certain balance, as amino acid deficiency is a factor limiting protein synthesis. Finally, consuming low-fat milk (skimmed or semi-skimmed) is also an interesting and low-cost post-exercise strategy favouring post-exercise anabolism.

12Endurance sports: prolonged exercise, which significantly activates energy resynthesis through oxidation, increases the production of unstable molecules, known as free radicals. These can cause significant muscle damage when the amount of training is high. Most free radicals are by-products of the cell’s normal energy production process. Free radicals are the body’s equivalent to exhaust fumes from a car: the more active an individual is, the more free radicals will be produced.

13Antioxidants are substances which neutralize free radicals. Our diet contains many, such as vitamins A, C and E, some trace elements (zinc, copper and selenium) and other components (carotenoid, flavonoid, coenzyme Q10, etc.). Given that high-level athletes present a high risk of antioxidant deficiency, we must insist on the fact that including fruit and vegetables in the diet maintains a balance appropriate to requirements. Therefore, it is essential that athletes who training intensely be aware of the advantage of consuming a lot of fruit and vegetables.

What foods should be favoured or avoided when the training load affects sleep quality?

14Foods to favour: many studies have investigated the relationship between dietary adaptations and sleep. Their results suggest increasing the availability of tryptophan, the precursor of serotonin, a neuromediator involved in sleep. However, very few foods, as such, have been studied to determine whether they favour sleep.

15In this context, we should remember the effect of carbohydrates with a high glycaemic index consumed in the evening. Experimental results show that this type of meal decreases the time it takes to fall asleep. The moment when they are ingested is also important: the beneficial effects are enhanced if the meal is taken four hours before going to bed rather than one.

16Other studies chose to give athletes tryptophan directly, in supplement form rather than as part of food. The best food source of tryptophan is milk, and carbohydrate consumption creates a hormonal environment favouring its entry into the brain (where it can be used for serotonin synthesis). On the contrary, eating protein (meat, fish, eggs) reduces the availability of tryptophan in the brain and favours the synthesis of other neurotransmitters such as dopamine and noradrenaline, which have stimulating effects.

17Other foods which are thought to have calming effects include plants like valerian, hops, lemon, hawthorn, passionflower, etc. Among these, the one that has been the subject of most research is valerian. However, the results obtained were contradictory up to now and we cannot definitively affirm that this plant promotes sleep. Nevertheless, if consumed as an infusion, these plants can help promote sleep through two effects: on the one hand, a behavioural effect, when this habit is part of the bedtime ritual and on the other hand, through its action on core body temperature. Drinking a hot beverage decreases the core temperature, which is required for good sleep. Similarly, it should not be forgotten that a glass of sweetened hot milk combines three conditions promoting sleep: tryptophan intake (milk), favourable hormonal context (carbohydrates) and decrease in internal temperature (hot beverage).

18Foods to avoid: to favour sleep, it is better to avoid hearty dinners and to reduce the consumption of stimulants such as coffee, tea, cola drinks and energy drinks as far as possible. Drink alcohol at night is not recommended. Even though its anxiolytic effect favours the onset of sleep, alcohol adversely affects sleep quality during the second part of the night, by prolonging the light sleep phase, favourable to night awakenings. In addition, alcohol has a diuretic effect which may increase the need to get up during the night to urinate. Finally, alcohol also triggers snoring and sleep apnoea (see Fact sheet No. 13 Effects of alcohol, p. 381).

19It is also worth noting that eating large amounts of protein (meat, fish, eggs) in the evening does not facilitate sleep, because of the negative effect it has on serotonin synthesis, mentioned above. However, even though this has been demonstrated at a neurochemical level, it remains to be proven at the behavioural level.

How can food limit the risks of infection linked to intense training periods?

20Several scientific studies have shown that the onset of overreaching was often accompanied by a decrease in immune protection, associated with a concomitant increase in the risk of infections. The immune system is complex and requires a well-defined nutritional environment to function optimally. Some micronutrients are essential for this (see Fact sheet No. 8 Immunity, p. 317). In terms of vitamins and minerals, vitamin A, some B vitamins (B6, B9, B12), vitamins C, D and E are necessary, as well as zinc, iron, copper and selenium.

Practical applications

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1. In everyday life

Maintain a positive energy balance...

