Nutritional considerations – Improving PDHPE
Study Notes

NUTRITIONAL CONSIDERATIONS

– Pre-performance, including carbohydrate loading

Pre-performance and carbohydrate loading are strategies conducted by athletes before competition to ensure their energy stores reach optimum levels during performance. An example of this is carbohydrate loading which is a strategy that requires the altering of exercise levels and the amount of carbohydrates consumed with the aim of maximising muscle glycogen stores (carbohydrates = glycogen) before endurance events.

In regards to its effect on performance, carbohydrate loading increases athlete performance by a minimal amount (2-3%) over the length of an endurance event like a marathon. While in general this is a small positive effect on performance, for professional athletes, this could mean the difference between a gold medal and the bronze at the Olympics.

There are two types of carbohydrate loading. The first is the ‘old school’ or traditional method which relies on around 7-10 days of high intensity exercise with a low consumption of carbohydrates. This initial stage is known as the depletion phase. This phase depletes the body of its glycogen stores. After 7-10 days this is followed by the saturation phase, which is 3-4 days of decreased training and increased intake of carbohydrates. This is done in the attempt to trick the body to overload the body’s cells with glycogen as a survival mechanism. If this process is timed correctly, this enables the athlete to have more glycogen available as energy during their performance and create a possible performance advantage.

The other form of carbohydrate loading utilises tapering. Tapering is the reduction of exercise intensity 2-4 days before competition and beginning a diet intake of around 80% carbohydrates to increase glycogen stores. It must also be clear that carbohydrate loading may not have positive effects on the general population due to their low existing levels of training which is a prerequisite for being able to store more glycogen than normal levels. Carbohydrate loading will also not occur if the levels of carbohydrates consumed by an individual are too low in the saturation or tapering stage.

Endurance athletes would also benefit from consuming carbohydrates or foods that are low on the Glycaemic Index (GI) prior to a performance, as these foods can release energy over a longer period of time and can help replenish depleted energy in the endurance athlete throughout an event. High GI foods are suited to athletes who need an immediate.

– During Performance

An individual’s needs during performance depends on the type of event or climate they are participating in. For example; an endurance athlete’s energy and fluid levels can be negatively impacted if they are competing in hot and humid conditions.

Nutritional considerations that must be taken into account during a performance include:

– Hydration:

A simple rule to follow to ensure that you are adequately hydrated is to drink fluids before, during and after physical activity. A poor indicator of the need to hydrate is feeling like your thirsty, usually by the time an individual experiences this desire during physical activity it’s too late to maintain adequate hydration. Another simple rule is to ensure the athlete has a drink every 15-20min with the amount (usually around 250ml) depending on the type of sport. Both of these simple methods are used to try and prevent a fluid deficit where the amount of sweat lost is not more than the amount of fluid consumed this would mean that if a female soccer player played 60 minutes of a 90minute match, she would need to consume 800ml of water or sports drink over that time as opposed to a female competing in a 10km run would need to consume 1.49L of water or sports drink over the space of an hour.

Sports drinks high in electrolytes are also a preferred fluid to drink during participation in endurance sports as they not only hydrate but replenish minerals which include sodium, calcium, potassium and magnesium, that are important for many bodily functions during physical activity.

– Glycogen levels and replenishment:

Carbohydrates are the body’s primary source of energy. Before glycogen stores are utilised for energy, carbohydrates that have been broken down into glucose are used. Fat stores may also be used before glycogen stores depending on the activity’s intensity, as well as it’s duration (known as glycogen sparing). The need for glycogen replenishment is only required if the athlete is planning on participating in physical activity for more than a duration of 60min.

How can athletes maintain glycogen stores?

Carbohydrate rich sports drinks, energy gels, lollies, sports bars and fruit are the most popular options for athletes who wish to have a quick boost of glucose or replenish glycogen stores. These are best managed in frequent intervals and consumed in small amounts throughout the performance. The target amount of carbohydrate that should be consumed every hour is around 45 grams. This would equate to 1 cup of cooked pasta or 1 cup of cooked rice.

Sports drinks are a very popular source of energy for endurance athletes as they not only provide energy but also hydrate. Sports drinks also have greater electrolytes, particularly sodium which assists in the absorption of carbohydrates and water. Sport drinks also help potassium absorption, which can assist with muscle fibre contraction. Added sodium will help to reduce fluid loss and prevent dehydration during competition. Keep in mind that sports drinks may not be able to provide the entire carbohydrate requirements for the athlete throughout their event.

– Post Performance

The main challenge of post performance is getting the body to return to its pre-performance state. Post performance proactive recovery strategies intend to restore glycogen stores in the muscles and liver and replenish fluids and electrolytes lost through sweating and respiration as quickly as possible. The most effective way to replace depleted glycogen stores in the muscles and liver is to consume foods and fluids that are high in carbohydrates (CHO) and are preferably high on the glycemic index (GI). According to the AIS, the consumption of 1g CHO per 1kg of BM should take place every 2 hours for at least 10-12 hours. In some cases it can take 24 hours for glycogen levels to fully resynthesise. This method is useful for those who are required to compete or train again the next day. This recovery method is particularly suited to endurance athletes who have greatly depleted their glycogen stores during competition.

Rehydration is equally important. Simple strategies like the athlete weighing themselves prior and post performance enables them to measure the amount of fluids they have lost during physical activity. This means that if someone has lost 0.5kg post performance, they will need to drink 1.5 times that of the fluid lost which would equate to 0.75L of fluid. It is preferred that this fluid is electrolyte based as this will not only help with restoring pre performance hydration levels, it will also restore sodium levels which assists in optimal hydration.

Depending on the sport and the type of muscular activity performed, proteins may also need to be consumed to aid in muscle tissue repair to support recovery of the athlete.

Full Written Notes

Critical question 3: How can nutrition and recovery strategies affect performance
Nutritional Considerations

Learning about nutritional considerations and how to compare the dietary requirements of athletes in different sports with a variety of pre-, during and post-performance needs, is an integral part of training.

In this section, information is provided about the nutritional requirements relating to:

– pre-performance, including carbohydrate loading
– during performance
– post-performance

 

Nutritional Considerations

Pre-performance, including carbohydrate loading:

Pre-performance and carbohydrate loading are strategies conducted by athletes prior to competition to ensure their energy stores reach optimum levels during competition.

Carbohydrate loading involves the moderation of exercise levels and the consumption of carbohydrates with the aim of maximising muscle glycogen stores (carbohydrates = glycogen) before endurance events.

Carbohydrate loading can increase athlete performance by a minimal amount (2-3%) over the course of an endurance event like a marathon. While this may seem like a small positive effect on performance, for professional athletes, this could mean the difference between a gold medal or a bronze at the Olympics.

There are two types of carbohydrate loading. The first is the ‘old school’ or traditional method which relies on around 7-10 days of high intensity exercise with a low consumption of carbohydrates. This initial stage is known as the depletion phase. This phase depletes the body of its glycogen stores. After 7-10 days, move on to the saturation phase, which consists of 3-4 days of decreased training and increased intake of carbohydrates. The aim is to trick the body into overloading the body’s cells with glycogen as a survival mechanism. If this process is timed correctly, the athlete will have increased glycogen and, therefore, energy available at the time of competition, potentially creating a performance advantage.

Tapering is another form of carbohydrate loading, which involves the reduction of exercise intensity 2-4 days out from competition and beginning a diet intake of around 80% carbohydrates to increase glycogen stores.

Carbohydrate loading is not beneficial to the general population who typically have low levels of training, which is an essential prerequisite for the increased storage of glycogen. Carbohydrate loading will also fail if the amount of carbohydrates consumed by an individual is too low during the saturation or tapering stage.

Endurance athletes can also benefit from consuming carbohydrates or foods that are low on the Glycaemic Index (GI) prior to a performance. These foods release energy over a longer period of time and can help replenish depleted stores for athletes during an endurance event. High GI foods are suited to athletes who need an immediate boost to their energy levels.