Image 10000000000000230000001F5B2871AD.jpgTo cover your needs in vitamins and minerals, make sure you are getting more than 2000 calories per day

21 Check your weight regularly, and always weigh yourself in the same conditions (in the morning, on an empty stomach)

22 Don’t forget that overload can affect appetite

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... and vary your food

Adjust your energy balance

23 Adapt your starch intake to meet the needs of your physical activity each day

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24 Distribute your carbohydrate intake (meals and snack) depending on what sort of training you have each day

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25 Make sure your food provides enough iron

Image 10000000000000230000001F5B2871AD.jpgIron deficiency results in significant fatigue

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2. During intense training periods

Image 10000000000000230000001F5B2871AD.jpgTo maintain a positive energy balance, increase the number of meals eaten

Before the training session

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During the training session

26 If your training lasts more than 1 hour, have a sports drink

27 Adapt the concentration of your sports drink based on the temperature conditions (See Fact sheet No. 10 Hydration, p. 342)

28 Take little sips every 15 to 20 minutes

After the training session

29 Training with high energy expenditure (endurance, long training sessions) (See Fact sheet No. 1 Energy recovery, p. 235)

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30 Training involving a high level of muscle solicitation (bodybuilding, strength sports, combat sports, speed sports) [See Fact sheet No. 1 Energy recovery, p. 235]

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Make sure you get enough antioxidants

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Image 10000000000000230000001F5B2871AD.jpgDo not start a restrictive diet during an intense training period

3. Warning signs

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Image 10000000000000230000001F5B2871AD.jpgIf you practise good food hygiene, but one or several symptoms persist, talk to your coach about it and consult a doctor

Recipe

Linguine with clams and squid

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Photo credit: Thibaut Ruggeri.

31Serves 2

32Preparation time: 30 minutes

33Cooking time: 30 minutes

Difficulty: Image 10000000000000290000001F4E9115B8.jpg

34Ingredients

35 300 g linguine pasta

36 800 g clams

37 150 g squid strips

38Coarse salt

39 250 g fresh tomatoes

40 80 g onions

41 80 g yellow bell pepper

42 20 g garlic

43 20 g flat-leaf parsley

44 Thyme, bay leaves

45 Salt, pepper

46 10 g basil leaves

47 20 g olive oil

48 Zest of half a lemon

49Wash the clams under running water and drain them.

50Peel the onion and garlic and dice them finely. Remove the stalks from the tomatoes before cutting them into quarters. Remove the seeds and dice finely.

51Cut the bell pepper into small cubes.

52Finely chop the parsley.

53Heat up two tablespoons of olive oil and add the onion, 10 g of garlic, the bell pepper, thyme and bay leaves. Cook on a low heat for 5 minutes, then add the diced tomato.

54Simmer gently for 15 minutes.

55In a deep saucepan, heat up two tablespoons of olive oil. Add the clams and the garlic, cover and cook for 5 minutes. The shellfish should open.

56Keep a few clams in their shells for decoration and shuck the rest. Strain the cooking water.

57In a pan, fry the squid in the remaining olive oil. Add the tomato and bell pepper mixture, then the shucked clams, the cooking water and the chopped parsley. Adjust the seasoning.

58Bring 3 litres of salted water to the boil in a large saucepan. Add the pasta.

59Cook for 8 minutes. Check if the pasta is “al dente”.

60Drain the pasta and mix with the vegetables.

61Decorate with the basil, the clams in their shells and the lemon zest.

62Chef’s note

63This dish contains many elements that help prevent the onset of overload. It is rich in carbohydrates, proteins and antixoidants (vitamins A, C, E, zinc, copper, selenium). It is perfect as a meal to be eaten following intense exercise. It covers 45% of the Dietary Reference Intake for iron in men, and 25% in women.

64Nutritional analysis per person

Energy (Cal)

Carbs (g)

448

49

Lipids (g)

Protein (g)

8

45

Pomegranate and berry cocktail

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Photo credit: Thibaut Ruggeri.

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65Serves 2

66Preparation time: 10 minutes

Difficulty: Image 10000000000000290000001DA16ED507.jpg

67Ingredients

68 50 cl organic pomegranate juice

69 125 g fresh blueberries

70 100 g fresh raspberries

71Place the blueberries, raspberries and pomegranate juice in a blender and blitz. Strain the pulp.

72Serve chilled.

73The cocktail can be diluted with water.

74Tip

75Use very ripe fruit so that the cocktail will be naturally sweet.

76You can also add mint leaves before blending.

77Chef’s note

78This carbohydrate-rich cocktail is ideal for restoring energy after intense training. It covers 25% of the Dietary Reference Intake for vitamin C and is a good source of polyphenols (berries), which boost the immune system and help prevent the onset of overload.

79Nutritional analysis per person

Energy (Cal)

Carbs (g)

209

48

Lipids (g)

Protein (g)

1

2

Auteurs

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