 

During Performance:

An individual’s nutritional needs during performance will depend on the type of event or climate they are participating in. For example, an endurance athlete’s energy and fluid levels can be negatively impacted if they are competing in hot and humid conditions.

There are a variety of nutritional considerations which must be taken into account during a performance.

Hydration

A simple rule to follow to ensure adequate hydration is to drink fluids before, during and after physical activity. A serious indicator low hydration is a feeling of thirst. Usually, by the time an athlete experiences thirst it’s too late to maintain adequate hydration.

Another rule is to ensure the athlete has a drink every 15 to 20 minutes, consuming a suitable amount of liquid each time, usually around 250ml, although this may vary depending on the type of sport they play.

Both of these simple methods are used to prevent a fluid deficit so that the amount of sweat lost is not more than the amount of fluid consumed. The table below from the Australian Institute of Sport (AIS) compares a range of sports and athlete sweat rates per hour during competition and training.

For example, a female soccer player playing 60 minutes of a 90-minute match would need to consume 800 millilitres of water or sports drink. Comparatively, a female competing in a 10km run would need to consume 1.49 litres of water or sports drink over the space of an hour.

Sports drinks, high in electrolytes, the ideal fluid for endurance athletes as they hydrate and replenish minerals like sodium, potassium, calcium and magnesium, which are needed to ensure optimum body function during physical activity.

Glycogen levels and replenishment:

Carbohydrates are the body’s primary source of energy. Before glycogen stores are utilised for energy, carbohydrates which have been broken down into glucose are used. Fat stores may also be used before glycogen stores, depending on the duration and intensity of exercise (known as glycogen sparing). Glycogen replenishment is only required if the athlete is planning on participating in physical activity for more than a duration of 60 minutes.

How can athletes maintain glycogen stores?
Carbohydrate rich sports drinks, energy gels, lollies, sports bars and fruit are the most popular options for athletes who wish to have a quick boost of glucose or replenish glycogen stores. These are best managed in frequent intervals and consumed in small amounts throughout the performance. The target amount of carbohydrate which should be consumed every hour is around 45 grams. This equates to roughly 1 cup of cooked pasta or 1 cup of cooked rice.

Sports drinks are a very popular source of energy for endurance athletes as they not only provide energy but also hydrate. Sports drinks also have increased electrolytes and minerals, particularly sodium, which facilitate the absorption of carbohydrates and water. Sport drinks also help potassium absorption which improve muscle fibre contractions. Added sodium can help to reduce fluid loss and prevent dehydration during competition.

Keep in mind that sports drinks may not be able to completely satisfy the carbohydrate requirements of an athlete for the entire duration of their event.

 

Post Performance:

The main challenge of post-performance nutrition is returning the body back to its pre-performance state. Proactive recovery strategies aim to restore glycogen stores in the muscles and liver, while also replenishing the fluids and electrolytes lost through sweating and respiration as quickly as possible. The most effective way to replenish glycogen stores us to consume foods and fluids which are high in carbohydrates (CHO) and are, ideally, high on the glycaemic index (GI).

According to the AIS, the consumption of 1g CHO per 1kg of BM should occur every 2 hours for at least 10-12 hours after competition. In some cases, it can take 24 hours for glycogen levels to fully resynthesise. This recovery method is useful for those who are required to compete or train again the next day and is particularly suited to endurance athletes who have severely depleted their glycogen stores during competition.

Rehydration is equally important. Simple strategies, such as a weigh-in before and after performance, can effectively measure the amount of fluids lost during physical activity. If an athlete loses 0.5kg post performance, they will need to drink 1.5 times that amount; 0.75 litres of fluid. Electrolyte based fluids are particularly effective thy restore pre performance levels, of hydration and sodium.

Depending on the sport and the type of muscular activity performed, athletes may need to consume proteins to facilitate muscle tissue repair and general recovery.